MadModder
The Shop => Tools => Topic started by: PekkaNF on March 22, 2015, 02:31:28 PM
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VT:s lathe thread has some Dan Gelbart tutorials
One thing is sort of interesting:
[ Invalid YouTube link ]
Laser centre finder. It is angled and a bit unusual design.
Found this one:
http://www.practicalmachinist.com/vb/deckel-maho-aciera-abene-mills/laser-centering-jig-deckel-using-dan-gelbart-s-concept-292450/
Looks like it would help me on many ocassions. Soooooooo......has anybody build it and used it?
Pekka
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Hi Pekka,
I have built two versions of the device, see:
http://mikesworkshop.weebly.com/laser-centreing-device.html
http://mikesworkshop.weebly.com/laser-centring-device-mk-2.html
John Gadgetbuilder (www.gadgetbuilder.com) has also built a version.
The device works well.
Mike
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So he makes a lathe / grinder accurate to 1 micron ,,,,,,,,,,,, then says using the mark one eyeball to line things up is very accurate :loco: aye right ! Bit of a builders tool :lol: :lol:
Why not just use the good old DTI and get it spot on :med:
Rob
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You'd kinda have to tram pretty darn good and have real nice bearings for that projection method to work out to 5 microns, as claimed. With projection any error is multiplied by distance, and bearngs don't always wear round, nor are shafts round enough generally on a commercial machine to allow a true circular 5 micron projection tolerance. And machine vibration? Well, I dunno, maybe I'm wrong on this. What do I know -- I live in a lot cruder world! :)
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You also have to allow for any drafts and the workshop door being open if you are working to microns in the real world.
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You'd kinda have to tram pretty darn good and have real nice bearings for that projection method to work out to 5 microns, as claimed. With projection any error is multiplied by distance, and bearngs don't always wear round, nor are shafts round enough generally on a commercial machine to allow a true circular 5 micron projection tolerance. And machine vibration? Well, I dunno, maybe I'm wrong on this. What do I know -- I live in a lot cruder world! :)
Agree,now hand me the centre punch :lol:.....OZ.
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Thank you all
I am aware that this concept looks very simple, but I'm pretty sure there are few snakes on this paradise too.
* usefullness must be very dependent on laser, you may want to very narrow beam. DG says focusable laser.
* I figured the bearing issue and balancing too, my main concern is actually degree of it.
* VT brought up the tramming issue.....This I didn't give attention it deserve. Although to some extent this laser angular adjustment should come handy in there.
Original paper has a mirror to deflect the beam, I was thinking of tilting the whole laser pointer. Mike &al. have done it before. I'm not getting here any points on originality.
Is there any magic on mirrors for lasers?
I'm going to read those links and think it over. I mounted ordinary laser pointer on my mill and it was very crude in near vertical and at small angle. Focus and linear distances in X/Y plane dictate whole lot. Also the piece and features of it.
VT pointed out interaction on centering and tramming....I have a knee mill and universal (in two planes) head and no drilling quill. I'm trying to found out easy method on centering and tramming (rather on one go.....).
Accuracy is not entirely futile exercise. I'm getting close finding out on my hobby when something is close enough and sometimes not even near close enough. I had some same feelings that John (MBE) about the 50 micron accuracy and stuff, but we all use units and accuracies/certaintity in pretty liberal context in out verbal communication.
Pekka
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To be honest I think we all have a tendency to go overboard when we can.
I do a 'lot' of bore for bearing fits which have to be good [ note, not quoting figures ]. Over the years I have bought all different types of gauges from my original 'el cheapo ' telescopic gauges to make the job easier / better / more accurate / faster [ delete as required ]
I have bore gauges with clocks , 3 point internal micrometers, internal micrometers of about three different types.
They all sit on a shelf largely unused and I still use my 'el cheapo' telescopic gauges on a day to day basis. :thumbup:
Also in the list of "must haves but never used" ®™ are co-ax indicators [ too long to get in most places ]
Centring microscopes [ too fiddly to use after the first hour has been wasted.
And anything prefixed by *new* because engineering has been around for 200 years and nothing except electronics and materials is new. The Victorians cracked all this years ago.
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Pekka,
Re Mirrors.
The astronomy people use 'optical flats' when making reflector telescopes. These are little mirrors that have the silvered side towards the user, as opposed to on the back and covered by a protective layer. This ensures that there is no parallax error as the beam doesn't have to pass through the thickness of the glass.
I suggest a quick look on some telescope or optical site.
Dave.
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John,
I share that sentiment too...I was about to buy one of those co-axial indicator but found it way too long.
Some of the tolerances and perpeticualrities and other words that borderline between obscurity and offensive are pretty damn hard to meet in many general production environment and bloody close to impossible to measure in any certainty at home work shop.
Last weekend I made (as I need a bushing between boring head and boring bar, it came "good eneough" becaue I did it without any unreasonable pursuit to perfection. Chucked scrabnium (TM) bar on lathe, took skin off, drilled 40 mm deep 6,5 mm, 14 mm and boored it close to 16mm. Then I sufaced it close to 22 mm OD (russian boring head). Tee time. Then I figured that it is way too tight inside, but light go with 16mm reamer did it and outside looked good. Took the bar on milling machine and if I had DRO I may have centered it on both axis, but because flat and cutout really does not matter here, as long as they are in about 90 decree shift I played it with an eye. Then I parted off the bush and deburred it. It did fit pretty good just by feel.
Before I used to measure everything and neurotically and tried to get all on the same temperature and to cut last one to 0,01 mm or better - and often end up being 5,00 mm off :lol:
But sometimes it is refreshing to build something new. Just to see what is there to learn.
Pekka
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I've seen something similar before somewhere and in spite of what's been said it looks like it would be a useful addition to my tooling. I didn't realise until seeing the video just how useful it could be to me so it looks like I'll be trying to source a suitable (focusable) laser at some point. If anyone has any more useful links please post away!
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I've seen something similar before somewhere and in spite of what's been said it looks like it would be a useful addition to my tooling. I didn't realise until seeing the video just how useful it could be to me so it looks like I'll be trying to source a suitable (focusable) laser at some point. If anyone has any more useful links please post away!
Might I suggest that you read my bit in 'All Squared away'?
Cheers
Norman
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It's a minefield out there. Crosses, lines, dots, blue, red and green...
Is this one any good do you think?
http://www.ebay.co.uk/itm/20mW-405nm-Violet-Blue-Laser-Diode-Module-w-Driver-Focusable-2-/151235760143
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It's a minefield out there. Crosses, lines, dots, blue, red and green...
Is this one any good do you think?
http://www.ebay.co.uk/itm/20mW-405nm-Violet-Blue-Laser-Diode-Module-w-Driver-Focusable-2-/151235760143
It is a minefield there....If I rememeber right, human eye is more sensitive to green light than red and 5mW is considered "safe" if you blink naturally and are not sighting straight.....then again it does not show on lit room (or work lights on). 20mW sounds like could damage eyes on worst case scenario.
There are safety goggles and some goggles "improve" visibility of the laser light ray. But I'm pretty sure using safety goggle would be counter productive in this case.
Pekka
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I didn't mean to dis the devicein the video, just question the stated tolerance. And if the real world tolerance fits my particular practical tolerance needs, then it seems like it could be be useful to make and have at some point.
Unfortuntaely all the practical details are missing -- focusing, or non focusing, safe power level, etc.
In the video, the beam looked quite wide -- but maybe it was purposely non-focused to make filming it possible.
I do realize there also are some tricks that don't actually depend on beam width (like centerng on a round, where symmetry of pattern and/or unbroken vee at the perimeter is what is being looked for) but for simple edge finding, how much can the unaided human eye resolve? Seemed like in printers we used to imagine much over 300 dpi was seen as continuous. That's about 3 thou accuity? Or is there some reason we can distinguish finer with the laser light?
Like I said, I'm not saying it wouldn't be useful a lot of times, but I'd have fairly relaxed expectations of it.
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The Victorians cracked all this years ago.
Amen to that .
Here you go , no batteries or goggles required ,,,,,,,,,,,,,,the zeroset indicator .
(http://i1066.photobucket.com/albums/u410/RobWilson100/DTI%20Mount/P1060073_zps4lzr85et.jpg) (http://s1066.photobucket.com/user/RobWilson100/media/DTI%20Mount/P1060073_zps4lzr85et.jpg.html)
(http://i1066.photobucket.com/albums/u410/RobWilson100/DTI%20Mount/P1060076_zps3w0ixs4a.jpg) (http://s1066.photobucket.com/user/RobWilson100/media/DTI%20Mount/P1060076_zps3w0ixs4a.jpg.html)
(http://i1066.photobucket.com/albums/u410/RobWilson100/DTI%20Mount/P1060079_zps3dd1mk55.jpg) (http://s1066.photobucket.com/user/RobWilson100/media/DTI%20Mount/P1060079_zps3dd1mk55.jpg.html)
Smaller than most coaxial indicators , internal /external and parallel indicating also handy for tramming :coffee:
Rob
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Uh, that looks a lot nicer Rob than the laser clip on! :drool: :clap:
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Looking around it seems a 1mw green laser should do the job. I have a 5mw red laser and would say it's too bright. 1mw red seems to be considered safe for use but not bright enough.
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Ok. I ordered the red 5mW focusable laser module and it should take few weeks to surface.....
Looks like I don't want get into optical flats and collimation -yet- unless I'll find some easy reading tutorial and I absolutely needs to.
Pekka
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Finally found the one I was thinking of the other day. Post #15 by Baron.
http://www.modelenginemaker.com/index.php?topic=4781.0
Doesn't get any easier than this does it, you could knock one up in an hour or two! :D
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The laser finder is old tech. Video camera is new tech.
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The laser finder is old tech. Video camera is new tech.
Would you elaborate a little further...possibly much further than using a standard webcam?
Pekka
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He's probably not looked at the video Pekka.
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Got the laser modules today from the mail. Now I could do some little testing before comitting anything time consuming.
I often do 3-4 projects "inerleaved" because I'm missing tools or something and waiting stuff irks me. I need annother project to go on. Usually works fine. Now I have had a hiatus on all my projects, pretty much all week but now I startted getting most of the missing tools and parts yesterday/today.
Pekka
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Got a couple of lasers in the post from the 'bay :ddb:
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Dueling banjos?
My intention is to test this concept very close to original DG:s idea:
* You can have drill or whatever on chuck and clamp this over the arbor end. No need to remove drill etc.
* Focusable beam, nominally 5mW red laser. 1mW would be safer, but let's see what kind of results this will do
I have plain spindle bearings on my mill and I think that rotating it will be more accurate than "static" in terms of location of the hole. I don't have DRO, but I could mark string of centres and use this laserfinder to find those marks and then centredrill them. Any suggestions? Make few mm deep holes and measure from edge to edge with sigital caliber, or pins and use micrometer?
I have seen on those links 3 "thou" and other numbers.
Pekka
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How is DG's unit held on, Magnets?
I believe one user reduced laser intensity by replacing one of the four button cells with a brass spacer.
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Hi Guys,
I just got one of these :doh: 5mw red laser. Its absolutely useless !
Its far too bright. The spot is rectangular in shape. At the distances it needs to be used at a 2.5 X 5 mm spot is far too big.
So this is one to be avoided.
I did try to measure the spot size of mine, and its about 2 mm in diameter, not quite round, it has a small flat on one side. I think that is why I get a tiny black dot in the centre.
I'm still looking for something like the original one that I got from Aldi.
HTH
Oops forgot to add the picture.
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How is DG's unit held on, Magnets?
I believe one user reduced laser intensity by replacing one of the four button cells with a brass spacer.
The one drawing I saw had flat springs on side. Balanced and snug fit. I haven't tried this laser yet. Have to go help my brother - a little logging to do. Literally. Some spruce.
Pekka
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Of course 'Baron' is right. This malarkey( it is) is now age old and has been flogged and flogged. So far, none of these so called 'miracle' modifications from Pound -stores or everythings a buck has been able concentrate what is essentially a toy or at best , a pointer on a children's blackboard.
A million years ago, I used a professional laser alignment kit in motor vehicle re-alignment- but it didn't come from a 'a dime a dozen store'
We have to do better-or buy a wallet spanner or-Give up.
Perhaps, I am being rude- but HONEST
Norman
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This one is only £5.20 and it says it has a Focusable dot of 2mm at 3 metres. Still 5mw though so probably too bright. I wonder what effect ND filters have on lasers?
http://www.ebay.co.uk/itm/Focusable-Dot-Laser-Module-5mw-Red-Laser-3-5V-650nm-UK-Seller-Free-UK-Postage-/321694174518?pt=LH_DefaultDomain_3&hash=item4ae6778d36
Update: I've checked the 5mw laser pointer I bought many years ago with some of my photographic filters. The ND2 reduces the output a little, the ND10 reduces it a lot, in fact far too much! A standard Polarisering filter reduces brightness only a little irrespective of rotation. A Circular Polariser reduces the brightness and is variable, depending on how the filter is rotated. None of the filters seem to effect the shape of the laser, which in the case of mine is an oval.
I've actually cut square resin filters on a lathe so if it comes to it, it should be possible to cut a small filter for the laser from one of these. I'm thinking an ND4 would make a good starting point. There may well be small filters for sale some where suitable for the job but I've not found any yet.
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Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?
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Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?
No, do you have a link please?
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Hi Arbalist,
Did you see my notes about salvageable lenses from dead CD drives ?
I tried to find it, but could not find it.
I got this laser:
http://www.ebay.com/itm/121212852782?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I was pretty sure 5mW would be to strong, but this was recommended. Soo....I have to check it.
I connected it to two practically emty AA batteries and aimed it to the wall. "Dot" was thin line, about 20 mm long. A little adjustment brought it round. It looked pretty bright - white wall, night outside, some normal living room lights.
Looks pretty bright and big spot on white surface, but then I tried black matte plastic and I was able to make sub mm near perfect round spot - so it seems.
This concept has it's merit and probably also some downside. Probably best to do some testing and see what kind of ecological niece it could have.
Pekka
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Not sure if it makes any difference but one guy is using a 3 volt CR2032 button cell to power his laser edge finder.
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Hi Guys,
Re lens for laser pointers et al.
All CD/DVD drives use a single lens about 5 mm in diameter to focus the laser inside, so that the disc can be read. In all the drives that I have played with the lens is easily removed and can be re-purposed for use with a laser pointer in order to focus the beam.
A Google search "focus laser pointer" came up with lots of hits for doing this, along with lots of warnings. I also discovered that in the UK at least there is a legal limit on laser power and class. It seems that 5 mw is the maximum for non industrial lasers.
Note that using a lens does not increase the power of a laser, it only concentrates the beam into a smaller area. This in turn increases the danger of eye damage, not only due to direct illumination, but also specular reflection, which will be more from shiny surfaces. I believe that some kinds of safety glasses used in engineering reduce the risk of eye damage from this cause. I haven't done any research into eye protection of this kind.
HTH.
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I don't have an old CD unit but I've seen these:
http://www.ebay.co.uk/itm/5-x-7mm-Collimating-Lens-Focusing-Lens-For-Laser-Diodes-/271604566954?pt=LH_DefaultDomain_3&hash=item3f3ce4cbaa
I've ordered a small unit and it says it's "Focusable" so I expect it's already got a lens in it.
Yes, as far as I am aware 5mw is the maximum here in the UK and maybe Europe as well.
I can see how important it is for a stationary laser but I'm not sure how small the dot really needs to be for a rotating laser. All the ones I've seen so far certainly weren't particularly small.
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mine definately has a lense on it and it does have an effect. I think it has regulator in it, I was measuring current and it lits when voltage is over aabout 2,4V and at 3.00V it draws 19,6 mA. From 2,7 to 3 V current decreases lineary. So...I think it is close to 1mW "laser power" 10% or so?. Electrically it looks good, but I either need to get smaller unit or have a way to adjust it optically.
I should rig it onto something and spin it to see how does it work on garage environment (lighting etc...). maybe I need to get lower power unit.
Pekka
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I'm just kind of curious -- at the distances we're talking about, small spot size, and using lenses, etc., why does it have to be a laser?
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I either need to get smaller unit or have a way to adjust it optically. Pekka
Do you mean the Dot is too big?
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I either need to get smaller unit or have a way to adjust it optically. Pekka
Do you mean the Dot is too big?
It looks like dot is small enough, but it is very bright. This I need to verify, but it looks like this 5 mW laser produces really bright spot, to the point that with even moderately reflective surface the dot "glares". On matte black surface the dot looks tiny.
Pekka
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I have the old Geometer's articles from Model Engineer called 'Microscope on the Lathe'. OK, it is all as old as Methuselah but nemes.co has still got most of it on the 'net.
Again, it was revived in ME or MEW on something similar which became a kit with Hemmingwaykits.
OK. can someone inform me -and others- what are the advantages of this new toy?
Norman
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It looks like dot is small enough, but it is very bright.
Pekka
Have a look at my earlier post Pekka. You can easily reduce the brightness with a ND filter over the lens. Resin ND photographic filters are easily cut to size and don't cost too much.
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I'm just kind of curious -- at the distances we're talking about, small spot size, and using lenses, etc., why does it have to be a laser?
Unlike an ordinary light source a laser beam is a single essentially parallel beam of light. The light from an incandescent bulb is scattered in all directions.
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OK. can someone inform me -and others- what are the advantages of this new toy?
Norman
Best have a look at the video in post #1 Norman.
Quick and easy to use. And, once we've collectively got the "formulae" right, easy and inexpensive to make. At least that's my take on it. I won't know for sure though till I've made one and tried it! :D
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mine definitely has a lens on it and it does have an effect. I think it has regulator in it, I was measuring current and it lights when voltage is over about 2,4V and at 3.00V it draws 19,6 mA. From 2,7 to 3 V current decreases lineary. So...I think it is close to 1mW "laser power" 10% or so?. Electrically it looks good, but I either need to get smaller unit or have a way to adjust it optically.
I should rig it onto something and spin it to see how does it work on garage environment (lighting etc...). maybe I need to get lower power unit.
Pekka
Hi Peter,
The current should not decrease as you said from 2.7 to 3 V ! Exactly the opposite should happen. You need to prevent the diode from taking too much current by using a series resistor. If as you say it already has a regulator built in then you can only adjust the voltage to alter the brightness.
Though I suspect that 20 ma current draw could be a problem. I can't actually get at mine to measure the current, but since the batteries are rated at only a few milliamperes, I would guess at less than a quarter of yours.
I would set it up at about 4 to 6 inches from a surface and examine the dot. I would say anything around a couple of millimetres in diameter is going to be fine. Now spin it in the chuck and see how much it wobbles from the centre line. This will give you an idea of how much thicker the line produced will appear to become when in use.
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From what I have read laser diode is very pricess form of LED and can't be trated as such.
Lucily we have well regulated (I hope) laser modules. As said before input current will drop when input voltage is raised.
I did register the comment on neural density filter, probably I have some with my old Cokin filter system. I'm not there yet.
I tested this 5mW laser module briefly with two LR44 cells briefly and it did lit. Maybe bigger sels would be in order, but before cutting too much metal I want to see what effect has:
' Brighness, Probably too dim as well as too bright might be a problem
' Dot size has some bearing, but probably more the shape it hits
' not sure how importat is dot shape
' cone angle is probably inportant
Before getting too workked out with all these variables, I'd like to check which are priority and which has consequence.
Pekka
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You could make the angle adjustable but apparently 9° works well.
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Thanks. I'll try first around 10 decrees or so. Is there any magic on 9 decrees? Sort of new 6?
Pekka
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Can't find the post now but I believe someone mounted theirs at 10° but with some small adjustment and found 9° to be best.
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I'm just kind of curious -- at the distances we're talking about, small spot size, and using lenses, etc., why does it have to be a laser?
Unlike an ordinary light source a laser beam is a single essentially parallel beam of light. The light from an incandescent bulb is scattered in all directions.
Baron I appreciate that, but it no longer holds true once you add a filter (which scatters to some degree) and a lens (which converges light).
Also it's entirely possible to make a dot with conventional non-coherent light at a 12" focal length. Every kid knows this when he focuses a spot of sunlight with a magnifying glass on a leaf. Collimators, focusing lenses for ordinary lght -- these have been around forever. I can see the advantage of a laser's coherent beam (no lens or filter) for a long distance dot. But not for a short distance dot. At least not for this relatively crude purpose.
Also, if you want the dot smaller (or rounder) with an overly bright laser, can't you just use a pinhole?
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Have another look at the video in post #1. Dan moves the laser up and down to achieve the required pattern on the workpiece. This clearly wouldn't be very practical if you had to keep refocusing. The filter I used didn't appear to scatter the light at all, that's not to say it didn't but I couldn't see it. Others are already using a pinhole to reduce the dot size and make it more round.
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Uuh...
Semiconductor laser beam from the chip is not round and even.
http://www.thorlabs.de/tutorials.cfm?tabID=38696
I'm using the laser module that has regulator, laser diode, optics and all that stuff to keep stuff simple and compact. I have no interest to mate regulator and laser diode (and for the same reason I don't want to use cheap laser pointer because they might have such a bad regulator that it fry laser if you change different size/type of batteries).
There probably would be a way of using normal HIPO LED, condencer and all that stuff, but it's not for me. Looks too involved and bulky, even though underlying principles are simple.
This laser approach has very complicated physics (and specially the laser diode regulator electronics) but it's all in a small and cheap commercial componenet.
All this talk about the lense is when laser pointer or a laser module that has no "adjustable focus" is chosen.
I have tested this unit with a prism and it seems to work also....it would bring some complication but it would also produce more compact unit as per original Dan design.
If I'll mange to get out of work early today, I'll gobble up something and borrow my daughters camera. My camera got dust on imaging sensor and it has been on shop two weeks allready.
Pekka
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Have another look at the video in post #1. Dan moves the laser up and down to achieve the required pattern on the workpiece. This clearly wouldn't be very practical if you had to keep refocusing. The filter I used didn't appear to scatter the light at all, that's not to say it didn't but I couldn't see it. Others are already using a pinhole to reduce the dot size and make it more round.
But this is 're-inventing the wheel' or worse. I recall Peter Rawlinson writing in Model Engineer- years ago- getting there.
Again, CentreCam was there. Part of it is still on the 'net. Trethewey WAS going to have another go- but for reasons unknown, hasn't.
I was going through the video again. There is something similar to what 'we were doing in production' in the early 1950's. We'd got to screw threads and spinning the threads- and they were not only sealing against liquids but air- and could vent. It was long before lasers! We used, if my memory is lasting out- a hacksaw, a file and an old M&W 0-1" Mike to test.
I'm simply left wondering.
Cheers
Norman
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It's just a centre finder Norman.
It's something most of us can make for a few pounds or dollars though rather than the $125+ that the commercial ones cost. If the commercial ones were a bit smaller and cost £20 I'd probably already be using one.
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Oranges and apples.
Optical centering microscope is fiddly to make and fiddly to use ocassionally. And requires removal of the drill/mill whatever tool you have. And takes up a lot of space in the spindle. Ok. if you like cranking the knee on the knee mill or aligning round column mill.
Centre cam et all. USB-cameras are whole lot worse...laptop, program all that. Maybe a cup of tea on the keyboard to go? Only benefit to optical one is that USB camera is shorter. Both suffer from illumination etc. Also USB camera has limited resolution, "dot" size is not that great. Like if the resolution is 650 "dots" and FOV is 6,5 mm, then it's only on 0,1 mm/dot and "optical" resolution is twice that no matter how big screen you have. Then all initial aligment and accuracy is not much better than 0,5 mm. I call it poor overall system efficiency.
Sticky needle or mechanical cetrefinder is whole lot usefull and faster here, probably whole lot more accurate too.
Now, this rotated laser gizmo does not need removal of the drill/mill and is a small complete unit that is simply clamped/clipped over spindle end. Not much knee/quill movement is needed. Because of the principle it centers also round and odd size objects.
When utmost accuracy is needed, "coordinated" drilling is way to go, displaces the marking out too and probably carefull use of old fashion centre finders.
That's my take on it. I just want to see how useful it is before jumping on conclusions. There is so much misinformation that sometimes you just need to DIY some experimentation....
How easy/fast it is? If it beats eyeballing, it's good for me.
Do you need any preparation? I don't like lugging PC or spray paint. is the glare real problem.
Is 5mW laer too bright? Night/day?
Etc...many things can be calculated, some guestimated, but best/fastes is to try.
Pekka
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Have another look at the video in post #1. Dan moves the laser up and down to achieve the required pattern on the workpiece. This clearly wouldn't be very practical if you had to keep refocusing. The filter I used didn't appear to scatter the light at all, that's not to say it didn't but I couldn't see it. Others are already using a pinhole to reduce the dot size and make it more round.
Sorry to ask so many questions, but my aim is to simplify, if I can, what you're trying to do.
Wouldn't a lens with laser light require re-focusing as much as a lens with ordinary light?
A CD laser lens would seem to have an extremely short focal length. Has it been tried over the distance needed by a spot of this type?
Why use a lens at all instead of a pinhole with a laser, if this is already commonly done?
For US based experimenters, one source of inexpensive optics is Surplus Shed.
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It's just a centre finder Norman.
It's something most of us can make for a few pounds or dollars though rather than the $125+ that the commercial ones cost. If the commercial ones were a bit smaller and cost £20 I'd probably already be using one.
Oddly, I made one from a couple of bits of rod and a spring and it is surprisingly accurate because it - multiplies the error.
Not new- and someone made something from modelling clay( plasticene) and a sticky pin. Now 'sticky pins' have to be bought in bulk but you can eat winkles with them. Again, I buy cigarette papers. Don't smoke but they work. I share them with my wife's addition to saxophones.
I'm real high tech.
I have a set of mikes and clock gauges in tenths and Jo blocks and a book on Statistical Control and a 'guessing stick' somewhere.
Cheers
Norman
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Have another look at the video in post #1. Dan moves the laser up and down to achieve the required pattern on the workpiece. This clearly wouldn't be very practical if you had to keep refocusing. The filter I used didn't appear to scatter the light at all, that's not to say it didn't but I couldn't see it. Others are already using a pinhole to reduce the dot size and make it more round.
Sorry to ask so many questions, but my aim is to simplify, if I can, what you're trying to do.
Wouldn't a lens with laser light require re-focusing as much as a lens with ordinary light?
A CD laser lens would seem to have an extremely short focal length. Has it been tried over the distance needed by a spot of this type?
Why use a lens at all instead of a pinhole with a laser, if this is already commonly done?
For US based experimenters, one source of inexpensive optics is Surplus Shed.
Laser optics is a bit involved, simple pinhole must be very big to remove just "dirt" on really nasty cheap laser pointer or so.
Small "pinhole" to clean up the "dot" is called spatial filter:
http://www.edmundoptics.com/technical-resources-center/lasers/understanding-spatial-filters/
Here it what happens if you use only pinhole to clean laser dot, lowest picture please:
http://laser.physics.sunysb.edu/~wise/wise11/spring2001/reports/PortJefferson/pjpage2.html
Therefore I much prefer laser module that has all the necessary parts and design to produce clean enough beam of light. In principle well colimated laser beam does not require much "focusing". The unit I have shows clear need for focusing between 5,0m and 0,5m. I should take a picture to make this clear.
I'm not too worried about exact dot shape or size, because it is spun on inclined axis, I'm pretty sure this is not very important aspect on real life situation.
First order of business is to find out if the widely recommended 5mW laser module is too powerful, produces too much glare etc. I would be happy to get away with whole lesser power and danger to vision. Put the proof of pudding is in eating.
I have one really nasty laser "module" that was removed from this kind of device, different color and probably cheaper too:
http://www.quarton.com.tw/laser_level_laser_chalk_laser_chalk.html
I dug out the "module" and light is spraying out of it in every and each direction. Beam on the back is about as strong than beam forward, beam is really fuzzy, even more than laser pointer. It has no good optics and beam size about dime in 5 metres. I tought I could use it because the module is really small, it has battery box for two AAA and a small switch. Seemed fine, but the beam let me down.
Pekka
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Well it seems to have run far afield of something simple and inexpensive, like just attaching a $10 laser pointer to a mill spindle and you're good to go.
Not that there's anything wrong with getting deep into specalized laser optics to make something useful as a project -- that sounds interesting to read about, but not really the same thing.
Cigarette paper works simply and inexpensively for edge finding, and wigglers. etc as Norman said. But the point here was to try to achieve what seemed to be promised by a simple laser pointer. So a laser finder is the premise of the thread.
So far, it doesn't seem simple or easy....... unless someone can come up with a specific off-the shelf pointer that is suitable.
btw, re papers, wiggler etc. This type of finder (if it worked) would be able to find edges, locatons, and centers quickly, with a single tool, and would not require changing anything in the collet of the mill. So it's different than other tools which do some of those jobs mechanically.
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Hi Guys,
This one seems to be very similar to mine. All the same specifications.
<http://www.quarton.com.tw/laser_pen_infiniter_ap.html>
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Well it seems to have run far afield of something simple and inexpensive.
This is what Pekka's bought, I'd hardly call that expensive.
http://www.ebay.com/itm/121212852782?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
And it should be a simple job to mount it.
It may need the addition of something like a ND filter but these are inexpensive as well and hardly difficult to fit.
I'm in agreement with Pekka, it may or may not prove to be an effective device but it certainly need not require a great investment in either time or money to give it a try. I'm encouraged enough by Dan's video to want to at least spend a little time on it.
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Sorry arbalist, I missed that one. If itworks, that would be great. I found Pekka's post and sounds like he already has a small spot size with a filter.
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Just a thought here lads , what about using a laser that mounts to an air gun scope ?
Rob
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I did not got any garage time today, not that much progress today.
I got battery holder for two AA and a small swich. I rigged two different lasers to try it out.
5mW cross hair unit is much more nice to eye on white wall. Pretty natural, because the light is streched whole much further. This laser module was about same price. It would be usefull on some ocasions, specially considering the price. Clearly not as nice line quality as 100€ complete brand units. They have selfleveling and all that stuff.
5mW focusable "dot" unit is whole lot more involved, dot is very much more obivious and definately I would not like to stare into that beam. It's funny how much bigger and glaring the same dot appears on white surface - compared to a miniature dot agains black matte surface.
This cheap "focusable" laser is not ideal, but it could be good enough. Hope I'll have chance of rigging it on arbor tomorrow or latest thurstday.
Pekka
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Little progerss today, I got a tad over 1 hour of garagetime and that was time well spent.
I made a POC (E.G. quick and dirty) test.
I desided to use plastic cable gland to insulate laser from metal, I read somewhere that some lasermodules have one polarity on body. Also rubber grommet holds the laser pretty well.
Body was made from sheet metal, I tested 20 degree and 10 degree angle. Easy to change angle and fast to make.
I used plastic batteryholder, lashed with wire.
5mW laser was way too bright with ambient light. Glare/diffration was disturbing.
I would prefer very much smaller and dimmer point. Has anybody tried 1mW and/or green laser?
Right now it looks very usefull on round/slatend surface and round hole/boss, but not that usefull on flat surface and scribed mark. Pretty sure weaker beam would help. I don'ät know ti what degree.
What do you think?
Pekka
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The results look just like that of the video Pekka :thumbup:
Rob
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I just made a test rig. mechanically it's still all wrong, my only goal was to test 5mW red laser. Very tempted to order lower power module, but it would be nice to find unit with smaller beam diameter.
baby steps
Pekka
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Make the holder solid instead of sheet metal? Machine vibration may transmit to the sheet, and that might be causing a thcker line than you'd get with a more solid mount.
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looks pretty good to me, just need to reduce the brightness.
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It is actually pretty stable, least at 200-600 rpm, much smaller rpm is a bit more problem, because eye does not "make" the dot track continuous. I first put the drawbolt only on finger tight and because this unit is not balanced it would shake it loose and I could see it it on the laser beam. Hmm...wonder how small dynamic runout (imbalance) it could show........ :smart: It might make better dynamic balancer fixture :lol:
I'm just trying prove here the concept and figure out what it is for me.
My first attempt is flawed, because I want to dispense with the arbor. It should be mounted over the bottom part of the spindle or such to allow drill/mill bit to coexist. It also has sharp edges and design is dangerous. I was thinking of using a holes saw to make a disc out of plywood and drill few holes to different angles to mount the laser. But it would have been slower to make.
But sheet metal is easy to fabricate, easy to bend to try out different angles and such.
Now I have to try it out with whole lot more ambient light to proved myself will that simple askew mounted 5mW laser work for me or not. Lucily this 5 mW laser is probably way under nominal value, but it's not the problem here.
If it doesn't then I have to look for 1mW unit or start thinking of attenuating it with ND filter or polarizing filter. If I choose filter approach, then I'm very tempted to fold the optical axis with prism or two. This would have a whole lot more involved structure with mounting the prisms and other optics, but it would be easier whole lot more versatile.
I took the collimating lens of the laser and the exit beam from the laser diode was really really wide and oval. Collimating lens has really big impact on dot quality. Not sure how deep I would like to get on this one.
Pekka
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Hi Lads,
I have to admit to agreeing with Rob and the Sheriff of Nottingham, telescopic gauges, wobblers and a coax indicator are all I've needed, mind you I don't make owt needing tooooo much accuracy...
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I am about to undertake the building of one, I bought one of those ones like chronos sell made by SDA manufacturing. I wanted it to use as an edge finder but the dot was to big, I bought a polariser (spelling?) which made the dot dimmer/smaller. For the current project I bought a 5mw red focusable laser the dot is a bit big/bright I tried the SDA polariser to v good affect, to that end i have ordered a phone repair sheet polarising sheet from that well known auction house, sheet is about 80mm x 55mm.
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The Laser I ordered arrived yesterday so I've just tried it out to see what sort of image it produces.
First shot shows the setup with Laser about 150mm from the bench and powered by a single CR2032 button cell. The unit itself looks very similar to the one Pekka bought. I paid £5.20 for it. You can get them cheaper but this one came from a UK supplier so arrived in only a couple of days and the vendor checks all units before sending them out.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3982_zpstts63cxa.jpg)
When first powered up the unit produced a short "line", after rotating the lens you can get it to produce the oval shown in the two pictures below. Without the lens it produces a very dispersed rectangle shape with a bulge in the middle. I thought all lasers produced a beam but this one doesn't without a the lens, the light is spread about a lot!
This is the focused "dot", which stays pretty much the same shape over a distance of perhaps 150-200mm so quite useful but clearly too bright.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3983_zpsunfir9ac.jpg)
This is the same setting but with a ND10 filter (very dark) held in front of the lens. Too weak for practical use but it clearly shows how small the "dot" is without any flare. It may be possible to make it smaller/more round over a short distance.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3985_zpsqn5tuanl.jpg)
The lens is in a threaded plastic mount which is not very tight in the barrel, as a result when you tighten the metal cap to lock it in place it rotates the lens altering the focus point! There is a spring behind the lens but it doesn't stop it rotating. I expect that some type of loctite will hold the lens in place so perhaps it's not too much of an issue?
Not sure whether to make a mount for this or try another type of laser first. The other type I've seen are only available from China so it could mean a 3-4 week wait. In the meantime I've ordered a cheap ND4 filter to see if that yields a useful output.
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If using an elliptical dot, you could arrange the minor diameter of the dot parallel to the axis of the fixture to minimize the line width when spinning.
I was thinking that maybe two lenses at 90 degrees would make a round dot, but then realized the above would take care of the line thickness problem as well.
In use, these things are always spinning to get a target, right? You don't stop them to find a scratched mark after finding the right quill height to minimize spot size. Or do you? Because if the first is true, then a round spot isn't necessary. The second would maybe benefit a little from a round spot. Just askin....
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As it's spinning I don't think the spot needs to be very round. For most purposes it's tracing a circle. Whilst we're doing this though a nice round spot may be useful. I've made a small hole in a post-it with a scriber and held it over the beam, it makes the dot smaller and certainly appears to make it rounder, so that' seems like it's easily doable. :thumbup:
I forgot to mention. I'm impressed with Dan's setup and I fully understand why Pekka wants to make something similar. Most others though have made spindle mounted versions and I'm leaning in this direction so I can mount it in any of my chucks/collets.
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Collimating lens , fixture rigidity to reduce line size, use of a pinhole.....I think you're on the right track, :beer:
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As it's spinning I don't think the spot needs to be very round. For most purposes it's tracing a circle.
It is tracing a circle, but the thickness of the perimeter of that circle depends on the orientation of an elliptical spot. If the minor axis of the dot (the narrower diameter) is set up in your spinning fixture so it is parallel to the axis of the fixture (a line from the diode to the center of the quill), your projected spinning line will be thinner than if you arrange it perpendicular. Just sayin......
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As it's spinning I don't think the spot needs to be very round. For most purposes it's tracing a circle.
It is tracing a circle, but the thickness of the perimeter of that circle depends on the orientation of an elliptical spot. If the minor axis of the dot (the narrower diameter) is set up in your spinning fixture so it is parallel to the axis of the fixture (a line from the diode to the center of the quill), your projected spinning line will be thinner than if you arrange it perpendicular. Just sayin......
Yes, you're quite right. And it could make quite a difference. As the Laser body is round though adjusting it to the best position is easy providing the design allows for it.
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I started writing this post but was called away before submitting, what I was about to say is now in part history as more has been posted since I started writing, either way this is what I was going to say.
Although the quality and definition of the spot is of value, the human eye is very clever at estimation etc. I imagine that the imperfect dot will be repeatably imperfect so that quicker and possibly more accurate results may come from centering the target point in the middle of a slightly larger rotating beam rather than centering the laser dot on the target, if you follow what i mean
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My laser shows identical behaviour. I did some testing and reading. Laser diode does not produce clean dot, but the beam projects out as a wide fan line. After that it is clipped and collimated. When simply "focused" only focused point is roughly round and after that oval again.
VT is on the right track (or least on the same line than me) that using mirror/prism/lens and inclination to minimize effect of ovality.
As pointed before, clean point looks nice, but most of the time is not that important...I found out that rpm is importat to give correct visual glues.
I think that best accuracy is reached by visual means when sightest amount of scattered light envelopes on clear edge/side of the work piece.
It looks like acuracy depends very much of the shape of the work piece and angle of the laser beam that hits edge/side of the work piece. Looks like a upright cylinder/boss that has clean edge and large diameter is easy to center. Also looks like a tiny dot on the flat surface is very much not ideal for this type of centering.
Turners buttons or bearing rings probably would probably work very fine with this method. This would be very interesting if it turns out accurate.
My aim here is has been easy method on work pieces that would be othervice hard to index/center on milling machine that has no DRO.
More thesting and we will learn more.
Pekka
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I'm guessing that probably the linear shape of the beam is related to the element shape inside the diode.
If you look at a regular unlit LED you can see the shape of the pieces making (and blocking in some directions) the junction.
I imagine somethong similar happens in a laser diode.
Not important, but just sort of interesting.
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I believe the key to achieving an easy to read device is not so much in the shape of the dot (within reason) but more in the size and intensity of it. Vibration and the speed of rotation will have some effect as well.
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Just got my 1 mW laser pointer/led torch from the bayand guess what?
The small print on the laser (i.e. warning label) says that its 5 mW. Its quite bright with 3 cells. Replaced one cell with a small 2 ba brass nut (I think its 2 ba) and smaller less bright spot!
ABout to knock up some fixtures
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Is there a safe way of testing if the body is live without damaging the unit? I have a small test meter.
I can insulate the unit if I need to but I'd rather dispense with it if I can.
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Is there a safe way of testing if the body is live without damaging the unit? I have a small test meter.
I can insulate the unit if I need to but I'd rather dispense with it if I can.
With your test meter set on DC volts (20V selection if not auto-ranging), connect black lead to your negative end of the battery, and connect the red lead to the laser body. If your meter reads the same volts as your battery then your body is "live"
The same can be achieved by using the Ohms test facility, but this time connect one test lead to the laser body and the other to the positive lead of the laser (doesn't really matter which lead is connected to which, but just make sure that the laser is not powered up). You may find that the laser body is connected to the Negative lead of the laser.
Tim
Tim
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If you make the fixture an aluminum sheet box section you'll get stiffness with reduced mass. Reducing the imbalance of spinning around on the arbor without a counterweight. Therefore less vibration and deflection, and again a thinner and more distinct line.
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Thanks Tim. Not sure of construction details yet but something alloy no doubt.
:update:
The ND4 filter arrived today so I continued the experiment.
Photo one shows the setup. I drilled a blind flat bottomed hole in some PVC rod for the module. The remaining 3mm thick material was drilled with the smallest drill bit I have, a .75mm.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3989_zpsradjk2yk.jpg)
I cut a small piece of the ND4 and turned a small disc to fit in the fixture. This is the result.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3986_zpsolbjnwxx.jpg)
This is the effect with another piece of ND4 held under the laser.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP3988_zpswjelgqxd.jpg)
Looks quite promising. I tried to lock the lens on the Laser module in place with some stud lock but so far it's not done the trick so it may need something like super glue. It would be nice if I could get a lower power Laser module with a nice round dot but as an inexpensive option this setup should work I think once it's mounted.
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Is there a safe way of testing if the body is live without damaging the unit? I have a small test meter.
I can insulate the unit if I need to but I'd rather dispense with it if I can.
With your test meter set on DC volts (20V selection if not auto-ranging), connect black lead to your negative end of the battery, and connect the red lead to the laser body. If your meter reads the same volts as your battery then your body is "live"
The same can be achieved by using the Ohms test facility, but this time connect one test lead to the laser body and the other to the positive lead of the laser (doesn't really matter which lead is connected to which, but just make sure that the laser is not powered up). You may find that the laser body is connected to the Negative lead of the laser.
Tim
Tim
I measured my laser module. Body was connected haed to positive (red) wire. On battery operated device this is of little consequence, just usefull to know.
Pekka
Almost OT:
https://astrophotovideo.wordpress.com/building-a-laser-collimator-for-newtonian-telescope/
http://www.withoutlenses.com/articles/how-to/drill-your-own-precision-pinhole-apertures
Some more reading and a little more experimentation to do.
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I had another look at Pekka's original post and saw this:
Hi Folks:
For all of you building a laser center finder, here are some notes:
1. The laser has to be focussed to a very fine spot (under 0.1mm) so a regular laser pointer is useless. Focus it to a minimum spot about 150 mm away. Since the spot is oval, orient oval spot with long dimension tangential to the circle created to get a finer line. You can buy a laser module that can be focussed on Ebay for a few bucks, for example: 2pcs Focusable 3 5V 650nm 5mW Red Laser Dot Diode Module 12x35mm | eBay
2. The tilt of the beam has to be adjustable by tilting the module or a small mirror. A fixed angle is a poor choice. I posted a link to a fully detailed design on the YouTube video where I show the device.
3. Note that the posted design slips over the chuck or toolholder, so you don't have to remove tool to check centering.
4. Make sure design is balanced so you can use it at high speed. Design and test it to withstand much higher speeds as the highest used.
5. You can easily get 25um (0.001") and even better by using some simple tricks. For example, to center a hole on a bar or shaft place piece of paper under shaft and adjust height or beam angle till you just see two tiny spots of light on paper, each one on one side of shaft (e.g. shaft blocking almost the whole circle). This will give you accuracies down to a few microns in a dim room.
6. For all of those who felt sorry for me because of my choice in a milling machine:
The machine shown (Jet) is what I use as a drill press. I have a Makino KE55 CNC mill , Moore jig borer and other fancy machines. This video is part of a course to teach students so I chose machines they will be familiar with. I don't show any of the fancy machines (like a 1um accuracy aerostatic lathe/grinder) in these videos.
Cheers,
Dan Gelbart
Several things come to mind after reading this and looking at the video again.
Dan provides a link to a Laser module that looks exactly the same as the one Pekka and I have bought.
He says the Laser needs to be focussed to a spot smaller than .1mm which is I think highly unlikely with the module I have.
It seems like the spot in the video is nowhere near as small as .1mm either.
He notes the ovality of the spot but just suggests "orient oval spot with long dimension tangential to the circle created to get a finer line".
There was also a link to Dan's design but the drawing is no longer avalable.
Interesting ...
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Interesting indeed.
If you look the device on DG:s video you notice how flat it is and it looks like the laser module flat inside and mirrot is used to skew the angle.
I found the patent on that finder....link somewhere and it looks a little different. Interestin g reading though.
Another titbit is the published drawin/writeup that is constructed nicely, looks like for a public domain design or small scale fabrication. You need a google account to download it. Laser module is on this design mounted on a sheet metal cradle that can be pivoted a little. This is hight in height, battery and laser are upward. I think that the laser linked by DG himself relates to this design.
I notices the same than you: Laser beam is almost a line as non collimated laser is, but this has "over colliamation" only with the lense, no pinhole on my model, therefore the "line" or ovality is turned 90 decree after the focal point, no biggie needs just more optics, which I have a coarse feel, but not really that good indepth knowledge. But monkey-see-monkey-do is probably here enough.
I like your pictures, it clearly shows a very nice small dot on the center and then big blob of difraction. Try matte black object and observe how amazingly smaller the dot comes. The difraction/interference is very easy to notice with eyes, but harder to capture on camera.
Now the interesting part: The "dot" has it worst on shiny flat surface. Very sharp edge is ok, but ragged edge perpenticular to beam is bad. Piece that has a side, close to beam shows fairly good resolution - just when most of the beam is blocked by the face of the object and a smal portion of the beam is cast to side.
One factor is a work piece, this laser method is very particular about the part surface, edge and angles, but for some parts this looks very good solution. This is something I want to verify before building the all of it.
Regarding the laser, the quality of it might or might not have major impact on accuracy:
* Shop light and more rpm might be eneough to reduce glare
* DG maintains that ultra small and precise dot is not required and pretty sure he is right on this one
* there are some fun details to find out
* laser he bought might be different, we are just buying here on very vague description
I'm very interested on filter you used on your experiment, it really seems to reduce glare and perceived dot size. Can you give some more information about that filter material?
Somehing like that looks nice, but the price....Variable Reflective Neutral Density Filters:
http://www.optosigma.com/products/optical-components/filters-apertures/variable-reflective-neutral-density-filters
I have some other things to finish today, but might have time to do few more experiments on tonight or very late tomorow.
Are you going to use the unit as it is or are you going to use some laser dot conditioning?
Do you have opinion about the slant angle? I found out that my mill has limited vertical space/travel, I probably need aproximately 10/20 degree two laser modules or adjustable angle. DG makes several remarks about the need for adjustable angle, even on latest design he suggests tilting the whole unit. It must be more than only for convenience.
When I powered up this module first time, my intial reaction was that no way this can be used as described, but after trying it out for real objects (pipes, bosses, bearings), some of my faith was restored.
Pekka
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I bought this Filter Pekka.
http://www.ebay.co.uk/itm/271427704703?_trksid=p2057872.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT
I cut some small squares out of it on my Bandsaw and then turned a 12mm dia disc on the lathe using double sided tape.
If you PM me your address I can send you a couple of small squares if you like.
I'm quite happy with beam shape and intensity at present. I just need to work out the mounting details.
One design I saw allowed the angle to be varied by a large amount so I may try this approach as well.
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I think I'd like to make the body from plastic as I'd be able to cut a battery pocket directly in the mount. I'm hoping to run the unit on a couple of SR/LR44 batteries as they are compact and I keep these for calipers etc.
Something like black Delrin would be good but I don't have any in stock. I have plenty of suitable bits of alloy but I'd have to add insulation for batteries etc. I'm going to give it some more thought before proceeding so I don't waste shop time or materials. Not absolutely essential but I've ordered a sub miniature toggle switch in case it seems a useful addition.
I'm actually fairly confident I could also make a stationary Laser.
Some images from around the net that may be of interest.
(http://www.model-engineer.co.uk/sites/7/images/member_albums/45353/492018.jpg)
(http://www.gadgetbuilder.com/Laser_Center_Finder.jpg)
(http://www.model-engineer.co.uk/sites/7/images/member_albums/45353/492160.jpg)
(http://www.model-engineer.co.uk/sites/7/images/member_albums/137795/591578.jpg)
Commercial Laser edge finder in custom mount:
(http://www.model-engineer.co.uk/sites/7/images/member_albums/49870/493199.jpg)
And a link.
http://mikesworkshop.weebly.com/laser-centring-device-mk-2.html
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This laser slurps 20mA @3V, LR44 is a bit marginal, DG says "CR2 lithium 3V camera battery" and it last about 40 hrs on his model. I got 2*AA battery holder, but I'm thinkking of cramming 2*LR1. They look like AAA, but 2/3 of the length.
I'm thinkking of using a aluminium as a body, I want it rigid. I don't expect too much trouble with batteries, just want to make sure no shorts are made.
I need to scarf up some reindeer and potatos. Hope I don't stuff my face, or I'll call it a day on garage time.
Pekka
* 'Burp'
too full
I checked linear polarizing filter at far field and it does work. Hmmm. Hmm. Needs a tad more testing. Anyone knows reliable source for OD or ID 10 mm polarizng filter? Or material?
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This laser slurps 20mA @3V, LR44 is a bit marginal, DG says "CR2 lithium 3V camera battery" and it last about 40 hrs on his model. I got 2*AA battery holder, but I'm thinkking of cramming 2*LR1. They look like AAA, but 2/3 of the length.
I'm thinkking of using a aluminium as a body, I want it rigid. I don't expect too much trouble with batteries, just want to make sure no shorts are made.
I need to scarf up some reindeer and potatos. Hope I don't stuff my face, or I'll call it a day on garage time.
Pekka
* 'Burp'
too full
I checked linear polarizing filter at far field and it does work. Hmmm. Hmm. Needs a tad more testing. Anyone knows reliable source for OD or ID 10 mm polarizng filter? Or material?
I ordered some the other day and mentioned it in my earlier post. Put Iphone 4s Polarizing Polarizer Film LCD Digitizer in ebay £2.99 delivered item no 121618388586
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This laser slurps 20mA @3V, LR44 is a bit marginal, DG says "CR2 lithium 3V camera battery" and it last about 40 hrs on his model. I got 2*AA battery holder, but I'm thinkking of cramming 2*LR1. They look like AAA, but 2/3 of the length.
Pekka
Ah, ok. Thanks for that. I saw the CR2 in the supermarket yesterday and thought they looked a good size if I needed more capacity.
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Interesting thread, I just received 2x 5 mw focusable lasers for this project. I had half an hour spare so the first one went into a torch body that has 3xAAA batteries in it.
(http://i210.photobucket.com/albums/bb270/rodweb/Lathe/Mill%20Mods/20150419_173845_zpsd7kuppmu.jpg)
I stripped the LEDs off the circuit board and made up a Flanged adapter to replace the torch lens turned up out of a bit of Delrin. Before I got this far, I had a play with some resistors and 3.3 V and 5 V power supplies. If you end up with one of these and it is too bright, a resistor will dim it down quite easilly. The unit weighs 13.4 grams so I will choose a battery that is similar in weight. Either CR2 or CR123. I had a quick play with a ND photographic filter. You can get plastic Cokin compatible photogrpphotographic filters off eBay for a few dollars. I may cut a filter out of what I have If it is too bright.
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Hi does anybody have a link to Dan Gelbarts centre finder design details that works please.
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Hi does anybody have a link to Dan Gelbarts centre finder design details that works please.
Hi,
My opening post, second link and a little down the page:
Found the link: https://drive.google.com/?tab=wo&aut...nU3V0E
Just above it is Dan's pointers, well worth of reading it. He recommends one type of laser module and I bought mine from that link. This laser seems to have a real regulator and it can't be dimmed same way than LEDs (decreasing the voltage).
Most people have taken the easy way and mount the laser on arbor. There seems to be few slip on designs.
Thanks for the polarizing sheet link, I never would have found it with those search words. What kind of material it is to hanadle? Post would be here way over the initial price.
Pekka
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Thanks for the Link I will have a look in a minute, The polarising film is just that looks very much like a standard phone screen protector, it came in an envelope on its own not even between 2 bits of cardboard but is no worse for it.
Have yet to try it but will do when I get a minute, to be truthful i'm not very keen on the eye risks with lasers and I am awaiting the arrival of some blue glasses, I assume the offer a degree of protection and enhancement
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Norman mentioned 'Centre cam'.
I remember that article, and did download Trethaway's software.
Did anyone here actually build one?
Dave.
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Hi Guys,
I just found this on the HMSC web site.
There is a PDF article on there but the interesting bit starts at page 5. I just grabbed an image of the wanted pages.
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I like the simplicity of using centrifugal force to operate the switch - very neat :clap:
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It's an innovative slant on the concept but I'm concerned about the safety aspect of one Laser, let alone two working at the same time. I'm also worried that two circles may prove to be distracting rather than helpful. Nice to see folks trying something different though.
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I have worked around and installed low power laser sensors and safety curtains/photocells. This power level is considered fairly safe. Generally laser beam is actually pretty thick and mW level laser has pretty low power density.
This design I would consider pretty safe, there is no good reason to stare into the beam. Reflection from the part is possible, but due to spinning "dwell time" is pretty low and these power levels are most likely don't cause damage on stray exposure.
That said, I consider my sight very important and I would very much use lowest power level that works.
Probably whole lot more damaging to our eyes is welding and UV exposure from leds/displays/TVs and stuff.
Pekka
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Good to know Pekka. :thumbup:
I have ordered what is described as a 1mw Laser from Hong Kong. The primary reason for ordering another is that it is smaller than the one I have at present so if suitable it will be easier to mount. Should arrive in a week or two.
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I ordered three "smaller" lasers as well, will take some time to get them. Those are small, but not "focusable", hope they are weaker. I have intention to check which parts I need for collimation, but I got sidetracked with ND filters and polarization if I need to live with this one. Some math involved to collimation lens calculation and some input values are required that not all are available....I will resort to normal lens calculator and approximate, questimate and testimate it.
Which laser you bough? I'm hating the idea of getting too exited and buying too much junk. "Just in case". But this is pretty cheap way to learn more.
Pekka
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This one Pekka.
http://www.ebay.co.uk/itm/381148296821?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
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Got one cross-line 5mW laser from mail.
I got some time to play with this cross-line laser.
1) I took the cap/grid lence off and noticed that there is a lense (group?) on threaded holer, that allows "focus" adjustment.
2) Original dot is not extremely clean, about the same than "focusable laser module" that has been linked here.
3) Tried prism to angle the beam and it worked out pretty well. I was expecting some artefact here, but quick look seems to confirm that with a little adjustment laser and prism will compensate oavality of the beam.
Laser inside a grey plastic cable gland
prism from a binoculars (roof prism type, pechan prism used)
ND filter, thanks Vic
Black cardboard.
It looks like it is possible to use prism, but to adjust the beam only with the prism is not optimal. Surface mirror?
Pekka
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Little testin with pinhole.
1) I made a pinhole onto black craft cardboard, smallest pin I had.
2) I placed the pinhole on front of the collimation lense and it produced interference rings as theoriy says, clearly visble when focused on about 200 mm and then viewed at three meters trough frosted glass.
3) Dot density is greatly reduced and dot is pleasingly round, but not exceedingly small at 200 mm, due to interference no doubt. However when projected onto machined metal surface it looks very promising.
My gut feel about this (not very sientifically based) is:
Pinhole can be used to clip the size of the dot, but to be highly effective it needs to be placed carefully, probably near focal point and in this system it means some extra lenses.
Pinhole naturally cuts some intensity, specially when placed into "wrong place" wether this is good or bad depends on situation.
ND filters I got do no seem to reduce quality of the beam.
Pekka
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I couldn't see any interference rings with the setup I used. It may be they are still there, just too feint to see? I have another mounting prepared ready to drill when the micro drills I've ordered arrive so we'll have to see what happens with that. I can't see the need for a prism unless for some reason you really want to mount the Laser horizontally? Adding a mount to house a ND filter and a reduced aperture increases the bulk somewhat but it's still small enough to use. The other Laser I've ordered is very much smaller so it will be interesting to see how compact this assembly will be. I'm still favouring a button cell, maybe a CR2032 if it lasts long enough.
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As you see on the bottom picture, interference artefact is not that visible on reflected light at 200 mm distance, but I assume that dot appear bigger because of that. The picture where interference shows is the same beam, but at three metres trough matte glass. When I viewed at laser side the effect was not very clear just a bigger dot (about 2-3 cm). But at the other side the effect is very clear. Last picture shows the interference nicely (Picture is taken at a angle, because head on the picture was just just a big blow of red light, but vhen observed the rings were very consentric and all around the central dot). But the dot was really round, only the interference rings to make it too large.
I'm testing the prism, because I want to slip the indicator at the end of the spindle and there is space only to very thin object. Therefore my preference is to make this flat, but if that is too much trouble or the smaller laser is not small enough, then "Plan B" is to fabricate one that will slip over dedicated ER holder - not as versatile, but plenty of headroom.
I don't know much of the pinholes, but I think that thinner the material you have the better the results are. I could not find my very thin copper foil, but I should have somewhere a little of thin brass shim stock and I was thinking of comparing that with domestic aluminium foil - hole pricked with a needle.
Pekka
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Interesting about the foil. I'm wondering about how to make a fixture for centering the hole on the lathe. I have some steel shim stock somewhere that may suffice. I think in one of the videos linked earlier someone was using the edge of razor or craft blades to chop the laser image.
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Interesting about the foil. I'm wondering about how to make a fixture for centering the hole on the lathe. I have some steel shim stock somewhere that may suffice. I think in one of the videos linked earlier someone was using the edge of razor or craft blades to chop the laser image.
I linked one video where instructor was using razor blades on magnet. pretty smart really, razor blade edge is pretty sharp and on magnet you have an adjustable iris.
This foil I haven't tried, but I read it somewhere. I noticed that it was easy to prick the hole on black cardboard and then pretty damn hard to align it to the beam. Hmm. Could a copper/brass metal foil be glued on a washer or something that has few mm hole and the pin hole middle of it? Thicker carrier should be easier to align and hole on the carrier should give better visual where about the beam should hit. Pity that local bolt shop does not have setscrews with pinholes on them. I have used some hydraulic orifices that were like that, but the bore was too long for this.
Any small plumbing fibre washer/cap olive fitting?
Pekka
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Thinking about it some more you could make a housing for the Laser similar to one I posted earlier. The ND filter slips in the bottom of the housing below the Laser. The aperture could be drilled out somewhat bigger then a piece of foil could be glued on the outside and then drilled with a small hole on the Lathe.
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And the mailman brought small lasers, quick and dirty testing showed that these would simplify mechanics greatly.
Pekka
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When this thread started I ordered a job lot of 50 of those small ones for a ridiculously small amount on ebay. Did a quick and dirty test with a variable voltage and current psu and was most impressed.
They then went back in the bag and still are sitting on the desk waiting for time to make a mock up :bang:
I have to say reading all that's been said people seem to be making this far more complicated than Dan's original simple concept :scratch: But what do I know, mine are still in the bag :ddb:
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Andrew, it's the brickwork holding you back. After that's done, then you can start on the planetarium...
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Andrew, it's the brickwork holding you back. After that's done, then you can start on the planetarium...
Steve I have to say the brickwork progress is hugely frustrating at the moment, that and we still haven't finished lambing (only 3 Ewes left to pop but they seem to be hanging it out deliberately and we have several needing bottle feeding)
I'm determined not to get involved deeply in another project until at least the pig sty and lambing is finished :bang:
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They look like the one I've ordered Pekka.
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A few items I ordered have now arrived. I drilled the new housing I'd made for the 12mm module with a .5mm drill bit but the resultant dot size seemed little different from the earlier one with a .75mm aperture. The 6mm laser module arrived and seems less bright than the 5mw laser pointer I have which is fine. The dot is still oval though and the focus has been glued in place so I can't adjust it without risk of breaking the module. I'm sure it will be fine though if I use a small aperture again. Not sure yet if it will benefit from a ND filter. Overall I'm quite impressed with the 6mm unit, inexpensive and very compact. Time to design a prototype.
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Here is a laser centre finder that I put together. Most parts were 3d printed.
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_140301.jpg)
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_140313.jpg)
It looks a bit like a laser guided toilet seat for mice but the strange shape is allow it to be used on a number of different machines with different spindle sizes. The centre finder is fixed to the spindle with magnets and is very stable when running, even on the drill where it looks a bit precarious!
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(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_140022.jpg)
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_135849.jpg)
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_135533.jpg)
A shot of it in action
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_135626.jpg)
sorry about the massive pics, the pics on the last post were a sensible size but for some reason these are much larger :scratch:
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Very nice Andrew. :thumbup:
That's one of the few useful things I've seen made with a 3d printer.
Phil.
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That looks nice.
What kind of results are you getting with that one?
I attented on one 50th birthday party and next day when I was returning from the trip I went on one "El cheapo" shop and tried to find something usefull for a 3V lithim batery holder. No, they had no cell clips, but there was a pagage of three electric candles and six batteries for about 3€. When I got home I cheed them and what a luck. The bottom part is one itegral unit and and it detaches with two philps screw, the bottom is about 34 mm round "lid" that has a battery holder and switch in one ready made unit. battery size is small, but this offers all the parts for further testing and some spares.
Something like this:
http://m.dhgate.com/product/electric-candle-tart-warmer-flameless-led/210849539.html
Battery tab and switch tab are solder tabs, quick to substitute the "candle led" with laser module. Seems to work.
3D printer could make holder easy.
I tried do dig a chunk of aluminium for the spinng part, but maybe a plastic would do.
I'm procrastinating between two fixed angle lasers, switched alternately or one adjustable angle laser....and two different attachmet method. I don't like the magnets. I have idea about coaxial excentrics or wire spring....
Pekka
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Pekka,
I have not had much of a chance to fiddle about with it yet, but it appears to produce a stable circle and the laser can be focussed to a fairly fine point.
I think these devices are most useful when centering a cylindrical object that is normal to the table. The angle of the laser to the surface of the object means that it can be quite sensitive in this mode. The shallower the angle of the beam to the surface of the cylinder is the more sensitive it will be. Accuracy is determined by how well you can judge how parallel the laser line is to the bed. Just using it projected on to a flat surface means sensitivity is limited to how well you can determine the edge of the laser. I am treating this as a rough positioning device for non critical applications though. If any accuracy is required it is time to get the dti or edge finder out!
I used £3 focusable laser module from ebay. This was good as the spot can be focussed. I also found out that the case of the device is bonded to the positive input. The module is at one end of a 12mm hole, two cells stacked up to the case and then the negative is connected to the other side of the cells with a screw in a threaded hole, to act as a crude but effective switch. There is also scope to convert this to centripetally operated switch arrangement in the future.
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This thread just keeps getting better and better. Very interesting. Thanks to all of you.
Jim
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Here is a laser centre finder that I put together. Most parts were 3d printed.
(http://i1031.photobucket.com/albums/y373/dreeewman/20150502_140301.jpg)
It looks a bit like a laser guided toilet seat for mice but the strange shape is allow it to be used on a number of different machines with different spindle sizes. The centre finder is fixed to the spindle with magnets and is very stable when running, even on the drill where it looks a bit precarious!
Hi Andrew,
Look very futuristic :beer: I like your description though, I can imagine a mouse sat on there. :bugeye:
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Any concerns about magnetizing spindles and chucks?
It may not be a problem for everyone, but I've been on a concerted effort to reduce super magnet usage in the shop, since I find more and more tools and fixtures attracting iron and steel filings and grit. True, a degausser can help, but it isn't always possible to use those on hidden and internal parts. And magenetism seems to get transferred from tool to tool if you aren't diligent in demagnetizing. Magnets are a nice convenience, but in many cases a simple clamp will work in their place without the assocated magnetc field. I believe Gelbart's laser finder used a clamp.
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Dan's original design is very elegant with just a couple of pieces of spring steel to hold it in place.
Most folks that have built these have used a spindle design for use in various fixtures instead though.
I'm torn between the two concepts but will probably go the spindle mounted route as most others have as it's easier for me to make and more economical on materials. We shall see though! No progress from me on this lately as I've not been too well recently. The hospital ED say it's nothing life threatening though so it's just finding a way to deal with the symptoms.
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Good to hear you are fine.
I did a little something.
1) Idea is to use 0-ring and close fitting to hold it on it's place. It is fairly close fitting. Ironically I walked on the workshop today and got a piece of springy steel band from the strapping machine. I would go that way now.
2) I may design an adjustable angle to the laser, I'm working now with r=40 mm and 10/15 decree inclination, which will give me Goldilocks range. Really try aim 15 degrees +/-5 degrees of adjustment.
Screws are not countersunk yet, centre of the plate is not cut out and plate is way too big, but I want to test few configurations first.
Pekka
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Well, I think I have a way.
Pekka
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Well sort of...
Led candle battery holder and swich are pretty low quality. Hope they will last this test.
Screw up royal with hole saw. You can see decorative markings on mounting plate.
All screws are M4 eccept small screws that hold the laser lever detent. And led candle gubbins. Tried to get away with only one thread size and screw length, but used two different length and slot head screw to test the detent mechanism.
I used reamer FOUR times to green nylon piece. Can't beleive how much it deforms during milling and fitting. Almost screwd it up too. Measure once and cut twice error. Had to make slot for laser beam bigger than I had planned, because I managed so seat laser holder (shaft) 1 mm too much down. herefore oval hole allows this shaft to rotate in this recess.
Laser angle adjustment works pertty good. Have to see if the range is usable. I may make the detent a slighty stonger on middle part.
All adjustments are to be done tomorow. It has not been balaced either....
While making it I got few better ideas.
Pekka
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Some interesting ideas there Pekka, well done. :thumbup: Be interesting to see some pics of it in action.
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Well the part I build works and the part I bougt doesnt.
Fought bit more than hour with battery holder/switch. It works intermitently. Plastic battery holder cap looks fine designwise, but apparently the lid is too thin and contact points may be not the best material for this purpose.
Any suggestions for single 3V battery or two small 1,5V battries?
Also I knowe that these laser modules does not generally have the laser beam axially to the body, laser beam exits more than one degree out of mechanical axis. Lucily on this design you can turn the laser module and the beam will be on the central plane, few degrees error here does not matter at all.
I used tape to hold down the wires.
I could not find from mthe hardwarestore or plumbing shop 52 mm ID 2,6 mm thick O-ring. I used short about half that size, cut half and a litlle tack to hold it in the grove. Even half of ot held the unit really nicely on the spindle. This one works.
Also the angle adjustment works. No problem there. The 10-20 degree angle is just about enough. I would not complain about bigger range. The mechanism works and there seem not to be any magic on the angle, just to find one that suits for that particular purpose.
Progress so far.
Turns out to be a mechanically a good testbed.
Pekka
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Good work! Looks like you've got a working device as a prototype, Pekka. How accurate are you able to locate a center with it at this stage?
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it all really depends how you can read these, but intially it looks like under 0,15 mm on flat features. On round features it looks very acuurate. Needs more testing.
On that black cylinder even spec of dust flares up. On bright flat a centre punch is not that easy.
Any suggestions of test? No DRO.
Pekka
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Hi Pekka'
Looking good, I've been quietly following from the side lines. Ok to make you marks show up, colour the surface in blue of you choice, scratch your cross lines, center punch or what every as the laser crosses from blue to the scratch mark the dot will go bright. My laser center finder has blue card with a white cross on it to use for checking / adjusting it ,working on this idea.
In this part of the world you can buy oring material off the roll & make your oring to what ever size you need ......glue with a contact adhesive, getting the ends lined up is a bit of a trick but in this instance it's probably not that important. Hope this is of help
Cheers Kerrin
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Hi Kerrin,
Thanks for the tip. I got the most part of it and will try....I have't got layout-blue yet. Almost got it two years back, but the shop would't air mail it to me. But'll find proper substitute. I allready have engineers blue and then two different stuff for scraping. I hope I will not emerge frm the shop all blue and join VT:s army of blue.
I have noticed that surface quality has a lot of do how easy it is to line up stuff, also the brightness of the beam is a big thing. Evolution version will have a filter or linear polarizer.
The last part escaped...would you alaborate a little bit more on "oring material off the roll & make your oring to ...." Sort of laser printable transparent material or cross hair printed on it, possibly on mylar or any non streching material?
Thanks,
Pekka
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oring = O ring. It means rubber material on a roll in different thicknesses. You choose your length and glue it together into a ring.
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I've got a bottle of Layout Fluid somewhere as backup but haven't used it yet.
These are far cleaner and quicker unless you're marking out large sheets Pekka.
(http://i230.photobucket.com/albums/ee286/Arbalist/eed3a29aa42faf6151e92289f94f707b_zpsti8hzgi5.jpg)
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Total agreement on layout blue switch to markers for small stuff. I went through two metal bottles of Dykem before switching over. The last one wouldn't seal at the cap, it leaked solvent into the shop drawer -- always smelled when you opened it, and the blue actually crawled out of the cap threads.
Markers are much cleaner and easier (for small areas). I would imagine black might be even better than traditional blue for use with a laser dot.
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I bought a re-fillable marker specifically intended for layout fluid - big broad felt tip, push on cap and the tip assembly screws out of the body for re-filling. JLA if I remember correctly.
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Hi Pekka,
Happy to help, sorry about the confusion on the lay out blue, different countries different words! Arbalist put you on the right path, I used to use a vivid permanent marker, then found one simallar to Arbalist's much better as it covers a bigger area in one pass, I find the vivid good to use in the lathe if doing a ruff mark up as to we're you want to approximatley end up
Sid sorted the o ring out, cheers Sid, you might have to go hunting but hopefully you can find some off the roll
Cheers Kerrin
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Thanks guys
I'm off to try some permanent marker pens.
I did a little internet search on layout blues and hobby solutions and got even a little more confused than I were before. I have some acrylic and oil colors, as well some blue pigment powder, I may try something later.
I did think of o-ring as a one continuous ring, I'm more used to them like that. I know that there is this material on reel, maybe I can buy somewhere a few metres or so.
Now I'm torn between just mounting a new switch and to make a battery holder or completely different design altogether.
Pekka
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Pekka, for layout you want a fast-drying thin-build hard solvent-removable color.
Oil colors are slow drying and undergo chemical change to harden. They are not solvent removable once cured, They tend to flake when scratched, rather than leave a thin line. Acrylics are faster but also also not solvent removable, and very elastic, so hard to scratch in a clean line. Both are high build. Neither is a good choice for layout work.
Usually real layout colors are dissolved by alcohol or stronger solvents like acetone. They flash dry as the solvent evaporates. They often use dye colors, not opaque pigments to keep the build low. They scratch with clean lines. If you are going to try to make your own from pigments and common ingredients, you might consider shellac with a lot of thinner (denatured alcohol/meths) as a starting point for a vehicle. And a dye pigment would be better than opaques, since they are finer.
But markers are so much easier and available, I'd say if it isn't just a matter of curiosity, just use markers. Markers and layout colors are very similar -- fast dry solvent based dyes.
I can understand the internet confusion -- it relates to the difference between layout and spotting. Spotting colors used for hand scraping are not supposed to dry, but to transfer marks from one surface to another. Therefore they are oil based -- and non-drying oils at that. So the two kinds of "blue" (layout blue and spot blue) are completely different in composition and purposes.
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Here in the UK we normally refer to them as Marking Blue (non drying) and Layout Fluid. If memory serves "Micrometer" brand marking blue came in small flat tins or small tubes. It's all messy stuff though if you're not careful. Glad I switched to markers! I have both Blue and Red ones but much prefer Blue.
I've decided to go with a spindle mounted Laser as it suits my needs better. I've come up with an adjustable angle setup as well, just need to think about what battery to use. Sadly other chores are getting in the way at the moment, hopefully work on it starts soon, maybe next week some time.
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As Instrument fitters we used to put a ring of marking blue on the eye end of a Watchmakers eye glass and say to the Apprentice come and look at this, they walked off with a ring of blue round their eye.
A tube of marking Blue lasts forever, I doubt the Engineering profession all put together have used a full tube, it's a bit like Dog Poo it gets everywhere.
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I finished off a tube of marking blue in this present lathe construction (bought in 2001), and had to switch to artist's Prussian blue oils (which I had on hand).
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I finished off a tube of marking blue in this present lathe construction (bought in 2001), and had to switch to artist's Prussian blue oils (which I had on hand).
How do you work with that? I tried some scraping long time ago and tube of oil color was what I tried. I had hard time getting a thin film of color on steel and aluminium. I think I tried pretty much everything only way that work somewhat was a little dot of color on glass, some turpentine a little on brayer and then rolling on clean class until it was all spread and then constant pressure application with brayer onto transfer surface. Palm worked better but blue does not fit to my complexion :lol:
Generally too many variable and I gave up because I lost faith on what I was doing.
Pekka
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I spread it on the surface plate with a brayer, no thinner if new, maybe a drop if it's getting too thick. Works for me.
Dykem Hi-Spot worked slightly better than Prussian blue artst's oils because a little more intense and non drying. But the old tube had a white painted outside, and bits of this flaked off and drove me nuts wrecking rubs until I masking taped over the tube.
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I'm beating this thread to death......
Anyway, I'll be sanding and painting living room roof. Swinging beltsander overhead is brutal for officeat. Then I'll remove carpet and grind concrete flat before laying hardwood floor. Should keep me busy week or two.
I tested a little pin hole...I pricked a little pinhole on black carboard, cut it round and fited between spring and lense. It worked pretty good.
I removed tha sticker and found out that rear end screws off fairly rapidly revealing the contol board. I wonder if the control board could be mounted remotely or turned 90 degrees to make the whole thing shorter. Looks like a simple regulator, wonder if it needs to be immediately next to laser diode, or could it be moved a little further.
Pekka
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Damn it. Frgot to add the pictures :bang:
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I think I've decided to go with these bits. I don't believe I'll need a filter but I will use a small aperture plate to improve the dot shape.
(http://i230.photobucket.com/albums/ee286/Arbalist/0c54cf204bd8d28a0bfc0b1902118635_zpszl29nxvd.jpg)
Just need some spare time now to put it together.
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Looks good.
How are you going to hook up the battery? Do you have parts for battery holder?
Are you going to build adjustable mount for the laser or use fixed angle?
I'm starting ti think this as an accessory to centrefinder.
Pekka
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The angle will be adjustable.
I expect to make the parts for the battery but if it's problematic commercial holders seem to be available for most batteries. All it needs is a hole for the battery, a couple of contacts and a spring.
I made a small "can" out of aluminium with a .65mm hole in the end for the Laser today.
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(http://i230.photobucket.com/albums/ee286/Arbalist/1af983a960a1ab8f09269819ff4996e7_zpsfxce1d4b.jpg)
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HDPE? You really didn't want laser body to make electrical contact on anything?
Looks nice. All parts in and then you'll find static balance?
How is the dot?
Pekka
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Just playing around with some ideas really. Dot seems pretty good. I didn't have any alloy the right size for the main body so it's some grey PVC I had. The laser mount is Ertalyte TX. Just thinking about how to mount the battery.
Update:
A quick lash up to see what results I get!
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP4037_zpsbs20arbi.jpg)
1400 rpm and the battery didn't come off! The laser housing has a taped hole for locking it in place but as its a nice friction fit it doesn't have a bolt in it yet but no movement on this either.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP4038_zpsair8zbub.jpg)
Looks good, I just need to work out the battery housing and check for balance.
(http://i230.photobucket.com/albums/ee286/Arbalist/IMGP4036_zpsdpigo8f0.jpg)
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Looks the part!
Have you tried yet how does the laser "paints" the edge of the boss, hole, or clylinder (pin). I have been thinking that that angle adjustment is not essential, but it's definately a conveniece. Reduces a lot of jacking the mill knee up and down.
Pekka
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I won't be testing operation until I've finished the unit. Shouldn't be too much longer hopefully.
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Off slightly to one side Sainsburys are doing some "garden" solar lights at a £1 one of ours was faulty and was going to throw it away as its 20 miles to Sainsburys, any way the Mrs opened it up and a wire had come off. But the bit i am getting to it contains a 1.2 volt 2/3 AA rechargeable battery (about 25mm long), could be useful
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Yesterday Postman Pat brought bunch of focusable small lasers, a lot like above. BUT exceptionally it had paper with it and at first look it looked like it says TTL????? 45s ON, 15s OFF...
I resumed ripping floor carper away and sanding the concrete floor----I'll have a look on it again when after I have leveled the floor.
Pekka
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The one I used was on for at least 4 or 5 mins whilst I fiddled about taking pictures and still seems ok. I expect in use it only needs to be on for a minute or two. If you do burn one out by leaving it on you'll remember next time and they don't cost very much.
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Seems odd, why would a laser pointer have a duty cycle of seconds? In their original purpose, 45 seconds seems rather short.
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My version :-)
Based on Mike's (of Mikesworkshop (http://mikesworkshop.weebly.com/laser-centring-device-mk-2.html)) design , I've pared this down to the minimum using a plastic body and automatic centrifugal switch.
Photo 2 - The cap is sized and shaped to clip into the 21mm battery recess
Photo 3 - the cheap 50p eBay laser module has the wires removed and a 40mm piece of tinned copper wire added to the negative (resister) terminal - the module's PCB has to be trimmed (grinder) to make sure the module will press nicely into the 6mm hole
4 & 5 - Once the module is pushed home the wire can be bent around to form the Negative battery connection. A small piece of plastic foam packing is used to push the 3V lithium cell away from the laser body (the +ve connection).
6 - Once the thing is rotating above a couple of hundred rpm , the battery is pushed against the body of the laser module and it lights up.
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Bill, Very nice
Mike
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Thanks Mike :-)
This is the simplest one I can think of:
The rod is turned down to weaken it and then bent . It is then pressed into the head using a barbed form on the end of the rod.(previous version was threaded)
If you need a larger circle, it is a simple matter to twist the head slightly.
The small offset weight does not upset my mill/drill.
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Finally; one that works like Dan Gelbarts' and mounts to the ER32 chuck nut. Using an offcut of Nylon 6 bored to be a press fit .
Incidently, adding an iris as mentioned in the posts above (e.g. something with a small hole between the spring and laser diode) improves the functionality immensely.
I used one hole from a piece of Vero (https://www.google.com/search?q=veroboard&ie=utf-8&oe=utf-8)board (matrix PCB ) filed to fit into the laser recess.
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Yes, using a small aperture does seem to work well. I turned a small aluminium housing for the laser and drilled a .65 mm hole in the bottom. It's the little silver canister to the left of the laser in this picture.
(http://i230.photobucket.com/albums/ee286/Arbalist/b5017305f9ab5e3af837ae6863e23146_zpsblz4xvsn.jpg)
Still not got round to housing the battery properly as I've had other stuff to do but I have used it as is and it works very well.