Author Topic: Aluminium CNC build (TEP mill converted) by Craynerd  (Read 35333 times)

Offline raynerd

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Aluminium CNC build (TEP mill converted) by Craynerd
« on: March 22, 2012, 05:15:09 PM »
I`ve been wanting a little CNC machine for the last couple of years, not specifically for anything, just to learn more about it really. I feel I`m doing well with my manual machines and want to keep machining that way. I`m learning all the time and this cnc build is just to help me learn the basics of cnc, not to take over my manual work (slightly irrelevent, as this machine won`t be up to it anyway!). I just don`t dare start from scratch and anything more complete is too expensive, as is buying a bench mill and converting. So this is a cnc build based on confidence and available funds.

I started with a TEP cnc mill. One went on ebay a while ago for about 200 and just the other day another went for £350!! I can assure you I paid only a fraction of that price for mine. These are a sturdy machine and quite well made...just a dreadful design and dreadful software which is locked onto the driver hardware!!

I was lucky enough to get hold of the original TEP software (isn`t available from anywhere!!) and it was dreadful. Imagine MSWindows Paint, no numberical input (so no saying I want a 20mm line, 10mm from the origin!!, just simple drag and click stuff!!) Then from that, tell the machine to move.

Here is the machine from purchased:





Very very bizzare design and many machine limitations:
Cons:
In my opinion the x axis should be mounted so the slides are vertical parallel, not horizontal.
No z axis, it is just a solanoid motor to raise and lower the spindle to a fixed level.
All hardware is locked so commands can only be sent from the PC interfaced by the TEP software - it won`t talk to Mach or EMC
Stepper motors are only about 50Ncm
Both axis are fixed off centre to allow space at the back for the electronics
Only 12v 5A supply.

Pros:
I had a working CNC machine as a basis
If all else failed, I strip it down and the ally bar/plate is worth more than the price I`d payed for the machine ! :D

In truth, there is little going for this other than having a solid working basis to start from.





 

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #1 on: March 22, 2012, 05:26:05 PM »
First job was to strip the electronics completely from it. I will be using a TB6560 3 axis driver. I`ve heard nothing but BAD things about these, but I have one anyway and it`ll certainly get me going if I can avoid blowing it up.

I wanted to flip the X axis and although replacing the entire side piece would have been ideal, I couldn`t afford it and had some pieces suitable in stock. I raised the sides and used a plate to join them. It may need some supports bridging the sides later on.

After flipping the X, I could then mount a Z axis. I made the Z axis from a small leadscrew someone kindly gave me and the slides are olite 8mm ID bushes on 8mm silver steel rod slides. The rest is just plate bolted together. There is a problem in that I`ve used a flexible coupling but I haven`t "trapped" the leadscrew. This means that the Z axis compresses on the flexible coupling and moves the relative position of the axis - not good!! This is easy to correct but I haven`t done it yet.

Once i had the X flipped and raised and the Z built, I couldn`t help try it out... it is running of only 12v at the time and the noise from these small motors is horrific, I think the TB6560 is also to blame but since then I`ve jumped upto 24v and the noise is quieter.




At this point, the mill went back to its owner while we negotiated price. Other than electronics that we both agreed wouldn`t be needed, it was all replaced to original, thankfully, if he had seen the work I`d put into it I expect the price would have gone up!

Further updates to come: Now running on 24v from two ATX supplies in series, spindle connected, first door sign engraving done...all good fun! Issues: still not sorted the z axis flexible coupling issue. Is the Z axis height too big. Flex is the spindle.

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #2 on: March 24, 2012, 12:25:03 PM »
First door Sign. Actually, that is a lie, I did one for my daughter that didn`t work out quite as well and I stalled the spindle whilest pocketing it out. This was my second attempt for my niece, with a slower feed during the pocketing.



I have an issue somewhere but I`ve noticed that when the spindle is turned on, the spindle drops a significant fraction of a mm! The sign is too deep as areas that should be a thinner line are deeper than desired.  I was pleased with my first results.

Chris

Offline HS93

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #3 on: March 24, 2012, 05:58:52 PM »
that may be due to you energising the coils the magnets are pulled in to line moving the bell with them in down and the spindle with it. you need to find a way of getting rid of the end float, did you put a collapsible washer on the spindle ? you should not need it with the thrust bearing.

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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #4 on: March 31, 2012, 07:52:04 PM »
Pete, thanks for that tip, you were right and I never posted a reply to say so...sorry! I removed the end float by applying pressure to the main shaft while locking down the bell and it got rid the float.

An update and advice if anyone has any!...

During the last week I`ve stripped the machine to do some mods and in the last few days got it back together. However, I just can`t get my head around the fact that the movement is well out of sync! Just a simple example, say I draw two ovals concentric to one another, they will end up overlapping and even with little flats on them instead of nice curves!

The wierd thing is, I get the same results on both Mach3 and EMC2... so either I`ve got a setting wrong in the software on both or something is wrong with the TB6560 driver?

I`m sure it was working OK just last week and so after nearly a full day trying to correct it today, any thoughts or suggestions would be helpful...I`m totally out of ideas!

Chris



Offline Brass_Machine

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #5 on: March 31, 2012, 11:46:59 PM »
Hi Chris...

I am going to go out on a limb and suggest it is the TB6560. I had one for my CNC... That just isn't a good board. I even supposedly had one of the "good" ones. I had problem after problem. Some left me scratching my head... kinda like what is going one with you. I bit the bullet and got a C10 breakout board with some real drivers. what a world of difference! I hear even more so with some of the more expensive stuff like the geckos.

Eric
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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #6 on: April 01, 2012, 04:34:02 AM »
Eric, I think you are very much right here in that the TB6560 is terrible.

I have another question and this might be stupid but what would something like this BOB -

give me over this LPT quick connect: http://www.routoutcnc.com/lptcon.html     

I have 3 x m452 drivers that I could borrow from other things in my workshop and I also have the LPT quick connect above. I have a 24v supply and also a 5 v supply. I believe the m452 like Arc Euro sell are opto-isolated inside the driver themselfs... so actually what is a BOB giving me extra other than perhaps a pull up resistor for inputs and maybe a relay for the spindle. Could I actually get my three drivers going with the LPT quick connect ??

Can anyone see any problems with this..... sorry if this is a dumb question. I`m just struggling to see what a BOB actually does for £50, above what my quick connect does (I have the quick connect for a project I attempted about 3 years ago and it is sat on a shelf doing nothing).

Chris

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #7 on: April 01, 2012, 04:49:33 AM »
Hi Chris

I am using this BOB ,,,,,,,,,,, only a few quid more http://www.zappautomation.co.uk/zp5aint-p-499.html?cPath=143 ,,,,,,, you get a true High /Low signal on the PP pins and a few other things  ,,,,,, fink thats right  :palm:

  http://www.ebay.co.uk/itm/CNC-5-Axis-Breakout-interface-Board-for-Stepper-Motor-Driver-Mill-/260948751632?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item3cc1c1f510#ht_2763wt_1110    a few quid cheaper


Rob

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #8 on: April 01, 2012, 07:22:07 AM »
Hi Rob, thanks for the link. I`ll make a decision tonight and get one ordered!

Another question for you cncer`s!

I`m questioning my wiring of my stepper motors: http://www.sanyo-denki.com/Data/Servo/catalogs/F2.pdf  page 53 of PDF pages but p52 at the bottom of the document page under bipolar winding. The colours represent my colours red, orange, blue and yellow. In terms of colours and A-, A+, B-, B+ - how would you guys be wiring it?

Chris

Offline David Jupp

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #9 on: April 01, 2012, 08:06:45 AM »
I would arbitrarily assign one coil to be A, say Orange and Blue wires - the other coil must therefore be B.
I don't thik it actually matters too much what you do after that (though good to be consistent across all drives).  I would take say the first row from the excitation order table and assign +/- based on that -> Orange A+, Blue A-, Yellow B +, Red B-.

If direction of rotaion is wrong, either change the sense of your direction control output, or swap the +/- connection on one phase only.

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #10 on: April 06, 2012, 06:31:04 PM »
Ok, this one is driving me bonkers and I know we have quite a few cut2d and vcarve users in here so maybe someone can help.

For the past 3 hours I`ve been trying to produce the code to cut a clock wheel:

http://www.raynerd.co.uk/images/wheel1.pdf

Nice big wheel, 2.5mm or there abouts gap between the teeth which is good because my smallest endmill is 1.95mm which I`ve selected along with a profile toolpath cutting "outside/right". However,  I keep getting an undercut on the tooth tips! Here is a picture of the preview:



Is it trying to get right into the corner of the root of the tooth and therefore the radius of the cutter is causing the undercut? If so, is there anything I can do to stop this. I know for a fact that a lot of people are using cut2d to cut wheel but none of them describe the settings they are using. Also, is there a better tool than an small endmill to be using to cut this out...I presume there must be a narrower option for smaller wheels i.e smaller gaps.

Very sorry if there is an obvious answer or way to correct this! Any help appreciated!

Chris

Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #11 on: April 06, 2012, 07:32:55 PM »
Ok, this one is driving me bonkers and I know we have quite a few cut2d and vcarve users in here so maybe someone can help.

For the past 3 hours I`ve been trying to produce the code to cut a clock wheel:

http://www.raynerd.co.uk/images/wheel1.pdf

Nice big wheel, 2.5mm or there abouts gap between the teeth which is good because my smallest endmill is 1.95mm which I`ve selected along with a profile toolpath cutting "outside/right". However,  I keep getting an undercut on the tooth tips! Here is a picture of the preview:

Is it trying to get right into the corner of the root of the tooth and therefore the radius of the cutter is causing the undercut? If so, is there anything I can do to stop this. I know for a fact that a lot of people are using cut2d to cut wheel but none of them describe the settings they are using. Also, is there a better tool than an small endmill to be using to cut this out...I presume there must be a narrower option for smaller wheels i.e smaller gaps.

Very sorry if there is an obvious answer or way to correct this! Any help appreciated!

Chris

Chris,

I took your PDF and opened it in Cut2d. I used a 2mm cutter and it looked fine:



Did you join all the vectors? I did. If you selected individual lines then that may be your problem.

Cheers.

Phil.
« Last Edit: July 13, 2017, 02:42:35 PM by philf »
Phil Fern
Location: Marple, Cheshire

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #12 on: April 06, 2012, 07:49:21 PM »
 :doh: ooops, that could be the issue.

What do you mean by join them, how do you join them? Your right, the wheel is made up of all individual small vectors. I`ve tried selecting them but don`t seem to have any option of joining them.

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #13 on: April 06, 2012, 07:55:23 PM »
Go edit show open vectors and you will see dotted lines, then go edit > Join open vectors and it tells you how many are left after the operation, should be 0.
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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #14 on: April 07, 2012, 03:53:59 AM »
 :doh: Wish I would have read about that earlier, that explains a few strange behaviours I`ve been seeing in the gcode!

Thank you both - preview shows it is OK now and I will try cutting later today.

Chris

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #15 on: April 07, 2012, 07:11:59 AM »
To me that part of the program is worth more than the program itself.

I get loads of drawings in via DXF for laser cutting and I bring them into Cut2D, join all the vectors and export as a decent DXF, then send to the laser cutters or process in another program to go on the CNC.

It's fantastic how well things cut when you get a clean drawing.
John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #16 on: April 07, 2012, 04:47:22 PM »
Well thanks for the advice last night - I swiped a piece of scrap hardwood from the wood yard before it closed at lunch and had a go at cutting - worked first time!

Sorry a little out of focus!


Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #17 on: April 07, 2012, 04:52:13 PM »
Well thanks for the advice last night - I swiped a piece of scrap hardwood from the wood yard before it closed at lunch and had a go at cutting - worked first time!

Sorry a little out of focus!


Very nice Chris.  :clap:

How long did it take?

Phil.
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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #18 on: April 07, 2012, 05:24:31 PM »
It took a good 20-25 minutes plunging at 2mm depths each pass, so with 7.5mm material, it took 4 passes to cut through. I was holding back on the feed speeds as my motor has stalled on me a few times, but this was before I modified the axis and was having flex on the spindle. I expect I could nearly knock 25% of that time off if I pushed the feed up.

Just a question regarding feeds and depth of cuts - I know it is very dependent on the machine, but what sort of depths of cuts would you be attempting if i wanted to attempt cutting brass on this? Do you think I could even give steel a bash or is it not worth even attempting? It is small, but pretty damn sturdy now I`ve supported that extra rail with the linear bearing.
- so I`ve been using 2mm plunges in wood with a feed of 12mm/sec. In terms of my machine, from what you can see in the vids and pics...what would you turn this down to for steel and brass with the same 1.95mm end mill. I feel that the depth of cut is in some ways more important than the feed speed - especially with my motor stalling if pushed too far.

Offline Swarfing

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #19 on: April 07, 2012, 05:57:51 PM »
Chris as an estimate ignoring feed and speeds you should be able to get half the diameter of the cutter in depth of cut. But a lot depends on the spindle speed, coolant and more etc.
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Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #20 on: April 07, 2012, 05:59:30 PM »
Chris,

Have you any idea what spindle speed you're running at?

How many flutes on the cutter and is it carbide or hss?

As you say, it depends very much on the rigidity of your machine and some trial and error is necessary.

I've emailed you a simple feeds/speeds calculator which may help.

Cheers.

Phil.
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Offline mattinker

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #21 on: April 08, 2012, 07:58:49 AM »
To me that part of the program is worth more than the program itself.

I get loads of drawings in via DXF for laser cutting and I bring them into Cut2D, join all the vectors and export as a decent DXF, then send to the laser cutters or process in another program to go on the CNC.

It's fantastic how well things cut when you get a clean drawing.

Cut2D also runs under Wine in Linux. I just tried it!

Regards, Matthew

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #22 on: April 08, 2012, 08:10:26 AM »

Cut2D also runs under Wine in Linux. I just tried it!

Regards, Matthew

Wash your mouth out and we'll forget you wrote that.  :lol:
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Offline mattinker

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #23 on: April 08, 2012, 09:08:26 AM »

Cut2D also runs under Wine in Linux. I just tried it!

Regards, Matthew

Wash your mouth out and we'll forget you wrote that.  :lol:

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Offline Swarfing

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #24 on: April 08, 2012, 11:12:06 AM »
There is now a linux version of cambam.

ubuntu
ubuntu
ubuntu  :ddb:
Once in hole stop digging.

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #25 on: April 08, 2012, 05:01:34 PM »
I know I`m going to get an absolute hammering for this especially off Swarfing, but I started off with EMC2 and don`t have a bad word to say, it got me going and was all free! I would consider myself a decent computer user but having never used linux before, I found EMC2 tricky to get my head around when wanting to do anything but the basic functions.  BUT I did install windows and have since run Mach3 on it. Mach3 was much easier to setup and the user interface can`t be beat! Despite all my tweeking of emc2, I still couldn`t get my motors to move as fast and smooth as I could with Mach3 - which I know makes no sense and the issue must have only been due to my inability to setup EMC properly, but it did show how easy Mach3 was to get up and going and to the best setup!

Anyway... enough on that before I get myself slaughtered by the linux crew! I have no doubt that if I knew what I was doing in emc, I could have got an identical setup than I have in Mach so I blame it on my inability! But on the flip side, it shows how easy it is to get Mach3 up a running with best setup.

Today I attempted a few more gears, big and small and practiced layouts in vcarve. I wanted to utilise wood/space and so attempted to cut a few smaller pinions in the crossing out areas of the bigger wheels. The third round disk is just a spacer washer.



The gear is 150mm and my wood is a scrap I had lying around at just the right size..infact, 151mm gives me little error in my alignment! Screwed the wood down to an mdf sacrifical piece with some double sided tape as well...


I did this in 4 steps:

Step 1: cut all the centre holes, this allowed me to go around and screw each part down so it didn`t pop out and get caught in the cutter at the end of each piece


Step 2: Cut all the pinions and spacer:


Step3: Crossing out:


Step 4: Cutting the teeth


And out it all popped...well, when I had unscrewed it all:




Really enjoyed this little project and learnt a lot.

Chris




Offline DaveH

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #26 on: April 08, 2012, 05:08:06 PM »
Very nice Chris - well done  :thumbup: :clap:
 :beer:
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Offline Swarfing

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #27 on: April 08, 2012, 07:00:27 PM »
Chris you should not worry about using proper control software, if using girly windoze and mach3 gets the job done then so be it  :lol:

You still did a good job and well done
Once in hole stop digging.

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #28 on: April 08, 2012, 07:25:43 PM »
There is a very good thread going on at the moment on the Yahoo DIY-CNC group.
An American Dan Mauch, very knowledge and much respected is trying to get a Gecko 540 running on EMC but it won't run the charge pump correctly.

Three EMC uses, one of them a developer, Kirk Wallace, are trying to sort this out. Dan first posted on March 26th asking for advise as messages to the LinuxCNC forum were going unanswered.
Since then there has been approximately 118 posts going backwards and forwards between various parties for 14 days.

Now if 4 people conversant with Linux CNC can't sort this out in this time then what change does a complete newbie have ?

John S.
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Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #29 on: April 09, 2012, 03:13:48 AM »
Chris,

Excellent stuff!  :clap:

Now for some metal?  :thumbup:

:beer:

Phil.
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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #30 on: April 09, 2012, 05:52:31 AM »
Phil - Metal is next before I stop any more tests and finish the machine properly -stops etc....

I expect this is probably asking too much, but I`m very much learning CAD and I`m getting OK now for more obvious parts. I know this is only a practice, but I`d love to make a part I want. Could any draw this up for me to scale in a dfx file? However, i want it modifying...I want all the little teeth with only a 3/64" instead of a 1/8" line to the centre. In an ideal world, the hypotenus would then come up at a corrected angle to meet the tip of the next toot, but it actually doesn`t have to..there could be little flats between each tooth. The one deep tooth, at the top of the drawing, would than be 1/8". So basically, the wheel exactly how it is in all dimensions but I want smaller teeth and the one deeper tooth can be like the "standard" 1/16 on the original plans.

I`m away from my normal computer right now which is why I`ve attached the image rather than posted it. While writing my message I have realised this is likely not a two minute job so I appreciate it if any could even just give me some pointers as to how to get that drawn up, I`d be thankful. I`ve not tried a gear yet although with it being a ratchet wheel (count wheel on the clock), I expect it is easier than a normal tooth profile !


Chris

EDIT: Just thinking, I expect i`ll need to use pretty thin bras sheet and a 15deg engraving bit to get a sharpish angle in the corner where the pawl gets hooked. I guess I`m always going to get a round corner due to the radius of the cutter.
« Last Edit: April 09, 2012, 09:13:00 AM by craynerd »

Offline kwackers

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #31 on: April 09, 2012, 05:58:20 AM »

Now if 4 people conversant with Linux CNC can't sort this out in this time then what change does a complete newbie have ?

John S.
If they're talking then things have moved on...
Used to be Linux fanboys were like the high priests holding the knowledge and trying to get help with issues usually just met with abuse and unhelpful comments.

Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #32 on: April 09, 2012, 06:33:20 AM »
Chris,

Is this what you wanted?



The deep tooth at 1/8" looks deeper than your drawing. I've put the three no. 55 holes in the centre of the hub as there was no pcd for them.

DXF attached.

Cheers.

Phil.
« Last Edit: July 13, 2017, 02:42:01 PM by philf »
Phil Fern
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Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #33 on: April 09, 2012, 06:43:36 AM »
This is what I got keeping to the 60 degree limitation.





John S.
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Offline mattinker

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OT Linux / Windows
« Reply #34 on: April 09, 2012, 07:37:59 AM »
There is a very good thread going on at the moment on the Yahoo DIY-CNC group.
An American Dan Mauch, very knowledge and much respected is trying to get a Gecko 540 running on EMC but it won't run the charge pump correctly.

Three EMC uses, one of them a developer, Kirk Wallace, are trying to sort this out. Dan first posted on March 26th asking for advise as messages to the LinuxCNC forum were going unanswered.
Since then there has been approximately 118 posts going backwards and forwards between various parties for 14 days.

Now if 4 people conversant with Linux CNC can't sort this out in this time then what change does a complete newbie have ?

John S.

First of all, I don't want to pollute this very interesting thread. I'm really glad to see the great results that you are now getting

One can always find an example of what doesn't work with something. I use Linux for everything, principally because I don't want to contribute to Microsoft and their practices. The communal spirit of Linux is important to me. I have never had a problem that I couldn't resolve so far. Apart from being free, Linux has the immense advantage having no virus. Problems. There is of course another very important consideration, "the best system is the one you know".

Regards, Matthew

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #35 on: April 09, 2012, 09:11:49 AM »
John, Phil...many thanks for both your drawings! I think John, you have actually drawn what I want and what I meant to say. Phil, you have drawn exactly what I said....sorry my fault... :doh:

I`ll have another go:

The drawing shows 1/8" rim with "normal" teeth at 1/16" depth to the centre. I have asked for teeth 3/62" to the centre BUT then incorrectly, I said:
Quote
The one deep tooth, at the top of the drawing, would than be 1/8
... I`m sorry, that should have read the one deep tooth would then be the standard 1/16" from the original drawing. i.e making all the teeth smaller and so the "deep tooth" becomes the standard depth of the old drawing.

However, I`m fairly sure that is what you have done John...!

I`ll give it a bash later today... not sure how well it`ll work as I`m invetiably going to end up with a rounded corner. This could also be quite critical in its failure as this is where the pawl binds to the tooth to drag it around!

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #36 on: April 09, 2012, 09:24:07 AM »
OK now we have sorted the sizes out this is the wheel with a 1/16" master tooth.



shout up which DXF you want and I;ll email it.

John S.
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Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #37 on: April 09, 2012, 10:14:05 AM »
Chris,

I thought it didn't look right - what's 1/16" between friends?

You're going to have 2 problems I think:

The radius you've already mentioned and the fact that, using a tapered engraving cutter, you won't have vertical sides to the teeth.

You could always relieve the teeth something like (drawn for a 1mm dia cutter):



Cheers.

Phil.
« Last Edit: July 13, 2017, 02:41:38 PM by philf »
Phil Fern
Location: Marple, Cheshire

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #38 on: April 09, 2012, 10:15:40 AM »
Neat Idea Phil, gave me an idea.

Edit,

Chris has said he wants to use a 15 degree engraving cutter so i drew the cutter and offset the tip by 30 thou to see how big the diameter is when cutting 30 thou sheet. taking a guess here as Chris has said 'thin sheet'

So alter two teeth, the one on the left to give a rad at the bottom as you would get by profiling and the tooth on the right by pre driling with the cutter, then profiling.
Looks like the pawl will have to me modified from a complete angle to a radiused one to fit in.



Comments ? bricks ? flying custard ? muuuuuuuum yummmmy

John S.
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Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #39 on: April 09, 2012, 11:09:45 AM »
Hi John,

I don't know if Chris has a 15 degree inclusive cutter or half angle.

Whichever, the wheel will still have non vertical faces which I suppose could be compensated for in the pawl.

Personally, I'd prefer to use a small diameter parallel cutter to do it.

I prefer the look of the radiused bottom rather than the drilled relief on purely aesthetic grounds.

I'm going in the workshop to experiment on the Quorn T&C grinder - I've plenty of broken carbide cutters as blanks.

Alternatively, it's the ideal job for a 4th axis using a 60 dovetail (or fly) cutter.

Phil.
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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #40 on: April 09, 2012, 12:03:29 PM »
Phil...
Quote
Alternatively, it's the ideal job for a 4th axis using a 60 dovetail (or fly) cutter.

The last time I saw your machine I`m sure you demo`d the 4th axis in motion and you were just looking for the ideal project to really test it out !!! :whip: :dremel: :ddb:   

-----------

OK, just to quickly clarify how this wheel is being used... it is the count wheel. The pawl attached to the pendulum drags it around and equally the back stop jams up against the teeth lower down to step it around.



The reason I want to change this wheel is because it takes too much drive and lift from the pendulum to step the count pawl OUT of the teeth. The pawl is only 1/32" so actually in theory the teeth only need to be 1/32 deep to catch and lock the wheel and drag the wheel forward. I`ve said 3/32" to give some tolerance but it certainly doesn`t need to be 1/16 as per the plans. The issue is not actually with the 1/16" teeth...it is because the 1/16" tooth FORCES the "deep tooth" to be even deeper and consequently, if the clock stops (which it does infreqently!) it is because it just hasn`t quite got the momentum to slide the count pawl up the hypotenuse to escape the deep tooth. Having 3/32" teeth and a 1/16" deep tooth will mean that the "effort" to escape the deep tooth will be massively reduced from what it is now. Escaping the deep tooth will be mill escaping a normal tooth on the current wheel. This will make a massive difference. The angles that the pawls (count pawl and backtop) are set at also mean this small difference in the normal and deep tooth, it takes a real extra bit of momentum to escape it! Unfortunately, the way this clock works means that the deep tooth comes around right at the end of the cycle when the momentum of the pendulum is at its lowest!!

So after that little rant and explanation, I don`t think either of the two wheel with the circular roots will work as the hypotenuse must be a clean slope for the pawl to slide up to escape the wheel. Actually, I have no issue with the radius at the bottom of the tooth as this will allow the pawl to slide nicely to its escape...however, will this radius cause the pawl to jump over the tooth and not engage against it. It is the pawl dropping into the sharp root of the tooth that drags it forward without popping up over the top.

Not ideal, but perhaps if I just went ahead with the radius at the bottom I could go around the wheel with a needle file and just sharpen it up a bit...however, it does defeat the CNC somewhat!

I hope that has given you some more info in what I am trying to achieve...truth is, I`ve read your posts and now I`m still not sure of the way forward.

My only cutters at present near narrow enough are the 15deg engraver or a 2mm endmill.




Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #41 on: April 09, 2012, 01:23:07 PM »
Aha! Alles Klar!  :thumbup:

So the big clearance on my drawing wouldn't work at all. I was picturing a solid pawl.

John's radiused root should be fine - particularly if the rad is smaller than the diameter of your pawl wire.

The slope would also be better going to a point then it's not as steep.

I've just been grinding a 0.5mm cutter:



The end looks like:



I've ground enough parallel to cut about 1mm.

The trouble is that (according to GWizard) you ideally need a spindle speed of 77,716 rpm at a feed rate of 468mm/min.

Do you know what the maximum spindle speed you can get is?

You'd need to reduce the feedrate proportionally.

You're welcome to try it if your engraving cutter doesn't work.

Cheers.

Phil.
« Last Edit: July 13, 2017, 02:41:12 PM by philf »
Phil Fern
Location: Marple, Cheshire

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #42 on: April 09, 2012, 05:30:16 PM »
 :doh:
Damn, Vcarve won`t let me plot a toolpath that it knows it can not fit! I`ve taken Phil's attachement and selecting my 30deg inclusive engraving bit set at only 1.05mm in 1mm material depth and it tells me "Error: Check tool can fit into selected vector at machining depth" if I try and cut outside/right.  If I try and cut on the line it will create the tool path so I`m guessing it is doing this because it knows it can`t get into the corner...fair play to it, but that is a pain. If I choose to cut on the line it`ll make my wheel smaller than desired

I`m thinking that 4 axis is the only way to do this properly.

Chris

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #43 on: April 09, 2012, 05:43:12 PM »
Try it at 0.5mm then file the rest, you will have a pattern to follow and that bit of brass will file out easily.
John Stevenson

Offline philf

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #44 on: April 09, 2012, 06:08:07 PM »
Chris,

I've just done the preview in Cut2d with a 0.5mm cutter and it's come out OK.



I've attached another 'clean' DXF  the previous one had some arcs left on the points of the teeth from a previous incarnation. (That may have been the problem or maybe Cut2d doesn't worry about fitting into the corners.)
 
Good Luck.

Phil.
« Last Edit: July 13, 2017, 02:40:29 PM by philf »
Phil Fern
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Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #45 on: May 04, 2012, 04:26:17 AM »
Hi guys, I`ve only had half hour sessions in my workshop recently due to commitments at work and home. But I`m just updating a few of my threads, starting with this one.

Here is the cnc machine as it now stands and I`m pretty chuffed with how it has turned out. I`ve now milled aluminium sheet, brass and of course soft plastics and wood. I`ve also purchased some wider angle engraving tips that have been cutting very well.

I have a big project planned for this machine but more on that in due course.

Here is the machine as it stands:

The flexible cable shield is very good. I must admit, I`ve got a cable I can`t fit through which is stuck to the top defeating the purpose of the shield but it works well and keep everything near:


Electronics are housed in an MDF case with a clear perspex top. Master on off switches for the machine and spindle with the pot also hooked up to the front perspex case.


Hall effect sensor with a collar and magnet on the spindle gives me what seems to be a fairly accurate reading of spindle speed in Mach3. Unfortunately, Mach3 does a very poor job of controlling the spindle directly even with my microcontroller pic controlling the PWM in line with the ESC. I have a dual boot system and EMC2 / linuxCNC has no issue at controlling my spindle speed directly from the software!! Unfortunately, I prefer Mach3 and so I am living with manually controlling the spindle speed but with Mach3 displaying the RPM from the hall effect sensor:


Thanks for looking and all the help I got from various people on this forum when building this machine. It is better than anything I had thought it would be capable of!

Chris

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #46 on: September 02, 2012, 04:43:19 PM »
Hi guys,

Just wanted to show you my latest project. I was going to put it in the wood section but actually, I`ve done no woodworking skills to do this, it has all been CNC!!

I`m laying some parquet flooring in my porch. It is only a small 3m sq area and so I fancied making a little more special by adding some inlays. This is my first effort and more hopefully to come.

I just wanted something simple to try so I choose a star/compass with a N letter. It could be much more intricate but for now I wanted to just go with a single wood inlay. The parquet block is oak and the inlay is in maple.

Using VCarve, which I must say in my opinion is probably the best piece of software to match its quite complex function, that I`ve ever used! I created a vcarve path in the oak block. I then inverted the image and created a v carve path between my image vector and a rectangle I`d purposly added and drawn outside of the material boarder. This then cuts the material in the inverse and you get the image above the main timber level. This takes a lot longer as it has to remove all the extra.



Push the male into the female and glue.




Machine away the excess material and sand level:


OK, only a simple inlay but I couldn`t have even dreamed of doing this by hand. To get the "N" so well pronounced as well. I bet it would take a little more sanding and I would hope that would make the edges even sharper but I`ll leave this for now. I might use it, I might not...I`ll see how some more complex designs come out!

Chris


Offline micktoon

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #47 on: September 02, 2012, 05:02:05 PM »
Hi Chris , that last project looks realy good :clap: , very nice edges between the two woods, like you say you would have to be very good to do that by hand.
  Cheers Mick

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #48 on: September 03, 2012, 05:32:53 PM »
Cheers Mick, got another more complex design on the way now. We`ll see how that turns out.

Offline John Stevenson

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #49 on: September 03, 2012, 06:25:38 PM »
If you made them with an E for East instead of a N for North you could sell millions in Bradford and make a fortune.
John Stevenson

Offline NickG

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #50 on: September 05, 2012, 06:44:39 PM »
Just found this thread ... brilliant stuff Chris, have been quite amazed at this and your 3D printing.

 :thumbup:
Location: County Durham (North East England)

Offline raynerd

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Re: Aluminium CNC build (TEP mill converted) by Craynerd
« Reply #51 on: September 06, 2012, 05:28:18 PM »
Cheers Nick - I built it early in the year. It works really well. I need to get some better images of it in action to be honest.