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Gallery, Projects and General => Project Logs => Topic started by: wongster on February 19, 2012, 11:45:17 AM

Title: Set-Over Centre
Post by: wongster on February 19, 2012, 11:45:17 AM
I'm documenting my build of the Set-Over Centre from Hemingway Kit here, beside my blog, hoping to gather comments, criticism, tips, and suggestions from the helpful folks of this forum.

The Set-Over Centre is the 2nd kit I bought from Hemingway Kit.  The first was the knurling tool which I've not the confident to start working on.  Maybe after a few simpler projects I'll start my attempt.

Like most of the little projects I did, I've the drawings drawn on my notebook as 3D models so that I can visualise how things fit together.  The raw materials were cleaned up and cut to size to prepare for marking.

Enough of writing.  Time for pics...

The Slide

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32831024x768.jpg)
I measure the thickness of the steel stock and realised that it is not the 3/8" as shown in the drawing.  Same goes for the width, which is narrower than the 1" dimension given in the drawing.  I supposed these are not critical.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32841024x768.jpg)
Cleaning one side of the stock to use as reference.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32851024x768.jpg)
Marking out the other end to mill stock to length. This was the maiden "scribe" by my brand new Mitutoyo Height Gage.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32861024x768.jpg)
I can't be more happy with what I saw on the caliper.  This is important to me as I've not been able to "hit the mark" on the mill since I started the hobby.  Hoping to see more accurate work!

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32891024x768.jpg)
Marking out the holes and the area to be milled. I used the permanent marker as "layout fluid". Tried shipping in Dykem but my order was held in US and can't be shipped.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32901024x768.jpg)
Need to improve on using the punch. Would the optical punch help? Tried correcting by "moving" the punch marks as shown in some YouTube vids - not much of an improvement.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32911024x768.jpg)
I was wondering if I should use the edge to move to the centre mark but decided to try using the Mitutoyo Centre Finder.  Not really sure of how to use it though.  With the point in the punch mark, I adjusted the handwheels on both the horizontal axes till I feel the Centre Finder smooth at the moving part. Anyone can share how this is to be used?

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32921024x768.jpg)
Centre drill...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32931024x768.jpg)
Drilling with 6.4mm drill for 5/16" BSF.  Took quite a while to drill through.  There was quite some vibration felt during the process, prompting me to reduce spindle speed and ease the feed.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32941024x768.jpg)
Hole done.  Not very round isn't it...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32951024x768.jpg)
Tapping the hole.  The spindle with a dead centre was used to start the thread.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_32961024x768.jpg)
Countersink used to deburr the threaded hole.  Should I be doing this before tapping?

After finishing with the centre hole, I moved along X axis on both side of it for the 2 1/4" BSF tap holes.  The 1/4" BSF tap doesn't have a hole at the end of its shank.  So it went into the ER16 collet held in the spindle as guide.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33021024x768.jpg)
The Z axis was lowered while the tap was turned using a wrench on the collet chuck.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33041024x768.jpg)
Thread done and tested with a 1/4" BSF cap screw that came with the kit.  I don't have anything BSF at home to test the 5/16" BSF though.  It is meant for the threaded end of the half centre.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33081024x768.jpg)The surface was then cleaned of chips and oil. I redid the layout of the recessed area as the dye of the marker was washed away by the cutting oil.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33091024x768.jpg)
I was a little nervous when milling the recess.  My last work in steel making the flycutter was quite a painful one; the Sherline mill vibrated like no tomorrow and it was really loud!

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33101024x768.jpg)
It wasn't that bad this round.  Each pass was only 0.2mm deep.  After reaching the final depth of the recess (1/16"), the slot mill was moved to open up the slot above and below the centre line at full depth but with rather slow feed and speed.  Conventional milling was used.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33121024x768.jpg)
The recess completed.  I measured the slots and found that I've one end at 15mm while the other end is at the correct width of 15.08mm.  Is my horizontal axes not perpendicular to each other?  Also, I went 0.07mm to deep though I dialed in the correct amount.  I'll do the adjustments on the Base.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33131024x768.jpg)
The top was drilled and tapped for 2BA setscrew, right to the 5/16" thread hole.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33131024x768.jpg)
The setscrew installed. You can see that it is not exactly at the centre of the 5/16" thread hole.  Don't think this will cause problem.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/IMG_33161024x768.jpg)
The Slide is now completed.  I may not want to mill the radius at the 2 ends of both the Slide and Base to simplify the build.  Maye I should, to learn how this should be done.

I'll work on the Base in my next session in the shop.  One question which I would like to ask.  The 2MT arbor needs to be machined and thread 5/16" BSF.  I'm scratching my head thinking through how I should be holding the arbor.  The Proxxon lathe has a 3MT in the spindle.  My Sherline lathe has 1MT.  Do I hold it between centre?

Thanks for reading and hoping for comments to help me along.

Regards,
Wong

Title: Re: Set-Over Centre
Post by: Chuck in E. TN on February 19, 2012, 12:37:59 PM
Get a MT3 to M2 sleve to hold your MT2 blank for threading. It can also be used for test fitting a MT2 taper if you make one with your new tool.
 
 Edit to correct spelling.
Title: Re: Set-Over Centre
Post by: wongster on February 19, 2012, 12:57:27 PM
Why didn't I think of that!!! Thanks Chuck.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on February 19, 2012, 03:07:43 PM
Wong,

That is a great start - it looks very good to me :clap: :thumbup:

If you have the scribed lines one may not need to centre punch. Just line up the "cross" lines with that 'pointy bit' and in my case with a magnifying glass, then use your centre drill  :) :) :)

BTW the hole looked perfectly round to me, must be the camera  :Doh:

Nice photo's well posted :thumbup: :thumbup: :thumbup:
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: Xldevil on February 19, 2012, 04:53:39 PM
Hello.
I've made the set over center this January.
I've not done the radius to the slight as well.
If you leave it square,it's much easier to set the center at right angle to the base of your lathe,using an engineers square.This is essentiell for turning accurate tapers.
I've also done the knurling tool from Hemingway.It has been an easy build and it is a good tool to work with.
If I could do it,I'm pretty sure,you can do it too.
I'm not very talented,but I'm stubborn,if you know what I mean.
(http://up.picr.de/9272592oqg.jpg)
Cheers,Ralph
Title: Re: Set-Over Centre
Post by: wongster on February 19, 2012, 06:06:39 PM
@DaveH, thanks for the encouragement.



@Ralph, yours looks nice!  You know what, I just remembered, from looking at your pic, that I missed out the witness line across the top of the part...  :doh:  For the 1/4" slots, did you mill the slots at full depth in a single pass?  I don't know if my Sherline mill can handle that and was thinking of using clamps when drilling the holes as stops so that I can mill them with multiple passes.

If I've not appointments or meetings on Tuesday night, I'll start working on the Base.  Wife will be away for meeting till late, so it will be just shop and me...  :)

Regards,
Wong
Title: Re: Set-Over Centre
Post by: jcs0001 on February 19, 2012, 07:09:56 PM
Wong:

Interesting looking tool and very good photos of your progress.  I've seen a simplified version of this in one of Guy Lautard's Bedside Reader books (#2) but have never given much thought to building one.

I would appreciate knowing how well it works for you (and Ralph since his is complete).

Thanks,

John.
Title: Re: Set-Over Centre
Post by: wongster on February 19, 2012, 07:13:46 PM
John,

When I get there, I will  :D

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on February 19, 2012, 08:12:16 PM
Wong,

There is a bit in this about milling a slot. It may you.

http://madmodder.net/index.php?topic=4678.msg51465#msg51465

 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on February 19, 2012, 08:32:16 PM
Thanks DaveH. I had that PDF'd when I read it last year. I'll clamps to mark the limits of the slots and take the D/2 depth (0.125") as indicated in your article.

One thing I realized when milling the slot in the slide. The 3/8" slot drill I used from Sherline actually cut 0.372" instead of 0.375". Don't think that will cause any problem with the 1/4" slots I'm going to mill in the Base.

Regards
Wong
Title: Re: Set-Over Centre
Post by: Xldevil on February 20, 2012, 03:25:43 AM
@Wong
I made the slots by multiple passes.Having a DRO on my mill,it has been an easy task.

(http://up.picr.de/9601197yps.jpg)


@John
The first and only MT I have  done up to now using the s.o.c., looks pretty good to me.

(http://up.picr.de/9601152dtu.jpg)

(http://up.picr.de/9601153asy.jpg)

Cheers,Ralph

Title: Re: Set-Over Centre
Post by: Fergus OMore on February 20, 2012, 03:38:33 AM
Ralph,
           I notice that you have a rotary table so you can happily round off 'ends' on your work.

Cheers

Norman
Title: Re: Set-Over Centre
Post by: MadNick on February 20, 2012, 06:40:41 AM
Good start Wong, some good questions being asked and answered.

Thanks DaveH for the link to your milling 'how to', lots in there I didnt know before.

Nick
Title: Re: Set-Over Centre
Post by: krv3000 on February 20, 2012, 06:46:43 AM
HI a Good billed I'm slowly gathering up materials to make one up my self
Title: Re: Set-Over Centre
Post by: wongster on February 20, 2012, 07:21:29 AM


@Nick, thanks for the encouragement.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: WillieL on February 20, 2012, 09:44:01 AM
Wong,

That is a great start - it looks very good to me :clap: :thumbup:

If you have the scribed lines one may not need to centre punch. Just line up the "cross" lines with that 'pointy bit' and in my case with a magnifying glass, then use your centre drill  :) :) :)

BTW the hole looked perfectly round to me, must be the camera  :Doh:

Nice photo's well posted :thumbup: :thumbup: :thumbup:
 :beer:
DaveH

Wong,

I also agree with Dave here. You are off to a good start.

I think center punch marks are great if you are going to use a tiny drill bit to make a guide hole for a larger drill. There is no benefit if the size of the chisel tip won't fit inside your punch mark. The chisel tip on a larger drill bit will just skid around on top of the punch mark and can wander off center. In that case, as Dave mentioned just use your scribe lines and center finder to locate the spindle to the work, and then apply your center drill.

If I am using a center punch I find I have much better control using a manual (plain) punch and tapping it with a hammer. I can never seem to push exactly straight down using an automatic center punch. It always ends up going off of my mark.   :(
They are great for quick jobs that don't need a lot of precision though. An optical center punch is a great addition if you have a good one. Other users have discovered that the "cheap" ones aren't very accurate and are a waste of money.

Something you might want to consider in the future, and this is just one man's opinion....
I would done those operations in a slightly different order myself. I believe I would have milled the slot in the part first, and then drilled the holes - followed by chamfering them and finally tapping the threads.

That way you aren't milling away the chamfers and threads you made previously. And doing the chamfers before threading helps to guide the tap into the hole and makes it easier for the tap to get the threads started cleanly. Any burrs raised will still be below the surface of the part, and won't rub on your other part as it slides.

Just my way of thinking anyway. I'm certainly no expert at any of this. You are doing just fine though IMO.  :beer:

Title: Re: Set-Over Centre
Post by: wongster on February 20, 2012, 10:07:24 AM
Willie,

Thanks for the tips and encouragement.  I find the automatic ones rather hard to push down.  May be the reason why getting the mark on is a hit and miss...  The optical punches I saw on Little Machine Shop and another site don't look cheap - but cheap is relative...

Regards,
Wong
Title: Re: Set-Over Centre
Post by: WillieL on February 20, 2012, 11:48:12 AM
- but cheap is relative...

Regards,
Wong

So true. I only meant don't buy from the bottom of the barrel. IIRC, one of the other members here bought the least expensive "import" optical punch that Enco had to offer. He said the base was missing the cork(?) washer that is supposed to hold it in place, and the base would move on the part as he was trying to hold it. I think he also said the punches were a bit of a sloppy fit in the holes in the base as well.

I believe he said another brand didn't cost much more, and was a big improvement over the economy model he first went with.
Sorry, I don't remember which one it was though.    :scratch:
Title: Re: Set-Over Centre
Post by: Xldevil on February 20, 2012, 12:20:37 PM
Hello.
The optical center punch I'm using is made by veritas tools.
It works great.
In the long term,the good tool is always the cheaper one.
Cheers,Ralph
http://www.leevalley.com/us/wood/page.aspx?p=45502&cat=1,180,42311
Title: Re: Set-Over Centre
Post by: jcs0001 on February 20, 2012, 02:36:26 PM
Ralph:

Thanks for showing the mt sample you made - looks good to me.

John.
Title: Re: Set-Over Centre
Post by: DaveH on February 20, 2012, 04:18:16 PM
The 3/8" slot drill I used from Sherline actually cut 0.372" instead of 0.375".
Regards
Wong

Wong,
Well that is just not acceptable, worst I ever heard  :(
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on February 20, 2012, 05:47:36 PM
WillieL/Ralph, the price range is rather big.  Veritas' is about $40, Little Machine Shop's almost $70 (up to 0.002"), and Travers' about $83 (up to 0.001").  I now believe in buying one time after the experience with the Height Gage which I just replaced.  The Taiwanese gage I have is not that cheap but its about 1/2 the price of the new Mitutoyo 570-312 (made in China though).  Don't know which Optical Punch to go for yet.  Will have to read more.

DaveH, I'll run some more test with a deeper slot to ease measuring with the caliper to confirm this.  One thing I observed during making the initial slot was the slot drill cut better when held in the the endmill holder from Sherline.  When I was using the the ER16 collet chuck (with 1MT shank), the surface finish wasn't impressive.  Maybe the collet chuck sticks out more to make it less rigid in the micro mill.

I'm hoping for another session in the shop this evening when my wife is away for church meeting till late.  Will be thinking of correcting the tapered slot in the Slide and see if I can mill the same width on the Base to match.  I'll try, as Norman shared, using the edges at one corner of the workpiece to layout the holes and lines instead of the centre hole.
Title: Re: Set-Over Centre
Post by: DaveH on February 20, 2012, 06:01:43 PM

DaveH, I'll run some more test with a deeper slot to ease measuring with the caliper to confirm this.  One thing I observed during making the initial slot was the slot drill cut better when held in the the endmill holder from Sherline.  When I was using the the ER16 collet chuck (with 1MT shank), the surface finish wasn't impressive.  Maybe the collet chuck sticks out more to make it less rigid in the micro mill.


Wong,
I wouldn't concern yourself with it at the moment, go with what works.

Just to let you know I have a sherline mill and lathe. See my avatar made only on the Sherline's.
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: Fergus OMore on February 21, 2012, 06:48:35 AM
Wong,
          By now you should have a couple of poor-ish copies of the little 'centre finder' or sort of D Bit from the other book by George Thomas.

It came from the write up on his Versatile Dividing Head which I made up some years ago. Again, this is a very worthwhile tool to gain  more machining experience but to be invaluable for all sorts subsequent worth.

I was musing- it had been a night of nights next door to a Chinese dragon display- and then innumerable courses and a disgusting lot of wine.
We all have problems :coffee:  And the coff/tea needs to be stronger but you made an Ian Bradley tool. Did you realise that George Thomas took many of the Bradley 'designs' and improved on them?

Now there is a thought :bow:

Cheers

N
Title: Re: Set-Over Centre
Post by: wongster on February 21, 2012, 08:32:56 AM
Thanks N.

Lunar New Year was towards the last week of January.  It went on for 15 days (by tradition) but most of us were back to work on the 3rd day (only first 2 days are public holiday in Singapore).  I started work on the 2nd day till 11 pm as I was scheduled on duty at a new property launch. This year was quieter with watered down festive mood in this country.

I'll spend some time reading through all the books and materials, including the 2 jpg's you sent.  My understanding should improve as time passes.

Just got home from appointments. Too tired to do anything today in the shop.  Will read instead.

Regards,
Wong

Title: Re: Set-Over Centre
Post by: Raggle on February 21, 2012, 04:04:00 PM
I'd call this optical and guaranteed vertical punching

http://www.schsm.org/html/marv_klotz_29.html

see the next 2 pages to complete your understanding.

(I still haven't made mine :) )

Ray
Title: Re: Set-Over Centre
Post by: wongster on February 21, 2012, 06:48:55 PM
Cool stuff!  Thanks Ray.
Title: Re: Set-Over Centre
Post by: Fergus OMore on February 24, 2012, 03:07:22 AM
I've just sent what is as near a copy of George Thomas's simple centreing device 'explanation' and drawing as I dare without  infringing copyright.

The device is so simple that there is virtually nothing that I can add.

Can anyone else- add or explain please? :doh:
Title: Re: Set-Over Centre
Post by: wongster on February 24, 2012, 10:23:22 AM
Hi Norman,

I received the jpg of the 2 pages, thanks.  Can't really read it as the jpg is a little too small and when enlarged, the text is to blur to make out any word.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: Fergus OMore on February 24, 2012, 11:37:42 AM
I'm afraid that for reasons of copyright, I am unable to copy. I deliberately only tried to print the drawing.

Simply make a D bit- or don't make one. If you use a bit of .500 round- all you allow for is 0.250 at the edge of the work rather than zero with a centreing device.
Title: Re: Set-Over Centre
Post by: Miner on February 24, 2012, 02:45:02 PM
Wong,
Everybodys methods and favorite techniques are a bit different. When it needs it, I make a layout as a general check for miscounting handwheel turns. But if your leadscrews are in pretty good shape and dependable for measurement? I don't use any center punch marks at all. Locating your marks and starting the hole with a center drill by coordinate measurement works real well. It does take a bit of time and practice to get fully used to using that system though. That's where those edge finders come in. If it was good enough system to use for the super accurate Moore jig borers and grinders? Then it's more than good enough for me. Having dial indicators for measureing the slide movements, Or a DRO makes the job that much easier. It is a bit slower way to work since your using a center drill to start, Then switching over to your drill. But if you factor in the fairly accurate center punching time, This method could be a bit quicker.

If my memory is correct, It's called the Cartesian coordinate system? But the correct name is not that important. It's the technique that is.

Pete
Title: Re: Set-Over Centre
Post by: Fergus OMore on February 24, 2012, 03:43:17 PM
Yes, it's the cumulative  Descartes stuff which many of us use.  It is far less prone to making mistakes with 'Simple Arithmetic' going from making what is in effect establishing a zero at each centre drilling. Of course the zero, may not be accurately determined.

Someone mentioned 'Tubal Cain'- not this Johnny Come Lately but the Tom Walshaw variety and he set off to knock the so called experts who were all called to centre on two scribed lines- and none of them could.

Interesting stuff. And it all gets worse with worn leadscrews 'et al' :smart:



 
Title: Re: Set-Over Centre
Post by: wongster on February 24, 2012, 08:58:02 PM
Thanks all for your input. I'll go it without centre punch for the next piece and use a corner as reference. Using the centre hole location is convenient the drawings uses that as the reference. I read from one book (can't recall the name) that if the drawings uses a certain point as the datum, all measurements are relative to that datum. Using a corner of the workpiece is more convenient for me as I'm more familiar with it.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: wongster on February 26, 2012, 11:40:47 AM
The Base

I started off my Sunday morning redoing the dimensions of the Base of the Set-Over Centre using the bottom right corner of the workpiece as datum (hope I'm not using the wrong word here).  The drawings from Hemingway have the location of all features relative to the centre 5/16" BSF tap hole, which I followed when fabricating the Slide.  Counting the number of turns on the dial is easier with the datum from the bottom right corner and I was moving the table in one direction, thus not having to worry too much about backlash.

The stock was cut almost to length on the bandsaw and trimmed to 3" as called out in the plan.  This is the 2nd time I'm hitting the exact dimension - a real boost of confident.  Wishing for more as I progress...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/b6357fdc.jpg)
Redoing the drawings with the bottom right corner of the workpiece as datum.
 
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/51215927.jpg)
The stock was held in the vise and carefully tapped down to ensure full contact on the parallels beneath.  The layout lines can be seen in the pic.  No punch mark this time as advised in the forum.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/b3968b9d.jpg)
Measuring the tip of the Proxxon Edge Finder. It actually measures 0.2", kind of strange from Proxxon which has everything else in metric.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/bac54124.jpg)
Finding the edge in Y axis.  The table was moved over by half of the tip of the Edge Finder to zero the spindle axis to the edge of the workpiece. X was next.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/d7ee3a0f.jpg)
Centre drilling of the 5 holes for later operations.  This is the first time I centre drill all the holes before drilling.  I always like to centre drill and drill through each hole before moving to the next location to reduce the number of times I have to move the table (and save on counting...).

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/76f67d2e.jpg)
Drilling the holes using 1/4" drill.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/a814d44f.jpg)
A pair of machinist clamp was deployed as limits for the slot to be milled.  There are 2 slots in this part; one connecting the 2 holes on the right and the other, the last 2 holes on the left.  This will save me from having to count the number of turns I've made to focus on the job at hand.  I plan to make mill stops in the near future for all 3 axes to ease the process.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/57897b66.jpg)
Begin milling the slot with a 1/4" slot drill. I started with depth of 0.2mm per pass but went on to 0.5mm.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/4021b726.jpg)
Slot done.  The 3/8" slot 1/4" deep was next.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/253f10eb.jpg)
A piece of scrap used as depth stop for the Z axis.  Wanted to use machinist clamp for this but I couldn't locate the other 2 pieces I bought.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/9ec1c439.jpg)
Done! Time to test if the cap screw will fit.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/7d1e06e7.jpg)
Unfortunately not... The supplied 1/4" BSF cap screw's head measures slightly larger than 3/8" and the 3/8" slot drill from Sherline cut the slot at 0.372".  The 0.372" seems to be consistent with the slot I did in the Slide before widening.  I will be buying another one locally for further testing.

Till the next session, be blessed.






Title: Re: Set-Over Centre
Post by: andyf on February 26, 2012, 12:19:47 PM
[quote)... The supplied 1/4" BSF cap screw's head measures slightly larger than 3/8" and the 3/8" slot drill from Sherline cut the slot at 0.372".  The 0.372" seems to be consistent with the slot I did in the Slide before widening.  I will be buying another one locally for further testing.

[/quote]
Hi Wong
Turning the head of the screw down by a few thousandths would be easier than widening the slot.

Andy
Title: Re: Set-Over Centre
Post by: wongster on February 26, 2012, 12:30:10 PM
Hi Andy,

You're right.  I may do just that.

One question which I need your input.  I'm re-reading the part on screw cutting the 5/16" BSF to provide a tighter fit.  Does screw cutting means using the lathe to cut the thread using a single point tool?  I'm not sure if I can do that with my proxxon.  This is my first encounter with BSF.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on February 26, 2012, 01:16:15 PM
Wong,

Nicely done :thumbup: :clap:  good use of the tool makers clamps.

The 5/16" BSF can always be changed to a 'near' metric one.
If one uses a split die it can be allowed to cut on the high side, adjusted until you are happy with the fit. Also if the threaded part is long, then at least a partial cutting on the lathe keeps it on the straight and narrow. The final 50% of the thread is completed with the die.

 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on February 26, 2012, 06:23:03 PM
Hello DaveH,

I've the split die  :D  I'll give that a shot.  The female tap hole has already been done, there goes my chance to change to a near metric one.  My experience so far on using a die to cut threads have not been at all pleasant, even with a chamfer at the end of the workpiece.  Let's hope I'm able to get it on this time and change the experience.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: MadNick on February 27, 2012, 08:52:13 AM
Glad to see you are getting stuck in!

BTW I found the same problem with cap bolts, the diameter of the head can vary. The time I didnt check this I had to take a few thou off as has been recommended - I made and used a mandrel to do this.

Nick
Title: Re: Set-Over Centre
Post by: wongster on February 27, 2012, 09:40:51 AM
Hi Nick,

Do you have a pic of your mandrel?

Regards,
Wong
Title: Re: Set-Over Centre
Post by: andyf on February 27, 2012, 09:50:01 AM
Wong, I had to turn down and slightly reduce the length of the heads on a load of them. I took a bit of round bar, drilled and tapped it (M5 in my case) in my 3-jaw, then screwed each Allen bolt in to it and did the turning. The tool pressure tends to screw the bolt tighter into the bar, si it is secure.

Andy
(with apologies for interrupting you and Nick)
Title: Re: Set-Over Centre
Post by: wongster on February 27, 2012, 11:39:23 AM
Hi Andy,

Thanks! Didn't realize it is as simple as that! I imagined something more complex... Silly me.


Regards,
Wong
Title: Re: Set-Over Centre
Post by: Tony Wells on February 27, 2012, 01:31:33 PM
You may also see issues with the concentricity of head vs threads. Fasteners generally aren't regarded as precision components. It's standard practice to make allowance for heads not running true with threads.
Title: Re: Set-Over Centre
Post by: wongster on February 27, 2012, 06:06:11 PM
I'm now wondering the reason why the plan calls for 3/8" slot for the screw head given that the 2 screws provided has diameter of their head at 3/8" being the smallest when measuring at one side of the head.  If I'm to press it in, I wouldn't be able to move them easily.  I'll do as Andy said, to trim the head just a tiny bit to have it seat in the slot.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: wongster on March 03, 2012, 11:59:52 PM
I continued with the work on the Base and completed it over 2 sessions of about 2 hours each.  I took it very slowly when milling the other slot with a 10mm slot drill due to the vibration and loud noise.  The feel on the handwheel while feeding didn't feel smooth at all.  This may be caused by the ER16 spindle chuck I'm using which extended the tool out quite a bit.  I didn't have that problem when using the Sherline's endmill holder but the largest holder I've from Sherline is 3/8"...  Some rectification was done to the Slide's slot as one side is tapered.  The 2 components now fit nicely together and the sliding one against the other is smooth.  4 more parts to complete before I can call this done.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/5a9cd046.jpg)

Moving over to the start.  The more I use the mill, the more confident I get in getting to the spot I want using the handwheels.  The right limit of the slot was set with the tool maker's clamp on the right of the job against the saddle.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/41b431af.jpg)

Moving to the left limit and setting the clamp.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/2dd66e09.jpg)

Milling the 1/4" slot with the Sherline 1/4" slot drill.  The Sherline's endmill holder in use here.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/1fc43498.jpg)

Slot done.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/6f5df518.jpg)

The 10mm slot drill in the ER16 collet chuck was employed to cut the counterbore slot.  To set the depth, I plunge the slot drill to the depth of 1/4" and fit another piece of the toolmaker's clamp on the column bed.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/de4108d5.jpg)

Slot done.  I went at 0.25mm per pass to minimise vibration.  The cap screw sit flush with the top surface of the Base.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/77c58def.jpg)

The centre hole enlarged to 6.4mm to tap 5/16" BSF.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/a26016d1.jpg)
Testing fit.  No side wobbling encountered.  I'm pretty pleased  :)

The instruction calls for the 2 x 2BA holes to be done on the drill press.  I was running out of time to set up the drill press (its under the bench...) and so stand the part in the vise and carry on.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/0e1ab572.jpg)

Locating the side and dialed to the centre of the workpiece.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/44f38d96.jpg)

Centre drill and drill through with a 4mm.  I'm at the limit of the z travel...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/7e7d8d5d.jpg)

A piece of card stock used at the back to check if I'm right in the middle.  Not too bad..

The part was then flipped over to drill and tap the other 2BA hole on the other side.  This completes the work on the Base.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/9adb815f.jpg)

View from the back where the 2MT Arbor will be screwed in from.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/6825cec0.jpg)

The front.  I'm wondering if the screws are a little too long.  The drawing shows them as almost flushed with the surface.  Can those who did this confirm if I need to shorten the screws?

The rest of the work will be mostly done in the lathe.  From the plan, I'm left with making the 2 adjustment screws, the Centre, and the 2MT Arbor.

I'm hoping to get back to the shop real soon!

Regards,
Wong

www.wongstersproduction.com
www.wongstersproduction.blogspot.com
Title: Re: Set-Over Centre
Post by: DaveH on March 04, 2012, 07:08:12 AM
Wong,

That is very nicely done, good use of the toolmakers clamps- clever idea.  :thumbup: :clap:

Milling is at the best of times a slow process, and you did a good job with your mill :clap: :clap: :clap:

Looking good :thumbup: :thumbup: :thumbup:

 :beer:
DaveH

Title: Re: Set-Over Centre
Post by: wongster on March 04, 2012, 07:16:27 AM
Hi Dave,

Thanks. Really feel good everytime I read your comments despite knowing that I did screw up on some parts. Thanks for the encouragement!

Regards,
Wong
Title: Re: Set-Over Centre
Post by: krv3000 on March 04, 2012, 10:32:31 AM
HI wong Very well done
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 04, 2012, 02:11:11 PM
Question! How are you going to cope with the three dimensional effect of Pythagoras when all is said and done.

Euclid only did it in two dimensions, if I recall :coffee: 

Title: Re: Set-Over Centre
Post by: Miner on March 04, 2012, 03:11:15 PM
Norman,
The dude that thought that up was bit behind times. If? I'm reading your referances correctly, A dial indicator across the top till it reads true will straighten out that theroy. Royal did much the same on their no longer built screw adjustable centers with a built in level.

Pete
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 04, 2012, 03:39:17 PM
Ah, yes but. You have to be a bit careful with debunking the theory.

So you are attempting to to revert to plane geometry- or back to Euclid.

To be honest, it's all an academic exercise in machining. Of course, this has a certain relevance but   Ian Bradley was merely 'fooling about'. It was the Beginners Lathe thing in ME which is not to be taken too seriously.

Title: Re: Set-Over Centre
Post by: Fergus OMore on March 04, 2012, 04:30:13 PM
Spririt levels, perhaps -- and females with balls :bang:
Title: Re: Set-Over Centre
Post by: Miner on March 04, 2012, 04:46:31 PM
LOL, Norman knows quite well I know exactly what he means. He's referring to George Thomas's writings where having the correct support while using an off set center idealy needs what are called Bell Center Drills that will drill a radiused center hole and also a hardened ball at the tailstock end. This gives you the best contact and support possible while your part is offset from the lathes center line.

Apologys Wong, We seem to have gone a bit off topic on your thread.

Pete
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 04, 2012, 05:08:30 PM
Hmm??  My top slide has a removable parallel dowel that automatically locks and  gives No 2 Morse Taper. Plain simple Plane Geometry and the setting is unaffected by the length of the material  and all sorts of circus perfomances.

Bung a peg in, and with nothing up my sleeve, one has a beautiful taper shank just for the turning.

The authority-- Martin  Cleeve ( Hart)- not George Thomas.

Title: Re: Set-Over Centre
Post by: wongster on March 04, 2012, 06:45:03 PM
Hi Pete, no OT at all.  All within the scope of turning taper.  I did some reading online and saw the bell centre drill used to create the radius-ed centre hole.  Though someone else in that forum mentioned about using a ball (balls? where did the other one goes...) on the centre, a pic was shown without one in use.  I don't think I'm capable to whip up a ball end type of dead or alive centre at this moment.  Would the 120 degree centre hole from the bell centre drill suffice?

To keep the set-over centre on plane, I would be doing what Ralph did - leave the side of the Base square so that squaring it up would be much simpler.

Will these work?

Title: Re: Set-Over Centre
Post by: Miner on March 04, 2012, 07:19:36 PM
Hi Wong,
Your right, And I didn't go far enough with my explanation. Your work piece would have a bell type centers drilled in it at each end. And then a ball type center is used at both the headstock and tailstock ends. You then just use a standard lathe dog to provide the drive.

Finding a hardened ball for the headstock isn't tough. You'd just buy what are commanly referred to as Tooling Balls. You would want the unthreaded or plain shank ones.

Using one at the tailstock end? And especialy as a ball end live center? That's a tough one. And for building something like you are right now? You'd need to design and incorperate the proper bearings in right from the start. None of it's impossible, Just quite difficult to do. Due to the slideing action on the ball as the part rotates. Even a hardened tooling ball will wear over time. So designing a simple system to replace that live ball center would be another high priority. Even that $450.00 Royal offset capable center in 1982 didn't have that set up, Or at least that I know of.

I can think of at least one way to do it. But it would take at a minimum a tool post grinder.

Pete

Title: Re: Set-Over Centre
Post by: wongster on March 04, 2012, 09:51:27 PM
 :jaw: this is starting to be beyond my capability at this point. And I was thinking that if I can successfully complete building according to plan, I can start  making taper...

I saw from some sites that sell live and dead centres some different tips. If I can find one with ball end for head and tailstock, will that work?

Regards,
Wong.
Title: Re: Set-Over Centre
Post by: Miner on March 04, 2012, 10:01:15 PM
Wong,
No problem, Yours will work just fine as designed. We just ended up moving towards the "ultimate" tool defination. Maybe a future project for you to keep in mind. I'm not all that sure I could do a proper 100% job on a tool of that type. It might be fun to try though. I do know there's members here that would have no problems making one.

Pete
Title: Re: Set-Over Centre
Post by: wongster on March 04, 2012, 11:57:34 PM
Thanks Pete. I'm sure we've folks here that have the ability.

Title: Re: Set-Over Centre
Post by: Xldevil on March 05, 2012, 03:01:23 AM
Hello.
I'm using no ball center with my soc. and my first attempt to make anMT 2 looks good to me.I've adjusted the soc. by the use of a dial indicator and the fomular given here at the bottom of this page:
http://www.digitalproducts.de/Kegeldrehen.php
You only have to fill out the form and it will show you how much you have to offset your tailstock.It even shows you,if the offset is too much to be safely turned between centers.
http://digitalproducts.aklein.org/formeln/Berechnen.html
Unfortunately the page is German,but math is international.
Nevertheless,a little translation:
D  wanted biggest taper dia.
d  wanted smallest taper dia.
L given length of taper
Lwgiven length of workpiece
VR needed offset of the tailstock
VR max  maximum safe offset of tailstock
Cheers,Ralph
Title: Re: Set-Over Centre
Post by: Xldevil on March 05, 2012, 03:01:59 AM
mistake,sorry
Title: Re: Set-Over Centre
Post by: wongster on March 05, 2012, 03:12:08 AM
Thanks Ralph.

Btw, the bear in your avatar is cute.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: Xldevil on March 05, 2012, 03:21:15 AM
Thanks Ralph.

Btw, the bear in your avatar is cute.

Regards,
Wong
Hi,Wong.
That guy is called flat Eric.
He has been popular in Levis commercials.

#Cheers,Ralph
Title: Re: Set-Over Centre
Post by: andyf on March 05, 2012, 08:34:25 AM
 He's always getting in the way round my shop


(http://i689.photobucket.com/albums/vv257/andyf1108/Ledlights/FlatEric.jpg)


Andy
Title: Re: Set-Over Centre
Post by: wongster on March 05, 2012, 09:05:00 AM
Cool...  :clap: :clap: :clap: :clap:

and Andy, what is flat eric sitting on the lathe with the swarf and everything?!

This chap didn't appear in any ads here.  The last Levi ads I ever seen on TV was so long ago...
Title: Re: Set-Over Centre
Post by: andyf on March 05, 2012, 12:26:02 PM
I only took him on to sweep up the swarf, Wong, but he's too idle to do it.

Andy
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 05, 2012, 02:28:54 PM
Pete( Miner) and I have been having our usual cross Pond banter about this. The first point is that my original reply from this AM seemed to disappear. There were 4 other posts- and all far less valuable.

The first point to consider is that it is almost impossible to produce a taper in hardened steel- with what you possess.You can produce 'soft centres' and I don't mean 'chocolates' but if you want points which will stand the hurly burly at the tailstock end, you need to re-think. You might have to resort to making a centre in soft metal and drill it and add a hss or perhaps carbide round insert. Again, you are going to be pushed to make a hard half centre which, despite all the shenanighans about rotating centres is going to be accurate to a much higher degree.
Having said that, you can make rotating centres with caged ball races but you will need to get friend Sparey's Amateurs Lathe book or similar!
If you are going to simply interspace a ball bearing between the fixed and rotating bits, you'll be wasting your time.

So let's move on. Pete and I came to the conclusion that the Hemingwaykits thing is the least practical of the alternatives. What are the alternatives? Ideally, the common or garden boring head- be it bought out or home made will create better morse tapers that the one mentioned. Again, the boring head will go on to produce ball handles!

However the taper be it soft or otherwise, is not going to be anyway as accurate as one which is produced on a regular taper turning attachment fitted to a lathe-- or better still, on a grinder. Does anyone really think that a kit containing a ready made Morse taper shank was done on a model maker's lathe on ' something or other'? :loco:

Pete and I got on to 'real' taper turnings. I had said that a 5 inch sine could be squeezed onto a lathe- if any sort of accuracy was required.
Recall that our Mr Morse adopted the taper to hold a cutting tool with accuracy and not causing murder and mayhem like the wheels of Queen Boudicca's chariot. :hammer:

Ten inches is better(  :lol:) but Pete had a yearning to fit a Sherline long lathe bed to the bed of his bigger lathe. I sort of gulped at the idea- which is sounder than one thinks. I simply countered with the comment about my little home made Stent tool and cutter grinder by saying that the working table is - well, 10" and it swivels and is able to swivel not only in degrees but will not  1.49107  or 1.42871 or 1.43069 or 1.43770 or even 1.48759 degrees for half angles. These are the quoted figures. I can just about manage the one and
half degrees on a good night with a following wind :smart:

This, despite all the Jazz, is what morse tapers is all about.
Title: Re: Set-Over Centre
Post by: wongster on March 10, 2012, 04:15:43 AM
I only had a short time to play before my scheduled weekend duty. Started on the side job making the washer for the drawbar to hold the ER32 collet chuck in the 3MT spindle.  I removed the lathe chuck and put on the ER32 collet chuck to determine the length required for the M12 drawbar. 

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/ad97a6f0.jpg)

A piece of steel rod inserted to roughly mark the length from the back of the collet chuck to the edge of the spindle end. It measures around 125mm.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/3ae3900d.jpg)

Picked up these while packing lunch yesterday. 3 lengths each of M12 bolts and socket head cap screw of 150mm, 180mm, and 200mm. 

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/8fe96ca4.jpg)

Of the six pieces of M12 bolts & cap screws, only the two 150mm fit nicely with an allowance sufficient to add in a washer of sort. Of the 2, I like the socket head better as it is smaller in diameter and allow the gear box door to close properly. Also, I don't think I'll have sufficient room to use a spanner to loosen the bolt should the hex head is used (unless a thick washer is made to extend the drawbar out of the gear box bore. But that would mean I have to leave the gear box door open when the chuck is in use). 

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/154c91a3.jpg)

The hex head in use to determine which length works best. Can't use the socket head ones as their head is smaller than the spindle bore. I decided on the 150mm length as it allows a washer to be used with sufficient threads engaged.  

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/154c91a3.jpg)

The gear removed to properly measure the ID and OD of the spindle end to make the washer. ID is 20.45mm and OD 24mm.  

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/12b67f60.jpg)

1" diameter steel stock is all I have for this job. 

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/cd858730.jpg)

A section of about 40mm in length cut in the bandsaw. 

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/0e15c9f5.jpg)

The uneven end was first faced.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/29063145.jpg)

Reducing the diameter to match OD of the spindle end. My target size for the washer is 24.5mm.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/03c7562d.jpg)

A short section was then turned down to 20.44mm for a loose fit in the spindle bore.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/4da698d8.jpg)

I've to stop here as I need to prepare to go to work. What's left is the drilling and boring of the 12mm hole and part it off.  Hope to finish it tonight and move on to work on the rest of the parts for the Set-over Centre. One thing I read about but don't understand how it works. Instead of tapping the drawbar hard to break the taper's grip, you turn another nut to squeeze the drawbar out. Anyone can explain how this work and what do I need to do to include that.

Hope to do more work tonight. 

Regards,
Wong
Title: Re: Set-Over Centre
Post by: wongster on March 20, 2012, 07:40:32 PM
I've not been updating my progress here as I was rather caught up with my day job.  The work continued last Saturday for a couple of hours and Sunday for another hour or 2.

The drawbar washer was completed and the collet chuck was put into use.  The bore at the gear box cover was widened due to its misalignment to the spindle end.  Now I can remove the drawbar without having to open the door.

The washer on the spindle through the bore of the gear box. You can see the misalignment here which require the widening of the bore so that removing the washer can be done without opening the gear box.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000016.jpg)

The ER32 Collet Chuck mounted.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000019.jpg)

The drawbar which is basically an M12 socket head screw/bolt.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000020.jpg)

The silver steel chucked up and turned to accept 5/16 BSF.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000046.jpg)

Adding a little chamfer.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000048.jpg)

Using the die holder I made for my Sherline lathe with the tailstock live centre pushing against the 3/4-16" tapped hole meant for the 0MT to 3/4-16 adapter.  Turning it is so tough with those little SHCS.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000051.jpg)

Swapping it with the die handle I bought.  One handle was bearing against the bed way while I turned the collet chuck with its wrench.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000052.jpg)

The tailstock removed so that I can finish threading without the carriage in the way.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000053.jpg)

Testing the fit.  The part test was supposed to be the Slide but since both the Base and Slide have the same tapped hole, it doesn't matter as long as it fits one of them.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000055.jpg)

The part was cut off to length with some allowance for cleaning up.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000060-1.jpg)

The partially completed 1/2 centre was removed from the chuck. See the gap between the 2 parts? I chased the threads with the die flipped over but realised that both sides have taper on them to help start threading...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000059.jpg)

Next was to make an arbor with a threaded hole to mount this for the turning of the 60-degree cone.  I found a piece of steel that was actually a tap guide I made when I first started.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000062.jpg)

Finish was rather bad when I attempt to true up the part though it is not required but to remove the rust.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/P1000061.jpg)

I was told by a reader of my blog that this was due to tearing and not cutting.  His post: "...problem of the rough finish it appears to be tearing, not cutting. Check the tool for a good sharp well honed cutting edge and that the geometry is correct for the metal you are cutting. I can't see just how the tool is shaped, make sure you have enough back rake to make it shear off the metal not scrape and tear."

I didn't have the problem when facing it.  I'll try again to see if I can solve that.

Title: Re: Set-Over Centre
Post by: DaveH on March 20, 2012, 08:01:38 PM
Wong,

You are doing  a great job, nicely posted and great pics  :thumbup: :clap:

That finish I agree looks like "tearing" I am suprised you didn't hear it as well. Also check the cutter is not chipped and it is still on the centre line.

A great job Wong  :thumbup:
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 21, 2012, 04:16:41 AM
As the late and and lamented George Thomas would remark 'It does look as if it has been gnawed by rats'

At this point, you have two obvious faults. The first is that your collet chuck is NOT designed to accept a larger diameter than that specified  to accept and secondly, it is not supported.

Somehow, the chamfer tool is wrong as it is one for brass and I wonder what the rest of the set up is.

If you think about it carefully, you are using a split collet and the whole thing is able to rock about 'like a pea on a drum'

Others may disagree but that is their prerogative.
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 21, 2012, 06:59:01 AM
I occasionally look at the postings on 'Homeshop Machinist'. There is an interesting discussion on taper turning in the General section.

Some of these posters are quite expert with wide experiences.  No further comment from me on what was written. However, it is worth more than a cursory look.
Title: Re: Set-Over Centre
Post by: DaveH on March 21, 2012, 08:18:39 AM
Norman.

The early and quick DaveH replies; the collet is an ER collet designed to hold machine tools like end mills in a ridgid and precise repeatable manner.

Provided it is tightened correctly on a nice round surface it should not be a major cause of problems.

 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 21, 2012, 08:58:28 AM


However there is a dreaded overhang of metal far in excess of the collet diameter.

Quite simply, he should change to his three jaw chuck and keep the collets for what they are intended for- the right size.

The work should be then supported, prior to putting a proper lathe tool to work.

I remain adamant, sorry!




Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 09:07:32 AM
Thank you guys for you comments and encouragement. I just finished a long day at work.

Norman, I was under the impression that the ER series of collets provide repeatability rigidity within its limit when used for workholding in the lathe. That's why I bought it.  What would be the right size?

Anyway, I did swap in the 3 jaw chuck on Sunday night for a quick session. A fresh piece of silver steel was used. Same finish. I'll try to angle the tool differently in my next session. The HSS tool is still rather sharp.

On the "chamfering tool", it is but a Proxxon roughing tool placed at an angle.

Regards,
Wong

Title: Re: Set-Over Centre
Post by: Fergus OMore on March 21, 2012, 09:39:48 AM
It's getting worse! You are using silver steel which requires a different treatment to mild steel.

Your book of words suggests that you use Garia H and a razor sharp tool. Again Thomas emphasises rigidity and problems of overhangs.

Title: Re: Set-Over Centre
Post by: DaveH on March 21, 2012, 09:40:09 AM
Wong,

This is a hobby mate, something we do to enjoy just doing it. :)

Don't get overly concerned, when things don't go the way you think (and know) they should.  :bang:

If it is not a critical size, "hit it" with some emery cloth, until it looks good. It is fine we all tend to do it. Then carry on with the next part.  :)


It's coming along just fine  :thumbup:

 :beer:
DaveH

Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 10:08:46 AM
Thanks Dave. You are right. I should just enjoy myself and pick things up along the way as I do more. It is a hobby.   I did use sandpaper to smooth of the surface. Wonder how you know I cheated... Hehehe...

Norman, I don't understand the use of the term "it's getting worst". What's getting worst?  It cant be as bad as the part i just scrapped. I'm trying slowly to digest the info on that book. The style of writing is not that easy for a non-tech person like me.  Anyway, the silver steel was originally part of the kit I bought from Hemingway. I merely replaced it with another section meant for the 2 adjustments screws. You mentioned about "the right size" for the ER32 collet chuck. May I know what's the max I should put in there. I've collets all the way up to 19mm.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on March 21, 2012, 10:45:36 AM
Wong,

For a given collet size 25% increase in diameter in metal size(dia) outside the of the diameter being held in the collet  is normally fine.

Eg. if your collet size is 16mm - then + 25% = 4mm.  So 16 + 4 = 20mm diameter. So you can hold the 16mm diameter in the collet with a 20mm diameter outside, the bit you are cutting.

These ER collets were designed to hold end mills in milling machines, the forces there are far in excess that a single point tool on a lathe produces.

 :beer:
DaveH




Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 11:03:30 AM
Hi Dave,

I read somewhere (can recall now) that each collet in the ER series can hold down to about 1mm smaller in diameter. That is, if I'm putting in a rod or an endmill, of diameter 3/8" (which I've a few endmills or slot drill from sherline with such shank size), I should be using 10mm collet but not 9mm.  Do correct me if I'm wrong.  So for the 1/2" diameter silver steel rod from the Hemingway kit, I was using the 13mm collet.

Would your last sentence about the forces mean that it is not suitable for workholding in the lathe?  If it is, I'll start practising on using the 4 jaw chuck...  The small sherline 4 jaw seems simple to use but not the 100mm 4 jaw chuck from proxxon.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on March 21, 2012, 11:12:18 AM
Wong,

Hi Dave,

Would your last sentence about the forces mean that it is not suitable for workholding in the lathe? 
Regards,
Wong

Not at all, just the oposite, collets are more than suitable for work holding in the lathe. The work (bar) needs to be round and clean, which silver steel is.
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: DaveH on March 21, 2012, 11:14:46 AM
Hi Dave,

I read somewhere (can recall now) that each collet in the ER series can hold down to about 1mm smaller in diameter. That is, if I'm putting in a rod or an endmill, of diameter 3/8" (which I've a few endmills or slot drill from sherline with such shank size), I should be using 10mm collet but not 9mm.  Do correct me if I'm wrong.  So for the 1/2" diameter silver steel rod from the Hemingway kit, I was using the 13mm collet.

Regards,
Wong

Wong,

You are dead right  :thumbup: :thumbup: :thumbup:
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 11:28:49 AM

Your book of words suggests that you use Garia H and a razor sharp tool. Again Thomas emphasises rigidity and problems of overhangs.

Norman, I thought about your comment on problems of overhangs while I was driving home (I was typing the post on my little iPhone while driving... good that I didn't get caught by the traffic police...).  The ER32 chuck do extend out quite a bit.  If I would like to continue using collet chuck while I get the hang of centering stuff on the 4 jaw, should I be getting, say, ER25 or ER16 collet chuck?  I bought the ER32 because I have the full set of its collets from impulsive buying...  :doh:  and also its bigger range... :hammer:

Regards,
Wong
Title: Re: Set-Over Centre
Post by: Miner on March 21, 2012, 11:43:19 AM
Hi Wong,
Your current ER'S should be just fine, It's the distance away from your lathes spindle bearings that is creating a rigidity problem. I'n not familer with what system Proxxon uses to attach the chucks to your lathes spindle nose. Replicate that exactly on a roughed in ER collet chuck out of a piece of good steel. After its attached to the spindle nose, You then bore the ER internal taper and cut the threads for the ER nut. That will get you as close to the lathes spindle bearings as possible and leave your spindle thru hole open while turning longer stock with the collets. The system you have right now does work fine on a mill. But the chuck is supported much closer to the mills spindle bearings.

Pete
Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 12:01:56 PM
Hello Pete,

Thanks for your input. I was thinking of making or finding one ER32 chuck like what you mentioned but couldn't figure out what to do it or find one that fits. The Proxxon lathe holds the 3-jaw chuck by 3 M6 screws. The PCD is 83mm and the recess is 70mm in diameter.

I bought a piece of 100mm diameter mild steel but find it hard to mount on my 4 jaw chuck (my 3 jaw chuck max'd out at 80mm+). I put this on hold for the time being to gain more knowledge doing some simpler project while I think of how I should approach this.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: Miner on March 21, 2012, 12:27:09 PM
Hi Wong,
Unless Proxxon offers an actual ER-32 collet chuck, It would be highly doubtful you'll find a off the shelf one that fits your lathe. Your 3 jaw is maxed out at 80 mm? You should have a second set of chuck jaws that are designed for holding larger diameter work by the outside diameter. That second set of jaws should have been included with your lathes 3 jaw chuck. There's a few more tips that could be mentioned about the best way to build an accurate collet chuck, But were pulling your thread off topic so I'll apologise for that.

Pete
Title: Re: Set-Over Centre
Post by: Fergus OMore on March 21, 2012, 12:41:17 PM
This is when a faceplate is desirable- and the ability to use it.
Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 06:13:40 PM
Pete,

Don't be. I would like to hear how I can go about making one. The 3-jaw chuck max'd at 80mm+, with the jaw reversed. The 4 jaw allows up to slightly about 100mm, with the jaw reversed.

Both are 100mm chuck.

Regards,
Wong.
Title: Re: Set-Over Centre
Post by: Miner on March 21, 2012, 06:41:13 PM
Wong,
Well for starters you need to build an EXACT reproduction of your lathes spindle nose. Every dimension is as close as you can get to EXACTLY the same as your lathe has and your measureing equipment will measure to.

That reproduction will be used as a proper gage while machining your embryo collet chuck. If that gage tightly fits the machined rear face of your soon to be collet chuck, Then it will fit just as tight on your lathes spindle nose. Less than .001" for tollerance would be what you'd want on all dimensions. Once that's achieved, You then accurately drill your bolt hole pattern to attach the unfinished collet chuck to your lathes spindle nose.

Now you can precision bore the diameter, depth, and collet angle into that collet chuck blank. Once those dimensions are correct. You can then single point thread the collet chuck to fit your ER nuts dimensions.

All of this just requires very careful work and not trying to rush the job. Any inaccuracys you machine into the collet chuck will repeate themselves in any further work you machine in that chuck.

There's probably a few real good examples on this forum showing how other people have done this job.

Pete
Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 07:23:18 PM
Pete,

Pardon me for my ignorance. When you mentioned spindle nose, are you referring to those with threads on it? If it is, I don't have any. The round plate is where the chucks, centre turning attachment, and face plate are attached to, using the M6 bolts. From the exploded diagram in the manual (all parts labelled in Germans), this round plate is part of the spindle. to mount the workpiece directly to this plate, I'll need to drill the 3 or 4 clearance holes right through.

The plate measures about 100mm:

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/b940b263.jpg)

I did something like what you discribed on my Sherline before, which has a 3/4-16 nose. Once I've the thread done in the middle of a work piece, I was able to machine the face and cylinder surface with it mounted on the spindle nose.

The steel stock I bought:

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/278a548e.jpg)

I'm trying to figure out how to start...

Regards,
Wong
Title: Re: Set-Over Centre
Post by: Miner on March 21, 2012, 07:45:46 PM
Wong,
Nope, The actuall "spindle nose" would be where your chucks attach to. They can be threaded, D series, Tapered like the L series chuck mounts ect, ect. You just need to duplicate all the dimensions that affect your chuck mounting. Possibly? The system your lathe uses for chuck mounting may be designated with and as a proper european DIN number. In fact I'd be suprised if it wasn't.

Pete
Title: Re: Set-Over Centre
Post by: andyf on March 21, 2012, 08:14:58 PM
Hi Wong,

As "7x minilathes" have a spindle flange similar to yours, though different as to register diameter and PCD of the mounting bolts, you might find it useful to join the Yahoo 7x12 Minilathe Group and have a look in its Files section at "ER Chuck Construction", and at the last file in that folder.

Actually, I don't think that's the way I'd attempt it, but you have taken your own thread a bit off topic, so  perhaps a new thread might be the right place for further discussion when you get round to the job.

Andy
Title: Re: Set-Over Centre
Post by: wongster on March 21, 2012, 08:53:20 PM
Hi Andy,

Apologies for veering off course. I'll start a new thread when getting to making the collet chuck.

Just a last bit. The chuck is fastened to the spindle flange from the from with 3 M6 bolts. I'll check out the file section you do kindly shared to see if I can understand how to go about mounting the big chunk to make the collet chuck.

Thank you.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: andyf on March 22, 2012, 04:10:06 AM
Hi Wong,

It is I who should apologise. It wasn't meant as criticism. This is your thread, after all.

If you want to look at files on the 7x12 Group, you will need to join it first; it isn't open to the public like Madmodder.  But membership is automatically granted to everyone who applies.

Andy
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 04:42:53 AM
 Hi Andy,

There will not be an end to apologizing to each other then.  :)

Found that I've those files on my iPhone. the chuck is for those with threaded nose, which I have mental images of the process needed. The front mounting one is something that I can't figure out how I can start. I'll think some more and start another thread if need be to gather comments and/or criticism.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: andyf on March 22, 2012, 07:31:10 AM
I think those are different files, Wong. The ones I referred to are definitely for a collet chuck which bolts on to a 75mm spindle flange.

Andy
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 11:31:47 AM
Wife was away with her pastor and church friend for dinner.  The tension at work today was so great that I promised myself to spend sometime in the shop no matter how short the session is going to be.  The session was indeed very short; I only had like half an hour after dinner.

I angled the tool away from the workpiece this time and it really cut.  The entire edge of the tool was too close the previous time that it rubbed on the workpiece than cut.  Genek was quite quick to point this out when my blog post went up the last time.

The short section for threading done.  Finish not fantastic but it was much better than the previous attempt.  In this pic, the tool was set to cut the shoulder.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/60c4b4ae.jpg)

The same method was used to square up the 5/16 die with the stock by pressing it against the live centre on the tailstock.  Once I've a few threads going, the tailstock was removed and the thread was finished up by turning the die handle and chuck by hand.  Instead of using the cutting oil I normally use for turning and milling steel, some tapping compound recommended by the tool shop I frequent was used.  It seemed much easier this time and the threads was done in a flash.  I turned the die around and chased the thread but remembered that both side of the die are tapered.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/191b4eae.jpg)

The same gap is still there.  Why can't it go all the way in?

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/ae6fdfd6.jpg)

From another angle.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/548c2d3b.jpg)

Any suggestion?
Title: Re: Set-Over Centre
Post by: DaveH on March 22, 2012, 11:49:14 AM
Wong,

Although the die seems to cut right up to the face of the die, like you said there is a chamfer to the die. Hence the thread is not cut right up to the shoulder of the work piece.

You can "undercut" the thread, which means using something like a parting off tool and reducing the diameter of the threaded part just a 1mm wide or so right next to the shoulder. Reduce the diameter and see if it wll screw on all the way, leave the work piece in the lathe until it fits correctly.

Thats one way.

 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 12:06:47 PM
Dave,

I tried that the last round and I've to use a plier to screw on the last bit.  Maybe I didn't get it right.  Read on one site that I should cut it down to the root diameter of the thread?

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on March 22, 2012, 12:12:52 PM
Dave,

I tried that the last round and I've to use a plier to screw on the last bit.  Maybe I didn't get it right.  Read on one site that I should cut it down to the root diameter of the thread?

Regards,
Wong

That is correct, then it will screw up to the faces.

We all have to do it - you are not special  :lol: :lol: :lol:

 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 12:32:28 PM
I thought I am... just need to do 1/2 the job and the rest get done on its own...  :doh:

My Sherline's blade is 0.04".  I'll use that to do the job.

Thanks Dave.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: arnoldb on March 22, 2012, 12:51:31 PM
Hi Wong

I've been quietly following along - you're doing fine, and running into all the same problems all of us faced at one point or another..

If you don't have a parting tool of a suitable width to make an undercut for the thread like Dave suggested, you can also just drill out a short section of the threads in the block - just as deep as the bit that's not screwing home - to the same size as the thread's outer diameter.
I also see that the cutting tool left a radius in the corner between the male thread and its shoulder - this will also prevent the two workpieces screwing together up to the shoulder once you have the thread sorted; you can just use a countersink (or a larger drill bit) to add an additional chamfer to the hole in the block, and that should solve the problem there.  If you make an undercut using a parting tool, you won't have this last problem though.

 :beer:, Arnold
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 06:40:12 PM
Hi Arnold,

That's a good one!  I should have incorporate this while drilling and tapping the hole in the Base. Since the rod is still in the lathe, I'll try the undercut first.  Just need to figure out how I should mount the Sherline part off tool on the Proxxon QCTP.

Regards,
Wong 
Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 07:25:49 PM
This session is extremely short; While my wife is having her shower, I steal into the shop to do the undercut for the screw thread I did yesterday night.

The parting tool from AR Warner in use.  It was squared up using the jaw of the 3 jaw chuck as reference.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/c4bc54a6.jpg)

I tested the Base on the thread after each bit of cutting done till it sit almost flash. Seemed to be so in this pic.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/695ea4fc.jpg)

Turning the chuck around to check.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/cdfbfef8.jpg)

The little gap formed doesn't seem to be uniformed throughout.  The base was screwed on finger tight.  It may be the tapped hole being out of square.  I'll check again when I get home after work tonight.

Regards,
Wong



Title: Re: Set-Over Centre
Post by: DaveH on March 22, 2012, 07:44:02 PM
Wong,

Looking good  :thumbup: :clap: Take your time, and that little gap, we all get that sometimes, just that we tighten it up and don't say anything.  :)
 :beer:
DaveH



Title: Re: Set-Over Centre
Post by: wongster on March 22, 2012, 08:17:09 PM
Before I left home for work, I did tighten it up and the misalignment is apparent. I'll just declare it good for the time being to carry on with the project. May make the replace part(s) if there is a need to.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: wongster on March 24, 2012, 10:16:00 AM
This session stopped prematurely when I cut my right thumb while tapping the arbor.  Blood was dripping on the floor and table when I rushed to wash the wound under running water.  The pain was terrible when in contact with water.  Thank God it was just a cut.  Though a little deeper than what I normally get, it was nothing serious.  My wife, of course, nagged a little while putting on the plaster for me.

The blood started dripping off my thumb when the latex glove was removed.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/106fec6e.jpg)
 
Back to the making of the 1/2 centre.  The 60-degree point was completed this session, after struggling to make the arbor.
 
While parting off the workpiece, the HSS parting blade snapped.  It was cutting after a while and snapped when I tried pushing it further.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/922c2835.jpg)
 
Another view.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/efdd6ed2.jpg)
 
Swapping in the Proxxon part off tool. It completed the job without much trouble.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/aae8fd16.jpg)
 
After facing the end flat, I centre drill and drill about 12mm deep for the 5/16 BSF.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/fddb9fd3.jpg)
 
Tapping the hole to hold the 1/2 centre.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/9996a6ed.jpg)
 
This was when I cut myself.  Notice how close the tool was to the tapping handle? My hand slipped and my thumb went on to the cutting edge of the tool.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/5c260d80.jpg)
 
There was still wobble when I mounted the 1/2 centre to the arbor. I pushed on this time, facing and turning it.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/813fa4a6.jpg)
 
The 60-degree point was completed.  Notice that the centre is now tightly screwed onto the arbor as if they're one piece of steel.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/4ec5d153.jpg)

After running a smooth file on the face and sanding it down with fine grit sandpaper.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/329122ac.jpg)

I fastened it down to the mill vise to prepare to drill the tommy screw hole.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/ccaa4204.jpg)

I stopped work at this point as the wound has started bleeding again.  I will try to complete this part of the work tomorrow morning before church.  Will also attempt to harden it by using my little Proxxon Micro Torch and quenching it in water.
Title: Re: Set-Over Centre
Post by: DaveH on March 24, 2012, 12:15:38 PM
Wong,

Nicely shown and posted, looks good, nicely made. :thumbup: :clap:

Sorry about your cut thumb, - try to make sure all the sharp bits are out of harms way. That goes for the dead centre in the tailstock as well because that can also cut you. 

Don't forget you don't always have to part things off, it is quite acceptable to use a hacksaw and face it on the lathe afterwards.  :thumbup:

It is really coming along very well  :bow:

 :beer:
DaveH



Title: Re: Set-Over Centre
Post by: wongster on March 24, 2012, 12:20:57 PM
Hi Norman,

A little flesh, blood, and sting indeed. Not the part on pride as I've yet to reach that stage.

The proper tools you spoke about are the tailstock tape & die holder? I plan to make them.

When I was using the tailstock, I always find the top slide in the way. Do you normally remove your tool post when using the tailstock for, say, drilling or tapping?

Also, I saw some YouTube videos showing tapping in the lathe under power. Is it advisable? Anything to look out for if it is.

Thanks.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: wongster on March 24, 2012, 12:33:44 PM
Dave,

Thank you. 3 more parts left to make; 2 adjustment screws (I'm thinking of just buying them than to make them) and the 2MT arbor.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: grayone on March 25, 2012, 01:17:11 AM
Hi Wong,

I have a question as I bought the kit as well (it's sitting in a box still in my workshop 5,000 miles away unopened)  You have just mentioned possibly buying the 2MT arbour.  I assume by this comment that the MT2 comes as a piece of silver steel and not a stub machining arbour.  If this is the case I think I would also buy it as they are not very expensive and my skill level is probably not good enough yet (or ever :() to be able to make one.

Graham
Title: Re: Set-Over Centre
Post by: wongster on March 25, 2012, 01:58:27 AM
 Hi Graham,

The 2MT arbor came with the kit with a section that can be machined.  I was referring to the 2BA adjustment screws that have to made from the supplied silver steel.

Have you come across 2MT arbor with stub of about 1-1/2" long? Planning to make set of tap & die holders.

Thanks.
Wong
Title: Re: Set-Over Centre
Post by: grayone on March 25, 2012, 12:06:48 PM
Hi Wong

I found one in the UK at

http://www.axminster.co.uk/groz-stub-arbor-prod21342/?searchfor=340307

2 MT with a machinable end 1" dia and 1 1/2" long.

Graham
Title: Re: Set-Over Centre
Post by: andyf on March 25, 2012, 12:31:33 PM
Wong, once you have finished the set-over centre, you shouldn't find it difficult to make your own MT2 arbor. I have enough travel on my topslide to make one, which is what I did for my die holder (it doesn't hold taps). That way, you can make the cylindrical section along which the die holder slides as long as you like. Some of my dies are small (13/16", or about 20.6mm) in diameter, so the cylindrical section had to be smaller than that. If I had bought a soft-ended arbor, a lot of steel would have been wasted getting it down to size.

(http://i689.photobucket.com/albums/vv257/andyf1108/Dieholder004.jpg)

I hang the tommy bar down between the bedways, so the holder can only turn a few degrees as I crank the spindle and workpiece  by hand.

Andy
Title: Re: Set-Over Centre
Post by: wongster on March 25, 2012, 07:01:17 PM
The 1/2 Centre was completed this morning, though much is desired when come to hardening it.  It was my first real attempt at hardening and quenching in water.  The test with a file, as described in some text I read, left some scratches on it.  I'll try the hardening part again when I completed the entire project.

The "edge" of the 1/2 found.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/c01c60dd.jpg)

Drilling the hole for tommy bar after centre drilling. The plan called for the hole to be 3/32" but I would like to use the Sherline's tommy bar, which is slightly smaller than 4mm.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/c4de9a24.jpg)

With the 4mm hole, I'm too close to the edge near the threaded portion.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/3cce84fa.jpg)

Using the Sherline's tommy bar to remove the Centre for deburring.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/d88b903e.jpg)

Mounted to the Base to hold it in the milling vise and milling away to almost 1/2 of the taper.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/e743201e.jpg)

Done. I couldn't go further with the mill as the edge of the Base blocked the endmill holder

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/7d172092.jpg)

Completed but before hardening.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/50cdd6e0.jpg)

After the first attempt in hardening. I heated the job till it glow and quench it in the little contain of water. I've had a hose near by (can be seen behind the torch) to spray water as standby.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/39d98ae5.jpg)

You may be able to see the scratches caused by a file. Hardening not done right? After I completed this part, I saw GeneK's comment on not directing the flame at the tip.  Wish I read his comment before I started...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/0510ddd9.jpg)

While assembling the parts, I realized that the 1/2 Centre threaded portion extended out a little too much into the Base.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/525af5b6.jpg)

The excess was carefully milled flush

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/39b30ebb.jpg)

Another attempt at hardening was carried out before putting the parts together. The cap screws provided are a little too long. They'll have to be shortened in the next session.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/f4307867.jpg)

That's all the work on Sunday morning.  I'm looking forward for my next session which will likely be next weekend.
Title: Re: Set-Over Centre
Post by: DaveH on March 25, 2012, 07:15:50 PM
Wong,

Well it is looking good  :clap: :clap: :clap:

And no blood makes it doubly good  :thumbup: :thumbup: :thumbup:

Well done, by the way that hole, that is what I would have called precision drilling :) :) :)
 :beer:
DaveH



Title: Re: Set-Over Centre
Post by: wongster on March 25, 2012, 07:33:26 PM
Hi Dave,

The precision part was definitely not my doing... It was the drill held in the collet (ER16)  :)

I was surprised as how easy the silver steel can be drilled through; no chatter, just felt as if it slided in and out...  The steel used for the Base and Slide weren't the case.

Regards
Wong

Title: Re: Set-Over Centre
Post by: wongster on April 07, 2012, 12:40:06 PM
The machining of the "softer" end of the 2MT Arbor was completed. The job was to turn down a 5/16" section and put on the 5/16" BSF thread to thread the Base on. The softer end of the supplied arbor seemed rather tough to work on with my little experience.

The 2MT arbor was fitted on a 2MT to 3MT adapter sleeve for the spindle bore. The "soft" end measured 1" in diameter. The first job is to turn this down to 3/4".
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/a32b5ede.jpg)

First is to reduce the 1" diameter to 3/4". Surface finish was rather bad.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/cd2eac74.jpg)

Next is to reduce a section down to 5/16" leaving 3/16" length of the stock at 3/4".  In order to know which I should stop turning, I tried cutting a groove but parting this material turned out to be rather unpleasant.  The AR Warner's part-off tool just jammed mid way through the cut.  But what was done provided sufficent visual of the stop point.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/40dc5950.jpg)

The section was turned down as planned but short by about 3mm in diameter.  Can't proceed as the live centre body was blocking the tool from furhter advancement.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/1f38208e-1.jpg)

I don't really have a good feeling of what I'm doing on the arbor.  There was slight wobbling when the lathe was powered on.  And so the Centre Turning Accessory was brought out and put in service.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/ee7722ea.jpg)

Too much pressure on the tailstock causing excessive heat. The grease was boiling, darkening the end of the section I was working on.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/4535935c.jpg)

The workpiece was taken out to clean off the burnt grease and reapply fresh dose. This time, I went easy on the tailstock when applying pressure.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/89e87d22.jpg)

After turning down to the required diameter, I tried parting off the excess with the sleeve back in the spindle bore.  It didn't work. I can feel the job flexing away from the parting blade. The spindle guard was removed and the hacksaw drafted into service.  Thank God I've only about 7.9mm diameter to saw through.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/17158116.jpg)

Facing done and sharp edges deburred with a file. The shoulder was also faced making it nice and flat.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/f1e1d97e.jpg)

Sherline's grooving tool in use. I find it rather expensive but it has proven itself to be a very useful tool. The groove created is the undercut for the threads. The live centre was only pressing against the stock lightly to keep the job in place.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/93eb6e16.jpg)

Threading the 5/16" BSF was next. The 3 M6 cap screws were used as grip while turning the die holder's handle. Hope they wouldn't damage the threaded holes for mounting chucks and other accessories.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/ed5cb71b.jpg)

Threading completed.  I had to cut away the half formed thread near the shoulder to allow the Base to go all the way in.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/725a23bc.jpg)

The whole works on the arbor. Next is to find a way to get the 2MT arbor out of the 3MT sleeve.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/5e5386fd.jpg)

The threaded end of the 2MT arbor is just a tad lower than the slot for easy knocking out with a wedge tool (I don't have one anyway...).
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/337b3fbb.jpg)

The 5mm Allen key and a small hammer did the job of breaking it free.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/f60d6be0.jpg)

Though still short of the 2 adjustments screws, a group photo of its members so far won't hurt.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/89a16c3c.jpg)

The Set-Over Centre on its rightful place. The 2 x 5/16" have yet to be trimmed flushed.
(http://i1207.photobucket.com/albums/bb469/wongstersproduction/Set-Over%20Centre/2c6777e4.jpg)

I'm getting excited as I'm coming to an end of this project.  Wanted to buy the 2 x 2BA screws but the shop I always frequent only have them in brass.  Maybe that will work.  Should have buy them to test than merely walking away disappointed.

I've yet to test if the centre lies up with the centre line of the lathe.  Feeling exhausted from the long boring showflat duty I was scheduled this afternoon, I decided to stop work, wash up, and do some reading before bed.  Got to get up early for Resurrection Day service tomorrow morning.
Title: Re: Set-Over Centre
Post by: andyf on April 07, 2012, 01:07:09 PM
Nearly there, Wong!

In my experience, the soft end of some of those blank ended arbors gets a bit hard at the back end, where it joins the tapered section.

You could probably avoid the 2BA screw hunt. I think you have already drilled the holes 4mm and tapped them 2BA, with a thread pitch is 0.81mm. An M5 screw has a pitch of 0.80mm, and the tap drill is 4.2mm. You could run a 4.2mm drill down the holes and follow it up with an M5 tap. The tiny difference in thread pitch would disappear in the process. M5 screws will be easier to find.

Andy. 
Title: Re: Set-Over Centre
Post by: wongster on April 08, 2012, 12:38:35 PM
Andy,

I will make the 2BA screws to complete the project.  If I screwed up making the screws, I'll use the M5 cap screws.  Thanks for sharing.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on April 08, 2012, 03:57:18 PM
Wong,

Well you are nearly at the finish post. Looking good  :thumbup: :clap:
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: wongster on April 14, 2012, 01:52:40 AM
Quick check done to see if I've the centre at the correct height

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/0e849344.jpg)

This pic doesn't show anything useful. Posted as it looks nice to me...

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/84a6c500.jpg)

I bought some 2BA screws for testing. If they work as intended, I will cut short the project and call it complete. Will try to cut a 1MT taper to make a holder of sort for the Sherline mill.

Regards,
Wong
Title: Re: Set-Over Centre
Post by: DaveH on April 14, 2012, 04:39:04 AM
Well that looks good Wong  :thumbup: :clap:
 :beer:
DaveH
Title: Re: Set-Over Centre
Post by: ozzie46 on April 14, 2012, 08:46:53 AM



   Well done Wong.   :thumbup: :thumbup:

   Ron
Title: Re: Set-Over Centre
Post by: wongster on April 14, 2012, 10:15:22 PM
Dave & Ron, thank you.

The point looks kind of rough.  Should I setup my proxxon rotary tool in the lathe to grind it smooth?

Update:
I managed to find some 2BA cap screws yesterday.  All rusted as there have not been any enquiry on it for the past few years, according to the shop assistant.  They're a little long (1-1/4") but still usable.  I tried it on yesterday night and they work as intended.

(http://i1207.photobucket.com/albums/bb469/wongstersproduction/0b456ebc.jpg)

I'm thinking if I should make a 0MT dead centre for my sherline tailstock just to test if I know how to use this set-over centre.  Or maybe a 3/8" shank endmill holder for the tailstock to flatten the bottom of blind holes after drilling.

Regards,
Wong