# W12 Collet Threads



## Mosey (Apr 20, 2010)

I presume that my W12 collets are a 12 mm buttress thread, and want to make some accessories for my mill in that size. What are the dimensions and the profile of that thread?
How do you measure the thread in progress to know when it is deep enough? 3 Wire method?
Any help here will be appreciated.
Should I look for a 12 mm Buttress thread die?


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## steamer (Apr 21, 2010)

Hi Mosey,

I have attached a W collet spec sheet for your review.

I have an Aciera F1.  What do you have?

I recently made a draw bar for my Waltham that fits W20 collets....A Waltham invention...copied by Schaublin....

http://www.homemodelenginemachinist.com/index.php?topic=7692.msg81400#msg81400

You need to set the compound for the long side of the thread flank.  I then single pointed it until my collets fit well.

Let me know if I can help...

Dave





View attachment W_Collets.pdf


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## Mosey (Apr 21, 2010)

Steamer:
Wow, that's what I need!
I also have Aciera F1.
Can you measure thread depth with 3 wire method as you go?


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## rklopp (Apr 21, 2010)

"Can you measure thread depth with 3 wire method as you go?"

Of course you can. Why not? Short of special tooling, that's about the only practical way to do it. Use a good quality factory-made thread, as found on a good arbor or collet, as the master to check against. Use some masking tape or clay to help hold the wires. I made W20 arbors for my Aciera F2, and I used the three-wire method. I have a set of Pee-Dee brand thread wires. Beware the W buttress threads, at least for W20, have non-standard flank angles, and therefore won't be found in handbooks.


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## Mosey (Apr 21, 2010)

What would you think about a little home-made holder for the wires? (so that I don't have to rummage around on the shop floor for the wires that I dropped) I know that Mitutoyo makes a fancy micrometer holder for the wires, but out of the budget.


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## rklopp (Apr 21, 2010)

"What would you think about a little home-made holder for the wires? "

I just use masking tape or clay. Whatever works to avoid needing three hands.


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## mklotz (Apr 21, 2010)

At last, a use for styrofoam packing peanuts.


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## steamer (Apr 21, 2010)

Hi Mosey,

Wires are a good idea. The thread is an odd ball, so if you have a collet already, measure two or three and get a good average dimension.  I would feed the compound in on the 45 degree side. Remember the flank has a 5 degree angle.

If you going to do it, make a bunch so you can set you lathe up for the thread.

Good luck!

Dave


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## Mosey (Apr 22, 2010)

Do you mean to set the compound at 45 degrees, or at 5 degrees and ride the flank?


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## steamer (Apr 22, 2010)

See sketch.....that should explain it.

Dave


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## Mosey (Apr 22, 2010)

Got it.
1.25 mm/thread = 20.32tpi.
What would you think about 20 tpi instead? That way, I can cut on my Imperial lathe.


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## steamer (Apr 22, 2010)

Well if your trying to match an existing draw bar, I would doubt it. The difference in pitch is about .002"/thread. If your cutting your threads real loose, maybe....but you won't need wires thats for sure...I don't think that is what you want....but thats just me.

I made transposition gears for my lathe so I could do this. 47t/37t in my case.

Dave


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