# Mystery collet holder



## cdhknives (Feb 2, 2015)

I finally figured out that I did have a working collet setup with this lathe...but I have no idea what size/type/quality.  It appears homemade.  The video explains it...




http://youtu.be/red4R7UwqTY


What do I have here?  How do I determine if it is a standard collet?


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## awander (Feb 2, 2015)

Some measurements of your collet would help us to give you an answer.


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## cdhknives (Feb 2, 2015)

Threads:
26 TPI
0.635" major diameter
0.750" threaded length

Body:
0.650
Straight (no taper) from top of threads to base of cone/head

Tool end:
0.849" max diameter

Overall length:
2.475"


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## chips&more (Feb 2, 2015)

Does the collet have any markings on it? Like maybe 3AT or 3C? Good Luck...Dave


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## cdhknives (Feb 2, 2015)

Found this:

http://www.loganact.com/tips/collet.htm

But I can't tell if it's 3C or 3AT from these dims...too close to call.


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## cdhknives (Feb 2, 2015)

chips&more said:


> Does the collet have any markings on it? Like maybe 3AT or 3C? Good Luck...Dave



No visible markings...and the surface is clean enough they would show.  Very smooth, not rough machined...no tooling marks at all in fact.  Flat faced.

Also, it's brass...not steel.:thinking:


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## awander (Feb 2, 2015)

To me it looks like a 3C collet.

Or a 1A:


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## wa5cab (Feb 3, 2015)

Clayton,

Measure the taper angle between the head and the straight cylindrical body.  If it is 12 deg., the collet was supposed to be a 3C.  Or at least the threads, body diameter and head angle would match the 3C.  So a 3C would fit the spindle nose adapter or closer if the head angle is 12 deg.  You might have to adjust the thickness of the thrust washer on the back end of the draw tube (the straight sided one, not the tapered one).  You might also be able to adjust the spacer to fit 1AT but I do not know what the head angle is on the 1AT.  Neither Andy's list nor two other ones that I have give the head angle.  Plus the 3C is much easier to find.  The 3AT is standard on the Atlas.  But it is is too large in diameter (0.687") and has a 15 deg. taper.  Unless the collet that you have is a sloppy fit in the adapter but has a 15 deg. taper.

Both the 3C and the 3AT have about 16 threads.  The proper effective length of the draw tube (with spacer(s) ) is that it should take about 8 turns to screw up onto and tighten the collet.

Robert D.


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## Alphonse (Feb 3, 2015)

.





cdhknives said:


> I finally figured out that I did have a working collet setup with this lathe...but I have no idea what size/type/quality.  It appears homemade.  The video explains it...
> 
> 
> 
> ...



I have a Logan 10" that uses 3AT.  I agree that yours looks like a 3C.   I have a set of 3C's  The 3C is almost exactly the same a s 3AT just a little longer in length, so a spacer is used on the draw bar


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## Wierd Harold (Feb 3, 2015)

Maybe this drawing will help.

http://conradhoffman.com/Collet Adapters.PDF

HWF


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## wa5cab (Feb 4, 2015)

Alphonse,

While it is true that the threads on the 3C and 3AT are near enough the same that you can use one draw tube with adjustable thrust bearing for both families, the OD of the 3AT is substantially larger and the taper angle is larger.  You can't use the same closer adaptor as the 3AT collet won't go through the 3C closer adapter.

Robert D.


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