Which Collet Chuck Do I Have

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Which Collet Chuck Do I Have

This topic has 13 replies, 8 voices, and was last updated 27 July 2023 at 22:10 by Mark Rand.

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26 July 2023 at 13:46 #11537
Antony Harding
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@antonyharding74298
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26 July 2023 at 13:46 #653784
Antony Harding
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@antonyharding74298
Sorry newbie..!!!! got myself a lover Beaver Mill but need to buy a new Collet Chuck. The manual notes it could be a INT30 or INT40… dose anyone have any mesurements of the two chucks that they can give me so i can work out which one i have?

Looking to buy a ER40 collet set to go with the new chuck, but see that they are M16 size Drawbar so will also need to get a new Drawbar as the one i have i think is a 7/16.
26 July 2023 at 14:31 #653788
bernard towers
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@bernardtowers37738
Google int 30/40 specs and you will be spoilt for choice.
26 July 2023 at 15:38 #653797
DC31k
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@dc31k
This page lists a whole range of machine tapers and is well worth bookmarking:

https://www.tools-n-gizmos.com/specs/Tapers.html

A 30 taper is 1.25 inches major dia.; a 40 taper is 1.75 inches.

Standard drawbar size for 30 taper is 1/2" or 12mm; for 40 taper it is 5/8" or 16mm.

Tooling with an imperial drawbar thread can have either BSW or UNC threads; the thread pitch for 1/2" BSW and 1/2" UNC differs.
26 July 2023 at 17:30 #653818
Nigel Graham 2
Participant
@nigelgraham2
AH!

Thank you for that last point!

My Myford mill uses R8 tooling but I wonder if some that I have is actually Whitworth 12tpi rather than Unified 13tpi threaded, hence being more awkward to screw in.

Alternatively, since I had to make a new drawbar (original one lost in a house-move) I may have given it the wrong thread!

Though I think there is a problem inside the spindle, to prevent reliable engaging.
26 July 2023 at 19:23 #653840
Mark Rand
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@markrand96270
1/2" UNC -s 13tpi, 1/2" BSW is 12tpi. If you are screwing one into another, then one or both threads will be buggered over the length of engagement you should expect for a 30 taper or R8 drawbar thread.

All of my holders for the Beaver are 12mm ISO30 with one 1/2"BSW, I recently aquired a Beaver made horizontal drive, which is original and standard 1/2" UNC NMBT30 thread. So I've got to make a third drawbar. Thinking of making double ended bars with M12 on one end and UNC/BSW on the others, with appropriately threaded nuts for the top ends. That way I'm back to two drawbarsand only need to change the nuts and ends over for the two least used fittings.

Edited By Mark Rand on 26/07/2023 19:25:04
26 July 2023 at 19:41 #653846
DiogenesII
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@diogenesii
Nigel, R8 stuff can also come with UNF threads
26 July 2023 at 19:51 #653851
DC31k
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@dc31k
Posted by Nigel Graham 2 on 26/07/2023 17:30:16:

My Myford mill uses R8 tooling

Though I think there is a problem inside the spindle, to prevent reliable engaging.

As below your original but above this post, I was under the impression that R8, being invented by Bridgeport was univerally 7/16" – 20 UNF.

I have seen it reported that it is often the fit between the key in the spindle and the keyway in the tool that causes issues. Less than perfect quality tools/collets can have undersize keyways.
26 July 2023 at 21:06 #653863
Antony Harding
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@antonyharding74298
Hi DC31k, thanks for your post. As the old Chuck i have has a dimamiter of 44mm (large end) that means its a INT40 ??
27 July 2023 at 00:15 #653888
Mark Rand
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@markrand96270
The large end of the tapered bit…
27 July 2023 at 12:25 #653948
Howard Lewis
Participant
@howardlewis46836
To identify the taper, study the charts noted by DC31k. Strangely, INT tapers do not seem to be listed.

If the taper is an INT one, the dimensions will be Imperial, fractions of an inch, not Metric.

The taper is 3.5" per foot.

For an INT 30 , the major diameter will be 1.250" reducing to 0.5625" over a length of 2.625"

Drawbar thread is likely to be BSF, possibly 7/16 or 3/8?

For an INT 40 , the major diameter will be 1.750" reducing to 0.6406" over a length of 3.8125"

Drawbar thread is likely to be BSF, possibly 7/16 or 3/8?

Metric units are unlikely to be exact "round numbers", and so cause you needless hassle.

HTH

Howard
27 July 2023 at 17:32 #654003
Antony Harding
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@antonyharding74298
Thanks Howard Lewis….
27 July 2023 at 19:22 #654024
John Haine
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@johnhaine32865
Also called bt30 or bt40
27 July 2023 at 22:10 #654036
Mark Rand
Participant
@markrand96270
Posted by John Haine on 27/07/2023 19:22:03:

Also called bt30 or bt40

BT is the same taper, but not the same shape. It's not as long as NMBT.

Pictures and dimensions here:- **LINK**
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