Draw bar thread size for a 2 MT Clarkson autolock milling chuck?

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Draw bar thread size for a 2 MT Clarkson autolock milling chuck?

This topic has 12 replies, 10 voices, and was last updated 31 August 2015 at 16:54 by Antony Price.

Viewing 13 posts - 1 through 13 (of 13 total)

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25 August 2015 at 15:03 #201888
Antony Price
Participant
@antonyprice56876
Hi

Is anybody able to confirm the draw bar thread size for a 2MT Clarkson autolock milling chuck? I think it might be 5/16 BSF, but when I try a bolt of that thread it only goes in a few turns. It is possible the previous owner has damaged the thread, but before I re-cut it, I would appreciate confirmation that it is 5/16 BSF

Many thanks

Tony
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25 August 2015 at 15:03 #32555
Antony Price
Participant
@antonyprice56876
25 August 2015 at 15:13 #201892
Keith Long
Participant
@keithlong89920
Looking at morse taper tooling on sale the standard drawbar thread on 2MT seems to be 3/8 BSW or M10. Possible that Clarkson used a fine thread but I'd have thought they'd have gone with the normal standard. If the previous owner has modded the thread either intentionally or by accident then all bets are off.

Edited By Keith Long on 25/08/2015 15:26:05
25 August 2015 at 15:14 #201894
duncan webster 1
Participant
@duncanwebster1
Mine is 3/8" BSW
26 August 2015 at 01:02 #201983
peak4
Participant
@peak4
Posted by duncan webster on 25/08/2015 15:14:56:

Mine is 3/8" BSW

As is mine
26 August 2015 at 08:15 #201991
John Haine
Participant
@johnhaine32865
Imperial mt2 tooling all seems to use 3/8 bsw. Standard studding is perfect to make a drawbar.
26 August 2015 at 09:50 #202008
Robbo
Participant
@robbo
3/8"BSW if Imperial, M10 if Metric
26 August 2015 at 10:51 #202016
S.D.L.
Participant
@s-d-l
Posted by Robbo on 26/08/2015 09:50:26:

3/8"BSW if Imperial, M10 if Metric

And some will be UNC

Steve
26 August 2015 at 13:06 #202035
Ian S C
Participant
@iansc
3/8" BSW, some will be 3/8" UNC, these are both the same pitch, only the thread angle differs, the UNC being 60*.

Ian S C
26 August 2015 at 13:32 #202040
Bazyle
Participant
@bazyle
Screw a piece of paper/wood/plasticine down it to pick up and measure the thread pitch and the core diameter. At least you have the tool to try things on.
26 August 2015 at 15:19 #202052
Mike Poole
Participant
@mikepoole82104
The drawbar thread is often etched on the body of genuine Clarkson holders, can be hard to find and read though! If it is metric it usually has a groove machined at the drawbar end

Mike

Edited By Michael Poole on 26/08/2015 15:19:58

Edited By Michael Poole on 26/08/2015 15:22:16

Edited By Michael Poole on 26/08/2015 15:22:40
26 August 2015 at 19:03 #202080
Robbo
Participant
@robbo
"The drawbar thread is often etched on the body of genuine Clarkson holders"

Like this one:-

Edited By Robbo on 26/08/2015 19:04:23
31 August 2015 at 16:54 #202674
Antony Price
Participant
@antonyprice56876
Many thanks for the responses to my original enquiry. I’ve managed to get back into the workshop today. I’ve attached a photo of both my 2 MT Clarkson auto lock milling chucks. The one on the left is an “S” type. The “S” type is 3/8 BSW. The “unknown ” has CS 7174 etched on the body. Using a drill bit I’ve measured the “core” of the unknown thread, and arrived at 17/64” (0.2656&rdquo ie a 5/16” thread It is not BSF as I first thought (I couldn’t get a BSW bolt to go more than a thread) . Having looked closely, through a magnifier , I found and picked out the damaged thread. I can now get a BSW tap to go the full length of the thread. I’ve just ordered some 5/16 BSW threaded bar!

Tony
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