Drawbar Thread

[Steve CrowParticipant @stevecrow46066]

I need to make a drawbar for some homemade MT1 arbours for use on a Sherline.

Now, looking a 8mm WW drawbars, I'm assuming that a fine thread would be advantageus.

Is this correct or could I get away with a metric coarse thread? Just to save me buying fine taps and die.

Cheers

Steve

[Steve CrowParticipant @stevecrow46066]

[JasonBModerator @jasonb]

Metric MT1 collets come with M6x1 thread so that should be OK

If using comercal blank end arbors you may find they are threaded 1/4 x 20 Whit

Edited By JasonB on 09/09/2019 18:24:10

[Steve CrowParticipant @stevecrow46066]

Thanks Jason, I was hoping someone would say that! M6 it is then.

I suppose the difference is that with the WW, you are closing a split tapered collet, hence the finer (40 tpi) pitch.

[JasonBModerator @jasonb]

Yes less closing force needed on the smaller collets and the finer thread is not so deep which means the through hole can be larger

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