Posilock threads.

[ChrisParticipant @chris16039]

Does anyone know what the thread is on the posilock milling chuck (mt 3)? I have a Clarke 500 lathe and need to make a draw bar.

Chris.

[ChrisParticipant @chris16039]

[David Clark 13Participant @davidclark13]

Hi Chris

What is the internal diameter of the thread?

Usually drawbars are 3/8 Whit or 10mm.

 

The Clarke is more likely to be metric so  I would try a 10mm bolt in it first.

If that fits, buy a bit of 10mm studding (threaded rod) from B&Q.

 

Larger Bridgeport type mills are usually 7/16UNF.

regards David

 

[RichmondParticipant @richmond]

Hi,

 

From memory, some of the MT3 chucks have an M12 thread for use as a drawbar.

 

A quick call to Chester should resolve this for you.

 

Rgds

 

[ChrisParticipant @chris16039]

Hi David and Richmond,

Thanks for your help. Turns out to be 100 but not the pitch of standard studding. Found a bolt at work ( I’m the maintenance man at a lead mining museum, how obscure can you get) that fit and cut,sleeved and welded it to the Clarke drawbar. Success. plus a lesson learned,10mm is not always what you think!

Thanks again, Chris.

[GarethPParticipant @garethp36498]

If its a old Clarkson posilock it’ll be whit – I took mine to the local engineering merchant and told them I thought it was 3/8 whit, they then produced a length of metric stud which did screw in but rattled about – I insisted on a piece of whit stud and it fitted perfectly.

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