Problems with chuck

[Andy Spence 4Participant @andyspence4]

Having a problem with getting my 3 jawed chuck centred. Can anyone advise on the best way to get it centred. It is not the self centring one.

Any help appreciated.

[Andy Spence 4Participant @andyspence4]

[Tony Pratt 1Participant @tonypratt1]

Hi Andy,

Are you saying you have a 3 jaw chuck but each jaw is moved independently? I must confess I have not seen such a thing, doesn't answer your question but need clarification.

Tony

[pgk pgkParticipant @pgkpgk17461]

Posted by Tony Pratt 1 on 01/11/2015 12:51:28:

Hi Andy,

Are you saying you have a 3 jaw chuck but each jaw is moved independently? I must confess I have not seen such a thing, doesn't answer your question but need clarification.

Tony

That's what i understood and I'll take a crack at the answer (although as a beginner I could be way off)…

Eyeball with a bar in .. take a dti reading with each jaw in line with the dti… add the three figs and divide by 3.. back off the tightest jaw(s) in turn to that number (tghtening the loosest towards that number).. remeasure and adjust/repeat…???

[JasonBModerator @jasonb]

If you look in Andy's albums you can see its a 3 jaw combination  chuck.

Just need to treat it like you would a 4jaw initially  – put a good straight bar in the chuck and use a DTI against the bar to clock it true by adjusting the individual jaws. Once that is true use the keyhole that moves all three jaws at once..

 

J

Edited By JasonB on 01/11/2015 13:24:54

[Andy Spence 4Participant @andyspence4]

Thank you all for the replies.

Yes it is a combination chuck sorry I didnt realise thats what it was called (beginner). Its seems a good chuck as in there isnt much play in the jaws they are fairly tight. I will try true it up with a DTI.

[NJHParticipant @njh]

Hmmm

My first thought was a Pratt Burnerd GripTru chuck. ( Nice bit of kit but pricey – I have one I purchased at a lower price S/H! ) This chuck a 3-jaw chuck but its position on its backplate is micro adjustable and a component can be gripped then set to run true ( they claim easily to within 0.0002" – I don't know about "easily" but maybe I need more practice!) . When machining is finished and the item is released other items, of the same size, can be gripped and will run true without the need to re-center. Looking at the photo though I think Jason has it right.

If anyone has a GripTru for which they need the operating instructions give me a shout.

Norman

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