# chuck insert adaptor



## acewoodturner (22 Aug 2015)

I have a chuck that I use on my woodturning lathe which has a spindle of 3/4 inch 16tpi. I need to use it on my rotary device of my laser engraver which has a spindle nose of 10mm 1.5 tpi. A local engineering company quoted me big bucks to make an adaptor so I was thinking of just buying a 3/4 16tpi bolt and cutting off the head and then boring and tapping it. Does this sound feasable. I have found the bolts on ebay us but I can probably get them in this country which will cut down on postage. Any thoughts?

Mike


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## NickWelford (22 Aug 2015)

Feasible, but I would have thought making sure the hole is dead centre would be difficult.


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## acewoodturner (22 Aug 2015)

I would hold the bolt in the chuck to drill it out rather than use a drill press. Am I right in thinking it is a unf thread instead of a unc thread. The lathe is a Record btw. Anyone got any suggestions for a UK supplier of imperial bolts of this size?

Mike


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## flh801978 (22 Aug 2015)

What do you call big bucks I'll make you one for £25


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## CHJ (22 Aug 2015)

To stand any chance at all to run true and in balance the adaptor insert needs to be turned and threaded in a one shot turning and screw cut process rather than tap and die.

Existing threaded bolts are never going to be true enough unless of a very high specification and alignment to cut the other thread would need a great deal of care.

I realise the chuck may only be used in an indexing mode but I would have thought stability was a premium requirement.

The alternate to a super precision adaptor is to ensure a normal Lathe scroll chuck (100mm?) secured via a 10mm diameter thread has a decent location and reference collar so that thread form errors can't influence its alignment, especially if the piece being worked is big enough to need a standard chuck.


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## graduate_owner (22 Aug 2015)

Not quite the same thing, but I tried once making a disc sander using a threaded bolt and some drilling. Damn thing wobbled all over the place.

K


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## dickm (22 Aug 2015)

I'd bite the hand off the guy with the bizarre identifier! Having made several adaptors and/or modified threads on chucks, £25 sounds to me like a bargain - I'd want quite a bit more to do a proper concentric job.


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## woodpig (23 Aug 2015)

Having a MW Lathe if I needed an adaptor like that I'd probably have a go myself but as I'd need to use a tap to cut the internal thread I'm not too confident of absolute concentricity. Good enough maybe. To be honest though I'm not a fan of single point threading, having only done it a handful of times!


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## flh801978 (23 Aug 2015)

Mike 
Its complicated as chj says

I do it by selecting a piece of steel for the adapter in your case 1 1/8" dia

drill and tap for your male thread 10mm x 1.5mm pitch ( not tpi as you stated) and if theres a register machining that ....concenricitty isnt too important at this stage
then mount concentrically in the lathe a male thread the same size..
mount the blank and turn the outside down to the finished size in your case 3/4" with a 1 1/16" flange at the end
then turn the register and a run out groove
then using a single point cutter cut the 3/4"x 16tpi thread
deburr and jobs done

Ian


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## acewoodturner (25 Aug 2015)

Hi Ian
Sorry for the late reply - man flu has knocked me out over the last few days! I would like to take you up on your kind offer. I will strip the tailstock off tomorrow and remove the insert from the oneway chuck. If you pm me your address I will post them off to you and include a fiver on top of the 25 for return postage if thats ok.

Mike


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## flh801978 (28 Aug 2015)

Mike
all done and in the post
many thanks
ian


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## acewoodturner (28 Aug 2015)

A piece of art Ian. Thanks mate


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## woodpig (28 Aug 2015)

I love a happy ending! :lol:


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