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Lathe quiery

Posted: Sun Aug 11, 2013 7:17 pm
by keith.hodgenia
Can one of you talented engineers run through the process of mounting a lathe chuck onto a mounting plate. I would like it to be centred when I finish!
The chuck has 3 threaded holes on the back that don't go through to the front and the mounting plate just has it's mounting thread in the centre. Keith.

Posted: Sun Aug 11, 2013 9:19 pm
by chaz.wheeler
sounds like either you have two different fitting items or you are missing an adaptor.
there is usually a register/spigot that the counterbore on the chuck locates on and the three threaded holes have bolts that pull it back onto the plate.
on a threaded central location the chuck just screws on and its centralised.

Posted: Mon Aug 12, 2013 1:22 am
by nevhunter
The original Myford (as an example) chucks screw on to the spindle direct. If you are fitting another chuck which has blind threads (3) and a step on the rear face for alignment, you have to purchase or make an adaptor that has a good fitting thread that bottoms on a nice face so it maintains alignment. All you have to do is mount the adapter on the lathe spindle and machine it to fit snugly onto the back of the chuck, then drill the three mounting holes for the bolts. Nev

Posted: Mon Aug 12, 2013 11:02 am
by keith.hodgenia
Thanks Nev and Chaz. It's easy when you know what you are doing. I hadn't thought of machining the face of the mounting plate. Keith.

Lathe Chucks:

Posted: Mon Aug 12, 2013 11:32 am
by Bob.Murphy
Keith,

'Chronos' have mounting plates and chuck combinations. Its a good site for info as well.

http://www.chronos.ltd.uk/cgi-bin/ss000001.pl?RANDOM=NETQUOTEVAR%3ARANDOM&PAGE=SEARCH&SO=1_3_4_0&SS=chuck+mounting&ACTION=Search&TB=A&PR=-1&GB=A&SX=0

My 1950s Denford Viceroy lathe has a threaded mandrel that the chuck & face plates screw onto (1.5" X 8tpi if memory serves) but I have a couple of blank mounting plates as well - just ready for attaching other devices.

Warning: The Chronos website is very bad for your wallet (I spend a fortune there :cry: ).

Good luck with it.

Bob.

Posted: Tue Aug 13, 2013 8:32 pm
by Mike Nash
Well Keith, as a bodger rather than a proper engineer can I add a thought?

My very ancient Drummond round bed lathe has a couple of extra chucks which are secured to mounting plates that screw onto the lathe mandrel in usual way, but the holes through which the bolts go that hold the chuck on to the plate are slightly larger than the bolts' diameter. So with the bolts just nipped up its possible to gently tap the chuck with a soft hammer and with a dial gauge on a bar held in the chuck to ease it central in relation to the mandrel by tapping and turning it.

I thought they were all like this! Regards, MikeN.

Posted: Wed Aug 14, 2013 3:48 am
by nevhunter
It should be located by the step in the face . If the adapter becomes out of true you can turn the face down again as long is there is sufficient thickness in it. Chuck direct on mandrel is the most rigid and best. The more the chuck hangs out from the spindle the more it will chatter when parting off etc. Nev

Posted: Wed Aug 14, 2013 8:28 am
by keith.hodgenia
Hi Mike, being a fellow bodger, your solution was what I had in mind. However machining the mounting plate sounds like more rigid solution. Keith.

Posted: Wed Aug 14, 2013 9:55 am
by john.whiting
Yes ,its best to reduce overhang of the chuck as far as possible.Its allways preferable to thread the inside of the chuck for mounting ,even if you need an adapter to match sizes.If you reverse the chuck,and grip the spindle end,you automatically centre the chuck,and can use your own lathe if you don't have another chuck. While on the subject of lathes, if you see an old lathe being scrapped,allways check it out to see if a bike gearbox has been used somewhere. I recently salvaged a near new army Indian Chief gearbox and clutch from a large old lathe loaded on a low loader headed to the scrapyard.The funny thing is the owner of the lathe is an old bike fanatic,yet he d never noticed the gearbox.He still doesn't know.Regards John.