Question on sizing a chuck

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PeteH
Posts: 1065
Joined: Mon Jun 11, 2007 10:49 pm
Location: Northern New Jersey, USA

Question on sizing a chuck

Post by PeteH » Wed Mar 28, 2012 10:37 am

For a Maximat V10 - what's the practical limit on chuck size ? I've got two 6" four-jaw chucks (univ. and indy) and want to add a 3-jaw.

Corollary - what's the largest size stock you can safely hold in, say, a 5" three-jaw ?

Thanks...
Pete in NJ

Torch
Posts: 1548
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: Question on sizing a chuck

Post by Torch » Wed Mar 28, 2012 12:54 pm

Most 3-jaw chucks come with 2 sets of jaws. With the external jaws a 5" chuck can hold approximately 5" or maybe a bit more. Safely? Well that depends on how far out the work extends from the jaws and how heavy a cut you are taking. That's what steady rests and tailstock centres are for.

Now, whether or not your machine has enough power or can be slowed down enough to turn a 5" diameter piece is a different question. If it is a variable speed motor with an SCR controller, you will lose a lot of torque when you slow it down. If it is a constant speed motor, the slowest speed depends on the gearing or pulleys. So with a lighter machine you might be able to turn a large diameter piece of aluminium (which takes less power) but not the same diameter piece of CRS (which takes less speed). Just something to think about before spending a lot of money on a large chuck you might not get full use of.

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