On Thu, 11 Jan 2018 15:24:14 -0800, Gunner Asch
wrote:

On Thu, 11 Jan 2018 11:38:55 -0700, Bob La Londe
wrote:

I recently got a good deal on a new old stock Bison 10" independent 4
jaw. Its the model with the FPJ logo instead of the actual Bison logo.
In my search to make sure I had actually gotten a chuck made by Bison I
ran across references to how fast you can spin a chuck. I'd never
really thought about it before.


The lathe I plan to use it on turns upto 2000 RPM. I have for short
periods spun the 10" import chucks that came with the machine at that
speed. Other than taking a little while to come up to speed I never
noticed any adverse issues. However! I'm certainly no expert on this
sort of thing.


How fast can I safely spin this big heavy Bison chuck? Is there a
reference where I can look it up? What about the cheaper 10" import 3
jaw that came with the lathe or for that matter the cheaper 10" 4 jaw
that came with it?

Im not an "expert" on chucks..but I do deal with them in my work. A
10" chuck...well..it largely depends on the size of the work IN the
chuck. Most 10" parts..depending on speeds and feeds..wont ever be
run much faster than 1000 rpm. Aluminum of course...shrug..spin it as
fast as you want. That being said..the jaws are now trying to fly off
the chuck at speed..the bigger the chuck, the bigger the jaws..the
more energy that they are carrying...trying desperately to leave the
chuck due to centripital forces.

If a jaw ever gets a crack in it...it will ultimately turn into a
rather nasty fragmentation device..having a pound of cast iron leaving
that chuck at speed...can be lethal..and can screw up your entire shop
even if it doesnt hit the operator.

Personally...I think you are "ok" at 2k rpm with a good quality chuck
in good condition. Its fast..but its not Real Fast.

Most CNC lathes will turn a 10" chuck up to about3000 rpm..but the
question is...SHOULD you spin a chuck that fast? It takes time to get
up to speed unless you are running a 25hp motor ....and it takes
significant time to slow down to a stop.

Most manual lathes that I work with..up to about 20"...max out their
speed range at about 1500 rpm. This is not just due to chuck size..but
all the spinning bits inside the head are also spinning pretty fast as
well...lots of energy trying to tear that chuck apart.....

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Most chucks will lose their grip on the work long before they're in
danger of exploding.

--
Ed Huntress