Re: [CAD_CAM_EDM_DRO] jacobs chuck question

On Wednesday 13 June 2001 12:11, you wrote:

> My jacobs chuck just popped out of my mill. (ruining a part of
> course). I can see that it looks like a tapered press fit. Is this
> normal? How can I prevent it from falling out again. does anyone
> have any experience with these?
> Thanks in advance.
>

My First guess: Stop using endmills in a DRILL chuck. ( #1 cause )

Second guess: The chuck was not properly seated the first time( Factory or
user ). I've had my #10 countersink cutter pull my chuck off the taper! ( I
didnt sreat it firmly enough. )


The tapers Male & Female MUST be CLEAN, with NO lubricant at all. No burrs.
Take the just cleaned chuck invert it jaw side up & take the shank/arbor
taoer side up, place the chuck on the arbor and raise it in the air, bring
your hand down striking the arbor on something hard ( vise, big piece of
steel on bench, big piece of ardwood on bench, etc. ). This will seat the
taper. place the chuck/arbor in tour machine with a piece of drill rod/reamer
in chuck & check with DTI for excessive runout. My Jacobs #33-34 or is that
34-33? has about .005" runout while holding my 1/2" reamer ( indicating on
the shank of course). My NO_NAME IMPORT keyless chuck has about .007" runout.

Try to never use endmills in a taper mounted chuck ( shouldn't use a chuck
for an endmil anyway ). The side loading on the chuck during a cut will knock
it off the arbor taper in a heart beat.


I'm not saying you ARE using a chuck for endmills just warning as a general
rule, as I've seen many others do this before.

Ty



--
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* Ty Hoeffer -- Network Analyst
* UVa. Health System/Computing Services
* pth3k at Virginia.EDU
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