Question About Drill Chucks (not Specifically Atlas)

[louosten]

Greetings to All;

While conducting my drill press rebuild exercises, I noticed that some of the newer chucks come with a hole thru the center, presumably for a screw to hold the chuck firmly to its particular mount, in my case, a JT33 taper.

I have read on other websites that drilling a hole thru your chuck for this purpose does not hurt it at all, and gives an additional measure of safety in terms of keeping the chuck mounted properly during drilling operations (and any other use for which amateur home machinists are known for!).

My question is simple; is there a preferred screw/thread size for this modification, and if so, what are the recommendations?

Thanks in Advance,
Lou O.

 

[mikey]

I wouldn't bother with the hole or the screw. A properly mounted chuck on a Jacobs taper will not require additional security - the drill will spin in the jaws before the chuck spins on the arbor. Buy a good arbor - Jacobs, Albrecht, ETM, Rohm - then clean the JT and arbor with lacquer thinner before installing the chuck. It will be there until you take it off.

 

[Dave Paine]

I agree with Mikey. I have never had a Jacobs taper come loose. The only chuck which I have with a screw mount is on a Milwaukee hand drill.

A good Jacobs taper and cleaning both parts should never spin or come loose.

 

[chips&more]

Heat the female taper part. And cool the male taper part. Then attach them. Then they will REALLY stay together!

 

[turnitupper]

Heat the female taper part. And cool the male taper part. Then attach them. Then they will REALLY stay together!

That sounds a bit like Marriage Guidance.
John.

 

[wa5cab]

Also, the hole through the chuck body (not present in all chucks) is there to aid in removing the arbor.

 

[louosten]

Does it matter that air gets compressed between the chuck and arbor when there is no hole thru the chuck, or does this eventually seep past the mating parts and equalize on its own?

 

[mikey]

No, it doesn't interfere with the fit. The typical chuck has a much deeper recess than the arbor taper occupies and there is enough space for the air.

 

[wa5cab]

Plus the pressure increase due to the last few thousandths of axial movement is not significant compared to pressure change due to temperature rise anyway.