Small drill chucks?

[Janger]

This is my small cnc lathe project. The round thing is the tool changer. It comes with these odd 90 degree holders for holding drills etc. I think the idea is to put a drill chuck in the holder. The drill chuck would have to be pretty small. Perhaps 2” in diameter or a bit less. Where can I get a decent chuck of this kind of size? I’d want two.

I also want to hold taps. For small taps 1/4 or less could I get away with using a drill chuck?

 

[Tom Kitta]

For 1/4 and under I like to use tapping head with build in cluth system. Yes you can hold taps in a chuck, collet chuck (you can get small ones like you described in aliexpress with say ER16 collet.

Main problem with drill chuck / collet holding small taps is how much do you tighten them. Usually drill chucks will spin tap much sooner then collet with "moderate" tightening. You can probably get away with this 99% of the time in aluminium and say 90% in mild still when not going to tap too deep, say no more then 3x tap diameter. This is with newish tap.

But for deep tapping even in mild steel - say all the way - so more then 3x - say 6x your success drops dramatically.

It takes about 20 times longer to remove a broken tap then to tap it. It also usually kills at least one carbide end mill.

If you have time and lots of holes to tap you could use some kind of torque wrench and progressively tighten the chuck till it taps easily what you want but then spins just after - sort of "manual" adjustment.

For taps around 1/2 and bigger I never got them to break in a collet even when hand tight with a wrench - so far they always spin.

If you are sure if your tapping - say not blind hole - you can get a small tapping chuck - they grab the "square" end of the tap and have a collet or similar to adjust the tap so it goes straight. Small ones are not torque adjustable.

 

[Mcgyver]

Neat project - is that your build? tell us more!

You can hard tap on that machine? For small taps probably ok, but for certainty I'd be thinking a bushing carefully turned to fit the bore of the holder and a set screw on the tap. As you probably know drill chucks get a bite on a drill because the top of of it isn't hardended .,...not so with taps

 

[trlvn]

If you do want to go with drill chucks, most chucks with 3/8" capacity or less have a body diameter of less than 2 inches. Less if you restrict yourself to 1/4" capacity.

I've attached an old Jacobs catalog that lists various models. I'm not sure all these are still produced but it should at least give you an idea. For example, a Jacobs model 31B, 1/16 to 3/8" capacity, with 1/2-20 threaded mount is 1-27/64" diameter.

Craig

 

[Tom O]

Another pic problem? This is what the iPad brings up.

now I can touch it and it brings it up in the usual display but still doesn’t load on the page.

 

[Janger]

Another pic problem? This is what the iPad brings up.

View attachment 18625
now I can touch it and it brings it up in the usual display but still doesn’t load on the page.

Trying again here. Adding full image works but not a small image. I’m not sure what’s going on here.

 

[PeterT]

You can get smallish chucks like shown. Some go under the name 'precision' although that's debatable. You might be able to find a clone inexpensively. The trick is finding or making an arbor that fits the internal taper of chuck & suspect you want straight for the tool holder?

If its only for tapping, I've seen tapping specific collets, but I'm not sure how they are different common holders are. I've seen them in ER maybe? Collets in tapping heads have a rubber between the jaws so there is some degree of float.

Your rotating tool changer would have to be dialed in close like a tailstock. Breaking centers & drills & taps at a rapid rate is almost guaranteed if its out relative to spindle axis.