Drill chuck capacity

PT Doc

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I will be getting a keyless precision drill chuck with integral r8 shank. Options are 1/2” capacity or 5/8”. My drills go up to 1/2” and I will be getting a collet set prior to this purchase. I know better than to use a silver deeming in a keyless. When do you use the capacity above 1/2” in the 5/8” capacity? Which would you get? Thanks in advance!
 
I have found that big drills and a keyless chuck makes for hard to loosen the chucks jaws. Stick with the 1/2 in
 
I would not pick a keyless drill chuck for my first chuck. One reason, can’t power tap. Second reason is chuck can lock up on bits. Third reason, can’t feel how tight you are chucking. I would get a key type and would be a Jacobs brand and be ½” cap…Dave
 
The larger ones often don't close to zero, so some small bits might not work. Just something to think about if you see yourself using smaller bits.

That is correct. The option is 0-1/2” or 1/8-5/8”.
 
I would not get a R8 taper shank for the chuck. I would get a straight shank. It is much quicker and easier to change out the chuck with another tool with the same shank size than it is to remove and replace the R8 taper tooling. It also takes up much less headroom and wiggle room to pull down and swing the chuck through the setup if you use a short straight shank on your tooling. Besides that, it will also fit other machines easier. A tool with an R8 shank will pretty much only fit a vertical mill. I would go with a 0-1/2" Jacobs ball bearing chuck, preferably one of the older ones in great condition that says Hartford, Conn, USA. Anything else is an import.
 
I just got a nice 0-1/2 keyless chuck for most of my work and then got a cheap 3/16- 3/4 keyed chuck off of ebay for the rare times I need larger than 1/2. The 3/4 keyed chuck with arbor was less than $30 and seems to be decent quality, but, I have not checked run out.
 
I power tap all the time with my keyless chuck.
Why do you take the position you took?
When you run the spindle/chuck in reverse. A keyless chuck can easily un-loosen itself. And when I power tap small taps, I like to know how tight I’m holding the tap. On small taps I want a slip and not a broken tap. And yes, I have slipped a few taps in my chuck. The chuck, its jaws and accuracy have been the same for decades, no problems. I don’t mean spinning all day. Just a slight move of the tap from holding position…Dave
 
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