Drill chuck

I learned that technique in a night-school machineshop class 25 years ago, and still use it. Seems to get a better grip on the bits. Must be that the second and third rounds of tightening take up any slack in the jaws of the chuck. Haven't figured out how to do this with a keyless chuck just yet...

Since applying force with the wrench at one spot tends to make the nosepiece cant a little, applying it more evenly all-round keeps it straighter.

It's also a mantra of all the old machinists I've ever met "to use all the holes" in any chuck.

LLoyd

Lloyd sez:

Well said, Lloyd. Think of four-jaw chucks if you ever doubt this particular truism.

Bob Swinney

That's what I was taught, and that's exactly what I do. I'd probably stop if I didn't sometimes feel the ring move a little on the 2nd and 3rd holes. I use Jacobs keyed chucks and when I tighten them as above they grip the drills so that the drills don't slip.

GWE

I generally use the 3-hole method too. It's especially important on consumer grade drill chucks (the ones with the deep drawn metal outer cup) supplied with many name brand drill motors. On some chucks there is a noticeable poor fit of the ring gear to the body, and tightening in 3 holes becomes absolutely neccessary to get a good degree of grip.

I also believe it's of benefit on better quality chucks, although reaching all the holes in a chuck in a lathe tailstock can be uncomfortable, so I generally just tighten those at 1 or 2 positions.

WB metalworking projects

I've just started doing this and have noticed that the chuck does hold the bits better. I've also noticed that it seems to be easier to untighten the chuck after tightening using all three holes, even though I'm assuming that the chuck is actually tighter. Am I nuts? Anyone else notice this?

Peter

I always figured that it was because, even though its tighter, the drill bit doesn't slip and wedge itself at a weird (very slight) angle.

I'll try to remember that for my 200mm universal (self-centering and independent) 4-way-chuck I just made a back-plate for. :-)

Nick, sneezing CI-dust

Yep! That's about it. Careful observation of runout between the 2 methods will show it.

Bob Sw>> E. Walter Le Roy wrote:

Not when running soft jaws. One, and only one, can and should be used. It's the one you use to tighten the jaws when boring them for the piece that's intended to be held. Otherwise the jaws don't run true. Many three jaw chucks have one hole marked, right from the maker.

Harold

You're not nuts. With a drill chuck, when all three holes are used, the outer ring is straightened, and all the jaws are equally loaded. It's good practice to use that procedure for almost all applications, even on the spindle chuck, assuming you're not running soft jaws. Each socket tips and shifts the scroll differently, loading the jaws with the corresponding difference. It's all equalized when all three holes are used.

Harold

Use you left hand first, then your right...

I tried that, and after hours it was still loose.

Waitaminute... Am I suppose to change directions?