Thread: Is there a right way to tighten a drill chuck?

The chuck key is just a pinion gear working on a crown wheel. The crown wheel turns and tightens the chuck pieces regardless of where the pinion is. Changing which hole is used is of no value other than perhaps changing the relative purchase of the pinion on the crown wheel. It would be about as non-sensical as turning a keyless chuck to three different positions, at 120 degrees stages, relative to where you are standing.

FWIW.

Cheers

Donald

Originally Posted by fraserbluff

TIt would be about as non-sensical as turning a keyless chuck to three different positions, at 120 degrees stages, relative to where you are standing.

Really? (note to self - stop doing that)

To be serious for a minute, why is it then that when I tighten the chuck in one hole, then transfer to another, it turns and bites again. Then possibly a third time when I do the last hole?

I like the keyless for convenience and have a very good keyless on my tailed Makita drill that hasn't slipped yet. But when drilling the heavy stuff I like to use the keyed chucks and tighten using all three holes. Maybe it just makes me feel better, but it seem to be tighter .

Originally Posted by Jacksin

I wonder if this 'tightening every hole' theory came from the old 4-jaw lathe chucks etc that had each of the 4 jaws moving independently?

4 jaw lathe chucks old ? They are still made and used daily .
The best chuckto use to get a job running perfectly true in a lathe is use a 4 jaw chuck.

Kev.

I was taught three hole method and I've noticed the same as you Groggy. You can definitely keep getting it tighter.


BTW, I had to break down my drill press for our recent move. A cat's paw prybar and a sharp whack with a hammer got the chuck right off if you've ever wondered how to pull it. I'm sure somebody has the right way to do it.

Originally Posted by Eli

BTW, I had to break down my drill press for our recent move. A cat's paw prybar and a sharp whack with a hammer got the chuck right off if you've ever wondered how to pull it. I'm sure somebody has the right way to do it.

When you pull the chuck down you should see a slot in the quill. Insert a drift in there and tap it out.

Hi

I have read this question before on other forums and it tends to raise similar answers. Here at least it seems (so far) that the majority favour using the three holes.

I was taught the same 3 hole principle by my engineering teachers (waaaay back in the dark ages of 1958). It does make a difference in the gripping power of the the chuck, there is no doubt about it. This can be proven by the fact that (as previously posted in this thread) that if you tighten the chuck using only one key hole, you can still get an "extra bite" on each of the other two holes.

While such action may not be very often required and perhaps chuck manufacture today has improved, if you are to drill larger holes in steel or other metal the three keyhole approach will help prevent the drill bit from spinning in the chuck if the bit "grabs" the metal.

I also STILL use the three holes most of the time, I had a good teacher

I know it makes a difference, How? I'm a lazy sort of person and when tightening a keyed chuck I normally only use one hole, which is fine in most cases. However if I'm using a larger drill and it starts to slip in the chuck I do as everyone does, I retighten the chuck usually with only one hole. But if the bit still slips after this retighten I will do the three holes tightening and almost every time no more slipping. For the doubters out there try it I think you will be suprised by the result.

Originally Posted by Wizened of Oz

That bit is factual.
The 3 holes are there simply for convenience.

X Wrong. Try drilling a 10mm hole through steel with tightening just 1 hole in the chuck.

Originally Posted by DJ's Timber

As someone who used to regularly drill 12mm up through to 32mm holes in 12mm up through to 25mm thick steel, I can say with great confidence that tightening the chuck via the 3 holes does make a huge difference.

+1. Its simple logic. Even pressure for maximum grip/holding ability.

No Matrix your quite incorrect.

By definition a drill chuck is a simple crown and pinion gear assembly and by tightening in 3 different possitions all you are really doing is dispacing the crown wheel more to one side of its centrally located position. It wont centralise under any circumstances by the fact that its a crown & pin gear train and that the force applied is lateral to movement of the crown.

The original concept of tightening in 3 places was for the 3 jaw self centering lathe chuck where by tighening each hole you were taking any slack out of the scroll gear and centralising the scroll to the machine centre. By centralising the scroll your actually centralising the work. These two gear trains are totally different in design and operation.

BTW yes I am a mechanical engineer and have been for the past 22 years.

Originally Posted by fraserbluff

The chuck key is just a pinion gear working on a crown wheel. The crown wheel turns and tightens the chuck pieces regardless of where the pinion is. Changing which hole is used is of no value other than perhaps changing the relative purchase of the pinion on the crown wheel. It would be about as non-sensical as turning a keyless chuck to three different positions, at 120 degrees stages, relative to where you are standing.

FWIW.

Cheers

Donald

I think this is logically correct. However, in Industrial Engineering school, we had to perform a Methods Time Measurement exercise that involved watching (more than once so I remember it like yesterday) a film of a drill bit being fitted to a keyed chuck on a power drill. All three holes were used. Nobody had ever seen it done that way and there was some bewilderment.... The engineer (proper engineer of old school) who ran the course explained that was the proper way to do it. Seems like a good idea if you are fitting a biggish drill that might bind in the metal.... well 2 of 3 holes maybe.....

And so it goes on............ and on.

Some goose back in the early 20th century thought it was a good idea to tighten a drill chuck using all 3 key entries. Somebody else noticed this and asked why - and he replied "cause it makes the drill tighter in the chuck". Neither of them had one ounce of understanding about machinery or geartrains but because this twerp said so them it must be true. And this myth gets perpetuated down through the ages where somebody with supposed credability such as "an old engineer" has dribbled this out and yet again its believed by the masses without question. Why is an "old school" engineer credible?? - maybe because you were too young to question his statements or to simply ask why.

As I indicated previously I can see the purpose in a 3 jaw self centering lathe chuck as each entry is a gear train in itself, but not a drill chuck. I will happily listen to any arguement based on facts and mechanical principles and concede to better knowledge if proven wrong but just because some old fart and a film said it must, be so it is - I don't think so.

Well humour me please Mark, why is it that when tightening my chuck, that if I tighten it as tight as I can using one hole, I can get it to move and tighten further in successive holes? If the practical application isn't meeting the theory then someone needs to tell this to my drills and drill press

Originally Posted by Groggy

Well humour me please Mark, why is it that when tightening my chuck, that if I tighten it as tight as I can using one hole, I can get it to move and tighten further in successive holes? If the practical application isn't meeting the theory then someone needs to tell this to my drills and drill press

Easy
Providing your not applying any further torque to the any of the keyways than what is already applied, what your actually doing is moving the the drill sleeve (the crown gear) in a sideways motion and taking up any slack between the sleeve and its screw thread. With each movement to the next key holes you move the sleeve in a 60 degree direction away from the previous position.

In the fictitious world where all forces are equal and friction is meaningless you could go on tightening your chuck for ever, but in our real world I would assume that with each twist of the key you add a bit more torqe to the system unit it so loaded it cant move in any direction.