5/8 Keyless Chuck

JPG · Post by **JPG** » Sun Dec 30, 2012 8:08 pm

fredsheldon wrote:That I did not know. What is the theory behind that suggestion.

Consider how the jaws are advanced inward(bit squeezing).

The outer sleeve(the part with the gear teeth at the end that the chuck key drives) is threaded inside. Those threads engage threads on the jaws. The jaw threads are offset so the jaws are 'synchronized'(advance 'together' in unison). There is a slight amount of play in those threads that the round robin tightening minimizes. After the tightening in the first hole, the other two will cause diminishing movement of the sleeve.

Those threads are also tapered to match the slope of the jaws[outside edge that rides in a groove in the (lower) body].

With a new chuck the triple tightening is less necessary, but on a worn chuck it becomes 'mandatory'. I have an old 3226 that requires twice around!

Same thing with 'cheaper' chucks.

reible · Post by **reible** » Sun Dec 30, 2012 9:25 pm

I had been taught to do only two positions. You can get carried away and jam a chuck. You get carried away tightening on the third but when you want to take the bit out you will find it will not turn the other way, yep jammed. Have I seen it happen, yes.

Granted metal shop was a lot of years ago and my days of working in a machine shop is close to 42 years ago so things might have changed. If they have then go for it. Me I never have bits slip with just doing two holes.

Those of you who do the three you can't say you weren't warned.

Ed

JPG · Post by **JPG** » Sun Dec 30, 2012 10:09 pm

reible wrote:I had been taught to do only two positions. You can get carried away and jam a chuck. You get carried away tightening on the third but when you want to take the bit out you will find it will not turn the other way, yep jammed. Have I seen it happen, yes.

Granted metal shop was a lot of years ago and my days of working in a machine shop is close to 42 years ago so things might have changed. If they have then go for it. Me I never have bits slip with just doing two holes.

Those of you who do the three you can't say you weren't warned.

Ed

Interesting! I be curious how the jamming occurs.

This is one of those where 'opinions' differ - http://www.practicalmachinist.com/vb/general-archive/there-correct-way-tighten-drill-chuck-84937/

dusty · Post by **dusty** » Mon Dec 31, 2012 4:18 am

[quote="JPG40504"]Interesting! I be curious how the jamming occurs.

This is one of those where 'opinions' differ - http://www.practicalmachinist.com/vb/general-archive/there-correct-way-tighten-drill-chuck-84937/

] Interesting read. I sorta do all three after hand tightening the bit in the chuck. To each his own.

Ed, I do sometimes have difficulty loosening the chuck. I'll be paying attention (for awhile) when at the drill press. I may alter my methods.

JPG · Post by **JPG** » Mon Dec 31, 2012 11:32 am

dusty wrote:Interesting read. I sorta do all three after hand tightening the bit in the chuck. To each his own.

Ed, I do sometimes have difficulty loosening the chuck. I'll be paying attention (for awhile) when at the drill press. I may alter my methods.

After securely tightening ala 3 holes, I would expect the amount of torque required to be applied to the key to loosen it would be greater than that required to tighten at each hole.

I do think excessive tightening could lead to wear and cause an 'over the center' condition with those worn parts that could result in 'jamming'. Those parts are quite hard and would resist 'unjamming'.

keakap · Post by **keakap** » Mon Dec 31, 2012 4:11 pm

reible wrote:I had been taught to do only two positions. You can get carried away and jam a chuck. You get carried away tightening on the third but when you want to take the bit out you will find it will not turn the other way, yep jammed. Have I seen it happen, yes.
..Ed

I tend to treat the three as if it were a multi-bolt torquing situation, like an engine head or a car wheel, 1st position just snug, 2nd, 3rd, then tight, tight, tight. Don't know why. Just seemed like the right thing to do. Never had a jam, tho. And I can believe it could happen.

keakap · Post by **keakap** » Mon Dec 31, 2012 4:16 pm

JPG40504 wrote:After securely tightening ala 3 holes, I would expect the amount of torque required to be applied to the key to loosen it would be greater than that required to tighten at each hole.
....

And now another angle- makes me wonder if the amount of torque to loosen would be less on the last one tightened.
So once the tightening is done, keep an eye on that last one cranked down and undo it first.
[oops, fuhgeddabowdit-- I tried it and got really dizzy...]

charlese · Post by **charlese** » Mon Dec 31, 2012 6:08 pm

I used to tighten two places. Did that for years. Then, just playing around, I used all three holes. That seemed to be better to me as the third most often had some movement to tighten.

The technique I use is to use only light pressure on the key in all three holes. Then I find all holes are now firmly tightened. I have not done much in the way of loosening one hole at a time. I think such a process would be a good thing for the longevity of both the key and the chuck.

Have you ever noticed how a new key will fit the teeth better than an old one?

Another technique that has helped is to use only my right hand to snug and tighten a bit - and use only my left hand to loosen the chuck. This way the teeth of the key are always firm to the teeth in the chuck. Think of it the old way as righty tighty- lefty loosey.

fjimp · Post by **fjimp** » Mon Dec 31, 2012 9:33 pm

When buying my Mark V at a Lowes Store in Virginia, the fellows doing the demo ask if I had any additional questions. As he was answering a few he offered the hint of tightening all three points multiple times until all tight. I have been using drill presses for years and continue to be surprised at the difference in results. Jim

Ed in Tampa · Post by **Ed in Tampa** » Tue Jan 01, 2013 11:09 am

Somewhere in the Shopsmith material it tells you to tighten using all three holes. It was the first time I ever heard this and I was surprized when I did.

I do what I'm told, in this case I don't believe tightening three different places does a thing, but that is what SS said to do, so that is what I do.

If the either the ring with holes or the ring that has the gears cut in it were anything other than solid pieces I would see why it is required however both are solid steel and unless compression of the steel by hand tightening is enough to deflect the steel ring I don't buy it. However I do buy by using all three holes you triple check you have the chuck tight and thus won't ruin the bit.