Drilling with Keyed Chuck

[syscore]

I was drilling 0.201" (#7) through holes in 1" 6061 stock, and it seems that no matter how hard I tighten the (tormach) keyed chuck, the bit seems to get push up into the chuck the deeper the hole. I switched to a collet and it seems to work fine. Is that a common experience? I was drilling at 3000 RPM, 12 IPM, 0.2" Peck. I started at 4000 RPM, 15 IPM, 0.1" Rapid Peck, and I think that would have been fine, if the bit didn't keep working its way up in the chuck. I didn't try the more aggressive drilling yet with the collet setup. All of this is with flood coolant. Holes less than 0.5" have never been a problem with the keyed chuck. I also tried the keyless chuck awhile back, and concluded that is maybe ok for plastic or wood, but not metal.

Bob

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[popspipes]

Possibly the drill is a bit dull or the relief angle is too shallow for 12 ipm, I have seen new drills with too shallow of a relief angle and the heel would rub.

I drill a .201 hole .625 deep, no peck, 1500 rpm, 5 ipm, oil coolant.

I would try regrinding the drill for more relief angle or dropping the feed rate a bit.
A chuck in my experience will slip easier than an ER collet.

[Labern]

Also try tightening the drill on all 3 key location points. As you might find you can get it a bit tighter.

Sent from my SM-A320Y using Tapatalk

[kstrauss]

I was drilling 0.201" (#7) through holes in 1" 6061 stock, and it seems that no matter how hard I tighten the (tormach) keyed chuck, the bit seems to get push up into the chuck the deeper the hole. I switched to a collet and it seems to work fine. Is that a common experience? I was drilling at 3000 RPM, 12 IPM, 0.2" Peck. I started at 4000 RPM, 15 IPM, 0.1" Rapid Peck, and I think that would have been fine, if the bit didn't keep working its way up in the chuck. I didn't try the more aggressive drilling yet with the collet setup. All of this is with flood coolant. Holes less than 0.5" have never been a problem with the keyed chuck. I also tried the keyless chuck awhile back, and concluded that is maybe ok for plastic or wood, but not metal.

Bob

Use an ER collet and never a slip.

[handlewanker]

Must be a crap chuck....I use Jacobs keyed chucks and never have push back even with .500" drills.

[RCaffin]

I agree with Ian - crap chuck.

Cheers
Roger

[syscore]

Possibly the drill is a bit dull or the relief angle is too shallow for 12 ipm, I have seen new drills with too shallow of a relief angle and the heel would rub.

I drill a .201 hole .625 deep, no peck, 1500 rpm, 5 ipm, oil coolant.

I would try regrinding the drill for more relief angle or dropping the feed rate a bit.
A chuck in my experience will slip easier than an ER collet.

Thanks for the info all.

I tried a new bit, but I think you are right, it is the relief angle. Thanks for the info. I halved my feed and speed to what you are using and it wasn't straining, and the chips seemed to come out of the hole more naturally. I am definitely going to stick with collets from now on, at least for the hole sizes I do a lot of. In summary, I tried 3 levels of speed (I have rounded the values). 4500 RPM / 15 IPM, 3000 RPM / 10 IPM and 1500 / 5 IPM. The 1500 / 5 IPM was certainly the least anxiety and smoothest operation. When I get time I will see about grinding the bits or getting different bits. I would like to be able to step it up at least to the middle speed of 3000 / 10 IPM. I am able to peck a full diameter though, which does speed things up. And I am using full retract (G83) on the 1 inch holes, rapid retract (no peck) on the 1/2" holes.

Thanks
Bob

[popspipes]

Thanks for the info all.

I tried a new bit, but I think you are right, it is the relief angle. Thanks for the info. I halved my feed and speed to what you are using and it wasn't straining, and the chips seemed to come out of the hole more naturally. I am definitely going to stick with collets from now on, at least for the hole sizes I do a lot of. In summary, I tried 3 levels of speed (I have rounded the values). 4500 RPM / 15 IPM, 3000 RPM / 10 IPM and 1500 / 5 IPM. The 1500 / 5 IPM was certainly the least anxiety and smoothest operation. When I get time I will see about grinding the bits or getting different bits. I would like to be able to step it up at least to the middle speed of 3000 / 10 IPM. I am able to peck a full diameter though, which does speed things up. And I am using full retract (G83) on the 1 inch holes, rapid retract (no peck) on the 1/2" holes.

Thanks
Bob

Glad to help......

I dont normally have drills slip in the chucks, usually if it slips when reasonably tight, something is wrong with the settings or the the cutting edges or relief angles and the faster the feed the more relief is needed for clearance.
The reason I dont need the peck is the coolant, I use ULSD diesel fuel, makes drilling cutting and tapping much easier, and the machine doesnt rust or corrode, water based is fine when used regularly but I dont use my machine that much, this just works for me..............

[74BurkeMVN]

I agree with Ian - crap chuck.

Cheers
Roger

I concur as well. I've used Albrecht and Jacobs keyless chucks on my manual machines for 20 years with zero slippage. The keyed chucks that Tormach sells are usable but far from great. One of mine out of the box can be endlessly tightened when you go around at all three points.

[RCaffin]

I have both Albrecht and Jacobs - and they are very good indeed. One of the Albrechts is even calibrated for drill diameter!

Cheers
Roger

[handlewanker]

Hi....one thing that has irked me for yonks......people think that tightening a 3/4 jaw self centering chuck by using every hole in the periphery is going to increase the gripping power or the accuracy do not understand the design of the internals.

Any one of the tightening spindles on the self centering chucks are designed to cause the scroll to rotate and thereby apply a force against the 3 jaws ....EQUALLY.........this applies in a similar way to a Jacobs chuck which has a type of split scroll to move the jaws out.....slightly different in design, but the same principle.

If your chuck only responds better by using all the holes to tighten the jaws to get accuracy or increased gripping force..........it is truly crap.....worn on the scroll......only fit as a welding holding device.
Ian.

[RCaffin]

Know your tools.
If necessary, by pulling them apart and cleaning them.

Cheers
Roger

[popspipes]

I usually use just one hole, however there are three holes in all the chucks I have and why would the manufacturers put in three holes when one would do, maybe balance? I do think tightening evenly at three points would be possibly more accurate from a friction standpoint on the gearing.

It depends on which posts or forums you read as to which is best.................

[RCaffin]

There are at least two good reasons for having 3 chuck key holes.
1) Balance - the hole is/was a solid bit of steel after all.
2: Sheer convenience. With 3 holes, there is always one easy to access with a key when the drill stops spinning.

A 3rd reason, of lower importance, is that these holes wear a bit. Having 3 holes makes the chuck last 3 times as long.

Cheers
Roger

[handlewanker]

Hi....all 3 reasons Roger mentioned are quite correct.

I "serviced" a 3 jaw chuck for someone once, and in the final assembly greased the inside of the body shell............this horrified the guy who adamantly stated, by thrusting a user manual up my nose, that the chuck inside mechanism must not be lubricated at all.

I've been in the trade for a few years and I've always used this method.........the reason is, when you get small particles of swarf inside the body they always get into the gears and scroll.....the thin layer of grease inside the body of the chuck shell......not the moving parts...... serves to trap them as they get flung outwards with centrifugal force.

The scroll is an exception.......it must be lubed with thin oil....or a thin coat of anti seize compound......... on it's back face and the bearing area it rotates on....nowhere else.

Most chuck bodies are iron and the scroll is hardened steel ground to a fine finish.........if the scroll is fitted dry it will seize up in the body.

It pays to stuff a rag inside the chuck bore when boring a hole to ,prevent the swarf from migrating out of the bore and into the chuck body via the jaw grooves.

Swarf will always get into the insides when the jaws are gripping small diams and the back teeth of the jaws get loaded with particles that you can't clear before retracting the jaws for a larger diam.

Periodic stripping and cleaning is the only answer.

A Jacobs keyed chuck doesn't have this problem but they can get wear on the jaw gripping faces......stripping one down is a very tedious and delicate exercise.
Ian.

[Labern]

Only reason I mentioned it as one I have never fully tightens by using just one. Each key hole you use tightens it a bit more and is fully tight when all 3 are done. It's not my general practice but thought it might help this case if his chuck is the same as one I have.

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[handlewanker]

I have to state that you are totally wrong in your assumption............tightening a "normal" 3 jaw scroll chuck by progressively using all 3 key holes is totally irrelevant.

This also applies to a Jacobs type keyed chuck.

The design of a "normal" 3 jaw scroll chuck has 3 chuck key holes for convenience.....and balance.... and the scroll can be rotated by just one key hole without any inaccuracy occurring from uneven jaw movement........the internals are designed in that way.

Once the jaws are tightly gripping the work piece any subsequent application of force to the other chuck key holes will NOT increase the holding force.......if you believe that this is not true you also think the World is flat...............I do get so wound up by stupid assumptions.

BTW, what do you do when you have a keyless chuck....be it a lever scroll type or a drill chuck?
Ian.

[RCaffin]

Quote from Jacobs Service and Repair manual:
"A good grade of grease should be applied to the jaw and nut threads, then the nut halves should be closed around the jaws."
Then reassemble.

Only reason I mentioned it as one I have never fully tightens by using just one. Each key hole you use tightens it a bit more and is fully tight when all 3 are done. It's not my general practice but thought it might help this case if his chuck is the same as one I have.
May I respectfully suggest you could buy a new chuck?

Cheers
Roger

[Labern]

Quote from Jacobs Service and Repair manual:
"A good grade of grease should be applied to the jaw and nut threads, then the nut halves should be closed around the jaws."
Then reassemble.

Only reason I mentioned it as one I have never fully tightens by using just one. Each key hole you use tightens it a bit more and is fully tight when all 3 are done. It's not my general practice but thought it might help this case if his chuck is the same as one I have.
May I respectfully suggest you could buy a new chuck?

Cheers
Roger

Yes it does need replacement. I'm sure greasing would help. I think it binds with the side loading and is why it tightens more at each point.

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[handlewanker]

Yes, I agree, drill chucks, not being prone to swarf entry but could get coolant in when drilling in the horizontal position in a lathe, are designed purely to hold round shank drills etc, and should be lubed.....but this does not also apply to a self centering lathe chuck.

I acquired 20+ 16mm Jacobs drill chucks from the firm I previously worked for as they just dumped them when the slightest problem occurred, mainly from the unskilled pseudo setter operators not being able to work out if the drill or the chuck was at fault.

At $5 for 20+ or a bucket full, it was bargain time.

I just disassembled them with a fixture I made, cleaned and polished them up and sold most of them on.....the rest got used in my old capstan lathe turret.

Nowadays, most, if not all cordless drills and others too, are coming out with keyless chucks and from a quick inspection of the plastic sheathed outside body I don't think they can be disassembled easily if at all, but I like them as they're quite convenient and do work very well.
Ian.