Improving cheap drill chuck runout.

J

John TV

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So I have a question about trying to improve the runout on a cheap drill press chuck. I have searched and read most of the treads regarding chuck removal and repair here but I am wondering if there are thoughts on grinding the jaws to improve TIR. The chuck is at least 25 years old and came on a import no name floor drill press. It is a keyed 5/8 inch and the arbor is mt2 and j3 in the chuck. In the past it was used exclusively for wood and it really didn't matter if the runout was high. Measuring with cheap dial indicator, the arbor and body only have .003 TIR but a end mill shank held in the chuck has 10 to 12 TIR. Spinning the end mill 180 degrees it still reads the same runout at that "spot" on the chuck so I assume it is in the jaws. I have not had the chuck apart but I have soaked it in wd40 and it works smoothly. Any thoughts on how to improve the jaws? Other ideas? I realize I will most likely need to get a new chuck, but kind of fun to fiddle and learn for this Nube. One last thing. I double checked the arbor runout on my lathe and both the arbor and nose/body read .003 TIR. But in the chuck 10 to 12 thou. Thanks for your thoughts.


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I've wondered the same thing. People do it on lathe chucks to recoup their investment. The process would have to be miniaturized obviously which bring up a few challenges
- Tiny grinding wheel going inside a much smaller chuck ID opening. Smaller grinder OD generally means higher RPM, so tool post grinder?
- Jaws would have to be similarly pre-loaded, not quite as easy depending on style of chuck
- would probably have to do this in a lathe. Now you should get your drill press arbor in there which might be a mismatch to headstock
Guess you have to weigh this against $$ getting a good one.

Also check your arbor independently. I've had good chuck + bad arbor = poor run out syndrome before. I've also seen bad arbor + bad chuck be decent run out when they happen to cancel against one another. But the opposite holds true in a different fit up position which is what had me scratching my head.
 
The issue may not just be the jaws. It can be the jaw carrier, the drive screw that moves the jaws or the inside of the hood where the jaws contact. These drill press OEM Chinese chucks are not hardened, jaws are not consistently shaped or sized, and machining inside the chuck is inconsistent. I have one that is near new and I cannot get it to run anywhere near true. Best advice is to dump it and buy a good chuck.
 
I had one of those cheap chucks on my Jet drill press when I purchased it. It was frankly, complete rubbish. I agree with mikey, a chuck
like that isn't worth the time. Your better options are a used chuck like an Albrecht or Rohm, which are both good quality pieces. I put a Jacobs
precision chuck on mine which is Chinese but excellent none the less. They don't come up used very often and are expensive new. An older
Jacobs superchuck or the like is also an option, and can be rebuilt since parts are available. I believe all the regular Jacobs chucks are now made
in China, but I don't own one so can't comment of whether they've kept up their quality. Check eBay: there's usually lots to choose from.
Another option is Glacern. I have one of their chucks on the tailstock of my lathe and so far am happy with it, though I haven't measured
runout and I think they come with integral Morse taper mounting which may not fit your drill press. They are nicely made however.
 
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I agree with all of the above recommendations; find a good quality USA NOS Jacobs if you don't want an Albrecht keyless.
Even a vintage USA hartford, CT Jacobs can have terrible run out, but I've read that they can sometimes can be improved by lightly running a small ceramic rod in and out of the jaws, using a lathe. Improving TIR. I have not done this myself. A very light pass of the ceramic rod may improved even new jaws. Brownells sell these small ceramic rods. I don't think it would work on a cheap import chuck very well. They're just not well constructed in general.
 
Give it a try! What is the worst that can happen? You end up ruining a cheap Chinese chusk and throwing it away? In the state it is in now it sounds like it is destined for the trash anyway. I would be much more inclined to experiment on a cheap Chinese chuck than an expensive American or German chuck. Maybe you might learn something along the way!
 
As Benmychree said bite the built and buy a good chuck I went through 2 Chinese chucks and ended up buy a Rohm from Germany .No regrets one less tool to introduce an error into the mix.
 
Interesting challenge.

First check the run out of the arbor with no chuck on it. There must be no measurable run out on the external J3 taper. If there is make sure the MT2 tapers are squeaky clean and rotate the arbor 180 deg. Check run out of the arbor again. If you get a zero run out reading put an index mark on the arbor so you can always put it back in the same position in the lathe spindle.

If you can not get zero run out on the arbor taper, take a skim cut on it to true it up. Put an index mark on it before removing it from the spindle.

Install the chuck on the arbor. Check run out with several different diameters in the drill chuck, from the smallest to the largest that the chuck will hold.

If run out is consistent then I would pull the chuck off the arbor, chuck up a straight pin of a diameter in the middle of the chuck capacity.
Then holding the other end of the pin in a collet on the lathe I would recut the internal J3 taper in the drill chuck to true it up. Check the run out of the pin in the collet before proceeding to recut the chuck taper. There must be no run out on the pin.

If run out on the different sizes is inconsistent throughout the range of the chuck, I would suspect dirt or breakage of some kind. Disassembe and clean the chuck then try run out again.

I would not attempt to grind the jaws. If run out is coming only from the jaws when everything else is good I would live with it.
 
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I have two very nice drill chucks, ( I also have a milling machine vise and shell end mill cutter) from Glacern Machine Tools. From them you can buy MT, JT, R8 and larger shank chucks for $80 including the shank. Tolerance on them is .002", Ive had mine for a few years and they have had what I would consider heavy home shop use and I am very pleased. Well worth the investment for a tool that gets used frequently and is very frustrating to have one that does not work well. My suggestion would be to buy one of theirs or some other quality build.

Flak jacket on now but a chuck does not have to be USA built to be quality, it just needs to be quality.
 
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