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Discussion Starter #1
I have an older Sears drill press that I bought new probably 25-30 years ago now, and it came with a taper mount chuck that I've never been able to get to work without a bit of runout, a bit frustrating when you're trying to drill holes in a marked spot with a small drill bit. I had bought a replacement shaft for it many years ago at the suggestion of someone back then and took it to a local machine shop to have the drill chuck mounting taper removed and then threaded for 1/2-20 threads for mounting a threaded chuck. That replacement shaft sat in a box with other stuff for many years, but I finally got around to swapping it this last week. An "interesting" project. I finally got the drill back together and then went to the hardware store and bought a 1/2 inch replacement chuck for the drill press, put it on, and discovered that the chuck had a ridiculous amount of runout, it was visible on the chuck without a drill bit in it. I took the chuck off the shaft and checked the shaft with a straight edge while the drill was running. I couldn't see any runout on the threads at all. I thought maybe the shaft was threaded crooked for some reason, but that doesn't seem to be the case.
Anyway, I took that 20 dollar Jacobs chuck back to the hardware store and went to Home Depot and picked up a Riobi replacement chuck. When I put that on, it did the same thing.

So my question is, are all the hardware store replacement chucks that crappy?

I've been looking at drill chucks on line, and they get really pricy in a hurry! I found a Jacobs keyed chuck that's supposed to have .006 or less runout for about 45 dollars, the light duty model. The medium duty chuck has a bit less runout, .004, but it's twice as expensive, of course.
I would assume that if I can't see any runout with a straight edge against the threaded part of the drill shaft while it's running, that it should be good, and that the chucks that I tried were poorly made.
 

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The cheaper the chuck the worst it will be. Jacobs are very good chucks. But their less expensive chucks are not very good. I have a jacobs keyless on my hand drill. I paid $60 for it 10 years ago. But its dead on. You can try a better chuck and see what happens. If you are getting the same problem, then its probably not the chuck.
 

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Discussion Starter #4
I don't have anything like a dial indicator, but then, I'm not too concerned about a couple of thousanths of runout. The cheap drill chucks that I tried looked like they were doing the hula dance, but yet, I can't see any wobble in the shaft when there's no chuck on it. You would think that if it wasn't threaded straight and true, you'd be able to see it with a straight edge.
I found a used medium duty Jacobs professional keyed chuck on ebay this evening for half the cost of a new one so I ordered it. I guess I'll see what happens when I get it. These chucks are supposed to have a runout of .004 at 1.5 inches, so it should be a good chuck. If it turns out that there is something wrong with the drill shaft, I guess I'll have to put the other one back in the drill press. At least that one works halfway decent.
 

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A trick to help a stubborn chuck is to tighten each hole a little at the time, rather then one big crunch. That trick works on a 3 jaw scroll lathe chuck anyway.


Traver's Tool and McMaster Carr have high quality chucks, but they are $$$$$$$$
 

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Discussion Starter #7
The only drill chucks that I could find locally are the Jacobs Multicraft chucks and a Ryobi replacement chuck. The Ryobi was no better than the Multicraft chuck. I checked the drill shaft again tonight with a straight edge held on the base of the drill press and slid up next to the shaft. I couldn't see any runout as I turned the drive pulley, so I have to think that the threads were cut straight on the shaft. I found a used medium duty professional series Jacobs chuck on ebay this weekend, so I bought it, it was half the price of a new one. According to the specs on the Jacobs website, these are supposed to have a max runout of .004 at 1.5 inches, so I'll find out when I get it if it's going to work. If I have to, I guess I'll put the taper shaft back in the drill press and put the old chuck back on. The reason I wanted a threaded thuck is because the tapered one used to fall off the shaft sometimes when I was drilling a hole, very aggravating. According to the stamping on the chuck, it has a JT-33 taper, so I should be able to find a replacement for that chuck that runs with less runout, if I have to do that.
 

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A trick to help a stubborn chuck is to tighten each hole a little at the time, rather then one big crunch.

I always do just that. Learned it in 7th grade shop class at PS #9. Decades and decades ago.

JackM
 

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With a threaded chuck mounting, the chuck "bottoms" on a shoulder on the shaft at the base of the threads. If either the shoulder or the mating surface on the back of the chuck aren't perfectly square, you'll get runout. Since two different chucks have "done the hula," take a close look at the condition and squareness of the shoulder on the shaft.

Just something else to try.

Steve
 

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Posted By JackM on 17 Jan 2012 05:35 AM
A trick to help a stubborn chuck is to tighten each hole a little at the time, rather then one big crunch.

I always do just that. Learned it in 7th grade shop class at PS #9. Decades and decades ago.

JackM
Old school is the best school.
 

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best place for chucks seems to be MSCdirect.com can search by size and also mounting. There are also a bunch on ebay. usually where I find mine, just take your time and wait for a good price with no bidders or just a few. I have bought all my Albrect chucks for under 50.00
 

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Discussion Starter #12
I didn't realize that the chuck had to "bottom out" on the shoulder of the shaft to work properly. The threaded portion of the shaft in my drill is too long for the chuck to screw all the way on to the shoulder. Maybe that's the problem with it. I had a tapered replacement shaft cut straight and threaded so the threaded section is probably longer than it's supposed to be. Once I get the chuck that I bought from ebay, I'll have to measure the depth of the threaded part of the chuck and then cut the shaft short enough for the chuck to bottom out on the shoulder. The shoulder itself should be straight if it was cut on a lathe, I would think.
 

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Posted By Amber on 19 Jan 2012 05:22 PM
The shoulder itself should be straight if it was cut on a lathe, I would think. Check the shoulder anyway for squareness, burrs, buildup of crud, uneven machining, etc.
Good luck
S
 

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Discussion Starter #14
I got the used Jacobs 33B chuck yesterday and put it on the drill press. I had to cut approximately 1/2 the threaded length off the shaft in order to screw the chuck all the way on to the shoulder. Hack saw with the drill running. :) The chuck fits nicely nice, but it's not straight. You can see that it was abused at some point, when I got it, it had a 1/2 inch fine thread bolt screwed into it with a nut as a stop, and the head cut off. The back of the chuck shows some marks on it, so I doubt that it's a true surface anymore. I suppose that could be fixed in a lathe, but I might be better off to just buy a new chuck. I checked the shoulder on the shaft and it seems to be square. Just my luck, buy a chuck that's been abused.
 

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Posted By Amber on 26 Jan 2012 10:56 AM

Just my luck, buy a chuck that's been abused.

That's certainly disappointing. If the chuck has been badly abused (and it sounds like it has), it probably isn't worth trying to save. Buy a good new one.


There's one more thing to consider, and that's getting professional help. Any competent machinist should be able to true up the shaft and (unabused) chuck with respect to the bearing surfaces as a unit. You might inquire of the local shops to see what this would cost. It won't be especially cheap, so ask for an estimate before authorizing the job. Ask also if it includes truing the chuck jaws themselves, so they are absolutely concentric.


This would work, but it might be cheaper just to buy a new drill press. Some of the imports are pretty good and not too expensive.


Steve
 

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Oh, yeah...and then there's the redneck method. Chuck up a small rod or drill bit and spin it up. Take a rubber mallet and bang hard on the chuck (NOT the bit) a few times and see what happens. Be certain the shaft bearings are properly set up tight before you do this.

I actually saw an old time machinist "true up" a drill press this way about 40 years ago; I'm still shaking my head in amazement.

Use this idea at your own risk :)

Steve
 

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Amber,

Contact a local community college that has a machine shop. The professor might find your project a great learning session. Your local high school might have a machine shop. Although that might be unlikely considering how most shop classes have been eliminated due to the infinite wisdom of most school administrators now! Just a suggestion from an old die sinker/tool and die maker.
 

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Discussion Starter #19
I haven't solved it yet. I'm thinking I need to find a machine shop that can true up both the shaft seat and the back of the chuck. For now, I'm going to put the other shaft and chuck back in the drill press so that I at least have the use of the drill press.
 
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