[Goatracer1]

I need a chuck for an old Sears drill press. My grand son lost the insides of mine. It has to have 1/2 by 24 threads. Yes 24. Nobody makes them anymore. I can buy one with 1/2 x 20 threads. Any ideas on if it would hold if I had it retapped to the 1/2 x 24.

[Jack Gifford]

If the length of mating threads is at least about 5/8" it would hold. But finding a machinist with an extra-fine thread 1/2" tap might be difficult- and would probably even require a bottoming tap. And the chuck could possibly be too hard to tap.
Alternatively, you could possibly use a die to cut a 1/2-20 thread on your drill press spindle. You would need to hold the die perfectly square to the spindle- perhaps by fastening it to the table. After threading until the die stops against the spindle's shoulder, turn the die upside-down to cut threads as close to the shoulder as possible.

[dataway]

I'm kind of confused ... he lost the inside of what? The chuck?

Usually the spindles have a Morse Taper in them, with either a chuck taper on the other side or a threaded stud that screws into the chuck.

Pull the spindle all the way down ... look for a long oval slot in the side of the spindle, usually you can see the top of the Morse Taper chuck arbor at the top of the slot. You tap (sometimes hammer) a taper release wedge into the space between the slot and the top of the arbor and it pops out ... then you could replace the arbor with a tapered arbor with more modern threads.

This video will show how to remove the arbor from the spindle. https://www.youtube.com/watch?v=KbI_7IHAsyw

Odds are the drill press uses a standard spindle taper of some kind ... you buy a new arbor that accepts the chuck you want to use (not expensive), install the chuck you want on it, tap the whole thing back up into the spindle.

[dataway]

And if you know the model number you could check here:

https://www.searspartsdirect.com/

And see if any needed parts are still available.

[Stuart]

Here's one on Amazon with 1/2-24 threads. https://www.amazon.com/Astro-JC12-Ja.../dp/B00AU7BC6O

[dataway]

Originally Posted by Stuart

Here's one on Amazon with 1/2-24 threads. https://www.amazon.com/Astro-JC12-Ja.../dp/B00AU7BC6O

Check the reviews on that chuck ... it's actually 3/8-24 ... which is a very common size.

[Goatracer1]

The spindle is not tapered. It has 1/2 x 24 threads it's entire length. The chuck had the 3 fingers that held the drill bit. Somehow my grandson lost those. The drill press is in an unheated garage. If the weather warms up I'll try checking the press out some more. I'll return with my findings. Thanks.

[fyrffytr1]

Would the fingers from another same size chuck work in yours?

[dataway]

I'm thinking maybe the chuck is just opened up all the way and the fingers are not visible, and perhaps tightened up that way. It's not a simple task to disassemble most drill chucks. Not sure why anyone would ever do that. Didn't want to press the point but about 95% of all drill presses have a Morse taper chuck arbor that fits into the spindle with either a threaded chuck end, or Jacobs chuck taper on the bottom side. I think we may be having some terminology issues.

[Goatracer1]

The 3 fingers are indeed missing. They were held in by a small spring I believe. I have seen the replacement chucks with the tapered shaft but this is not constructed in the same way. I see no way of removing the shaft which is the same diameter all the way up and is also threaded the whole length.

[dataway]

I did some looking around and it appears Sears used some odd ball designs in the 70's and 80s. Looks like they used spindles without replaceable chuck arbors. So yep, you have to find a solution on the chuck.

Do you have a model number for the drill press? They made millions of these things, you can be sure there is a chuck out there for sale somewhere.

[Goatracer1]

It says "DUNLAP" 1/3 hp made for Sears. No model number seen.

[dataway]

Did some more searching ... you have a problem on your hands.

You have a Sears/Dunlap (actually made by Atlas Machine) model # 101.03521 with the "standard" chuck ... unfortunately the standard chuck is FAR from standard, it was a proprietary primitive keyless chuck, and the chuck wasn't well liked by most people.

The manual below shows parts for both your press, and the optional Jacobs chuck model that used a conventional taper mounted chuck.

http://vintagemachinery.org/pubs/269/1813.pdf

From what I can gather, it would cost you more to set it right than the machine is worth. There are cheaper solutions but they would involve fairly detailed machine shop work.

I have seen a couple of what appear to be entire spindles for that model that include the chuck.

It's doable .... but you'd have to be emotionally attached to the drill press for it to be worth it, the used spindles I saw were in the $60-80 range and would require disassembling the entire press to install them.

There may be a shot you could get the part number for the jacobs taper spindle show in the parts diagram above and look for a used one, that would allow the use of a standard Jacobs chuck.

So basically ... if you are not in love with that drill press ... might be time for a new one

[Goatracer1]

It was my dad's but maybe enough is enough. I can't bring myself to throw it out but that doesn't mean that I have to fix it. I'll put it away with the other stuff I can't get rid of and let my kids throw it out some day.

[Jack Gifford]

The chuck mentioned in post#5 says "1/2-24 thread" and is only $22. Wouldn't that do?

[dataway]

Originally Posted by Jack Gifford

The chuck mentioned in post#5 says "1/2-24 thread" and is only $22. Wouldn't that do?

The information in the ad is wrong ... check the reviews. It's a 1/2" chuck size, with a 3/8-24 thread size.

I checked every source I use for my machine tools and a bunch of others, couldn't find a thing in 1/2-24. The press could be as much as 70 years old so it's not that surprising.

I noticed in an old parts/price list that the "standard" chuck was like 50 cents, and the tapered mount Jacobs chuck was about $5 ... big difference 60 years ago .... I'm guessing Jacobs might have still had a patent on the Jacobs taper or keyed chuck maybe. That's probably why people opted for the "standard" keyless chuck.

[Goatracer1]

I can buy a 1/2 x 20 chuck for under $10 and thought of possibly retapping it or recutting the threads on the shaft but don't know if either would work.

[65CatCoupe]

could you get a chuck with a larger shaft so you could turn it down first and not have to try to cu threads on top of threads?

[dataway]

On a few forums I've heard people say just tap the chuck to 1/2-24 and screw it on. It's not like that particular press is going to be used for very critical machining.

It's dang close anyway ... and if it's a choice between usable and not usable ... might as well tap a chuck and try it. 1/2-24 taps are commonly available.

Others have said if you have the equipment to turn the spindle down and cut 3/8-24 threads on it.

[Goatracer1]

When the weather gets warmer maybe I'll give it a try. It's in a very cold garage so I wouldn't use it now anyway. Thanks for all your suggestions.