Jacobs Ball Bearing Chuck Rebuild (14N) Done My Way

[EmilioG]

Sounds good. I do not want to F this up.
Should I go ahead and tap the hole? What about a 5/16" drilled hole for a 3/8"-16 tap?
Is that enough to punch (3/8") and/or push out with a 3/8":-16 bolt?
This shank is in tight!
Yes, it's a Jacobs 14n. *the chuck key holes are through holes. Your 14n's look they have blind chuck key holes.

Good old days>> http://www.clockmaker.it/files_forum/monografie/jacobs/mandrino_jacobs.pdf

removal>>

 

[EmilioG]

If I can find someone with a lathe that can drill the chuck hole for me, I can then try punching it out.
Otherwise, I'll try putting it in a mill with a V block and drill down, tap and put a bolt in it to push it out.

 

[darkzero]

If I do have to end up cutting off the shank, what's the best way?
Then the remaining piece can be step drilled out.
Can all of the drilling be done on a mill? I know a lathe is better for centering.

The arbor isn't hardened, well at least it shouldn't be stock. You can easily cut it off with a bandsaw or with a hacksaw. You could certainly do all the drilling on the mill. You can still indicate it pretty well on center for that job.

the chuck key holes are through holes. Your 14n's look they have blind chuck key holes.

I also have through holes. Not that it matters, on 2 of mine, the key holes are through, & the 3rd one has blind key holes. They all are Hartford models.

 

[EmilioG]

I was thinking that someone drilled through holes in the key holes. I have never seen the through holes.
Anyway, I'm not going to be hasty about this arbor removal. I have to decide what the best way is.
I'll try drill a larger hole in the body first, applying Kroil and heat then try punching it out.
But if I drill it out larger, I should tap the hole while it's set up.

Thanks so much.

 

[rwm]

My arbor was seriously stuck in place after heavy use in a machine shop. Once I got a 1/4" punch in there it dropped right out. Drill it to 5/16 first and try a punch. I feel like a punch can generate a higher peak force than a screw will. Then you can always thread to 3/8" if you need to. The chuck bodies are not hardened and are easy to drill.
R

 

[EmilioG]

How do I indicate the chuck hole center on a mill?
I'll try that; drilling to 5/16" first.
Should I chamfer the hole a bit with a countersink in case I go with the 3/8" tap?

 

[EmilioG]

Success! Thanks to Will (DarkZero) I was able to safely remove the 1" JT3 straight shank arbor from my newly acquired real USA Jacobs 14n
drill chuck. ow I have to press it out, clean it up, grease it and press it back on. I'm putting a new JT3 R8 arbor on it for milling. The removal went well and no damage to the chuck or arbor. The chuck and jaws look good so far.
Thank you all, thank DarkZero for all of your helpful advice and instructions.

 

[rick9345]

Success! Thanks to Will (DarkZero) I was able to safely remove the 1" JT3 straight shank arbor from my newly acquired real USA Jacobs 14n
drill chuck. ow I have to press it out, clean it up, grease it and press it back on. I'm putting a new JT3 R8 arbor on it for milling. The removal went well and no damage to the chuck or arbor. The chuck and jaws look good so far.
Thank you all, thank DarkZero for all of your helpful advice and instructions.View attachment 97212 View attachment 97213 View attachment 97214 View attachment 97215 View attachment 97216 View attachment 97217 View attachment 97218 View attachment 97219

Did you mean you are to use to drill in the mill? Or do plan on using to hold end mills and mill!! End mills in a drill chuck are a NO/NO.. Drill chucks and Jacobs tapers are not designed for side forces. Danger, coming loose and messed up work or personal injury.

 

[EmilioG]

I would never use an end mill in a drill chuck. Collets only. I will use the Jacobs for drill bits and spiral point taps.
I still have to press out the chuck to clean and grease/oil. The jaws look nice but I have to look at all the other parts.
I'm ordering a new R8 JT3 arbor and should be good to go. The wedges worked really well. I was surprised at how
easy it was. I was very methodical about doing all this because I've looked at all the attempts on the web and some didn't turn out well.

A lot of people complained about the wedges not working but I had enough shoulder width on the arbor. I couldn't see how it wouldn't work.
The forces on the wedge had nowhere else to go except laterally and the steel held up. At least Jacobs/Apex Tools can make a good wedge.

Nothing was bent, marred or scratched in the process. I can still use the arbor and wedge set.
Thanks. Will (DarkZero) was very patient and answered all of my questions.

 

[EmilioG]

Just out of curiosity, did the 14n with excessive run out that you mentioned, was that the one with the shorter
chuck body jaw hole part? I've never seen a Jacobs like that with such a short body where the jaw holes end.