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

Whn I irst took a jacobs chuck apart I thought it was trashed as the alf nuts where broken apart.:nuts: Then learned the break them so they fit together perfect. Mine had alot of runout. I found that the grove that the jawsride in had slight burs on the edge cleand tem up with a round diamod file. Runs pritty true now.
 
I would like to remove the arbor on my newly acquired USA made Jacobs 14n.

You mentioned that the Jacobs 14n has a through hole running to the arbor side yes?
Can I use this existing hole to drive out the JT3 straight shank arbor? It's 1" diameter/
The chuck has a few scrapes but overall looks good. Jaws are good but I may get a McMaster Carr rebuild kit. I also need a good R8 arbor. I got the chuck for free.

IMG_20150226_142742_181.jpg IMG_20150226_142757_919.jpg IMG_20150226_142809_908.jpg
 
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EmilioG said:
I would like to remove the arbor on my newly acquired USA made Jacobs 14n.

You mentioned that the Jacobs 14n has a through hole running to the arbor side yes?
Can I use this existing hole to drive out the JT3 straight shank arbor? It's 1" diameter/
The chuck has a few scrapes but overall looks good. Jaws are good but I may get a McMaster Carr rebuild kit. I also need a good R8 arbor. I got the chuck for free.
Click to expand...

The older super ball bearing chucks have a through hole in the chuck's body. Not all of them have the through hole but per Jacobs a through hole can be drilled on their keyed chucks only. All mine have the through holes. I primarily use the wedge removal keys to separate arbors but they didn't work on any of the 3 14Ns shown in this thread. I had to use heat, Kroil, & a punch.

You may want to confirm what rebuild kits Mcmaster has. I remember their prices for them are very high. The rebuild kits for the older super ball bearing chucks have been discontinued so you'll have to find NOS as the new kits (service kits) are not fully compatible with older chucks. I have heard the jaws from the newer rebuild kits will still fit the older chucks though.
 
McMaster shows Jacobs rebuild kits for old and new chucks. Maybe a NOS kit will show up on Ebay.
What size punch did you use to drive out the arbor? Where do you apply heat?
I want to remove this JT3 Straight shank arbor without damaging the 14n.
When punching, how far do you retract the jaws? Thanks
 
Is it OK to polish up the tips of the jaws with a fine 3m roloc conditioning disc?
The flat ends of the tip.
 
EmilioG said:
What size punch did you use to drive out the arbor? Where do you apply heat?
I want to remove this JT3 Straight shank arbor without damaging the 14n.
When punching, how far do you retract the jaws? Thanks
Click to expand...

I used a 5/32" punch. YMMV as the 5/32" punch did not fit one of my chucks, the hole was slightly too small. I torched the chuck body surrounding the arbor hole. You have to be kind of quick about it so heat doesn't transfer to the arbor. If it does you can use freezer spray on the arbor or canned air upside down. Brake cleaner would probably work too or anything fast evaporating. The jaws don't necessarily have to be retracted to use the punch, they only need to be retracted when pressing off the sleeve. I inserted the punch & closed the jaws to where they barely fit loosely over the punch to prevent the punch from bending to the side when it.
 
A word of caution about punching the chuck off an arbor. My 18N had a very small hole in the base and I initially didn't want to make it much oversize. I first drilled it out to 1/8" and then tried to punch out the arbor. Well... I could not budge the arbor with the small punch and worse, the tip of the punch mushroomed locking it in the chuck /arbor assembly! Great! After screwing around for an hour I finally got the punch out (I think I broke it off) and then drilled it and the hole larger.
I would drill the hole out to at least 1/4" and use a high quality punch that has a little clearance.
R
 
Yeah, definitely don't use a cheap punch. I used a Starrett punch. Most people do drill out the hole to a larger size which is much safer to use a larger punch, I didn't need to. It helps to keep the punch straight by closing the jaws close on the punch. 1 or 2 quick moderate rasps is all that's needed. If it doesn't budge, reheat & cool down the arbor again. I first heated the body & sprayed some Kroil between the joint. Let it sit, then I torched the body again, shot a quick burst of freezer spray on the arbor, stuck the punch in & the arbor popped right off.
 
Thanks, that is right. I have had punches get jammed before and everything just gets marred.
I have mostly Starrett punches and my 1/8" punch sits nicely in the hole but is a bit small.
Maybe I'll drill open a 1/4" diameter hole to the shank.
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.
 
If you have a 1/2 capacity drill chuck like a 14N, drill a 1/2" hole through the web in the ID of the chuck. It won't hurt anything. That way you can get a 3/8 or 1/2 punch in there and give it a couple sharp blows and the arbor should come loose without any heat. My 20N chuck has a 1"-14 threaded hole in the ID. All I have to do is thread a piece of rod into the hole and tighten until the arbor comes loose.
 
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