# Jacobs Portomatic 500



## PantherAKS (Feb 7, 2015)

Hello all! I was wondering if anyone has had any experience with these chucks? Specifically I would like to disassemble it and give it a thorough cleaning. I inherited this chuck from my great grandfather and it has been sitting unused for decades. It spins freely but gets gummed up about half way. I tried soaking it in WD40 overnight and then exercising it to no avail. 

Looking in through the throat of chuck you can see where the inner portion rotates, possibly on a bearing. The tightening collar is held in place by one setscrew and has been removed without too much trouble. It looks like you might have to press the two pieces apart through the throat of the chuck. I know on standard Jacobs chucks you need to have the jaws retracted approximatly half way so that they do not get caught on the chuck body as its being pressed apart. So anyone have any ideas how to get this guy broken down?


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## kd4gij (Feb 8, 2015)

This link should help. http://www.jacobschuck.com/keyless-precision-chuck-repair-guide


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## PantherAKS (Feb 8, 2015)

Thanks for the reply! I think I posed this in the wrong section but I am glad someone had some tips. It actually looks like the chuck in the instruction is similar to an Albrecht design, but it got me thinking. I believe this chuck unscrews as well, only instead of the body separating in the middle you actually unscrew the tapered front off. I believe that is why there are three holes on the nose of the chuck, so that you can use a pin wrench. I'm sure at one point this chuck had a special wrench that went along with it, but that's long gone by now.

Oh for anyone who is wondering, the taper is a JT6.

**Update**
For those of you who are interested, to disassemble this chuck you must unscrew the tip from the body at the first set of knurling. Clamp around the adjacent set of knurling and use a pin spanner or two similar sized punches and a screw driver as a level to unscrew the tip. (Don't do what I did initially and try to use a couple of allen keys and wind up chipping one of the holes.) Then its just a matter of cleaning, regreasing and you are good to go.


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