# Jacobs Chuck Model Number?



## Monk (May 11, 2014)

Hi: My dad just bought a couple chucks on ebay. One is an 18N Super Chuck that specifies a rebuild kit 30347 (the cheapest I've been able to locate is around $225 for what appears to be the nut, jaws and bearing race). Anyone done a rebuild on one of these? Is it worth it?  Second question. He also bought a second chuck with a model number 75A, which I can't find referenced anywhere on the Jacobs site (or anywhere else). Is that an old and discontinued model? The only model numbers I can find out there in that size are 33-34s, etc. Anyone out there hear of a 75A?


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## Terrywerm (May 11, 2014)

Yup!  The 75A came with a mate, namely a model 100 chuck if I remember right. The two were used together for working on DC motor armatures or generator armatures.  If I remember correctly, the 75A would handle 1/4" to 3/4" and was placed in the spindle of the lathe, and the 100 was placed in the tailstock. The 75A would drive the armature and the 100 had bearings in it so it would turn freely while supporting the far end of the armature.  If you look closely at the 75A it probably says 'armature driving' or something similar on it. They were used for supporting an armature while the commutator was turned down to get it trued up.


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## awander (May 11, 2014)

Actually, the # 100 chuck has bronze jaws, and the workpiece revolves in them-sort of like a tailstock-mounted steady rest.


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## Terrywerm (May 11, 2014)

That's right!! I had completely forgotten!  You had to keep them well oiled. 

It's been twenty years since I used a pair of them. When I first read this thread I knew the 75A part sounded familiar and I had to think about it a bit before I remembered what it was and could post an answer.

Thanks for correcting me on the #100 chuck, Andy!


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## awander (May 11, 2014)

I only know because I bought one recently.....

Now, the real question-was there anything special about the 75A except it's ability to open up to 3/4"?


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## Terrywerm (May 11, 2014)

Not that I remember. It would only close down to 1/4", opened to 3/4", the one that I used was on a morse taper stub, fit right into the spindle on the lathe.


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## JimDawson (May 11, 2014)

terrywerm said:


> That's right!! I had completely forgotten!  *You had to keep them well oiled*.
> 
> It's been twenty years since I used a pair of them. When I first read this thread I knew the 75A part sounded familiar and I had to think about it a bit before I remembered what it was and could post an answer.
> 
> Thanks for correcting me on the #100 chuck, Andy!



Back in the day we used white lead as the lube, don't think you can do that any more.


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## Monk (May 13, 2014)

Thanks everybody! I was out of town so it took a while to get back. I was trying to find some tech info on them to order an R8 arbor for my dad. The chuck is at his place so we haven't had it apart to see. Thanks again everyone.


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## Monk (May 13, 2014)

Next question guys: I've got a 20% discount on Enco, and they have the 18N Super Chuck on sale for $216. The "kit" costs $220 to rebuild it. I know they farmed stuff out to China, so the sale chuck is probably sub-standard compared to the old ones. Are there newer models that designate the 30347 kit that were still made in the USA that make the kit worthwhile, or is it just an ENCO fluke?


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## Monk (May 16, 2014)

I'm still trying to figure out whether to rebuild the 18N Super Chuck or pitch it. The jaws were either stripped or bored out to about 3/8s when closed. The rebuild kit is just about what a sale priced new chuck goes for. Is there something I'm missing here? Are the old but newer version USA built models that much better (worth a $220 rebuild)? The build quality seems to be solid on this one, but it specifies the "Kit" rather than the separate jaw, race, sleeve parts like the "old" chucks. Any help/advice would be appreciated before I pull the trigger. I''ve already missed the 20% off deal, but I'd like to rebuild this chuck if it's worth it.


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## HarryG (May 17, 2014)

Monk said:


> I'm still trying to figure out whether to rebuild the 18N Super Chuck or pitch it...
> The rebuild kit is just about what a sale priced new chuck goes for. Is there something I'm missing here? Are the old but newer version USA built models that much better (worth a $220 rebuild)?



If I understand correctly, the 18N is USA-made?
I'd try to find out if the rebuild kit was also made here. 
If it was, I'd rebuild it.


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## Monk (May 19, 2014)

Hi Harry: Yeah, that's the question. I know Jacobs farmed stuff out to China in I think around 2006. I don't know if that is the period that began the "kit" rebuilds, or if the kits pre-dated the move to Asia. If it's the latter case, I'll rebuild. Thanks for responding! I'll post what I find out.


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