# Holding gear in lathe chuck



## cobra46 (Sep 9, 2019)

Just got my new 3-1 lathe mostly set up.  In the process of rebuilding I broke the smallest feed screw transmission gears.  I bought a new gear knowing I needed to modify it.  The modifications include boring it out, removing the hub and broaching a keyway.

I was able to hold it by the hub to bore out the ID but I'm not sure how to hold the teeth to cut off the hub.  I have a three jaw and four jaw chuck.  The only method I can think of is to machine a split bushing with the ID of the bushing close to the OD of the gear.  I'm sure there has to be a better way.  How have you guys done this?

The gear is a Mod 1.5 14 Tooth

Thanks

edit - added gear info


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## benmychree (Sep 9, 2019)

The split bushing is the safest way to do it, but the 3 jaw may be good enough for such a minor operation.


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## Latinrascalrg1 (Sep 9, 2019)

Could you make a mandral to fit the new ID to cut the hub?  I would think you could either turn it off or use a parting tool.


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## cobra46 (Sep 9, 2019)

benmychree said:


> The split bushing is the safest way to do it, but the 3 jaw may be good enough for such a minor operation.



I tried to put it in the three and four jaw and neither seemed too secure.


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## cobra46 (Sep 9, 2019)

Latinrascalrg1 said:


> Could you make a mandral to fit the new ID to cut the hub?



Wouldn't it have to be an ID collet to do that?


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## Latinrascalrg1 (Sep 9, 2019)

Not quite sure wht your asking but i was thinking a shaft with a slighty tapered end that would slip fit into the gear to lock it into and tightly against your 3 jaw, i dont see a need for a collet of any sort but then again im not a machinist!
After you cut the hub the 3 jaw should be more then enough  to hold the gear securely to cut the key way since it wont be rotating.


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## cobra46 (Sep 9, 2019)

HAHA.

I'm not quite sure I understand your tapered shaft/mandrel idea but I'm intrigued.


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## Latinrascalrg1 (Sep 9, 2019)

Im no picasso but i think you should get the idea.


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## cobra46 (Sep 10, 2019)

Got it figured out.  An expanding arbor is what I need to make.


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## cobra46 (Sep 10, 2019)




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## Latinrascalrg1 (Sep 10, 2019)

Yup that would be even better but in a pinch not absolutely necessary.


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## Nutfarmer (Sep 10, 2019)

Soft jaws bored out to fit the gears od would also work


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## HarryJM (Sep 10, 2019)

Maybe a step collet might work.
https://www.hobby-machinist.com/thr...p-collet-used-for-and-how-do-you-use-it.1564/


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## stupoty (Sep 10, 2019)

Pot chuck to hold a gear



__ stupoty
__ Apr 28, 2016



						first time using a pot chuck to hold a part, cut the hole and hand pressed the gear in then...
					




I made a pot chuck from aluminum to hold a gear by the edge for doing work on the center, worked well. the gear is pressed into it.

Stuart


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