32A Gear Question

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miken
Posts: 23
Joined: Mon Aug 02, 2021 10:56 am
Location: Maine

32A Gear Question

Post by miken »

Hi, I have an Atlas 12" 3990 (Commercial model I think it's called). It has a standard gear train meshed to a Quick Change Gear Box. When I purchased it I found an additional 32A gear in the box of goodies. I was wondering if someone knows if this gear has a purpose for me on this lathe, or perhaps it's just an extra gear the previous owner found along the way and thought it could be useful someday. I was originally hoping it was a 24 tooth as I would be able to slow the lead screw feed rate in half if it was, but I don't know what the purpose of a 32 tooth gear may provide? Would it be needed for metric threading perhaps?

Thanks in advance for any info.
Mike -
12" Atlas Commercial (3990) 12" Back Geared, Undermount, Screw Cutting Lathe with Quick Change Gear Box (6802), Universal Compound X-Y Vise (1614), Taper (6822), Milling (500A) and Grinding Attachments (10-450)
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miken
Posts: 23
Joined: Mon Aug 02, 2021 10:56 am
Location: Maine

Re: 32A Gear Question

Post by miken »

I guess if I combine it with a 64A it would serve the same purpose of slowing the carriage feed rate in half as a 24 combined with one of my 48's. And a 64 appears to be cheaper than a 24 on ebay anyway.

Mike -
12" Atlas Commercial (3990) 12" Back Geared, Undermount, Screw Cutting Lathe with Quick Change Gear Box (6802), Universal Compound X-Y Vise (1614), Taper (6822), Milling (500A) and Grinding Attachments (10-450)
RGS
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Joined: Tue Jun 17, 2014 12:52 pm
Location: Poulsbo, Wa

Re: 32A Gear Question

Post by RGS »

Here is a link to gear settings for thread sizes and feed rates not on your qcgb using additional gears. File is too large for me to upload to this site.

https://www.machinistweb.com/forum/show ... php?t=1973
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miken
Posts: 23
Joined: Mon Aug 02, 2021 10:56 am
Location: Maine

Re: 32A Gear Question

Post by miken »

Thank you RGS, appreciate the link.
Mike -
12" Atlas Commercial (3990) 12" Back Geared, Undermount, Screw Cutting Lathe with Quick Change Gear Box (6802), Universal Compound X-Y Vise (1614), Taper (6822), Milling (500A) and Grinding Attachments (10-450)
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