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Gear module and specs on jet 1236 lathe

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Cmdevans

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#1
Does anyone know what the gear module for the change gears on the jet 1236 or grizzly g9249 is?

Been wanting to order or make a gear or two to expand it's threading capability, but the numbers I've been coming up with on the existing gears may or may not be accurate. No experience measuring metric gears at all.

If anyone has the specs for the 120/127 gear or the two 40 tooth gears that engage those gears that info would be much appreciated.

Thanks
 

Ulma Doctor

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#2
your(and my) change gears are metric module 1.25
 
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RJSakowski

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#3
FWIW, you can determine the module of a metric gear by measuring the O.D. in millimeters and dividing by the number of teeth + 2.
 

Cmdevans

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#4
your(and my) change gears are metric module 1.25
Ok. Thanks. That's what I got with my calculations. Was hoping I was wrong and it was a 1 or 1.5, since 1.25 seems to be a little less common.

Now to find a 1.25 module 20 tooth gear and an 80 tooth gear that will fit the lathe.
 

Cmdevans

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#5
It seems I am having all sorts of issues measuring this gear set.

Do you happen to know the pressure angle? I've been coming up with 17-18 degrees, which means I'm off just enough that it could be either 14.5 or 20.

The root is rounded, so I'm inclined to think it's 20pa, but before I order some cutters I thought I'd double check.

Thanks.
 
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