# Yangzhou TY-CO632 13x40 Gear Head Lathe. What are these gears for?



## ChrisAttebery (Feb 9, 2018)

Hello,

I recently bought a 1994 Yangzhou TY-CO632 13x40 Gear Head Lathe. Most of the accessories were still covered in cosmoline and wax paper. I found these gears in one of the boxes. They are 30, 36, 42, 50, 54, 60, 66, and 156T. The machine has a 120/127 metric transposition gear, so I'm not sure what they are for.

Can any of you clue me in on how they are used?

Thanks,



Chris


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## Mitch Alsup (Feb 9, 2018)

The gears are used to set the pitch of threads the lathe is capable of cutting.
The gears also end up setting the forward speed per turn on the carriage movements.
The 120/127 gear switches between Imperial and Metric since there are 25.4mm in an Inch 25.4/(0.2) = 127

Someone will be along in a few minutes with a thread calculator URL so you can figure out which gears create which thread pitches.


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## benmychree (Feb 9, 2018)

I would think that the change gears would be shown on the plate that shows setups for metric threading or in the machine's manual.  Generally speaking, they are for cutting thread pitches not provided for by the stacked gears in the machine's quick change box.


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## ChrisAttebery (Feb 9, 2018)

The threading chart on the machine only shows 30, 40, 120 and 127T gears. I didn't get a manual. I've been using the Grizzly G4016 manual since it is basically the same lathe, but that manual shows the same gears as the threading chart.


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## markba633csi (Feb 9, 2018)

The previous owner may have purchased extra gears to cut special thread pitches, or they may be from another lathe and got tossed in
Keep them they may come in handy some time


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## benmychree (Feb 9, 2018)

Using those few gears, you likely would not be able to cut all metric pitches, just (some of) common ones; I will look at my charts (generic) and see what pitches the extra gears would allow to be cut.  It appears that my lathe, which has a 4TPI lead screw does not jive with what you have; assuming that yours is set up for "imperial" threads and has the normal; numbers of positions on the quick change, that metric thread leads would be severely limited with just the 30 and 40 tooth change gears, so the extra gears would be necessary for a broad range of metric pitches.  Somebody with a clone lathe like yours must have a more detailed chart that shows all the possibilities with the change gears at hand.


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