Change gear threading confusion.

H

Half Nut

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Hello all, I'm very new to this hobby and I'm a bit confused about gear changing. The diagram for the proper gears isn't the problem, What I am having a bit of trouble on is, lets take an example. on page 140 of the Craftsman Lathe Operation manual it lists gear set up for 8 thru 16 threads per inch.

Once I have the gears set up for 8 thru 16 TPI, What determines the TPI? Do I just change the belt onto different pulley positions and from normal drive to back gear? That seems to make sence to me, but am not sure. Like I said I'm new to this hobby.

My lathe is a 12" Chraftsman/Atlas 101.07383. Ser# 10582 S.

I hope this question isn't to dumb.:lmao: Thanks in advance..
 
Last edited:
the tpi is determined by the final drive ratio.
once you have selected the TPI you wish to turn,it doesn't matter what belt position is.
although you may wish to start threading at the slowest speed possible until you get the hang of it.

the ratio of spindle to carriage movement will be constant and is governed by the selection of change gears.

there are no dumb questions.
 
Thank you sir, but I'm still a bit confused. According to the manual, that one set of gears will cut all those thread pitches without any other changes to the initial gear set up. What am I missing?:thinking::noidea:
 
I assume that your lathe has a quick-change gear box? If so you select the TPI by setting the levers on that correctly.
 
Half Nut,

Look at the drawing again. Note that all but the tumbler gear and the screw gear have the tooth count given, and their relative positions given. The tumbler gear never changes (it is a 16T F x 32T B), although whether you used the 16T or the 32T does change. Then notice that for the gear on the extreme right the drawing says "SCREW GEAR" and ""SEE CHART". If you look at the threading chart, you will see that the SCREW GEAR varies from 32T for 8tpi up to 64T for 16tpi but that the other gears on each line remain the same between 8 and 16. You will also see that the drawing on page 140 is the same as Figure 2 on the threading chart, except much easier to read. And that the other drawings on pages 139 through 147 each match one drawing on the chart.

Also, what is the bed length of your lathe (choices are 36", 42", 48" and 54")?
 
wa5cab, Thank you very much, I think I got it now.:)) I knew something was not right, and it was me.:lmao: The ways are 36". Thanks to all who replied.

Thanks again guys.:thumbsup2:
 
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