Gear change help

[Tomme boy]

Need help on gear change. This thing did not come with any instructions at all. I need to make a bolt with two threads on it. The top closest to the head has to be 3/8x16 and the. Bottom half has to be 1/4×20. I am making a rivnut tool. I got the body of the tool made now I just need to make this bolt. I might go and see if I can find a 3/8 bolt that is threaded all the way to the head then turn the bottom of the bolt down got thread 1/4×20.

But I need to change the gears to do this. Not sure which ones to change. I know which to use but not where they go.

 

[Brad]

Black gear with larger silver washer is A
Large silver gear behind bracket behind A is B
Small black gear below A and B is C
Silver gear behind C is D

As you adjust the gear mesh don’t make them too tight. I often use a piece of paper in the mesh to adjust them. Once the paper is turned out of the mesh they are just right. I use a lube for bicycle sprockets to lube mine.

I don’t really enjoy gear changes but they are just a fact of life. My gear box prevents most changes but going from 14 TPI to 28 TPI is just gonna require a change, no way around it.

 

[Tomme boy]

So what is the bottom right 80 tooth gear? That is the drive gear for the lead s screw.

 

[Ian]

D is the leadscrew gear. For 20 tpi it will be a 50 tooth gear, change the 80 on there now to a 50. There will be a spacer behind it.

A is the top gear (small black one)

B and C always run on the same stud on the banjo.

D is the leadscrew gear.

For your three or four gear arrangements, look at the illustration on the left under "stud gear box", it shows the position of the needed gears called for in the chart as viewed from the front of the lathe. If using only three gears, D will be installed on the leadscrew first with a spacer outboard, for four gear (like your turning setting (slowest feed rate) that you have set up now) the spacer will be inboard and leadscrew gear outboard.