I want to make new lathe feed dials

[Mr Ron]

I watched a video on how to make new lathe dials. In it , a 100 tooth saw blade was used to index the 100 scribed lines on the dial. Great! I can do that, but I checked the dials on my Sheldon lathe and those dials are scribed with 125 divisions. I searched for something that had 125 divisions on it and came up with nothing; no saw blade or gear. I don't have a dividing head, only a spin indexer that has 1° increments. Do you have any ideas how to get the 125 divisions without a dividing head. The increments on a 125 dial are 2.88° apart.

[liveaboard]

Could you use the old dial as a guide?
I used a dial from my lathe as a guide to make a dial for another machine with the same pitch feed screw.

[Magicniner]

Make a strip of material which wraps exactly around your dial.
Then mark it out -

https://www.mathopenref.com/constdividesegment.html

Grade school geometry, or it used to be,

[John Hasler]

4 teeth on your 100 tooth blade is 5 divisions on your dial. Mark every 5th division using the 100 tooth blade and then interpolate.

[WesHowe]

Maybe put the new dial on your lathe, an indicator on the toolpost, then crank the dial 0.001" on the indicator and make a mark to line up with the index line. Don't forget about backlash, always move in only one direction.

[Mr Ron]

The old dials are small and pretty worn. I want to make larger dials. Possibly I can layout a strip with 125 divisions using Autocad©; cut it out and wrap it around a cylinder, the circumference of which will accommodate the strip.

[Orrin]

Take a length of band saw blade and count 100 teeth. Now, cut a disk of plywood either using a sander or mounting it on your lathe to cut it true. Wrap the saw blade around to test the circumference. Then, very carefully reduce the circumference a little at a time until the blade is a perfect fit. Get the picture?

Now, back up to step one. Make that saw blade, say, 110 teeth long. When you test the wooden disk for size, aim for a perfect overlap of those extra ten teeth. When you get the disk sized correctly, attach the blade to the disk with whatever works for you: holes in the blade and screws, holes and nails, epoxy, or whatever.

If your blade pitch is too fine, double the count to 200.

Above all, do not use a variable pitch blade!

[Mr Ron]

Take a length of band saw blade and count 100 teeth. Now, cut a disk of plywood either using a sander or mounting it on your lathe to cut it true. Wrap the saw blade around to test the circumference. Then, very carefully reduce the circumference a little at a time until the blade is a perfect fit. Get the picture?

Now, back up to step one. Make that saw blade, say, 110 teeth long. When you test the wooden disk for size, aim for a perfect overlap of those extra ten teeth. When you get the disk sized correctly, attach the blade to the disk with whatever works for you: holes in the blade and screws, holes and nails, epoxy, or whatever.

If your blade pitch is too fine, double the count to 200.

Above all, do not use a variable pitch blade!

Why didn't I think of that! You are a genius. Thank you much.

[John Hasler]

4 teeth on your 100 tooth blade is 5 divisions on your dial. Mark every 5th division using the 100 tooth blade and then interpolate.

Every *4th* division.

[whateg0]

4 teeth on your 100 tooth blade is 5 divisions on your dial. Mark every 5th division using the 100 tooth blade and then interpolate.

Every *4th* division.

Nope, every 5th division which would be every 4th tooth.

[John Hasler]

Sorry I was unclear. I was thinking of the teeth on the saw as divisions on the saw.

To be clearer (I hope) using the 100 tooth saw blade as an indexer put a mark on the new dial for every four teeth on the saw blade. You will then have marked every fifth desired dial division.

[spro]

I'm really a proponent of how things are done. We are talking .001+ dials now. Sorry but I wouldn't trust my used or even new stock for this.