Shopsmith Forums

Go to shopnotes.com and there is a link called "online extras" all the gears are there in pdf format. The acme rod is only $33 at mcmaster carr.

What size acme screw are they using to build this machine? I'm trying to understand how they derive the spacing of the spirals using the various gear ratios they show in the on-line extras.

It is 1"-5 The spacing of the spirals is determined by the index wheel, not the gearing. The gears determine how far down the leg the router travels per each revolution.

This is like the old Sears spiral crafter. Instead of the threaded rod Sears used cables to move the router back and forth.

Ingenious idea!

Could you adjust the cable, somehow, or were you stuck with a fixed amount of turns per length of the leg?

Thanks for the info on the screw size, sevassusej. But, the index wheel determines where the spirals start on the turning in relation to one another. The gear ratio determines the distance between spirals.

The part that didn't compute for me was that if the 1:8 ratio results in a spiral spacing of 1 5/8", then a 1:16 ratio should be 3 1/4", not 3 3/16" as shown on Shopnote's website. Actually, using the 5 threads per inch leadscrew, a 1:8 gear ratio results in a distance of 1.6" between threads and a 1:16 ratio gives a 3.2" distance. I guess Shopnotes did some rounding.

sevassusej wrote:Could you adjust the cable, somehow, or were you stuck with a fixed amount of turns per length of the leg?

I don't have a clear memory of it, but from what I remember you could change the gear ratio (by changing gears) as on this one in Shopnotes.

I also think you could change the rate the cable moved. I know you could cause the cable drive to go into a neutral mode so the router didn't move. You could use this to make special features or to machine equally space rings and such on the spindle.

You could also stop the turning of the spindle so you could use the cable to groove or whatever the spindle.

pennview wrote:Thanks for the info on the screw size, sevassusej. But, the index wheel determines where the spirals start on the turning in relation to one another. The gear ratio determines the distance between spirals.

The part that didn't compute for me was that if the 1:8 ratio results in a spiral spacing of 1 5/8", then a 1:16 ratio should be 3 1/4", not 3 3/16" as shown on Shopnote's website. Actually, using the 5 threads per inch leadscrew, a 1:8 gear ratio results in a distance of 1.6" between threads and a 1:16 ratio gives a 3.2" distance. I guess Shopnotes did some rounding.

Sorry, I thought you were referring to looking top down on the leg, and the spacing there, as far as how many spirals on the circumference, not "threads per inch" per say

You could just buy an old metal lathe and mount a router at the tool post. My old South Bend is a 10" x 36" and has a quick change gearbox for threading. It gives you a half zillion choices.

Check out E Bay they have two of them, and manuals.