Blue print for 1930 16" single tumbler ?

Does anyone have or know a source for a blue print for gear box tumbler for my old lathe? In order to rebuild mine; I need to know some dimensions. The bore that rides over the main shaft is worn out and deformed; as well as the bushing that the tumbler stud rides in. I am going to have a friend bore out and put bushings in both bores. We need to know the center-to-center of the 2 bores. And the finished ID to make both bushings. Any help would be greatly appreciated guys...Barry

The shaft (which you have - the one with teeth full length) will need running clearance in the tumbler - that's one dia

The pair of gears housed in the tumbler determine the center distance

That distance will be near to the two pitch diameters added together and divided by two

Add scan from 1930

In other words, tumbler houses idler gear 605 and slides along the pinion 603. Both of these have a certain Diametral Pitch and a certain number of teeth, from which Pitch Diameters can be calculated - resulting in center distance

You have either 606 stud, or will make a new one, which will need a running fit in whatever bushing is used

Thanks to Mr. Wells for the scan

Great info and thanx John. That all makes sense to me. However, I don't know how many thousandths of clearance "running clearance", and "running fit" have. And hopefully there is enough of the old idler gear for my friend to figure out the pitch and diameter of it; it is pretty chewed up. Do you know if that gear is available or if someones makes them. It seems to me like it would be a part that gets damaged often...Barry

Handy info from 1910. More extensive coverage in Machinery's Handbook

Machinery's data sheet series - Google Books

Barry,
I have a 1941 14-1/2" and decided to go look inside my single tumbler QC box to see how good/bad it was. There's a little wiggle in the tumbler, all teeth appear to be 100% intact, and the lathe isn't particularly noisy. Anyway, my tumbler idler has 26 teeth and an OD of 2.81". Shaft gear has 12 teeth and an OD of 1.40". Based on these measurements, I figure a Diametral Pitch of 10 for the gears. This gives me a pitch circle diameter of 2.6" for the idler and 1.2" for the shaft gear. Add them together to get 3.8". Divide by 2 and get 1.9" for the center to center distance that you're looking for. I was laying on the floor while doing my measurements and doing my best to fit my calipers inside the QC box, but I'm pretty sure I got everything right.

If you count your teeth and measure your diameters, I'll run the numbers for you and see what you have. I didn't check to see if all single tumbler QC boxes were created equal.
-George

thank you for the great info and effort George.