Can Anyone Id This Lathe?

Thanks James, I gave Martin gear a call, and found a borable gear the right size. 4.116 diameter, 12 DP, 48 teeth. Now, what I need to determine is the pressure angle I want to use. The gear train is worn enough that I don't think I will get a good measurement to do the math on the angle. I was going to just go with a 14.5 pressure angle with the thinking being that the steeper tooth would take up some of the wear better. Any thoughts there?
 
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My 1935 Brown & Sharpe catalog does not list anything other than 14.5 degree hobs or cutters for spur gears.

Most of the discussion on pressure angle seems to be academic to me as I have only seen 14.5 degree DP gears and 20 degree Metric.

Did Martin Gear give you an option for anything other than 14.5 degrees?
 
yup, they offer that gear in a 20 degree as well. Well, there is a bit of engineering academia involved in the pressure angle selection. 14.5 has been the base standard for years. However, the 20 degree offering does provide a quieter running interface between the gears, but it is a weaker tooth design. 20 degrees is also a better choice for smaller gears at times. I found some very interesting info on pressure angle selections for spur gear teeth, that included pressure chromatic spectroscopy showing in color the different stress distribution patterns on the spur gear teeth for 14.5, 20, and 30 degree pressure angles.

Short answer is, 14.5 degree pressure angle gives the strongest tooth in a high torque environment. Where torque is not a big factor, the 20 and 30 degree pressure angle will run much smoother. That is the conclusion I drew from the engineering papers I looked up.

If you are interested, go here for the pressure chromatic info: http://www.ijarse.com/images/fullpdf/1425984847_400.pdf
 
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Well, the cleaning process has begun. Items so far to repair. Cut new keyway in tailstock screw, increase from 1/8" to 3/16" keyway to cleanup wear and slop between the screw and handwheel. As far as the headstock spindle gear, I have decided to cut my own. I have ordered the necessary tooling, and a dividing head for my Atlas mill. Now I need to decide whether or not to use type 40 Cast iron, or ductile iron for the gear. type 40 is cheaper, but appears to be a wee bit more brittle. I can also buy the type 40 by the inch vs. the ductile in 6" pieces. The ductile iron is probably best, but I don't think it is a crisis using either. Comments are definitely welcome. Tailstock cleaned up very nicely, and compound is shaping up decently as well. Next I will disassemble the apron. Pictures soon.
 
Man it's fantastic these old machines show up now and then and people can put them back into working order. Nothing like that ever seems to turn up out here on the left coast. Keep us posted!

How badly are the ways worn? Something to think about maybe, is having the ways ground flat. I recently talked to a shop in Chicago that quoted a precision grinding job at around $600. (Also a couple in California with similar pricing). Which I thought was not a bad price price for a 48" lathe bed. They claimed flatness to less than .0005" variation with their CNC controlled grinders. I know there is a lot more to it than just grinding the ways flat, but might be a reasonable intermediate step in restoring the machine - if the ways show significant wear.

Glenn
 
I have not totally cleaned up the ways yet. So far, they look reasonably good. A couple of nicks in them here and there, but overall, they don't look too bad. I won't know for sure until I get the apron cleaned up and re-installed. To be honest, the apron "wings" that ride on the ways are close to 18" long. If the ways are worn, it surely would take a lot of hours to get there the way the apron is designed. however, that is conjecture on my part, not measured fact. I probably won't be to a point to do any indicator work on the ways until after xmas. However, who knows......as I said, I will keep this group updated and pictures as I can. I can tell you this much. The scrape pattern is still visible on the bottom of the tailstock, and in the dovetails of the sliding portion of the tailstock. That is a good sign..........
 
Holly smokes, if you've still got scraping visible, after all these years, then maybe a real diamond in the rough. It's certainly possible. I bought a 1925 SB 9 x48 last summer with flaking clearly visible all along the bed. Never was used more than a few hours here and there by a hobby owner until it went into storage back in the 40's.

Here is something you could try to explore bed wear. Just lay a 48" aluminium carpenters ruler on the bed and see if you can slide a feeler gauge underneath anywhere along the bed. If any serious wear exists you will likly find it with one of the gauges. Also can shine a flashlight on the backside and look for the thin shaft of light showing possible bed wear, or lack thereof. Not scientific, but it works.
 
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.....snip..... Now I need to decide whether or not to use type 40 Cast iron, or ductile iron for the gear. type 40 is cheaper, but appears to be a wee bit more brittle. I can also buy the type 40 by the inch vs. the ductile in 6" pieces. ....snip......
I have plenty of G-2 Durabar class 40 cast iron. If you are interested in a piece, PM me and I'll be glad to put a piece in the mail for a very small price. I can get ductile iron too, just don't have it on hand at the moment. Ken
 
Most of the older lathes like yours, the gears in the gear train were probably of cast iron back then. Most of the lathe builders went to a mild steel or very low alloy steel by the late 1920's early 1930's. And most were 14-1/2 deg. pressure angle.
 
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