SB lathe blueprints etc

BigB · Oct 24, 2020

I’m looking for a book or books or a web site that shows the dimensions of the parts of these lathes. I have my 14.5 apart, and I have no idea if some of the parts are in spec or worn out.

Things like hole and shaft diameters. It’s pretty easy to measure a shaft and see how bad it is, but I’m not sure if the shaft and the hole in the gear is worn out.

Any ideas if this kind of thing exists?

TIA
BB

SLK001 · Oct 24, 2020

BigB said:
Any ideas if this kind of thing exists?

Sure, this kind of thing existed at one time. However, it was all proprietary information. Grizzly, the new owner of South Bend probably has (or had at one time) some of the info, but since they no longer make any of the older SB lathes, it could have been discarded long ago (plus, it is still proprietary).

As for your current fits, you'll have to use your own judgement and your Machinist's Handbook to create your OWN standards.

texasgeartrain · Oct 24, 2020

Grizzly will sell serial card info, but not dimension prints. Not sure if they have them or not, they just listed they won't sell them.

Your best bet is finding someone's particular repair of a certain item. Some guys with better skill sets will show a print or drawing of what they did. Though this is a little more rare.

In general any shaft to hole, or bushing. . . you are looking for .001" oil clearance, if shaft spins in the hole. You can have some variance, but .001" is a real good general number on oil clearance.

Depending on speed of shaft, stability of whatever it does, potential gear mating and so on. . . .002" could be acceptable, maybe .003".

Usually above .003" I'm looking to make a repair. Things clanking around at .010" and higher are kind of obvious.

In those cases I chuck up the shaft and cut it till its clean and true, but not waste "meat". Then bore the hole, I try to go atleast 1/8" bigger on hole. This gives me at least 1/16" thickness on a bearing material, all the way around.

I like c932 bronze(sae 660) as bearing material. I press it into hole, then bore hole to shaft size with .001" oil clearance. I bore after pressing material, because the ID will shrink with press fit if I try to bore hole prior to pressing.

BigB · Oct 24, 2020

SLK001 said:
Sure, this kind of thing existed at one time. However, it was all proprietary information. Grizzly, the new owner of South Bend probably has (or had at one time) some of the info, but since they no longer make any of the older SB lathes, it could have been discarded long ago (plus, it is still proprietary).

As for your current fits, you'll have to use your own judgement and your Machinist's Handbook to create your OWN standards.

That’s kinda what I figured. My lathe came out of a trade school so it’s been painted many more times than it ever had real maintainance.

I have a bore gauge so I guess tomorrow I start measuring holes and mic’ing shafts and writing it down.

Thank You
BB

BigB · Oct 24, 2020

texasgunsmith said:
Grizzly will sell serial card info, but not dimension prints. Not sure if they have them or not, they just listed they won't sell them.

Your best bet is finding someone's particular repair of a certain item. Some guys with better skill sets will show a print or drawing of what they did. Though this is a little more rare.

In general any shaft to hole, or bushing. . . you are looking for .001" oil clearance, if shaft spins in the hole. You can have some variance, but .001" is a real good general number on oil clearance.

Depending on speed of shaft, stability of whatever it does, potential gear mating and so on. . . .002" could be acceptable, maybe .003".

Usually above .003" I'm looking to make a repair. Things clanking around at .010" and higher are kind of obvious.

In those cases I chuck up the shaft and cut it till its clean and true, but not waste "meat". Then bore the hole, I try to go atleast 1/8" bigger on hole. This gives me at least 1/16" thickness on a bearing material, all the way around.

I like c932 bronze(sae 660) as bearing material. I press it into hole, then bore hole to shaft size with .001" oil clearance. I bore after pressing material, because the ID will shrink with press fit if I try to bore hole prior to pressing.

My other question would be is it ok to use the bronze materiel you suggest in places like apron worm bushings, or is just plain cast iron good enough or better.

I don’t mind making this stuff out of bronze or CI, I think the bronze might be more durable but I could be wrong about that.

Thanks in advance.
BB

texasgeartrain · Oct 24, 2020

BigB said:
My other question would be is it ok to use the bronze materiel you suggest in places like apron worm bushings, or is just plain cast iron good enough or better.

I don’t mind making this stuff out of bronze or CI, I think the bronze might be more durable but I could be wrong about that.

Thanks in advance.
BB

Bronze is better, particularly c932. It has a little lead in the mixture. The lead has anti friction properties which make it preferred in bearing material. Nearly all the shafts in apron turn very very slow, even at high speed settings. Slow, like they crawl along. The gears at left end of lathe spin fast.

Besides bore or ID gauges. You can stick a dial indicator somewhere on a shaft while its in the hole. Use a pry bar to lift up and down on the shaft while reading the dial indicator.

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