Help assessing old SB 10 L lathe

[Glenn Brooks]

Hi all,

We have an old SB 10” belt drive lathe at the Hawaii Railway Society that has some serious issues making chips. Iam not familiar with these older SB lathes, so hoping for some assistance/advice trouble shooting this machine. And whether, the lathe is worth reconditioning. Basically this lathe is an old, well worn tool room lathe surplused out of the Pearl Harbor naval shipyard machine shop, a loong time ago. New in 1942 maybe...

Model: SB 10L - 3 1/2’ bed, with taper attachment. Motor and belt drive mounted in the cabinet, below the headstock

Catalog number : 8187Z
SN: 135111.

MA E127 also shows on the right rear flat portion of the bed.

It currently has two significant problems:

1). Only will do a DOC of around .015” on 1” mild steel stock on middle and lower ranges of the upper gear range (200-300 rpm, Iam guessing). Any deeper cut (feed rate .003”) stalls the machine. As in the tooling just bites into the work and stops the spindle - belts don’t slip, the motor just stops turning. (Iam thinking the motor is worn out and can’t turn the belts any more with load on the spindle???)

2) the spindle locks up when back gear engages the low gears. In low gears, the spindle won’t turn at all when power is applied and the motor tries to spin up. Note: the pin in the bull gear appears to be disengaged. But it is stiff to move in and out, so maybe it is not fully disengaged??

Any thoughts on quick fixes for these two issues???

Thanks much for any assistance you could offer.
Glenn

 

[MontanaLon]

The serial number indicates post 1947 manufacture date.

Both issues sound to me like the motor may be ready for replacement or repair. Is it a 3 phase motor or single phase? Any details on the motor can help figure out what may be going on.

 

[Glenn Brooks]

Yes, thanks. I neglected to check out the existing motor today, but can get the specs on Tuesday when I go back into the shop. thanks.

BTW, the SN I posted must be an old Navy SN or shipboard accounting num of some sort. I found an older post about this lathe which listed The actual SN as: 135111. It must be hidden under dirt and new old scarf now. Looks like More cleaning to do next week....

Thanks
Glenn

 

[woodtickgreg]

If none of the belts are slipping I would suspect the motor also. I would also refelt a machine that old to make sure it is getting proper lube.

 

[benmychree]

Pull the pin in the bull gear and see if the step pulley rotates freely, if not, there is a problem. As to the motor, check and see if it it wired for the correct voltage.

 

[Superburban]

Try turning the spindle by hand when in Back gear. I suspect it is due to dried grease, or worn bearings. It should be much easier to turn by the belts when in back gear.

 

[Glenn Brooks]

I did try to turn the spindle by hand, in back gear. Felt like it was mechanically locked in place. Looks like it’s time to disassemble at least part of the headstock to see what’s going on.

 

[Superburban]

I'm thinking the two parts of the spindle are held together by hardened grease, not allowing the bull gear to spin separately from the belt section. The other thorught is the back gear is stuck to its bearing. either should be easy to check.

 

[Glenn Brooks]

I’d like to thank everyone who commented. Got the lathe up and running today, and started making the parts we need.

Indeed, the pin in the bull gear was “glued shut” with dried oil. I doused the pin with solvent, let it sit half a day and worked it till it came loose. Now the back gear slides in and out easily, and the lathe runs solidly in the low gears.

I do want to pull the gear cover off and run some more solvent through the bull gears to flush any residual debris. The Hawaiian environment is tough on machine tools- lots of red lava dust, natural oils (fragrance), humidity and salt in the air all the time- plus the heat cycle can evaporate machine oil fairly quickly. So more solvent, and a good dose of fresh way oil seems in order.

Also solved the motor problem. Turns out, existing motor is a recent replacement ( last 5 or 10 years). Apparently the v belt on the motor was to long(and the original pulley was worn to wide) to properly tension the existing drive belt. So with two guys watching the drive with flashlights, we could see the lathe stall with a decent DOC, and see the V belt slipping on the lower Pulley.

So replaced the pulley (wobbly, worn to wide, and out of true), and bought a new smaller belt. Now it cuts metal like a champ.

So many thanks for your assistance.

Here’s the old war horse at work, this afternoon.

Still like to decipher the stampings on the end of the ways! Definitely WWII USN anchor stamp next to the SN. But the other inscriptions are anyone’s guess. Pearl Harbor facilities numbers perhaps. Or maybe a Ship ID. The lathe definitely helped in the war effort. But I doubt the ships files or facilities inventory records exist anymore. Anything look familiar?


Glenn

 

[woodtickgreg]

Good to hear you have it freed up now. Very cool piece of history you have there.