Sustitute Delrin for steel bushing

If you make the choice to use Delrin, I'd strongly urge you to not use conventional stuff just because you have some available. Delrin AF is a Teflon filled material that will serve quite nicely as a bearing material, although I don't know if even that will serve the purpose.

I think it's safe to assume that if a bearing bronze has worn out, Delrin won't serve nearly as long, although for home use, where you may not use the machine much, could be it would serve you a life time. I'd make the complexity of the job a factor. If you can replace the bushings easily, a fast teardown and assembly, go for it. If not, and it's a tough job, guarantee your work by choosing a known properly performing material.

Harold

It's not that bronze bearings wore out, this lathe has steel on steel. Steel shaft with steel bushings, and no oil. That's the real culpret, no oil. The shaft is much more difficult to make than the bushings. I'd much rather the bushings wore out than the shaft. My whole lathe is suffering from no oil syndrome. I oil everything. Too much. I'd rather wipe up oil than make parts for my machine. When I went to machine shop school, (3 years) if you didn't clean and oil the machine, you missed the bus ride home. My Mom didn't drive so I had to walk home, several miles. Once I got home, there was hell to pay, so my machine was the cleanest in the shop, every day! It breaks my heart to see machines worn out becasue no one oiled it, but had time to sit on thier butt and BS. I'll try delrin Bushings and see what happens.

You'll find some superior alternatives to delrin here:

For example... Small sizes are inexpensive there's no minimum order.

That sounds like the Chinese lathe I bought. When taking it apart to clean out the swarf - it was a NEW lathe! - I noticed the steel on steel bearing idea on some places of the gear change shafts. They did provide oil holes and a crude gallery, I make sure its always oiled well. So far its been running well. I did make a new, longer, lay shaft, it was not that difficult. The idea of the longer, counter rotating shaft is to pick up drive power for a rotary table mounted on the cross slide. Now I have a poor mans milling machine capable of machining worm gears and pipe bender mandrels. Klaus

What type of gearbox is this, a single or double tumbler?

I'm not aware of steel bushings on Southbend gearboxes, but they do have steel shafts running in holes bored in the cast iron. These are lubricated by wick fed oilers.

I've rebuilt double tumbler gear boxes by boring the cast iron to accept sintered bronze bushings.

If you have steel bushings in there perhaps someone has modified it before.

Delrin "AF" is more expensive than bronze FWIW.

Tony

16" South Bend. Single tumbler, 1947 vintage. 6' bed. Doesn't seem like a retrofit, but it might have been. Lots of steel shafts truning in holes bored in casings. Changing lots of felt wicks and checking all the oil feed holes. Even drilled a few and added where they were missing. Some shafts, steel on steel and no way to lube them. Wonder what they were thinking there?

on a Southbend single tumbler gear box, there are over 7 oil points, with most of them having Gits oilers. Plus felt wicking to feed oil to internal points. What shaft do you have that isn't getting oil?

The housing is cast iron, steel shafts run nicely in cast iron jornals. I don't see any steel bushings in my gear box, or the exploded parts diagram reference I have.

On my single tumbler machines , my pet peeve is that the excess gearbox oil drips down over the motor cabinet and makes a mess. But a few drops of oil with each use will keep those gearboxes running smooth forever.

Tony

I have a parts breakdown that clearly shows the bushings. I'm not sure of the exact names of the shafts. In the gearbox, there are two shafts. One shaft has gears made up on the shaft and they only rotate with the shaft. The other shaft has the gear in the center that shifts from left to right. It is this shaft that has bushings on the ends on the casing. Look at this drawing. It's item #613

Tony, you ask," What shaft isn't getting oil?" All of them! Some person used this machine and didn't oil anything! I can't tell you how much that pisses me off! I have a lot of worn parts that need to be replaced simply because someone didn't take care of the machine.

As far as Delrin is concerned, I made some masthead sheaves for a little sailboat I own and I have leftover material, so I thought I could make some bushings. Rest assured I will oil this machine with the proper oil. I have a chart blown up on the wall right behind the machine that shows all the oil points and what oil to use.

I disassembled the apron this weekend. The oil plopped out onto a newspaper and it looked like a 4" diameter jet-black pancake full of chips. I spent 6 hours cleaning out the apron housing with WD-40, kerosene, and denatured alcohol. Surprisingly, the internals are in pretty good condition. The worm bushings are worn but everything else looks pretty good. The clutch looks brand new.

So after I get a few needed parts, I'll make the rest of the parts I need and I'll be running well. I bought it knowing it needed work so I can't complain too much.

I see, the prior owner didn't oil anything. Yeah, that will mess things up after awhile, but they really have to run it dry a long time :^(

I see on your chart the 16" single has a bushing, my 10" single tumbler doesn't seem to have that. My 10" double tumblers of 1960's & 1980 vintage seem to have bronze bushings, probably sintered bronze.

On my 16" x 10' of late '40's vintage, double tumbler, it had a messed up gear box when I got it, shafts seized from lack of oil. I rebuilt it with torrington needle bearings, hardened inner rings, and INA thrust bearings. It should outlast several lifetimes even without proper lubrication.

Good luck on your rebuild

Tony