Southbend Fourteen QCGB rebuild

New owner on a south bend Fourteen. Noticed small bits of needle bearings under the levers of the QCGB. Would like to disassemble the QCGB and inspect/repair but have been unable to find directions on how to do so. Any help would be greatly appreciated.

Thanks

A fast question for you. Is your lathe a South Bend 14" geared head or is it a 14-1/2" flat belt drive with the motor in the pedestal under the headstock (known as a UMD or undermotor drive)? A photo of your lathe will certainly help you to get responses.
I am attaching a link to an excellent site showing the rebuild of a 13" SBL with UMD. If your lathe looks like this one but just larger then use the instructions here but be advised, the part numbers for yours will be different. If this is the wrong style lathe then igore the information.
Lathe

Bruce

I've never been inside the gearbox on the SB FOURTEEN lathe, but the layout of the handles suggests that it is internally just like the gearbox on the other double tumbler models, inside a square housing. The apron controls are also very similar. So, I'd be inclined to get the ILION rebuild book on ebay which covers the 16" conehead lathes, and start from there.

allan

About 10 yrs ago I had to rebuild the GB on a then recently acquired 10K double tumbler.
The shafts had wallered out the bores in the CI box to where they would jam or jump teeth at one end.
It was necessary to strip the box, find where the centers should have been, rebore the holes and put in bronze bushings.
Re-felted everything as it was re-assembled

I can't remember the details, but the box is not complex. Most important thing is take photos, add tags or magic marker, and keep things in order, wired together if it helps.

One thing I did, instead of making new shafts, I turned the ripped up ends down to clean, and polished them. Then when making the new bronze bushings, I merely bored the bushings to the new journal sizes. That saved a ton of work over making new shafts, and I am confident that the lathe that lasted 40 yrs of grimey daily use in the local Shepherd-Niles over head crane plant will function for several more generations at my rate of use without a gearbox problem unless it is crashed.

smt

Gear box promptly seized up after I wrote that post. I was able to get the box out and found the main culprit to be the needle bearing in the left hand side change lever let go. After leaving little bits of bearing everywhere it wore through the shaft it rode on then in to the arm its self. The bore of the gear looks to be ok, the rollers did not wear through the race. The shaft that all the main gears ride on may be bent, i will check that tomorrow at work.

Well at least that is an easy fix!
Should have thought of that problem when you mentioned rollers in the first post. (Being the rest of the bearings in the gear box are plain bearings. )

The SB mill has the same gearbox as the 10K, but with a different plate on the front reading in feeds (IPM) instead of threads and leads. One of the tumbler gears on that came to me stripped, not sure why. Clean up the flats in the casting, and just make your replacement gear a little wider to fit. Or clean up the old gear since the teeth look ok, and put a shim washer beside it. Sounds like you might need to make new shafts, though. I'd guess they are hardened, or should be, but mine did not need work so I did not check.





smt

stephen thomas said:

...One thing I did, instead of making new shafts, I turned the ripped up ends down to clean, and polished them. Then when making the new bronze bushings, I merely bored the bushings to the new journal sizes...

Click to expand...

I had the very same thing done for my 9A gearbox. Took the shaft and bushing that were heavily grooved into work and had a machinist friend turn the shaft end down just enough to make it smooth, then they made me an oilite bushing that matched the new shaft diameter with the original bushing OD. (I think he actually made the ID a few thou oversize to account for shrink when its pressed back into the gear box..)