South Bend Heavy 10L

I have a 1964 South Bend Heavy or 10L that I purchased 8 years ago as a retirement present. I’ve used it quiet a bit at times, nothing hard. I had to replace the carriage feed screw nut & associated bearings, cleaned it up and replaced all the felts & proper oils. All shafts and bushings were fine. About 6 months ago, it started slowing to a stop in forward, no mater of the operation. It would run fine in reverse. I first thought it was the spindle, so I disassembled it only to find nothing. Then I determined it was the quick change gear box and after taking it apart two times and cleaning it, I finally figured out it was in the apron. I completely disassembled it, inspected everything. The only thing I found was the clutch disks were a little worn and whoever put it together last did not put the two 1/8” pins in the worm gear nuts and the small clutch bearings were installed wrong. I corrected all this, reassembled it and it ran about 5 minutes and locked up in forward. I put it in reverse and it did fine. I let it run in reverse for more than an hour while I cleaned and put tools away. I went back over and put it in forward and it froze right up.

I just left the shop. I’m disgusted that I can’t fix it. I spent a lot for it and spent a lot for tooling. I’m looking at other machines but it’s such a waste. This machine is in awesome condition, but I cannot find anyone in my home state to take it to and I obviously don’t have the skills to fix it.

When it jams up, it only does it in forward. It will jam regardless of the position of any lever on the apron. I removed the quick change gear box one more time and hooked a high speed drill to the feed screw and spun the hell out of it in reverse while pouring Type C oil in the gits . I had oil pouring out. I switched the drill to forward and it spun a minute or less and Jambs up. At one point, I helped the drill over-ride it and it came free. I then kept spinning it forward at high speed and like always, it jammed tight.

I’m at the end of my ropes with it. There is one constant. It only jams up in forward and it will jamb regardless of any operation as long as it is in forward. In my opinion, it can only be the worm. Specially, the nut on one side of the worm, because as the worm turns in a given direction, it pulls the one nut to the hardened bushing. When you reverse directions, it pulls the opposite nut to the opposite hardened bushing. It has the be the bearing surface between the one nut and bushing, but checked them and lapped them. I set the final assembly with .004” play, then .002” play, nothing changed.

What am I doing wrong????? Is there anyone out there that is familiar with this lathe that could fix it for me? I emailed Lilion, where I bought my parts and manual, but they’ve never replied. If someone is experienced enough with these lathes, I could pull the apron and ship it to you. I will of course clean all the oil out so it will be clean when you get it. I know it’s something simple that I am doing wrong or overlooking, but I have no idea what it is.

Thank you
....JR

Troubleshooting time...

Sneak up on it one step at a time.

We do not know what actions you are doing when this happens so generic processes.

When stuck do NOT change into reverse.

Disconnect possible causes one at a time until clear.

Release the belt tension from the motor so you can turn spindle by hand.

Is this in a power feed operation, we assume yes?

If so release the clutch or 1/2 nuts and try again.

Next drop the gear selector at the QC box.

Work your way back to spindle one item at a time.

When it frees up you now know where the action that is causing issue is so you can look for cause of action.

I cross slide gib too tight can cause this as the carriage is driven into the wedge caused by too tight of adjustment as one example.





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Tony Quiring said:

Troubleshooting time...

Sneak up on it one step at a time.

We do not know what actions you are doing when this happens so generic processes.

When stuck do NOT change into reverse.

Disconnect possible causes one at a time until clear.

Release the belt tension from the motor so you can turn spindle by hand.

Is this in a power feed operation, we assume yes?

If so release the clutch or 1/2 nuts and try again.

Next drop the gear selector at the QC box.

Work your way back to spindle one item at a time.

When it frees up you now know where the action that is causing issue is so you can look for cause of action.

I cross slide gib too tight can cause this as the carriage is driven into the wedge caused by too tight of adjustment as one example.





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Click to expand...

In my post I stated everything I did to finally trouble shoot the problem to the worm and also stated that the problem only occurs in the forward direction, regardless of the position of any levers on the apron. It happens under all processes or no processes as long as it is in the forward direction with or without load. Reversing direction instantly unjambs it without any force. I can put the spindle back in forward rotation with or without load and it will slowly jamb up and spin the belt in a minute or less. I keep taking the gears and clutch out of the apron, looking for scoring and there’s nothing. I’m missing something. A fresh pair of eyes from someone with experience with this model machine would likely catch it.

Thanks
....JR

Thanks
....JR

Forward what?

1/2 nuts engaged or the gear drive?

Can you move the carriage end to end with the hand wheel?

When it stalls release whatever control that is engaging the drive the farthest from the spindle and with drive belt released check to see if it is free.

DO NOT use reverse as you want it stuck.

This should be a relatively simple process, when stuck release parts of the drive train until unstuck.

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Ill take a shot at this....
As I understand it when your lead screw is turning in the forward direction... or clockwise when viewed from the headstock. The machine binds and the drive belt slips.
If you reverse the drive direction the machine frees and spins without binding.

A while back I had a similar issue. My problem was the collar that holds worm was worn and loose .When running in reverse the worm moved away from the headstock towards the tailstock hard against the apron. When in forward the loose worm moved towards the headstock and would bind against the clutch gear.

At 11:13 in this video Mr Pete222 removes the collar that was my problem.

Good luck

When it jams up, I can pull the main drive gear from the quick change gear box and verify it’s not the spindle. If I am real careful not to turn the feed screw, I can remove the quick change gear box to verify the feed screw is stuck. The slightest movement of the feed screw will cause the Aron to free. I have made several attempts to remove the apron & feed screw together while they are stuck, but each time, I wound up freeing it first. There is only one part of the apron that moves all the time, regardless of the direction the motor is turning or the placement of any of the controls on the apron and that is the worm. No matter what feed is engaged or disengaged, the worm is the only part that moves and it will get stuck only when the motor is spinning in the forward direction and it is easy to free by reversing the motor or turning the chuck by hand. I feel stupid that I can with 99% certainty say it’s the worm and not figure out what it’s problem is.

Thanks
.....JR

I forgot to answer your other two questions specifically. Yes, the half nut disengage properly and the carriage will travel it’s full distance easily with the hand crank.

Thanks
....JR

Thanks, I watched this video a dozen times before I worked up the nerve to tackle it. Lol

Thanks
....JR

Jazz, I set the gap on my worm nut to .002”. The worm has no visible wear. Their was two thin shims originally on the headstock end of the worm between the nut and bushing. On assembly, I left the two shims out, because the nuts are designed so you can flip them to give it more or less gap. After thinking about it last night, maybe I need to reinstall the two shims. Effectively, that will add two more bearings surfaces and should take three times long to jamb. I will polish the bushing, nut and shims and report my findings.

Thanks
......JR

Is there no pin through the worm nut?

see these photos JR: https://www.practicalmachinist.com/...ilers-192623/index6.html?highlight=apron+worm

start at post 119

Reversing the bushings and or the retaining nuts can cause the binding worm. if these are correct and they both fit the pin holes
and you still have movement, you will have to tighten and re-drill and pin them (or shim them equally) until the worm does not bind in the gear.
You should be able to see the binding or shifting movement with the apron off and driving the worm by hand, correct the backlash and align the worm, lock the retainers.

Steve

The bushings were installed without pins but the nuts were pinned.

I am planning to reinstall the original shims. I will check the gap between the nut & bushing and if it seems excessive, I will redrill a pin hole. It will be a few days before I can get back to it, but I’ll keep the post updated.

Sometimes, it’s the simple things you miss. I decided to machine Oil Impregated Bronze Thrust Bearings for the worm. The bronze came in today, so I took my apron off to to take my measurements for the bearings or shims. As I was getting ready to remove the first pin in the worm nut, the nut turned on the worm freely. I removed the nut and noticed the 1/8” pin was not long enough to pin the nut to the worm. I made a longer pin, reassembled everything and it runs with no problems now. I’m so happy it works but it reminds me to measure and check everything. I assumed this had been the original assembly, but apparently not.

Thanks guys for your help.

JR