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Scrap or push on with leblond 21 heavy duty

notwrkg

Plastic
Joined
Jan 31, 2023
Location
Independence, MN
A while ago I acquired a WW1 era 21" heavy duty leblond lathe. So far ways and gears are good. A few manageable repairs are needed but for its age it's quite decent. One show stopper though. The quadrant gears to drive the Quick Change Gearbox are missing. There was some flimsy v belt pulley system under the guard so I overlooked the potential problem.

I doubt there is any chance of locating a used set so that's probably not an option, regardless of price.

Having all gears needed custom made would in all likelihood cost more that the lathe would be worth unless I am mistaken. If so, please advise me how to proceed here.

I believe I could drive the gearbox with a belt system at a low cost. The only problem I see here is there is no way to cut left hand threads. When the spindle turns, the QCGB turns in the same direction. I could probably live with that.

Lastly, I have thought about driving the QCGB with a separate motor powered by a VFD. This would allow running the drive backwards and infinite settings but I am not sure it would provide accurate results. For example, I could calculate the correct speed to turn the lead screw but it would only work if both the spindle and lead screw were running at precisely the calculated speed. Also, it creates a more complex running process with 2 drives running independently.

And of course, I could cut my losses, sell the whole lot for scrap and look for something better suited for my shop in the first place, What does 5,000 pounds of cast get these days?

I would really like to bring the old gal back online. Is there a best approach here?
 
As always, it depends on how you derive your satisfaction. If your priority is to use the machine, i recommend you move on. If however, you view the restoration process as I do, an endless source of satisfaction, by all means, do what you need to do to acquire the change gears. Perhaps a small investment in a horizontal mill with a decent dividing head is your best option as you could make the gears yourself.
 
For me it would depend how much I like the machine. If it was in good shape, I really enjoyed the machine and it fit in well in my shop I would probably try and make a set of gears out of durabar. If it was a beat up old pig, I would use it until I found or could afford something better. You could also look for some used or blank gears and adapt them to fit if you know tooth count and pitch info.

I have an old south bend I took to work to use that was given to me, that was missing a change gear. I found a NoS gear blank on e-bay and machined/broached it to fit.
 
What gears DO you have - if any
The image you attached looks like my machine. All I have is the gear on the end of the spindle, and that has a v belt pulley welded to it. I think it is still usable. I do have the cast iron bracket which attaches to the QCGB. Nothing else. That means I need at least 5 gears and the shifting mechanism for the drive reverse.
 
For me it would depend how much I like the machine. If it was in good shape, I really enjoyed the machine and it fit in well in my shop I would probably try and make a set of gears out of durabar. If it was a beat up old pig, I would use it until I found or could afford something better. You could also look for some used or blank gears and adapt them to fit if you know tooth count and pitch info.

I have an old south bend I took to work to use that was given to me, that was missing a change gear. I found a NoS gear blank on e-bay and machined/broached it to fit.
The machine overall is in decent shape but I have never seen it under power. Frankly, it's embarrassingly large and I have no real need for anything this large. Probably the largest things I would make might be pins for a small backhoe or something of that nature. Something with a 12" swing and 36" between centers would be a much better fit for my shop. However, I enjoy the process of working on machines. I feel like a detective at times sorting out what has happened over the years, replaced bolts, nicks and scratches from earlier work, etc.

In the end I want a reliable machine to use. It does not have to be a concours restoration, just look decent and work properly.

That's why I am strongly considering a second motor to drive the carriage. Since the top spindle speed is only 300 rpms I wonder if a vfd controlled motor would be a workable solution. I have a 1/2 hp 3 phase motor on hand. This would give me the ability to cut metric threads, lefthand threads, and slow the feed way down to make finer passes on a monster of a machine.
 
That means I need at least 5 gears and the shifting mechanism for the drive reverse.
For that type of thing you can almost always use something out of a catalog. Still a bunch of work to make the quadrants and all that but the gears are not a killer.

Since the top spindle speed is only 300 rpms
Oh. I'd scrap it. Get a little South Bend or something, you'll be much happier.
 
A usable "banjo" you could make out of 3/4" plate with a cutting torch, or hot-bend out of 3/4" square hot-rolled bar. Many different combinations of stock gears could give you the needed ratio. Boring the gears and making journal bushings COULD be done to functional level of accuracy on a drill-press, if you have no other lathe. 21" heavy LeBlond sounds eminently worth fixing.
If you were near me I might advise that it is dangerous and unrepairable, and I'd be willling to properly dispose of it for you.
 
Electronic lead screw. Encoder on the spindle and a stepper driving the gearbox, you'll even be able to cut metric threads.

Lots of info here
Same idea for sure. I did not track his progress through the 20 plus videos on the subject. The issue here is scale. My lead screw probably weighs more than his lathe. I was thinking less complicated and significantly more robust. I have a lot of homework to do should I want to go down the separate feed motor path.
 
A usable "banjo" you could make out of 3/4" plate with a cutting torch, or hot-bend out of 3/4" square hot-rolled bar. Many different combinations of stock gears could give you the needed ratio. Boring the gears and making journal bushings COULD be done to functional level of accuracy on a drill-press, if you have no other lathe. 21" heavy LeBlond sounds eminently worth fixing.
If you were near me I might advise that it is dangerous and unrepairable, and I'd be willling to properly dispose of it for you.
Given the size and low rpms involved I think my plasma cutter, bandsaw and drill press would probably get the job done. However, a quick look at McMaster Carr and it looks like I would be well over a grand in gears alone. Unless I am way off course that amount doesn't make sense to me for this machine . I would probably be better off applying those dollars to a more complete and more practical lathe instead.
 
Is it not possible to simply make the gears?

Milling machine and dividing head you may have, you would need the cutters for the gears you want. With luck, one cutter will have a range good for more than one of the gears.......

Gears are expensive, but the investment in the tools needed can pay off in more than one restoration project.
 
Same idea for sure. I did not track his progress through the 20 plus videos on the subject. The issue here is scale. My lead screw probably weighs more than his lathe. I was thinking less complicated and significantly more robust. I have a lot of homework to do should I want to go down the separate feed motor path.
The only difference would be the size of the motor needed to power the gearbox.
 
The machine overall is in decent shape but I have never seen it under power. Frankly, it's embarrassingly large and I have no real need for anything this large. Probably the largest things I would make might be pins for a small backhoe or something of that nature. Something with a 12" swing and 36" between centers would be a much better fit for my shop. However, I enjoy the process of working on machines. I feel like a detective at times sorting out what has happened over the years, replaced bolts, nicks and scratches from earlier work, etc.

In the end I want a reliable machine to use. It does not have to be a concours restoration, just look decent and work properly.

That's why I am strongly considering a second motor to drive the carriage. Since the top spindle speed is only 300 rpms I wonder if a vfd controlled motor would be a workable solution. I have a 1/2 hp 3 phase motor on hand. This would give me the ability to cut metric threads, lefthand threads, and slow the feed way down to make finer passes on a monster of a machine.
Given all you've said, and depending on your budget, i would look for something smaller and more appropriate to your needs. You'll be using it sooner and there'll still be plenty of satisfying tinkering to be done. Like was suggested above, a 14"-ish swing south bend or something similar might be a good option. Probably set you back $2-3K depending on condition. My daily driver is a 14" Reed Prentice from 1935. I paid $850 for it and it will hold .001" all day long.
 
You might go the route of drawing the gears up in CAD and have them laser cut from plate since they are straight spur gears. Laser cut parts are pretty darn accurate and since the machine turns slow, it would probably work. Price always is the killer, but I just had a bunch of small parts cut and had 17 made due to the fact that the company had a minimum charge of $30. I only needed 1 made but now I have lots of spares... 8-)

Kevin
 
I have a burly 20" Leblond Flat belt Gap Bed Lathe rusting in my garden. I took all the gears and moving parts off. I have all the banjo gears, the banjo, change gears, apron, etc. This old lathe would be happy if she could provide some life to another. I live in WA state.

It looks like a small lathe in the attached photo, but it is all of 6,000 lbs. It's an odd perspective going up a 15% incline.
 

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