Gear Head Operation w/ VFD

Orphanbrg said:
Hello All,

I am again looking for my first home shop lathe and leaning towards buying used American vs an import. While I am somewhat familiar with VFDs and the principles on how they work (HVAC equipment), I am trying to wrap my head around how you operate a gear head lathe using a VFD. On the face of it, I assume that the most often used practice is to set the lathe on it's highest gear and make speed changes using the potentiometer on the VFD (or remote) to change speeds. Given motors do not like to run in a low speed for extended periods, is it possible to set your VFD to provide full power to the motor and then regulate the speed of the lathe using it's gear box? Are there pros or cons to running a machine in this way?

Thanks for the help.

Rick
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A couple of thoughts.
When I got my old 3 phase lathe I did a lot of reading on here and other places about whether to go with an RPC or a VFD and was torn which way to go. What settled it for me was I got a 7 1/2 hp 3ph motor for Free so I built an RPC - for under 2 hundred $.
I recently added a second drill press so now have seven 3 phase machines and can run any of them.
But...
I say concentrate on finding your Leblond and don't worry about powering it for now.
 
Thanks to all who have chimed in, I truly appreciate it.

On the subject of a Leblond, I've found several recently within a reasonable driving distance. My question is, what is a reasonable price for a 15x30 not beat up gear head? The latest candidate is in the link below.

For Sale - LEBLOND REGAL Lathes, Engine - 15″ X 30″ LEBLOND REGAL ENGINE LATHE. STOCK # 0849022 | G-2000, Inc.

For Sale - LEBLOND REGAL Lathes, Engine - 15″ X 30″ LEBLOND REGAL ENGINE LATHE. STOCK # 0849022
g2000inc.com g2000inc.com
 
Orphanbrg said:
Thanks to all who have chimed in, I truly appreciate it.

On the subject of a Leblond, I've found several recently within a reasonable driving distance. My question is, what is a reasonable price for a 15x30 not beat up gear head? The latest candidate is in the link below.

For Sale - LEBLOND REGAL Lathes, Engine - 15″ X 30″ LEBLOND REGAL ENGINE LATHE. STOCK # 0849022 | G-2000, Inc.

For Sale - LEBLOND REGAL Lathes, Engine - 15″ X 30″ LEBLOND REGAL ENGINE LATHE. STOCK # 0849022
g2000inc.com g2000inc.com
Click to expand...

That's such a loaded question. Depends on what it comes with and what it needs, right? For me, the total cost of acquisition, logistics, hookup and tooling all end with a bottom line that I try to commit to early on. Sometimes, the economy and timing force the prices wildly, so you need to decide what you are willing to put out to get what you want. My most recent machine purchase went way over budget because of the crazy economy and timing, and I had to pay a lot more than I would have before COVID, war economics, and the government bailouts, and the resulting interest rate adjustments changed everything for us. That is not a political statement; it is an example of the external forcings that make the "how much should I pay" question that much harder to answer reasonably. This is meant to be an esoteric statement, not meant with any condescension, but the true answer to the question comes down to how much you are willing to pay to get everything you want to run that lathe in your shop this year. I am certain that with my purchase, if I hadn't sucked it up and paid the asking price when I did, I'd still be frustrated trying to turn tough projects on my little flexy Atlas, and I'd be crying my eyes out over the classifieds every morning.
 
Well put.

I do have a little more info on this particular lathe. It came to them (G-2000.Inc) from a one man shop. It comes with a 8" 3 Jaw, 10" 4 jaw and Aloris style tool post....no other tooling. I have no tooling now, just odds and ends metrology tools. They are in the process of completely rewiring it with the only explanation being that they were not happy with the wiring when they acquired it. Asking price was $4950, offered/accepted price $4000 contingent on acceptable powered inspection. 7 hour round trip drive.

Flip side is a basic PM12x36 will run me $5000 plus delivery with no need for a VFD or RPC and I'm in the same spot with the tooling.
 
Orphanbrg said:
Well put.

I do have a little more info on this particular lathe. It came to them (G-2000.Inc) from a one man shop. It comes with a 8" 3 Jaw, 10" 4 jaw and Aloris style tool post....no other tooling. I have no tooling now, just odds and ends metrology tools. They are in the process of completely rewiring it with the only explanation being that they were not happy with the wiring when they acquired it. Asking price was $4950, offered/accepted price $4000 contingent on acceptable powered inspection. 7 hour round trip drive.

Flip side is a basic PM12x36 will run me $5000 plus delivery with no need for a VFD or RPC and I'm in the same spot with the tooling.
Click to expand...

I looked at your link several hours ago.
Just looked again and they've taken it offline.
My impression when I saw it earlier was it was a great machine and now when you stated the agreed upon price it seems like you did well
Of course, as they say, the devil is always in the details...
Do you know how to give a lathe a once over, shake down test? Use a dial indicator to check the ways? Take magnet on a stick and push it down into the oil dregs of the head stock to see what you dredge up? Run the thing forward and backwards in all the gears and listen for the ticking/clunking of chipped or broken gears?
Slightly tighten the carriage lock to see how sway backed the ways are? Test the lead screw and feed rod in both directions? Check the QCGB in several gears?
Those are just a few things off the top of my head. I am sure others here can add more.
There is likely even a how-to written up here if you look for it.
For what it's worth, I ran a few Leblonds as a machinist in the Navy - 15, 17 inch models - our little machines :)
They were older models with Servo Shift.
Us guys loved those machines and would fight over them.
IF the guy in "the one man shop" didn't abuse it some how or use it as a cylindrical grinder or cut cast iron his whole life I don't see how he could have worn it out.
Sorry for the looong post.
 
pontiac428 said:
Freight cost can vary. I've paid for several freight shipments in the last couple of years. Sometimes, you can get freight cheaper than the actual fuel cost, it happens, don't ask me how it works.
Click to expand...
This is just a side comment, but "how it works" might be useful to someone.
Certain places have a "season" for trucking. My experience is produce out of Florida. In the right season, there is practically nothing to carry in there, but every orange farmer is harvesting and truckload after truckload to carry out. I was happy to have a barely paying half load of paper towels to come out with a nearly overloaded truck of orange juice.
It is a matter of timing, but getting it right will mean that there are a dozen trucks lined up to carry your lathe for half the fuel cost, so that they don't have to make the same trip empty and still paying the full cost of the fuel.
 
Ultradog MN said:
I looked at your link several hours ago.
Just looked again and they've taken it offline.
My impression when I saw it earlier was it was a great machine and now when you stated the agreed upon price it seems like you did well
Of course, as they say, the devil is always in the details...
Do you know how to give a lathe a once over, shake down test? Use a dial indicator to check the ways? Take magnet on a stick and push it down into the oil dregs of the head stock to see what you dredge up? Run the thing forward and backwards in all the gears and listen for the ticking/clunking of chipped or broken gears?
Slightly tighten the carriage lock to see how sway backed the ways are? Test the lead screw and feed rod in both directions? Check the QCGB in several gears?
Those are just a few things off the top of my head. I am sure others here can add more.
There is likely even a how-to written up here if you look for it.
For what it's worth, I ran a few Leblonds as a machinist in the Navy - 15, 17 inch models - our little machines :)
They were older models with Servo Shift.
Us guys loved those machines and would fight over them.
IF the guy in "the one man shop" didn't abuse it some how or use it as a cylindrical grinder or cut cast iron his whole life I don't see how he could have worn it out.
Sorry for the looong post.
Click to expand...
All great points, and thanks for the post.

While I am a complete novice when it comes to being a machinist, I do have the benefit of almost 30 years in plant maintenance. That being said, similar to the comercial where the guy takes over flying the plane after the pilot becomes ill and when asked by the stewardess if he knows how to fly a plane, his response is, "No, but I stayed at a Holiday Inn Express once", I have watched a couple of YouTube videos on what to look for when buying a used lathe.

Any and all pointers would be greatly welcome, the more detailed the better. I will hunt for it, but if anyone has a link to any info here or elsewhere that would guide me along the way, that would also be much appreciated.
 
If it doesn't have a steady rest, that is a negative. Even with the relatively short bed, a steady is going to be necessary for some common operations. They are hard to find, and expensive when you do.
 
Provincial said:
If it doesn't have a steady rest, that is a negative. Even with the relatively short bed, a steady is going to be necessary for some common operations. They are hard to find, and expensive when you do.
Click to expand...
Building one is possible, but can be a big job as size goes up. Finding them is tough, and they are always overpriced no matter what lathe it's for. I would kill for a bigger 5"+ steady for my 17" lathe, but holy crow that's a chunk of metal. Substitutes can be adapted to fit if they're close, however, since lathe rests aren't critically aligned, that part is done with the fingers.
 
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