I'm considering buying this for my garage. Just wanted some opinions. You can look it up on Youtube, it runs through all speeds.
Problem is; if I want to buy a RPC or not....
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Opinions on this Lathe.....
- Thread starter Litlerob1
- Start date
I'm considering buying this for my garage. Just wanted some opinions. You can look it up on Youtube, it runs through all speeds.
Problem is; if I want to buy a RPC or not....
Herding Cats
Hardplates
I have no experience with that machine but I wouldn't bother with a RPC for most manual machines. I would just use either a surplus industrial VFD or a cheapo one. I have manual machines running off both and the cheapos have worked fine. I really don't vary the frequency but rather use them to make 3 phase.
My 15hp compressor is on a 40hp drive and even if I had 3 phase I would still run the drive for the soft start.
I do have 50hp worth of RPCs but pretty much only use them for CNC.
My 15hp compressor is on a 40hp drive and even if I had 3 phase I would still run the drive for the soft start.
I do have 50hp worth of RPCs but pretty much only use them for CNC.
RJT
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The ad says single phase, why do you need a RPC? Are you going to change motors?
Mr. M
Active member
I have a 10hp rotary phase converter that I used for my 3ph manual metal and woodworking machines until recently. I had it so it plugged into a 50amp outlet. It worked well and was not a big deal to setup. Although now I have 3ph power so if you are in MN I would willingly sell it to you 
Herding Cats
Hardplates
Yes, most machines are 5hp or less as I don't do much manual work and the manual machines are more support equipment for fixture or the off job shop work for a friend. My 15hp compressor is the largest thing I have running on a VFD but in the past I have used them to drive up to 25hp. Each machine has it's own VFD.
If you don't already know the VFD needs to start and stop the load and can't be used strictly as a phase converter. Another nice thing is you can add a braking resistor and use them to stop the spindle quickly. Some high end VFDs will be regenerative but I don't think that would work well hooked to single phase.
At one time I almost bought a complete shop that included a half dozen 1980's era Le Blonde manual and crude NC lathes. The seller was a good guy and had a real hard on for Le Blondes. One of them was an itty bitty boxy little thing that looked much like your linked lathe.
It was kind of a weird little thing. Sitting next to a 40" swing Le Blonde that little guy looked like a toy or a salesman's sample. Almost cartoonish how everything was squared off. The little guy even had toolsteel insert ways.
I don't think it was a bad machine, but I sure wouldn't pay a premium for it.
IMO, a really good garage lathe would be a Takisawa TSL-800 or 1000. They made a cubic shitload of them so availability is good and the prices aren't usually crazy.
It was kind of a weird little thing. Sitting next to a 40" swing Le Blonde that little guy looked like a toy or a salesman's sample. Almost cartoonish how everything was squared off. The little guy even had toolsteel insert ways.
I don't think it was a bad machine, but I sure wouldn't pay a premium for it.
IMO, a really good garage lathe would be a Takisawa TSL-800 or 1000. They made a cubic shitload of them so availability is good and the prices aren't usually crazy.
Herding Cats
Hardplates
Okuma made some very nice manual machines also. I would put them on par with a monarch.
I only mention the little Takisawa manual lathes as a reasonable thing for a home shop guy to keep an eye out for because they aren't real heavy or beefy or anything spectacular, but they are pretty feature packed and they made enough of them that you can find one in any area.
A lot of folks get crazy about the Mori-Seiki manual lathes and copies and they're about the same damn thing as the Takisawa. Only people usually want $10k for a nice Mori and you can buy a nice Tak for $3000.
I have never seen an Okuma manual lathe in person. They look like a really sweet heavy machine.
A lot of folks get crazy about the Mori-Seiki manual lathes and copies and they're about the same damn thing as the Takisawa. Only people usually want $10k for a nice Mori and you can buy a nice Tak for $3000.
I have never seen an Okuma manual lathe in person. They look like a really sweet heavy machine.
Herding Cats
Hardplates
I'm gonna ASSume that is cause of slow accel/decel. Most of how something runs on a VFD had to do with the settings and integration. So likely the VFD didn't suck, the person that set it up sucked
Edit: I'll add that even if the VFD was the issue that was likely because of poor selection.
I'm interested to hear what problems you saw with a VFD.
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What’s the concern about a VFD? I run my manual machines on single phase VFDs. Biggest of those is an old 14x40 lathe with 3 HP motor. Been running that for years now. Previous set up was a static phase converter and that was crap. Way down on power compared to the VFD.
I also run my Mori all on single phase. The spindle is only 5HP continuous and it has no problems running at the factory accel/decel settings which are really quick. For decel it uses the original braking resistor with no problems.
I also run my Mori all on single phase. The spindle is only 5HP continuous and it has no problems running at the factory accel/decel settings which are really quick. For decel it uses the original braking resistor with no problems.
First time I'd seen an Engine Lathe run on a VFD, so I have zero expectations or comparative experience......but what I don't like about it is;
-Using a control off the machine itself.
-It was set up above the gear box-left-weird to cross over.
-This particular lathe has no foot brake, so you need to use the VFD to turn the spindle off. No quick stops.
-From stopped to slow, seems like a very fine line. And when it's moving as slow as possible, I can stop the chuck with my hand.
-and it seems over my head, as far as electrical problems (personal issue of course)
This was/is on a Standard Modern lathe, nice one.
I just don't know if I could get used to it.
-Using a control off the machine itself.
-It was set up above the gear box-left-weird to cross over.
-This particular lathe has no foot brake, so you need to use the VFD to turn the spindle off. No quick stops.
-From stopped to slow, seems like a very fine line. And when it's moving as slow as possible, I can stop the chuck with my hand.
-and it seems over my head, as far as electrical problems (personal issue of course)
This was/is on a Standard Modern lathe, nice one.
I just don't know if I could get used to it.
Herding Cats
Hardplates
These all sounds like setup/integration issues to me.
-Every VFD I've seen had I/Os and you could set up buttons or switches to externally start, stop, vary frequency, estop, exc. If the forward, off, reverse lever on the carriage operates switches these could be set up to control the VFD. Also a knob mounted near the gear levers could be used to control frequency
-If a machine has a foot brake it can be setup as part of the estop chain so it shuts down the VFD.
-most VFDs can be set up with a braking resistor to enable very fast deceleration.
-When the frequency is super low they will not have any torque. The solution to this is to set a lower frequency limit in the drive, if you need to go slower then you need to change gears
These are all simple yet complicated things to implement. I say they are simple cause it is very basic electrical and ladder, but I say it is complicated because it takes time to do and even longer if you are learning the process. If it is a road you choose to go down we can help you fix-setup the VFD correctly. If it's something you rather avoid due to time exc I totally understand that also.
Paul
I agree with Paul that the bulk of your concerns revolve around poor integration of the VFD and possibly a poor choice of VFD. In regards to lack of low speed torque, that is primarily due to having an incorrect gear ratio choice, assuming that there is a geared headstock. Just like in a CNC lathe with a geared head, if you try to cut something in high gear with low RPM, you will stall the spindle. Put the CNC in low gear and at the same RPM you can break the tool before stalling. In case you did not know, the spindle drive in a CNC is a high end VFD. Seriously, that's all it is unless you start talking a machine with Cs contouring ability with live tools.
The VFD chosen for the machine could be a factor if the headstock does not have selectable ratios. In that scenario, some higher end VFDs have a "torque boost" function (increases electrical current allowed) for low frequency operation that might prove useful. If using a VFD with this ability it is important that the motor have a separate powered cooling fan. When running a motor with shaft mounted fan at low frequency, particularly if using a "torque boost" capability, the slow fan speed will not move enough air for sufficient cooling.
Another option for good low speed torque in a fixed ratio spindle is a dual winding motor. This is the technology used in most direct drive or integral spindle CNCs An integral spindle with dual winding motor and a torque boost function in the drive can produce crazy torque at low speeds. The Makino A82M cell I bought ~12 years ago uses that technology and at 100RPM developed about 1000lb/ft of torque. Enough to pull a 10" diameter by 1" wide inserted slotting cutter in Ti6Al4V at twice the feed of the old school geared head Okumas that were replaced by it could manage
The VFD chosen for the machine could be a factor if the headstock does not have selectable ratios. In that scenario, some higher end VFDs have a "torque boost" function (increases electrical current allowed) for low frequency operation that might prove useful. If using a VFD with this ability it is important that the motor have a separate powered cooling fan. When running a motor with shaft mounted fan at low frequency, particularly if using a "torque boost" capability, the slow fan speed will not move enough air for sufficient cooling.
Another option for good low speed torque in a fixed ratio spindle is a dual winding motor. This is the technology used in most direct drive or integral spindle CNCs An integral spindle with dual winding motor and a torque boost function in the drive can produce crazy torque at low speeds. The Makino A82M cell I bought ~12 years ago uses that technology and at 100RPM developed about 1000lb/ft of torque. Enough to pull a 10" diameter by 1" wide inserted slotting cutter in Ti6Al4V at twice the feed of the old school geared head Okumas that were replaced by it could manage
For a small lathe the VFD wins in every case.
More efficient. An RPC has a substantial power use to run the idler motor even when the machine is not running. VFD is a tiny fraction of that power.
Cost to purchase. I have 4 VFDs on stuff in my shop. The 3HP unit on my lathe was the most expensive yet less than $150 when I got it 7-8 years ago.
Convenience. In the past year, I have maybe shifted gears a couple times on the lathe. 99% of the time it stays in the ~500 RPM gear setting. That gives me usable spindle speeds of 150 to 1000 RPM at the turn of a knob. Similar benefit on the manual mill and for tapping on the mill it is more consistent for spindle reversing due to controlled decel and accel.
The one area that the RPC wins is in larger machines. Single phase input VFDs top out at 7.5 to maybe 10 HP. RPCs can go much higher.
More efficient. An RPC has a substantial power use to run the idler motor even when the machine is not running. VFD is a tiny fraction of that power.
Cost to purchase. I have 4 VFDs on stuff in my shop. The 3HP unit on my lathe was the most expensive yet less than $150 when I got it 7-8 years ago.
Convenience. In the past year, I have maybe shifted gears a couple times on the lathe. 99% of the time it stays in the ~500 RPM gear setting. That gives me usable spindle speeds of 150 to 1000 RPM at the turn of a knob. Similar benefit on the manual mill and for tapping on the mill it is more consistent for spindle reversing due to controlled decel and accel.
The one area that the RPC wins is in larger machines. Single phase input VFDs top out at 7.5 to maybe 10 HP. RPCs can go much higher.
Van, I'm intimidated by the wiring part of the VFD. RPC is basically plug n play. I think that's the biggest benefit for me. I can use it on multiple machines, I can run more than one machine on a single RPC.
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Well, being intimidated by wiring and setup is understandable. I have no idea of your knowledge of electrical circuits or systems, but know by some of the things you have posted on another forum that you are no dummy. With that in mind, I am certain that you could get a VFD wired in with a remote fwd-off-reverse switch and a pot for speed control. Particularly if you were willing to accept some help and advice from members of this forum. Adding a braking resistor for fast stops would be easy as long as the VFD selected was capable. Adding an off signal from a foot brake device would up the complexity of the circuit and likely send you looking here for assistance.