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Lathe VFD?

Susquatch

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What is your frame size? I have lots of 3ph 3hp motors.

Thanks Tom, but it's already someplace between Montreal and here. But not to duck your question, it is a European Metric Motor with a YL90L-4 frame.
 

Upnorth

Well-Known Member
I have two VFD's in my shop both running a 2 HP motor. One on a lathe and the other on a mill. The mill has an Automation Direct GS-2 the other is a generic amazon VFD. The one from automation direct has been 100% flawless and came with a great quality manual. I have the one on the lathe set up as a constant speed mode and still use the gearbox to adjust speeds to spread the wear around on the gears. It works mostly ok but it's not possible to get max RPM because it faults out before reaching maximum RPM. It came with a sort of manual that is missing a lot of things. Probably there is a setting somewhere related to acceleration that is wrong.

My point is in the future I will only buy a VFD from a reputable source.
 

DavidR8

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I've had three VFDs in my life, two Tecos and one HY. The two Tecos were flawless, easy to set up and never missed a beat in two years of being continuously connected to power. The HY for my CNC router is hit and miss. I have the settings written down on a card inside the enclosure because it randomly resets and loses all of the settings.
 

Ironman

Ultra Member
I just did a VFD for 3 phase mill. If the mill has a pile of mag relays as this one did, and a single phase transformer for the feed motors strapped to 2 legs of the 3 phase, you will have to disconnect the transformer, and power it from the input legs of the VFD. If you don't, when you lower the frequency to control speed, the transformer will cease to function and everything will quit. The transformer for feeds and mag switches needs 60 cycle always.
I used a Vevor 10 hp unit for 200 bucks just because. They are fairly easy to set up but the annoying thing is that it comes defaulted to 400 cycles. Most come with 60 cycle default settings.
 
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Rauce

Ultra Member
It works mostly ok but it's not possible to get max RPM because it faults out before reaching maximum RPM.
I had this same problem with a cheap VFD on a gearhead lathe. Changing to slower acceleration in the settings solved the problem.

Best I can tell the cheap VFDs are a bit under rated and spikes in current can trip them. Had the same issue taking heavy cuts but couldn’t do anything about that.

I think the solution is buy a cheap VFD that’s a higher HP rating than the motor or get a brand name unit.
 

Susquatch

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I think the solution is buy a cheap VFD that’s a higher HP rating than the motor or get a brand name unit.

@Upnorth - But don't get a brand name unit rated for more than 50% bigger than the motor. The better VFD's work just fine if they are a little bigger than needed, but a LOT bigger can actually hurt. The better VFD's know what current to expect and can even learn about a motors parameters in use. They can get quite unhappy if the motor doesn't do what they expect it to do. Teco told me to use the proper size or a little bigger NEVER SMALLER. Best not to oversize it.

I think @Rauce is right about the cheap ones. But I have no experience tovsay that with confidence.

Personally, I vote strongly to buy a good one.
 

Upnorth

Well-Known Member
Thanks Tom, but it's already someplace between Montreal and here. But not to duck your question, it is a European M

I had this same problem with a cheap VFD on a gearhead lathe. Changing to slower acceleration in the settings solved the problem.

Best I can tell the cheap VFDs are a bit under rated and spikes in current can trip them. Had the same issue taking heavy cuts but couldn’t do anything about that.

I think the solution is buy a cheap VFD that’s a higher HP rating than the motor or get a brand name unit.
My lathe is a gearhead type. 2 HP and a VFD rated for 3 HP. I played around with the acceleration settings it got me a bit more RPM but never got to max without a fault. I tried changing the parameter for time before faulting to allow for more acceleration but it never seemed to work right. I really never run the lathe at full RPM so its not a huge issue. If this VFD packs it in I will get a better quality one next time.
 

Upnorth

Well-Known Member
@Upnorth - But don't get a brand name unit rated for more than 50% bigger than the motor. The better VFD's work just fine if they are a little bigger than needed, but a LOT bigger can actually hurt. The better VFD's know what current to expect and can even learn about a motors parameters in use. They can get quite unhappy if the motor doesn't do what they expect it to do. Teco told me to use the proper size or a little bigger NEVER SMALLER. Best not to oversize it.

I think @Rauce is right about the cheap ones. But I have no experience tovsay that with confidence.

Personally, I vote strongly to buy a good one.
Good advice. I upsized my VFD to 3 HP for a 2 HP motor because it was a cheap Amazon VFD. If it fails I'll replace it with a better one. At the time when I bought it the budget was limited.
 

Rauce

Ultra Member
My lathe is a gearhead type. 2 HP and a VFD rated for 3 HP. I played around with the acceleration settings it got me a bit more RPM but never got to max without a fault. I tried changing the parameter for time before faulting to allow for more acceleration but it never seemed to work right. I really never run the lathe at full RPM so its not a huge issue. If this VFD packs it in I will get a better quality one next time.
Interesting my situation was 2hp motor and 2hp vfd. I assumed going up to a 3hp VFD would solve it but sold the lathe before that happened.
 

Susquatch

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Interesting my situation was 2hp motor and 2hp vfd. I assumed going up to a 3hp VFD would solve it but sold the lathe before that happened.

A wise man pointed out to me that the highest load a lathe sees is during start up. Spinning up that gear train is very hard on the motor. That is actually the reason I am installing a slightly higher horse power motor in my lathe. I'm going from 2.0 to 2.4. I had wanted to go to 3 but it didn't happen.

Some might argue that a bigger motor will stress the machine. That could be true except that a VFD allows one to set the acceleration rate to be equivalent or even lower that the original motor. That way the lathe is not overstressed and neither is the motor! Best of both worlds.
 

Xyphota

Ultra Member
I just purchased two vfds from AutomationDirect (one for my shaper, one for my lathe). Free shipping and they are acting as a broker so theoretically there shouldn't be any duties to pay for when Fedex delivers them.
 

Finhead

Member
Sorry if this sounds stupid. lol But do you guys that run a 3 phase VFD setup on your lathe or mill still use the gearbox or do you just control the spindle speed with the VFD?
 

DavidR8

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Sorry if this sounds stupid. lol But do you guys that run a 3 phase VFD setup on your lathe or mill still use the gearbox or do you just control the spindle speed with the VFD?
I set my belts on the mill to the lowest speed and then over speed the motor as and when required.
That way I had low speed with torque for power tapping.
 

DPittman

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Sorry if this sounds stupid. lol But do you guys that run a 3 phase VFD setup on your lathe or mill still use the gearbox or do you just control the spindle speed with the VFD?
VFD gives the gearbox(or belts) great range and makes it sweet and easier to fine tune the spindle speed. Of course on a lathe you still need the gearbox to get your exact carriage travel speed ratio to spindle speed.
 

Susquatch

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Sorry if this sounds stupid. lol But do you guys that run a 3 phase VFD setup on your lathe or mill still use the gearbox or do you just control the spindle speed with the VFD?

I think most of us like to keep the gear system working unless there are good reasons not to. A VFD will not normally give you the same speed extremes as belts or gears will. But it will allow you to minimize the number of gear/belt changes you have to do..

In the case of my mill, the replacement motor shaft was not long enough to allow me to use all 4 original belt grooves. So I lost one groove (the lowest speed one) because I had to push the pulley onto the shaft further than the belt engagement would allow. This was not an issue at all because I use the VFD to do most of the low speed driving.

Basically, the VFD allows you to run 3phase but also gives you more flexibility. But don't disable the gearing or belt system unless you have to.
 

Finhead

Member
Thanks guys, kinda what I was thinking but wasn't 100% sure. Only VFD I have is on lift for my shop door, 3 phase door openers are super cheap used. lol
 
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