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Adding a VFD to my ML7

MashingMetal

MashingMetal

Ultra Member
I have been searching for a suitable 3 phase motor for months now, I sware I have give a few away in the past. Oh well. I came across this almost new Marathon a little large compared to the 1/3hp it came with but has a 50/60 hrz rating 1425/1725rpm so I am sure you can hurt it on a VFD.
Had to rework another pulley and machine for a 7/8 shaft and or course I didn't have a broach for the keyway so as @trlvn says I went "Old Skool" and scraped it out with a boring bar on the lathe. Next is to figure out where to mount the VFD. I might just add an upright pole behind the lathe to mount it on.
Oh and added a tool tray to the drawer in the base this weekend.
 

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Upnorth said:
How long of a ramp up time is a good starting point?
Click to expand...

That's the hard part. I'd recommend measuring it with the original motor for the highest speed. The manufacturer designed the gears for that accelleration. So it should also be a safe acceleration for a bigger motor. You can also set it a little slower if you want. It won't hurt.

If you can't do that, I'd probably start with 5 seconds to full speed in the highest gear. That will probably feel quite slow, but remember that the worst case is with a big chuck and a big heavy part. The accelleration time doesn't know about that, but you do and you should care because that's what is hard on your gear train.

You can always set it faster later on if it feels too sluggish.

It would be a very sad day if you snapped your gears the first time you fired it up.
 
Susquatch said:
That's the hard part. I'd recommend measuring it with the original motor for the highest speed. The manufacturer designed the gears for that accelleration. So it should also be a safe acceleration for a bigger motor. You can also set it a little slower if you want. It won't hurt.

If you can't do that, I'd probably start with 5 seconds to full speed in the highest gear. That will probably feel quite slow, but remember that the worst case is with a big chuck and a big heavy part. The accelleration time doesn't know about that, but you do and you should care because that's what is hard on your gear train.

You can always set it faster later on if it feels too sluggish.

It would be a very sad day if you snapped your gears the first time you fired it up.
Click to expand...
Ok thanks. It's something I was curious about. My lathe came with a motor I could not use so I replaced it with a lower voltage one. I did use 5 seconds when I set it up originally. It does work on anything but the highest speeds. On high speed, which I never need to use it faults out before reaching maximum speed. I use the motor as a single speed motor and I use the gearbox to set the speed. I thought it was best to do it that way to spread the wear around on the gear train.
 
Susquatch said:
What do you mean by "faults out"? Breaker? VFD quits? If it's the VFD, what does the error code mean?
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VFD quits and throws an error. Happens about 90% of the time. It's been a while so I can't recall what the error was. It's one of those off brand units from Amazon. If it ever fails completely I'll replace it with a good one from Automation direct. My experience with theirs has been flawless. The Amazon unit did come with some documentation but I recall it had some common parameters missing. If I can remember I'll spin it up and get the error code after lunch.
 
Susquatch said:
What do you mean by "faults out"? Breaker? VFD quits? If it's the VFD, what does the error code mean?
Click to expand...
I was walking by the lathe today and remembered to get the error code. It's a ERR 1. According to the piece of paper that came with the VFD that means Short circuit/Current overload/Power module protection. It only occurs on the two highest speeds and it faults out within a few seconds when the motor is selected on.
 
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