which chinese VFD for motor conversion?

REK Knives

REK Knives

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Knifemaker / Craftsman / Service Provider
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Apr 3, 2011
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any recommendations are welcome... I just got a used surface grinder (picking up monday) and it's got a 208/230v 3 phase leeson motor on it.

I am leaning towards a cheap chinese vfd for now instead of a phase converter... I have read from another guy's experience (and in the Harig manual) that the phase converters can cause electrical vibrations and not give good finishes.

I suppose I could wire up my KBAC 27D to that as well, it already runs my bench grinder, 2x72, and disc grinder lol. This will be just a bit further away though than those other things.

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I like the huanyang VFDs, and have had good luck with them. That said, any of chinese VFDs will probably be ok for what you're using it for.
 
I use a teco fm-50 for my grinders all my grinders, but my harig has an external Oiler so it’s not tied in.
 
Most any cheap Chinese ebae vfd will likely do the job. The key is to make sure you get one at least 50% larger then needed and keep it clean. Maybe even mount it remotely if possible to keep the metal dust out of it. If you can't then blow it out before and after each use and it should last many years
 
Drew Riley said:
I like the huanyang VFDs, and have had good luck with them. That said, any of chinese VFDs will probably be ok for what you're using it for.
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Looking at those huanyang vfd's on ebay, they seem decent for the $$. should I get the one rated for 2hp or 4hp? The motor is only 1hp on the surface grinder...

shoot, the more that i look at it I may as well just get the KBAC 24d, not much more expensive...
 
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razor-edge-knives said:
Hmm... Why would the external oiler matter?
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I’m not sure if oilers normally work off of the motor that comes with the surface grinder or not. When I recommended my setup to another member on this forum he was concerned with his internal Oiler and went a different route.
 
Josh Rider said:
I’m not sure if oilers normally work off of the motor that comes with the surface grinder or not. When I recommended my setup to another member on this forum he was concerned with his internal Oiler and went a different route.
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gotcha, yeah I think there are 2 separate plugs for each motor but I'll get it in and verify that
 
Of the cheap Chinese ones, the HuanYang drives have the advantage of having been around a while. They have been used by good few folk who have a pretty good idea what they are doing and who have documented their experiences online. There is also a reasonably decent manual that comes with the drive.

Most of the others seem to have rather poorer manuals. The drives themselves may be better or worse than the HuanYangs, but any small technical advantage/disadvantage will pale into insignificance against the frustration a poor manual will cause.

If you use your existing drive, you need to be REALLY sure you do not drive the SG too fast. This is particularly important if you run your belt grinder above 60 Hz. Exploding wheels are a very real thing and they make a proper mess of anything/anyone in their path. Personally, I’d use a dedicated VFD for the surface grinder.
 
razor-edge-knives said:
Looking at those huanyang vfd's on ebay, they seem decent for the $$. should I get the one rated for 2hp or 4hp? The motor is only 1hp on the surface grinder...

shoot, the more that i look at it I may as well just get the KBAC 24d, not much more expensive...
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I use a 2hp for both my 2hp knee mill and 1hp surface grinder. Never had any problems. I'd stick with the 2hp.
 
timgunn1962 said:
Of the cheap Chinese ones, the HuanYang drives have the advantage of having been around a while. They have been used by good few folk who have a pretty good idea what they are doing and who have documented their experiences online. There is also a reasonably decent manual that comes with the drive.

Most of the others seem to have rather poorer manuals. The drives themselves may be better or worse than the HuanYangs, but any small technical advantage/disadvantage will pale into insignificance against the frustration a poor manual will cause.

If you use your existing drive, you need to be REALLY sure you do not drive the SG too fast. This is particularly important if you run your belt grinder above 60 Hz. Exploding wheels are a very real thing and they make a proper mess of anything/anyone in their path. Personally, I’d use a dedicated VFD for the surface grinder.
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yeah you are probably right... the motor plate says it can run 50-60hz so I'll make sure the vfd isn't set above that or any turbo or anything.

i-4JNkZb5.jpg
 
I wouldn't be to scared about sticking only to 50/60 hz. Most well made (and leeson's are) can tolerate being run outside that quite well.

Just watch the motor temps. Higher frequency can cause excess heating if the laminations aren't thin enough for it and the eddie currents buld up.

Lower frequency can lead to increased amp draw but a properly setup vfd should keep them in check

If your motor runs at less then about 250* you will likely be fine for many years
razor-edge-knives said:
yeah you are probably right... the motor plate says it can run 50-60hz so I'll make sure the vfd isn't set above that or any turbo or anything.

i-4JNkZb5.jpg
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Backyard said:
I wouldn't be to scared about sticking only to 50/60 hz. Most well made (and leeson's are) can tolerate being run outside that quite well.

Just watch the motor temps. Higher frequency can cause excess heating if the laminations aren't thin enough for it and the eddie currents buld up.

Lower frequency can lead to increased amp draw but a properly setup vfd should keep them in check

If your motor runs at less then about 250* you will likely be fine for many years
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The issue isn’t what the motor can handle, but what stone wheels can handle. Spin one too fast and it'll blow apart in a not too friendly manner.
 
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Drew Riley said:
The issue isn’t what the motor can handle, but what stone wheels can handle. Spin one too fast and blow apart in a not too friendly manner.
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Isn't there a laser or some type of gage that I can use to verify the rpm of the wheel? Probably would be good for me to have when getting this dialed in
 
razor-edge-knives said:
Isn't there a laser or some type of gage that I can use to verify the rpm of the wheel? Probably would be good for me to have when getting this dialed in
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You're thinking of a laser/photo tachometer. You stick a little piece of reflective tape on the spindle and shine the laser on it, and it will give you the RPM.

If you search Amazon for "non contact tachometer" you should get several results, many of which are under $20. Most of them appear to be the same model, just different brand names and colors.

If you're going to use a VFD and ONLY use it as a converter for your surface grinder, I'd probably just set the min and max frequency to 60Hz and call it a day. You can verify RPM if you want, but as long as you put in all of the motor specs correctly, it should be fine.
 
Since you've got a 1 hp motor I'd expect any 1.5KW (2hp) VFD to work just fine. Here's a VFD I'm using - got 3 of them in service at this time: https://www.ebay.com/itm/122794378916? for about $68 shipped from USA.

They have one of the best manuals around - good printinig, good English, and only a few pages. This VFD only has 31 or so parameters to set and works pretty good.
 
Ken H> said:
Since you've got a 1 hp motor I'd expect any 1.5KW (2hp) VFD to work just fine. Here's a VFD I'm using - got 3 of them in service at this time: https://www.ebay.com/itm/122794378916? for about $68 shipped from USA.

They have one of the best manuals around - good printinig, good English, and only a few pages. This VFD only has 31 or so parameters to set and works pretty good.
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Thanks Ken! My only question is that I was told by the kbac technician that if I ran my 27d at the 2hp setting for a 1hp motor it makes the motor run hard and would wear it out prematurely... Do you know if that would be the same case here?
 
Yep, setting at 2ph only means the VFD will provide "up to" the amount of current required for a 2 hp motor. Your 1 hp motor will only "request" about half of that so the VFD will simply be working half as hard. Most of time you won't be pulling 2hp with a 2 hp grinder anyway, only when the motor is fully loaded.
 
As far as I understand it, the parameters are mainly going to affect your overload protection, i.e., if you're running a 1hp motor with a 2hp VFD, you'll have to load it to the limit of the 2hp motor before it goes into fault. This assumes that your machine would ever get to the current level necessary to trip the VFD. Now, this could happen, if for instance, you go to take too deep of a cut and completely stop your wheel.

The easiest solution is simply to set any jumpers or parameters to the specs of the motor you're using, and your protection should be fine. Now, if you're running 2 different machines from a single VFD, you'll want to set it up for the bigger of the two, and just be mindful that your built in motor protection isn't really there for the smaller motor, as it would be for the larger.
 
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