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Should a $79 VFD make me nervous?

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BFHammer

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I'm embarking on a 2x72 belt grinder build and one of my goals was to keep the cost down. Having said that I see the benefit of having variable speed depending on various grinding/polishing tasks, etc.

I have 240V power available and my initial plan was a 2HP 1PH 3600RPM motor. Plug up and done. Curiosity got the best of me and I started to look around at 3PH motors and I realized they are no more expensive and even cheaper in some cases, but of course require a VFD for both phase conversion and to obtain the coveted variable speed.

Should I be nervous about a $79 VFD like this one on eBay?

https://www.ebay.com/itm/2200W-3HP-...967312?hash=item3f9901bbd0:g:0g4AAOSw8BRay1Gd

I realize I now have some expense in enclosures, switches and potentiometer. As well as the challenge of deciphering a Chinglish manual. But aside from that should I worry about any safety concerns or damaging my motor.

Any thoughts or experiences will be appreciated!
 

BFHammer

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Ray C

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I have that same VFD in 1HP rating. It works fine. Apparently, a lot of people are using that VFD and some commonly available 3 phase spindle motor for a high speed lathe setup. It comes pre-programmed for 400Hz operation. I took mine and changed all the 400Hz values to 60Hz, shut off the ramp-down parameter and changed the ramp-up parameter to 3 seconds. The manual is terrible.

I have not used it much but, it works fine so far.

Ray

EDIT: I've used/setup many different types of VFD over the years. If you are new to them, this particular manual is totally unforgiving.
 

ttabbal

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#4
I agree, the manual sucks, but it's good enough if you google a couple terms. I have the 2HP version running my 2x72 with a 2HP motor. I didn't see any point in oversizing it.

On a grinder there is the fact that this is an open design and grinding dust can get in there. There are a couple methods to combat that. You can get something to put it in, an air filter, and a fan to move air through the enclosure. And/or use longer cables and remote mount it. Right now, mine hides in a cabinet while I grind. It's not perfect, but hasn't caused any problems. I'm considering options to stuff it into for additional protection.

I also use a remote control box for run and speed controls. It's just a random box with a switch and 5k pot on it. I did give it a fancy 3D printed knob, but it wasn't necessary. The manual has some diagrams for connections to make it work. You need to change the setting for speed control to "voltage". Note that's not "pot", what the "pot" setting is for is that some of them have a pot built into the onboard control panel.

Mine also came set for 400hz. I changed it to max out at 120hz as my motor is a 1750 RPM and it's rated for inverter drive at 4000 RPM, so it lets me run a "normal" size drive wheel. I run ceramic belts faster at about 100hz most of the time, and AO belts slower, more like 50-60hz. The ceramic belts love the higher speed and chew up HSS.
 

Bob Korves

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I have a similar/same VFD on my surface grinder. It works just fine. I installed mine in an enclosure with just the display/controls mounted to the front of the enclosure cover and the ribbon cable to the VFD mounted inside. I put a computer muffin fan on the top and filters both top and bottom, also mounted a thin sheet of clear plastic to one side of the muffin fan (two screws) so it gets pushed up with the air flow, and lays down with the spindle off. That also helps to keep the grit out. The VFD is mounted behind the wheel guard and above the spindle, to the right side of the column, away from most of the grit flow. Grit and metal swarf can and will kill a VFD. I also installed a separate potentiometer to control CPS (speed) and a toggle switch for motor on/off in the cover of the enclosure. The push button controls on the cheap VFD's are a weak point and when they fail you will not be buying parts, you will likely be throwing the whole thing in the trash. I only use the factory buttons for programming (rare), nothing else. I have a switch at the wall to control power to the VFD. Switch the wall switch on, turn the spindle switch on, dial the speed you want with the pot. Couldn't be happier with it. I bought a three HP unit even though my grinder has a 1.5 HP motor. The difference in price was only $10, and I think that gives me a more robust unit, one that can be moved to a bigger machine later on, and one with better resale value.

What I did not like in the ad you linked to is the seller's rating, 96.7%. That means that 3.3 out of 100 (1 out of 30) was unhappy with the seller. I don't like those odds. I look for 99%+ to buy on eBay.
 
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agfrvf

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#6
I have a chineesium 4KW Huan Yang VFD off flea bay on my van norman. Directions could be better. Otherwise no complaints.
 

westerner

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#7
I spent about $120 ish on a GS II from Automation Direct. Great reviews. Still chinese, but at least the manual was written by someone who's first language is English! I had no trouble programming it, or tweaking parameters after the initial trials. My first VFD, zero problems in the year I have had it. And by the way, I surely am no IT kinda guy!
 

Z2V

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#8
I used a free treadmill motor and board for my grinder. About $30 for a 12x12 outdoor box from HD and a 3k pot from Fry’s for $5 and up and running as far as a motor and controller are concerned.

I picked up a 2 hp Delta VFD off eBay for $80 that is going on the mill. The owners manual is great.

I know you asked about a VFD but you first mentioned keeping cost down, just offering a low cost option.

We like belt grinder builds around here, just ask Mikey!!
 
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Ray C

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#9
Quick update... I just checked and discovered I have 3 of these VFDs. The other 2 are older units. The wiring hook-ups are the same but, the programming parameters are different but they are otherwise, the same copy of a copy of copy that's been around for a long time. The oldest one I have is rated at 2 HP and it powers a 2 HP motor on my main lathe (PM1236) that I converted to VFD about 6 years ago. It's been used almost daily and is holding-up just fine.

Ray
 

BFHammer

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#11
Thanks for all the comments and insights. It’s good to know that others have had decent experience with these VFDs.

I ordered the 2hp motor linked above for $152 delivered and just ordered the VFD also linked above for $78 delivered. I think I’ll be in for another $50-$60 on enclosures, switches, bearings and some miscellaneous stuff. Fortunately I have a pretty good scrap pile to work from for the frame as well as enough aluminum to turn my own wheels (if I don’t screw any up!).

I’ll start a thread once I begin the build. My goal at this point is to end up with a quality variable speed grinder for about $300 out of pocket.
 
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