# VFD Recommendation



## jbolt (Dec 9, 2014)

I have a 3ph 2hp 1725 rpm inverter duty motor to use for a belt drive conversion on my rf45 clone mill. Looking for a VFD recommendation for this motor. 

J~


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## Karl_T (Dec 9, 2014)

automation direct has been my favorite vendor. Just surfed over there, but the site is down at the moment.


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## countryguy (Dec 9, 2014)

I used these guys.  Fast, and lowest prices I found fir the Hitachi line. 
http://www.driveswarehouse.com/?gcl...TBwT_NbDqQ82tsiDpeUHk-_1A8IN_GwvnPRoCEQDw_wcB

From amazon I used: 
http://www.amazon.com/Sanven-Freque...125544&sr=8-2&keywords=VFD&pebp=1418125580839

If you want the higher end, get the hitachi.   Sort of the Gold standard from me readings.    On the China imports-  they seem to be popular and there are lot of good reviews on them.  I bought a 3HP above for the wall mount I setup for different gear.    

Many posts also offer to rate the VFD higher than the load by 1HP or so.  So on a 3hp device, use a 4hp VFD.   you can check into that.  

check EBAY but be sure you trust seller.   

Best, CG.


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## arvidj (Dec 9, 2014)

+1 on the Hitachi VFD's. I have several and they appear to be both idiot and bullet proof.

+1 on driveswarehouse for the purchase based on price but the one time I sent a post-purchase question to their customer support email address I did not get a response. YMMV and I was able to eventually figure it out by trial and error.


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## TomS (Dec 9, 2014)

jbolt said:


> I have a 3ph 2hp 1725 rpm inverter duty motor to use for a belt drive conversion on my rf45 clone mill. Looking for a VFD recommendation for this motor.
> 
> J~



Jay - you are going to post pictures of your belt drive conversion, right?  I'm sure there are several of us that would like to see what you are doing.

Tom S


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## Ulma Doctor (Dec 9, 2014)

at work i use a lot of Yaskawa VFD's.
 they come as OEM drives in many of processing machines and seem to have long service lives.

The Chinese VFD's also have come a long way.
 i recently purchased a Chinese VFD for use with a 3 phase lathe motor conversion.

I'll +1 on the suggestion of over-rating an inexpensive VFD, if it's going to be a daily money maker.
if you are not going to run the mill in a production setting a 2hp VFD should suffice.
keep positive airflow to the VFD and it will be happier and stay cooler!!!

good luck!!!


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## jbolt (Dec 10, 2014)

In doing some research it sounds like I need to size the VFD by the FLA vs HP? My motor has a FLA of 10.4 amps @ 230vac so it looks like I need a 3HP unit. Does this sound right? 

What features should I consider when controlling the speed from Mach3? I'm guessing my basic BOB is not setup to send the proper speed signals from Mach3 to the VFD. How the is actual speed of the spindle verified?

What is the maximum speed the motor can be run over the rating? I have read here that the motors can be run to 2x the rated speed but on some other sites they say only 20% over the rated speed? Ideally I would like to get up to 6K at the spindle.


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## JimDawson (Dec 10, 2014)

I think a 3HP VFD will work fine.  A VFD will normally run at least a 125% of it's rated power for some period of time.  It would be rare that you would ever hit the FLA on you mill.  

You can set the spindle speed in the G-code by a M3 S 1000 command, where M3 is spindle rotation CW, S 1000 tells it to run at 1000 RPM (M4 is CCW rotation, M5 is spindle off)  There is a way to feed back the spindle speed to Mach3, but I'm not sure how to do it.  Google will be your friend here, I also think there is a thread on that subject on H-M.

Most 17xxRPM rated motors are safe to run at 2x speed, or 120Hz.  I would not do this with a 34xxRPM rated motor unless the motor is specifically rated for high speed operation, like a high speed spindle motor.


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