Need help choosing motor and VFD for grinder.

Nighthawk1975

Nighthawk1975

Joined
May 2, 2010
Messages
20
I have a KMG grinder with a 1.5 hp motor and the 3 speed pulley system and would like to upgrade to a 2 hp motor with a VFD.

I read on here before that Ironhorse motors were good to go so I was looking at this motor.

https://www.automationdirect.com/ad...Phase_Motors,_56C_(0.33_-_3HP)/MTRP-002-3BD36

I know KB Electronics makes a good sealed VFD, I have one on my KMG 1 hp horizontal grinder so I'd like to use one on my vertical grinder.

I was looking at this one and was wondering if it's compatible with the Ironhorse motor I have listed above.

https://motorsandcontrol.com/kb-ele...-nema-4x-enclosure-variable-frequency-drives/

I honestly don't know much about motors and VFD's so I was looking for some insight from those of you who do. I'm guessing you just make sure the motor is 3 ph and match the hp to the VFD but wasn't sure if their was anything else I needed to make sure was compatible.

I saw a similar VFD for sale on a knife grinder site but it was about $200 more and I didn't know if there was something I was missing or if the price difference was because it included the wiring and was pre wired for the motor.

I was looking at this setup because it's fairly inexpensive but I still want a quality setup so if anyone has any other suggestions, I'd like to hear them and I'd appreciate any help you guys can give me.
 
What you have linked to will work just fine, though personally, I'd go with the 1800RPM 2HP ironhorse and double the KBAC speed, as you'll get a little better torque on the low end.
You'll also need a wiring kit for hooking up the motor to the VFD, and then an appropriate plug to go into the wall, unless you hard wire it. Unlike your 1hp vfd, this will have to be 220vac input.

I recommend SO cable (flexible) for the plug and motor connections. you'll need something like 12/3 cable for the incoming power, and 12/4 for the connection to the motor. 14 gauge would also work, but I like 12, personally. I'd also recommend using dust/water tight fittings. IIRC, the KB drives have 3/4NPT knockouts, and you'll need two cable glands out of the kb drive, and 1 cable gland for the motor's pecker head. The kb drives don't come standard with a power switch, so if that's important to you, add that to your order, or you can source your own with a dust boot for probably just a little bit cheaper. Just a stander DPST toggle switch will work, along with a couple of short jumpers with female spade connectors. If you want forward/stop/reverse, you'll have to add that too.

Last is the outlet and the plug, which is up to you. 15 amps will be plenty. iIRC, I have a 20amp twist lock on mine.
 
This is exactly the kind of info I was looking for. I appreciate it.

I have 220 in the shop for my welder and I plan on running a drop to my grinder table. I'm also going with a 56C face motor to convert the grinder to direct drive and using a 5.5" drive wheel.

I'm glad you mentioned adding the on/off switch. I was wondering about that since they listed the switch as an accessory. The VFD I have on the horizontal grinder didn't come with one either but I have it plugged into a surge protector with its own on/off switch so it didn't matter but I'll need one for the 220.

Thanks for the excellent advice.
 
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