DIY Belt Grinder Build Questions

3,470 rpm is fine, and you can always change the size of the drive wheel (assuming you're direct driving). I use a 2hp 1725 motor with about a 3.5 inch drive wheel, normally on a 5:4 pulley ratio from the motor, and I'm pretty happy with the speed and torque. I guess that would translate to roughly 2000 SFM. That's the middle of my pulley range though, so I could go higher or lower. I still suggest you use some pulleys so you can change it around and get a high torque low speed setup if you want.

Also if you're going to have a very fast setup, I would recommend you not get longboard wheels with cheap 608 bearings. They'd just explode on you with that kind of demand. Use at least 1/2" ID bearings, and either buy or turn your own wheels. Like I said, laminated MDF is a good choice, especially if you're not doing production work.

If you're not in a rush, watch ebay or FB marketplace for motors. You'll see some amazing deals on them pretty regularly, even ones that ship out. No need to pay full price for a new motor, especially if you're looking to save money overall.

One thing to keep in mind is that for low grit ceramic belts, you want enough torque that you can really shove work into the belt. At least on most ceramic belts I know of, the grit is able to fracture and reveal new cutting edges. You could also use a bench grinder wheel dresser for that.
 
I was hoping to go with direct drive to make things simpler.

So, is 2 HP needed or is 1-1/2 HP enough?
 
Direct drive with 3400 rpm and a 6" wheel is a good target. 1.5 HP is overkill in my opinion; I used 3/4 and it is fine. The bearings you select are critical at these speeds. Make sure they are properly rated. I had to change mine out and redesign the pulley to fit. I built my 2 x 48 out of aluminum with the vertical support made of steel. That worked out well. Here is the thread if it give you any ideas.

www.hobby-machinist.com

2 X 48 Belt Grinder (again)

I started on my belt grinder! I built this motor from scratch from scrap bin parts. I think it looks OK, although the capacitors are a little big. (Yes I know it reminds you of your ex but please refrain from commenting.) Specs are 3/4 HP @ 3450 RPM. Already blows 15 amp circuits. It's a...
www.hobby-machinist.com www.hobby-machinist.com

Robert
 
The motor size depends how you plan to use it. I like to really lean into it, and my 2hp 1725 rpm motor is about right for me. If I put my body weight into it I can get it to stall on large pieces.

Like I was saying before, you need the pressure to break the grit on ceramic belts to expose new edges, and you won't get a ton or torque out of a 3400 rpm motor with a 6" drive wheel. With a given motor horsepower rating, if you double the speed, you halve the torque. Power = speed x torque

I recommend you include a pulley system so you can get a higher torque setup if you want, assuming you go with a high speed motor.
 
I can stall my grinder, but if I do, the workpiece and the belt are definitely overheated. I am running Zirconia belts and I have had them come apart from overheating.
R
 
I found this Dayton motor at Grainger that is 2 HP, 3 phase, 3480 RPMs, 56C frame, and TEFC for around $270. So, I'm thinking of using that. I see one Youtuber uses an Ironhorse motor and is highly recommended and is only $169, but it's out of stock. The Grainger motor I can pick up locally without shipping fees.

For the VFD controller, I'm thinking of using this which is under $100.

I may have to buy the drive wheel since my 7X16 mini-lathe would have a tough (impossible) time turning a 6" diameter. I may wind up buying a set although most sets seems to use a 4" or 5" drive wheel.

I'm still searching for power and drivetrain options. I need to research the glass platen, too.
 
For a 2HP motor I would want to know the amp draw for the VFD. Do you have 20 amp circuits or 240V available?
2HP on a 120v 15 amp circuit at the 80% rule is gonna be close.
Robert
 
Yes, I have 220V, 20A power available.
 
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I still think you should be looking toward used motors instead of trying to get one new. Even if they bearings need to be replaced, they're going to be far more cost effective than getting something from grainger, which I've always found to be super expensive anyway. Here are two new options I found, but you can even get them cheaper used if you wait and keep looking. I gotten similar motors for about $40 shipped on multiple occasions.
www.ebay.com

Weg Electric Motor Model GM2000-KUTF-14, 1740 RPM 2 HP 3PH 208-230/460V 60HZ | eBay

WEG ELECTRIC MOTOR FOR 2HP 208-230/460V 60HZ. SEE LABEL PICS FOR ALL INFO.
www.ebay.com
www.ebay.com

New Marathon AC Motor 1725 RPM 1.5HP 3PH 208-230/460V | eBay

Checkerboard Farms-. Continuous Duty.
www.ebay.com

I like that VFD you linked and use two of them myself, though they are going to be less reliable than a more expensive name brand in the end. The nice thing about that specific one compared to other chinesium VFDs is it has a heatsink fan that only runs when the machine runs.
 
I was looking at 3400+ RPM motors to get the belt speed up. Both of those you listed are around 1700 RPMs.
 
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