Thread: Hoping to build a grinder.

I built the "grinder in a box" set-up.

I'm running a KMG controller and a 3 phase 2 hp motor that is 1800 rpm's. IMO, with a VFD, you should go with a 3400 rpm motor as the high speed is not very high speed and you have the controller to get your 2x72 belt down to almost 1 fps. Hogging material takes a while for me even with a fresh belt when working with .250" stock.

Keep in mind something that a electric motor guy told me when I ordered my motor. Apparently there is a difference in motors that are designed to be on a vfd. Mine didn't cost but like $10 more, but the salesman said there was a difference...I honestly don't know.

If you dare going with a single phase motor and pulley's, you will have no problem...just make sure it's not an open motor like mentioned above.

What do you think of this set up? http://dealerselectric.com/item.asp?PID=24498

Scott, I have a similar 1/5/2hp variable speed setup on my KMG and the problem that I see is not so much the speed but the horsepower or lack thereof. A lot of the modern ceramic "hogging" belts like the Norton Blaze are designed to work best not only at top speed but with you REALLY leaning into them with a lot of pressure. My experience has been that they will actually glaze over a bit and not fracture new grains if you don't push hard enough and what ends up happening is that I wear down the joint and get that dreaded bumpily bump or gum up the back and leave glue on the platen from the heat in the case of the Blaze belts before the abrasive material wears out. The glue thing is one reason that I have shifted over to the 3M Cubitron 984 belts of late. they have a better joint and the glue doesn't seem to melt. The problem that I have with that 1.5/2 hp motor is that you can bog it down relatively easily on big blades which I have been known to make on occasion. Most guys I know who have bought one recently have gone with the 3hp and a couple of guys have retrofitted an 5hp motor and more burly VFD to their KMG's. I bought the small motor because I was running it at 110v 1.5 HP initially and did not have a 220v outlet in my garage. If I was doing it today, I would buy the 3hp 220v rig at a minimum.

Originally Posted by shooter74743

I built the "grinder in a box" set-up.

I'm running a KMG controller and a 3 phase 2 hp motor that is 1800 rpm's. IMO, with a VFD, you should go with a 3400 rpm motor as the high speed is not very high speed and you have the controller to get your 2x72 belt down to almost 1 fps. Hogging material takes a while for me even with a fresh belt when working with .250" stock.

Keep in mind something that a electric motor guy told me when I ordered my motor. Apparently there is a difference in motors that are designed to be on a vfd. Mine didn't cost but like $10 more, but the salesman said there was a difference...I honestly don't know.

If you dare going with a single phase motor and pulley's, you will have no problem...just make sure it's not an open motor like mentioned above.

That almost looks too good to be true at that price. I would definitely look into it, but don't get your hopes up too high.

Originally Posted by drmccubx

What do you think of this set up? http://dealerselectric.com/item.asp?PID=24498

Ok. Thanks. I will look into it. I know some people who know electrical who could give me some advice. Define try the way I would rather go. Especially for finish grinding with finer belts.

Dealers is where I got my motor. Call them up and tell them your application...they will steer you in the right direction. As mentioned before, when I talked to the salesman to place my order he asked the application & recommended another motor as the one I had chosen would have not lasted very long.

Maybe this one is better for me . only 1/5hp though http://dealerselectric.com/item.asp?PID=24496

Originally Posted by drmccubx

Maybe this one is better for me . only 1/5hp though http://dealerselectric.com/item.asp?PID=24496

1.5 HP is good enough. I have one, and it has never bogged down, even at low speed.

Ok, vfd and motor purchased. Now what next ? there are so many design plans online. I am thinking just using the KMG variable speed design. One pully to shaft and pillow block bearings to drive wheel. Simple. simple is better to me . see attached. But instead of using many pieces of steel and taping a lot . I was thinking steel square tubing for the structure and plate steel for base and misc ? I figured why source the metal I need , get it in my hands, then purchase wheels, nuts bolts , whatever. Then Head over to my nephews , "he knows how to weld and cut steel" with plans and get started with creating the frame . I guess my thoughts are "have a complete design in place" . I am in no rush by the way . Then build the structure. Tap, weld, paint , etc. Then next step . Coments are welcome. Oh, and I spoke to my nephews brother who can wire the vfd. I am excited but I know this will take maybe 2 months to complete.

Depends on the motor, the kmg clone from Polar Bear Forge called "grinder in a box" requires a specific motor face.

You state: "I am in no rush by the way"...Ya you are, just like a kid with a new toy...can't wait to play with it!