Which motor for no weld grinder 8" wheel??

[LARRYZ10]

Hi, I am seriously considering building a no weld grinder because of my financial situation. I do not want it to be totally lacking in what a good grinder should have however. I plan on having an 8 inch wheel to start and I would really like to to run the grinder on 115 volt current which I have in my garage unless I am convinced that a 230 volt motor is so much better. My neighbor is an electrician. I am thinking about a 1 1/2 hp motor running at about 1800 rpm on the pully system. What is the advantage of a 3 phase versus a single phase motor. I do not want to get off cheap if am going to regret my initial choice. I have been reading some comments by experienced knifemakers on the subject but I need a little more info. I know some of you have done the same thing I am planning. Please tell me what works well and what didn't so maybe I can build something decent the first time. I am not a professional knifemaker but I love to make knives. Any advice would be appreiciated. Thanks, Larry Lehman Bakersfield, Ca

 

[ERIK KNIVES]

Hey Larry,

If you build it right, the NWG is very good. It also has a lot of room for custom modifications, depending on your skill set.

A 1.5 HP motor will be plenty. I have a single phase 1750 rpm that can be wired for 115/230. Mine is wired 230. I have a 4 step pulley set-up with a 6" drive wheel. I believe my SFM is between 900-6800. A three step and or a 4" drive wheel would be fine as well.

The advantage of a three phase is they are cheaper, but you need a way to support them. VFD or 3-phase converter. I wouldn't worry about that for now, unless you know you will be buying multiple motors. It sounds like you are on a budget, aren't we all. Your best bet for now is to find a good (new) TEFC motor for less than $150 to your door.

 

[LARRYZ10]

Thanks for the advice. One more question though. Do you have to move your motor to line up with the pully you select to change speeds and provide proper tension since they are different diameters? I mean can you run your drive belt on an angle to another pully and would you have to use a hinged motor plate to accomplish this? The photos of the nwg's I have seen show the motor bolted in place on two layers of heavy plywood lined up with only 1 of the three or four pulleys shown. Larry

 

[12345678910]

What is the advantage of a 3 phase versus a single phase motor



Do you have to move your motor to line up with the pully you select to change speeds and provide proper tension since they are different diameters?

I mean can you run your drive belt on an angle to another pully and would you have to use a hinged motor plate to accomplish this?

Fully Variable speed.



No

You could if it would give you more ratios, but that's not the idea

When you step pulleys, you use a pair of identiical pulleys.

They line up as different diameters, but the sum of the diameters is always the same.

4-3-2
2-3-4
====
6-6-6

So you may want a loosening, tightening device to make it easier to change, but the length of the belt is the same for each set.

 

[LARRYZ10]

Thanks!! You are brilliant and I feel less than brilliant. This could work if I did not have to change speeds often. Larry