What's your end goal? How many knives do you make a year, in other words are you wanting a grinder to use as a hobby or full time maker? I am a full time maker and use a KMG but, I payed for it by making knives on a my homemade grinder. My first grinder was a KMG knock off made of square tubing I welded together, all my drive and idler wheels came from Mcmaster Carr ($4 Per). Nothing about my grinder was square inline etc. I put a bunch of electrical on the tracking wheel and it worked fine. It probably cost $150 and a full day to build. I had a large single phase motor that I put step pulleys on, all said and done $200 ($50pulleys, belts) and I was grinding.

Personally if you can afford it buy a KMG frame, the expensive part is the motor and controller Aprox $800. You can get by for a long time with a single phase motor and step pulleys.

If you want to make your own go to youtube and search DIY grinders.

Hope this helps

Steve

Thanks for the thoughts! This will most likely just be a hobby for me but i could use the grinder for other things as well. What horsepower should i be looking into for the motor?

Depends on how you use it. If you go 3phase and a controller then 1.5-3 horse ( bigger is better but expensive). If you use single phase and step pulleys you can easily get by 1horse (no reduction of torque when running slow). Look for 1725rpm in single phase and 3600rpm in 3 phase. Someone please correct me if i missed something.

Ok so do you have to have 3phase to run variable speed or is it just better?

Yes, 3phase allows the the motor to be "controlled" up or down. The controller is a separate unit the has either a dial or digital adjustment by which you can change the speed (up or down). The controller is as expensive as the motor, sometimes more and this combination is what makes it twice as expensive as single phase. Single phase runs at a continues speed so, the use of step pulley on the motor shaft and the drive shaft of the grinder allows for the speed adjustment . Step pulleys are how most drill presses, bicycles etc. are speed adjusted . Both get the job done but 3 phase allows for much more finite adjustment, single phase is limited by the number of pulleys (3pulleys...3 speeds).

Beaumont Metal works sales KMG grinders as well as the motors and controllers. The header image on his web page shows both setups.

http://www.beaumontmetalworks.com/shop/category.aspx?catid=7

I don't have a variable speed grinder but I believe the speed control input is single phase and the output to the motor is 3PH, that is why a 3PH motor is required for the variable speed. You won't need 3PH power to your shop although that would be nice for mills, lathes and surface grinders. If you need 3PH for those type machines you can get a static or rotary phase converter to supply it from 1PH.

Steve Seib

OK thank you!

I got the ridgid number 12 in the other day! It seem like it is going to be a great anvil!

Congrats Trent, Looks like a good buy. You must be getting ready to do some heavy forging with a beast like that. Now for a belt grinder.

just wanted to start off with a good one!