Considering building a grinder and need some parts advice

I

IrishSteel

Joined
Nov 12, 2012
Messages
88
Hello all,

My step father caught wind that I started making knives by hand filing and he wants to tackle building a KMG style grinder with a vertical platen. I'm looking for any way to save some money. We already got a free 1hp single phase motor and we can pretty much get any motor we need for free 1hp doesn't work. I looked up individual part prices for wheels and the cheapest I can find 2 inch idling wheels, drive wheels, and contact wheels are for approximately $50 each at usaknifemaker.com. I'm wondering if there's any other sources for wheels that are cheaper; could I take the wheels off a portable belt sander (or some other burned out, free, craigslist sander) and use those? Could I go to harbor freight and get some cheapo sanders and steal the wheels off of those? Any tips would be greatly appreciated.
 
Grinder wheels can be made if one has the tools and the skills, read: is a machinist with access to a shop. That was about the cheapest way that I was seeing them. Other than that, they can be bought, and you found about the cheapest place to get them. Check wilmont and beaumont as well, but neither of them will probably beat the prices. If putting one together cheap was so easy, then more people would do it.

As a side note, what college do you go to? Check and see if they have a shop. It could be quite helpful to have as an option.

I'm not an expert because as I was getting ready to get started I got the deal of a lifetime, that is, I got to borrow a KMG for 9 months. All I had to do was provide a motor. I am still going to be building one as well, and so I am looking forward to what people say.

Note: I am not an expert. There is quite a good chance that I have no idea what I am talking about. Take what I say with a grain of salt.
 
I'm a mechanical engineering student. I've had CNC mill training and I would love to use one of our 3 axis mills or even one of our lathes to fabricate my own wheels. I would use the university's shop for this if they would let me, but unfortunately they have rules specifically against helping student's make non-school related stuff. Kinda puts a damper on innovation if you ask me =/.
 
As much as it hurts the wallet to buy the right parts, cobbling a grinder together from odds and ends will usually give you a sub-standard device. As a mechanical engineering student, I am sure you realize that the task desired and the abilities of the parts used need to be matched. Using parts made to run for short periods of time at 1/4HP from some discarded shop tool on a 1HP+ belt grinder would just end in parts failure....and more expense.

Buying grinder wheels also has another reason...parts availability. If you use a standard grinder wheel, you can buy a replacement from any supplier and change it. If you tear down an old B&D model XZ1097 sander for the wheels....where are you going to get the replacement parts when they fail. You might not even be able to switch to the proper ones if the build was around a different shaped part.
 
Stacy is right. I made a 10" wood wheel with the lathe and ran it for over a year but I was unable to use the wheel for anything just the very platten. I did not know what I was missing simply because I did not know. Buy the plans from Tracy at usaknifemaker and quality wheels and idlers. You wont regret it and can use the contact wheel which runs cooler and moves metal quicker than using just the platten.
 
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IMO, the wheels can make or break the grinder. If you skimp any where, don't skimp here.

Fortunately, you really only need to buy two wheels to have both flat platen AND slack belt capabilities. You just have to make your flat plated removable, similar to the KMG.
If I had my NWGS build to do over again, I would go with rubber wheels over the solid aluminum too.
 
Ive built 3 2x72 upright 2 wheel grinders using salvage parts.

For the wheels i used castor wheels. Automotive water pump bearings for the tracking wheels and made bushings for the drive wheels out of wood.

The last grinder i built, i recently replaced the wheels with those bought from usaknifemaker. I have one more grinder planned and will purchase the wheels again instead of using scrounged ones.

It can be done with scrounged wheels, but in the end it is way easier and cheaper to buy the wheels.

You can reduce costs by scrounging metal for the frame, and building your tracking device. Also big money to be saved in used motors. But the wheels are better bought.
 
just out of curiosity... would these work??? both for your information and for mine...
http://www.mcmaster.com/#roller-feeders/=kt0m9q
for the idlers
22875tp1s.png

P/N: 22875T6
andhttp://www.mcmaster.com/#roller-feeders/=kt0lri
for the drive roller???
61065kp1l.png

P/N: 61065K58
 
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The problem is balancing.
Ask for the max rated speed on those I don't see it listed.


Tracy has them made at Sunray and specifies a tighter tolerance
You may get a lower price but longer wait time by buying from Sunray direct ?
.

Keep in mind a small wheel will be running several times faster than the drive wheel according to the ratio.

for example
3400 rpm motor

6 " drive / and 2" platen wheel is

3400x3 = 10,200 rpm


Castors are certainly not balanced for that




The one wheel I looked at from your links needs a bearing with a 1.250" bore

Which bearing would you use with that ?
 
I appreciate all the advice! I suspected that using wheels from a lower rated sander might give me problems, but I wanted to pick the brains of the community before diving into anything. We can definitely save money on the metal and like I said we can get motors for free so that saves us a couple hundred right there. If we end up spending just over $200 on wheels and save money on the metal we will still come out cheaper than just going out and buying one. I definitely benefited from this.
 
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