Will try to make a grinding arbot tonight

You're unlikely to be pleased with the hole you'll drill due to runout. The best way to go about this is to drill the hole undersized, then bore it, providing a snug slip fit on the motor shaft. Barring that scenario, the next best thing to do is drill two sets of three holes @ 120 degrees---spaced one set at each end of the arbor, so you can adjust the runout once it's assembled on the motor shaft.

If you haven't made anything like this before, you should give it considerable thought before striking out on the project. It is important for the arbor you make to run dead true, and be the proper size for the wheel you'll use. It should also have flanges of the proper size, which support the wheel only on the outside edges. An improperly made arbor can cost you your life. Be careful, and feel free to ask for guidance if you have any questions. Any number of us can provide enough information to keep you safe.

Harold

[ ... ]

I agree with all that Harold has said, but in particular, I suspect that I should add a little more detail to the bit about the flanges. what he means by the "outside edges" is that the flanges should be dished, so they only apply pressure to the wheel at a diameter just a bit within the maximum diameter of the blotter-paper labels on the wheels. And you should *never* mount a wheel without those blotter paper labels -- they are needed to prevent crushing the stone and starting it to fracture. Once it starts to crack, it *will* explode at speed. The bigger the wheel, and the faster it is turning, the more energy is stored in it, with the capability to do serious damage, possibly fatal.

Good Luck, DoN.

These holes would be tapped and set screws installed. Sorry to have left that part out.

H

Sigh..Ive about 800 lbs of shaft arbors, from about 1/2" to 3" OD.

What size do you want? I still have those electical boxes if you need one

Gunner

The two highest achievements of the human mind are the twin concepts of "loyalty" and "duty." Whenever these twin concepts fall into disrepute -- get out of there fast! You may possibly save yourself, but it is too late to save that society. It is doomed. " Lazarus Long

Thanks to DoN and Harold. I read your warnings in time and decided not to undertake this project. I realized that I did not know what I was doing and the risk was too great.

i

I don't know how large a wheel you are going to mount on that motor, but if it's small enough to be safely held by a 1/2" bolt, you could consider turning the motor shaft down to 1/2" diameter far enough back to put one of these cheapies on:

I'm not proud to say this, but more than once in my short life I've successfully "turned down" the diameter of a motor shaft by carefull application of a flat file while the motor was spinning, combined with frequent stops to check the progress with a mike.

Perhaps I was lucky and never encountered a shaft with hard spots in it which could have screwed things up. The shafts always came out with less runout than the crummy die cast V-belt pullies I was making them fit, and you've got to true up a grinding wheel after it's mounted anyway. .

Jeff

Thanks Jeff. I became a little fearful about this project. If I went ahead with it, it would be for large wheels, since I already have a small 1/6 HP grinder. I would not want to rely on a $3 Harbor Freight adapter. As someone pointed out, I or loved ones could get killed quite easily.

i

Yeah, I agree. Any you certainly would want some heavy guards around a large wheel too. Might be better to keep your eyes open for a used "tailor made" larger grinder and find something else to hone your machining skills on.

Have a great weekend,

Jeff

That's why I suggested a belt sander (I think in another thread). Lots less risk, faster removal rate. Of course, it's a little to a lot more complex depending on how fancy you get. There are lots of plans or at least photos on the web. I'm considering building one myself, although probably not as fancy as the Beaumont one.

Pete Keillor