OK, drills and circular saws and sanders seem to work great right out of the box - why is it so hard to get a grinder to run smoothly?
I’ve had 3 of them now, and fussed extensively, and still they vibrate like hell and often only use part of the wheel circumference because they run out of true and out of balance.
The wheels themselves often have soft paper disks on the sides of the wheel around the hub, and manuals say you’re supposed to clamp the wheel in the right spot so the impression in the paper locks the wheel in place. True enough, there’s a few mills of clearance over the shaft, and often what looks like a malleable lead bushing on the ID of the wheel. But how do you establish the original position accurately? I’ve tried replacing wheels and holding the grinder with its shaft vertical so I can play with the wheel and turn it by hand and inspect it before tightening the mounting nut.
I’ve bought wheel dressers, the kind with the star-shaped wheels and the kind with a diamond point, and they do remove wheel material but don’t get rid of the vibration. Looks to me like the shaft curves a bit under the stress of unbalance, so of course the dresser makes the OD run true in this condition, but the thing still vibrates incredibly. Mounting the entire unit to a heavy support passes the vibration along elsewhere, but I wish it weren’t vibrating to begin with.
In machine shops I see sometimes very big grinders, with maybe 24" wheels, for example mounted on lathes to grind the ODs of web rollers or calender rolls to 0.1 mil or so. Those don’t look like they’re vibrating, and the bolts holding the lathe together don’t vibrate out every 20 minutes.
So, what’s the secret here?