Oregon 520-120 wheel runout

[user 140828]

Setting up my new Oregon 520-120 grinder this evening. Put the 1/8" wheel on and noticed a bit of side-to-side wobble when spinning it by hand--not a huge amount, but there. Same with the 3/8" wheel. Well, could be the wheels, but I got out my old Federal dial indicator and checked further. With the flange held in place by a few washers and the bolt, I repeatably got aroundd .002 runout near the edge of the flange.

I'm no machinist and my math classes are ancient history, but I think the .002 at 13/16" out from the center of rotation translates to about .014 at the edge of the 5 3/4" wheel. Even a perfect CBN wheel would have that runout, by my understanding. My experience with my disk sander and turning stuff on my lathe is that this would be quite noticeable.

I don't want to be too picky, I just want this thing to sharpen my chains. Is 2 thousandths runout okay or not? More importantly, is some eyeball-noticeable wobble at the business edge of the wheel okay or not? If this is generally how the 520-120 and the wheels are, and it all works, I'll just forget about it and start using it. But I thought I'd ask what people think, and what people's experience has been who have this machine.

 

[CR888]

Some of the wheels aren't perfectly true, but with use and wear (reduction is size) they seem to improve a lot. As for the grinder arbor, I'd fit a known true wheel and measure the 'wobble/movement' at the grinding end as its rotating. That's really what counts. If its unacceptable you have good reason to return it & get a new one. But how 2 thou runout translates in the real world using the grinder is something you'd have to test and find out, my guess is it won't be a problem.

 

[Jeffkrib]

If the grinder isn't wobbeling or pulsing and the surface finnish is good then its not a problem. I noticed my wheels weren't perfectly true either, when you grind and stop the wheel you will see only part of the wheel is actually grinding. If your doing precision grinding on a surface or cylindrical grinder thats a different story you need balanced and dressed wheels of you get an uneven surface finish.

 

[user 140828]

That's kind of what I figured, but I thought I'd ask.

I continued with the setup last night and found myself wondering how to use the wheel wear scale on the bottom right of the base. Nothing in the manual except this sentence I couldn't figure out in the little section on centering the vise:

Move the vise assembly forward or back
until the straight edge lines up to the guard
securing screw (F), referencing the grinding
wheel wear reference marks (20).

 

[user 140828]

Oops, hit send too soon. Anyway, the manual says to "pull the motor unit downwards and see if the ruler lines up with the guard securing screw (F)", and if not move the vise forward or back until it does, "referencing the grinding wheel wear reference marks (20). Huh? That's two lineups, the screw and the reference marks--what if they don't agree? And just how far are you supposed to "pull the motor unit downwards"? I would have guessed right to the top of a chain already placed in the vise, but what do I know?

In fact, there's an Oregon video which says to set the motor unit at 90 degrees to the base (the back vertical part of it I assumed--by which I also assumed was meant the line between the pivot rod in back and the guard securing screw in front would be 90 degrees to the vertical base, since the guy didn't show how he measured the angle), then check/adjust the ruler against the screw. No mention of the wear scale, and I couldn't find any other mention of the wear scale in the manual. So exactly how is the wear scale used?

Probably overthinking this again and it's not that critical.