Grinding wheel truing....

[John Rudd]

I've not had alot of experience with grinding wheel replacement, so, do new wheels need truing up when changing them?
Am I expecting too much when it comes to changing a wheel and not seeing it run true?
I guess if this is the case then truing is done with a diamond tipped dresser?

[vtsteam]

It's a bit worrisome if you have one that isn't running relatively true out of the box. But perhaps this is a hypothetical question?

At any rate, you particularly want to be wary if the sides of the wheel are not true. Something would be seriously wrong then. But I also expect the grinding edge would be true in a new wheel.

[John Rudd]

Err...mebbe I should be a bit more specific..

The wheels in question are not your standard wheels but more the cup type....

Does this help?

[Jonny]

Assuming this is for a proper grinder and not a bench tool grinder.
In that case all wheels should be dressed prior to any work. More to the point, grind part fairly close then dress for a finish.
Secondly due to tolerances in fit on bore, it could run out. Larger wheels need balancing as well.

Wondered why most of the asian tools are not true, by the time its gone across the part its worn and undersize.

[rotorhead]

Hi John,

It's strange you should be asking about grinding wheel run-out, as I've just had an issue with a supplier, I bought a new 900W 200mm x 30mm bench grinder for £160.

It arrived with a broken base casting, they sent out a new base immediately, I re-built it then tried it.

The wheels ran out by a long way, one more so than the other, so they sent out a new wheel, and that ran out just as bad.

I liked the grinder so persevered, I checked the spindles for truth, they were within 0.0015" TIR.

After making a dummy shaft in the lathe to mount the flanges on, I skimmed the sides true.

But the mounting flanges were 0.010" larger in the bores, this is what seemed to be causing the run-out of the wheels.

I bored out the wheels truer than they were, then made new flanges to suit that new bore size, (I will be able to true up replacement wheels to the larger mounting flange)
 
There is only slight peripheral run-out, which I will dress when necessary, but the sides now run true.

Chris