They are intended to be dressed in-situ on the grinder, which should make sure they are true to the spindle. As long as the guards are fitted and you take it easy there shouldn't be a problem. Keep a negative rake between the dresser and the wheel. If you can mount the hose of your shop vac where the grit goes to help avoid it spreading over the workshop.

You should only take a very light skim with each pass.

I found this guide to grinding wheel use.

http://www.toolingu.com/images/finished_pdf_files/250230.pdf

I've been disgusted with the wheels I have bought of late. Some of that might be down to the grinders they have been on but the wheels definitely don't come running anything like true. I have a grinder in the garage that I use if I want to make a new tool or do a lot of grinding on something. It's been in there for something like 20 years. Make Nutool. The wheels hardly needed any touching up at all new and the grinder has never been bolted down. It doesn't need it and stays dead still.

Anyway on that grinder I use a hammer headed dresser lightly on it when it needs it which isn't very often. I use that style because they are easy to use, They just need holding square to the wheel surface. This dresser has proved to be pretty useless for truing up wheels as they tend to bounce off the wheel. They also need a fair amount of pressure applied which means they tend to follow the shape of the wheel rather than correct it, A single point tool is a lot better but take too much off and the diamond will probably fly off. Neil's pdf suggests suitable amounts,

John

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Edited By Ajohnw on 21/05/2016 10:40:31