The biggest question we get about grinder bits is "how long will it last?" Tough one! Depends on how much you use it. A bit can be adjusted up and down, and carefully you can use lots of the surface. Once you get a bare spot, move the bit up or down. Normally your wear will be even all the way around the bit. Occasionally, you will get a bare spot. You can still use the space above and the bare spot.
The next biggest question we get is, "how do I get my bit off the shaft?" It's stuck! What you do not want to do is bend your shaft so do this very carefully. We send someone to our classroom every week to take the bits off, rinse them, and put them back on. That keeps the gunk from building up between the bit and the shaft and behaving like it is cement. The only way to get it off is patience! That is a bit tough when you just want to use your grinder. Take some 3 in 1 penetrant, (or any of these chemicals designed to loosen metal), let it set and see if it comes loose. If not, do it again and again and again until it does.
In this "there is a gadget for everything" world, there are now different grits. These grits include: XFine, Fine, Medium, and Coarse.
The fines are great for when what you are grinding is chipping. Glass with a surface, like mirror or irid for example. In the old days, we saved our old worn regular bit for this. Coarse or speed bits are for when you have quite a lot of glass to grind off. When you get too close to where you want to be you will probably switch back to regular as the coarse is a coarse grind.
There are also sizes to get you into smaller spaces:
For these bits each manufactures look a bit different, but most are interchangeable.
There are also some specialties bits---like a lamp bit.
The ripple bit is so you can grind rippled glass and it is smoothed out for foiling. The radius is a combination of flat and a place to round the edges to get rid of a sharp edge. It is used mostly for mosaics. The lamp head allows a nice, angled grind so angled pieces will fit well together.
The Quick Fit System has become popular with the new Techniglass Grinders and can be used on other grinders. When the grit wears off you can just buy a replacement sleeve and not the entire fixture.