Now, there are some things you should know before you use this.
The first few things are regarding safe usage.
Be sure that you only use these on low speeds only!
Also be sure to wear proper safety gear (eye protection). Since the roll is not
one piece like the actual dremel sanding drums/rolls, it is much easier to catch
and edge and have the whole thing come apart.
Next is for the sake of whatever you're working on. If you're working on
something that can be easily damaged, like a straight razor, then pay special
attention.
First is the same as a normal sanding disc, stay away from edges that may catch
and cause the thing to come apart. Of course, you can fairly safely sand near edges
so long as the rotation of the tool goes out or away from the edge.
Second is that I recommend sanding for no more than a second at a time; use a
touch-and-go method. This will prevent anything over heating due to friction.
You could otherwise just keep the bit moving along the surface so that it's never in
contact with the same spot for very long.
Ideally you'd have some sort of flexshaft to use. The low profile of the flexshaft will
allow the bit to be parallel and flush against the surface at all times. No such luck
with a bulky dremel or some such thing; it's likely that you won't be able to get the bit
parallel to the surface at all times. This is why I told you to have abit of the roll protrude
past the top of the drum. This part (unless you used some thick tape and sandpaper) should
be rather flexible and allow you to gently press the bit against a surface at an angle.
It also doesn't sand as vigorously as if you were to have the bit flush against the surface
either.
The angledness is as illustrated in my super fantastic diagram.
I'll typically use 2 or 3 rolls for each face of a 5/8 sized razor blade. They're really easy to make and take no more than a minute to do so. The cost of making these things greatly outweighs the effort required in sanding entirely by hand. Also, if one end becomes used up, just loosen the drum, slide off the roll and put it back on the other way around.
There is still one caveat. Due to the speed at which these things work paired with the small surface area they cover. You may find that the finish is a little uneven. Used properly, such an effect is virtually unnoticeable in normal indoor lighting. However, under bright light, it may show. To counteract this is quite simple. When sanding is complete, sand once more over the blade by hand.
Well that's it, can't think of anything else to say. except visit the straight razor place :)
-Tox|k