Sounds like an interesting solution. Have never thought of that,
nor seen anyone else showing this. As an engineer, Andrew, I am
semi-awed at the problem solving that you come up with. My mind
does not think as creatively as yours does.
Ditto. Repurposing rocks! However, one question that comes to mind
is whether you can actually obtain a toothbrush that moves the way
you want. Most of the inexpensive electric brushes I know of are
rotary; presumably you're not going to use an $80-plus SoniCare brush
or such for this, right?
Also, I don't know exactly what you are trying to sand, but I've
been wrestling over the past year with the problem of sanding in
small spaces, and have found a couple of tools that work well for me.
The first, which is good for crevices that are only accessible from
one side, is these little things that might be called "abrasive
points" (as labeled at my local jewelry supply store, where I get
them) or "polishing pins," as in the following listing:
The ones I get look like the pencil-shaped diamond-impregnated ones
that Rio Grande has, but come in different colors and are much
cheaper. And I don't know how well they would work with a Dremel--the
weight of the tool and the lack of precise speed control (as compared
to a flexshaft tool) could make it challenging to use them--since
they break easily and can create unwanted ripples if you press too
hard or too long in one spot.
The other thing I'm using is a Flexi-File. This one is good for
sanding the insides of saw pierces, where you have access from two
sides. It's a springy aluminum frame that holds a thin abrasive
strip. You start with the strip attached to one arm of the frame, and
just as you would feed a saw blade through a drill hole to pierce
sheet metal, you feed it through the hole and attach it to the other
arm of the frame. Then you can hold the workpiece firmly with one
hand and sand with the other. I find that when it's possible to use
this technique, it turns out to be easier than any mechanized
solution I know of.
If you do use a Flexi-File (or something like it that you make
yourself), I'd suggest you not buy the abrasive strips made for it.
In my opinion they're not suitable for metalsmithing: they break too
easily, and the grit wears out too fast. I have been making my own
strips out of 3M Microfinishing Film. Although gluing the loops at
the ends is a bit of a challenge, when I can get the glue to stick
they work very well, and are a lot cheaper than the Flexi-File
company's pre-made ones.
Whichever technique(s) you end up with, best of luck!
Studio Yanagi | Original Art Jewelry