I made my first Dremel powered belt sander more than 2 years ago.
It works really well with making smaller parts, crafting, model making etc..
Hardest part was to find good solution for the pulley.
It needs to be light weighted, but still strong enough.
3 D-printed pulley "worked" but it had no enough friction.. also, i wanted to find diy solution.
Step 1: Materials and Tools..
Material list is very short.
Rubber plug like this:
Dremel drum sander:
Drill and drill bits sized 7mm (Little over 1/4 Inch)
and 12mm (Just short of 1/2 Inch)
Chart to millimeters to inches conversion:
Vise, or clamp.
Sanding paper. ( 40 or 60 grit ) Fine paper melts rubber easily.
Step 2: Getting Started..
First, and most important thing is to measure and mark center point to the rubber plug.
I had washers that we're same sized with the plug i used. I used washer as a template.
If you don't have center finder? Easy solution is to draw similar sized circle to the paper with compass.
Cut it out and use as a template.
Then drill 7mm hole trough the rubber plug.
And 12mm hole to 15mm deep.
Then press sanding drum inside the plug in vise. Or with clamp.
Try to get even pressure. And notice that stem of the sanding drum comes out from the backside.
Use something with suitable hole behind the rubber plug.
If fitting seems too tight, then gently remove more material with 12mm drill. Just re-drill 15mm deep hole.
These kind of plugs are somewhat soft, and some drill bits are duller, or sharper than others..
Step 3: Installing..
Idea is simple..
7mm hole fits tightly around dremels collet nut.
Open collet nut.
Guide stem of the sanding drum inside the collet.
Press rubber plug so far as it goes.
Finally tighten collet nut and sanding drum.
Connection is strong enough without glue.
But if you want to secure the connection, you can apply rubber glue between plug and sanding drum.
Pulley gets support from the sanding drum, and collet nut. This makes it strong.
Step 4: Shaping and Using..
I shaped pulley to barrel shape. That keeps belt on its place.
I clamped piece of 40 grit sanding paper to my worktable.
And gently pressed spinning plug against the paper.
Its better to avoid sanding at the same spot more that couple seconds. Rubber starts melt and smell very easily.
If it happens that hole on the pulley is of centered.
Then its somewhat impossible to sand it round by holding dremel on your hand.
Then, clamp dremel firmy above the table, leaving enough gap between the pulley and table.
Use sanding pad as a guide, and keep it pressed against table.
Then slowly move sanding pad against pulley, and sand it to desired shape and size.
Plug that i used was originally with little too big diameter.
I sanded the shape so that its about 30mm from the middle and 26 from the edges.
My opinion is that 30mm is the largest diameter that can be used. Smaller is better.
Dremel is made to be use rather higher rpm, it doesn't have much torque.
I have used my sander with 8200, 8220, 3000, 4000 and 4300 models.
My conclusion is that, cordless models and 3000 models work nicely. No heating problems.
4000 and 4300 models have "Electronic feedback for enhanced torque and performance"
That ingreases torque with lower rpm, but makes motor run much hotter.
Specially with these models, you should use pulley with smaller diameter, and use dremel with higher rpm. (20-25mm)
Otherwise.. i haven't noticed any problems with my dremel belt sander.. and i have used it very much.
I hope you find this helpfull, if you have been planning something like this.
Thanks for watching!