Sanding inside pockets, fast

Question

I have a sanding job that requires sanding inside many small pockets - a few thousand. I tested the speed I could get doing it by hand, and it might be as much of a week of non-stop work. It's time for power tools.

What tools are there for sanding inside small pockets, quickly? The pockets are slightly larger than 1" x 1", and 1" deep, plus a 45º slope extending out one side, for the smallest pockets. There are larger pockets in the job, also. Heck, what tools are there overall, for sanding inside pockets?

I know some people use emery boards, others use sanding sticks, some use abrasive nylon rotary tool wheels. What all options are out there?

Answer 1

Personally I would have aimed for an internal milled finish that didn't require sanding, that's the ideal. Obviously too late for that now and I don't know if that's possible with the Shopbot and the bit you were using anyway.

Instead of sanding to smooth the rough surfaces I recommend scraping. It will be faster, give a better finish and is more controllable, with much less chance of accidentally rounding edges.

For the flats the ideal tool is a bar scraper or scraping chisel. These are one of the tools traditionally used in planemaking for flattening the beds on wooden planes. These beds were never sanded as far as I'm aware and the finish is as smooth as you could ask for.

You can make one yourself from a beater chisel, just grind the end flat:

Here's the same thing explained in Classic Hand Tools by Garrett Hack:

As you can see from the old cast-steel chisel to the right in the photo above you don't have to start with a chisel that has flat sides (a firmer or registered mortise chisel), a bevel-edge chisel will work fine.

Ideally a tool like this would be specially heat-treated to make it a dedicated scraper (the tip being made ultra-hard) but a chisel of standard hardness is more than adequate for limited use.

Answer 2

Bandfile Belt Sander

Not advocating any particular product but showing the product picture

^{Image from Harbour Frieght}

That should help you get into the tight spots quickly and efficiently. Only issue would be the corners. For that I would use a small rotary tool. Hopefully you have one that will fit in there. Mine is a little too clunky to get into a hole that small. They make all sort of attachments for those things so a sanding ball might work just as well to conform to the shapes you have.

Answer 3

You could use a small-diameter sanding drum on the drill press, similar to that pictured below.

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You would have to lower/raise the drill press table each time you move to a different pocket, but that's not too big of a hassle.

It's hard to tell by your pictures, but the sides of the pockets look straight, so this should work for the sides.

The bottoms, however, you'll need a different solution.