Air power file conversion to 12 volt.

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I bought an air belt grinder a while back which proved a little too air hungry for my compressor, so, rather than buy a bigger compressor I converted it to run off 12 volts.

The motor came from ebay as a 12 volt cordless drill motor spinning at 5000 rpm. I removed the air motor and as luck had it the 12 volt motor fitted perfectly in the grinder housing. I also turned up a 12 mm bush with a 3mm hole to fit over the motor's shaft and shrunk fit that into the belt drum, constructed a handle from 22 mm tube and inserted a switch in it. To protect the motor I turned down a PVC pip fitting and heat shrunk it over the motor leaving an air gap to coincide with the motors vents, Sikaflexed an end cap in place and cut some grooves under the cover to aid cooling.
The grinder works great and is certainly better than forking out $300 for a Makita belt grinder. some pics and a video:






I am glad you posted this, I have a belt sander identical to yours that the air motor no longer works, You gave me a good idea to put it back into commission.

Very nice too! I have a old B&D powerfile, I used to use it for finishing the recess for mortise locks in metal doors. Apart from a hand file (which is slow going) it's the only tool for jobs like that. I will look out for an air powered belt sander to convert.
I also have a B&D power file. Whilst they are good, the drum came off mine not long after i bought it so I had to turn up a new one using delrin. I've also found the belt very small and so it wears rather rapidly and breaks often.
th62, how old is it? Mine must be 30 or more years old, dark grey case. I bought a new one a while ago, made by B&D but not the same and a nice orange color scheme, I didn't much care for it so I gave it to a friend. I used to buy B&D drills when they had metal cases, they usually lasted a year or so. The plastic cased ones only lasted a week or two so I stopped using B&D stuff. I made an exception with the Powerfile because I couldn't find a similar tool anywhere else. The belts used to be available in 1/4" and 1/2" widths and with a choice of aluminum oxide or silicon carbide grit, I mostly used the silicon carbide belts. I haven't bought any for a while so I'm not sure what's available now.
I've been looking for an electric power file without much success in the affordable range (for a hobby shop).
Then I came across an angle grinder attachment on BangGood:
This turned out to be surprisingly usable.
It didn't fit any of my 4" grinders (all too old), but I was able to bore and internal thread one half of the drive pulley M14x2, the standard thread on all my 5" angle grinders. I have fitted it to my cordless 5" angle grinder (9000rpm) and it really works very well.
And at US$22 that is a bargain! Spare/different belts are also cheap at about 44 cents each:
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