Has anyone here used these? I guess since they are gear driven they don't bog down like a regular DA. I saw a picture of one (TP Tools, I think) and with an 8" 40 grit disc I would think it would make quick work of old paint and rust.

I had a chance to try out a National Detroit model at a manufacturing demo once. The thing was aggressive as hell. The demo guy put some 40 grit paper on, started it, and stood on it. You didn't even hear it sound much differently with that much weight on it. Any gear drive model is not going to be cheap but it is definitely powerful.

After I posted my question I went back to look, and I had seen the tool on the TP website. It is about $100 or so, and to me doesn't seem like a whole lot of money if it does what I'm looking for. I like the idea of a DA type tool ( easier to control at lower RPM) than a grinder. I also think holding a DA for extended periods of time would be easier than a grinder.

For gear drive that's cheap.... National Detroit models were at least double or even triple that depending on the model. Those models were all easy to move around with....with 40 grit discs I don't think there's much out there you couldn't get off pretty quickly. Just watch out for CFM consumption. A lot of these more powerful machines can still suck down a lot of CFM.
Hmm... went and looked up that unit. Not bad 7 cfm with 850 rpm operating speed. That's about half the air demand of a typical da and that speed shouldn't overheat the paint as you cut with it.

How does it work differently than a non gear driven DA? Obviously a normal DA bogs down when pressed too hard, so this one doesn't? So if you have the required CFM, or more, it just keeps cutting? Seems like the perfect tool for fast, controlled paint and rust removal.

From what I've "seen" of the guts of most units like this they have an additional "transmission" which works much like linear actuators work and high torque car starters. The air driven high speed gears are reduced down to slower speed/higher torque gears. This limits the overall speed (notice most are under 1000 rpm) but makes the action more unstoppable. Regular da and orbital sanders are pretty simple inside with air chamber/piston/ratchet, etc. type drive going only at full speed.

I had one HUGE air hog and the disc turns real slow better off to buy an 8" angle sander its still a air hug but it will sand much faster an easier I loaned my mud hog to a friend and never got it back , best thing I ever did.
Jay D.

badsix wrote:I had one HUGE air hog and the disc turns real slow better off to buy an 8" angle sander its still a air hug but it will sand much faster an easier I loaned my mud hog to a friend and never got it back , best thing I ever did.
Jay D.

Do you have a specific make/model of the air angle sander you're talking about? Thanks.

Go to Grainger its item NO. 5KB20. I think you can get them a lot cheaper, try Horrible Freight or EBay. I use an 8" foam Velcro disc then use 8" sanding discs with the Velcro you can peal them off and reuse them.
Jay D.