I went looking at sanders today, but left after not knowing if a Dual action air sander will work the same as an electric random orbit sander. I was looking at the Dewalt electric, random orbit with the air ports in the backing pad to draw the dust out into the small bag. I would usally opt for air, but my compressor is only a 3 hp, and the CH Dual action required 13 cfm to run it. (My compressor would certianly be wheezing)

Would this work the same?

Yes, they produce virtually the same patternless finish which is desirable. The electric machine just does the same thing with a little different mechanism. The D/A has the option of locking the orbital swivel so it can also be used as a straight grinder, thus the dual action moniker.

3HP is just too small to support most useful air tools. D/A sanders, paint guns, even air driven orbital sanders (look just like the electric ones but air driven - I like it better than the D/A and electric orbital on wood working projects), etc. all require at least a 5hp compressor with at least 10cfm @ 90psig. My 5HP unit will run full time w/ my D/A but keeps up OK.

I once used a B&D orbital on my Camaro many moons ago and boy was that a mistake. I was trying to strip the old paint off and the courser grit left nice little circles in the metal that were really deep. I don't know if that is the same as a random orbit but I'll never use one on metal again. I plan on getting a DA soon, much better.

What I have run into on the electric sanders is that the ones I have used all had a very short stroke or in the case of orbital, a small circular pattern. Basically, compared to a good air powered tool, they just sort of buzzed and did'nt do much sanding. When I switched to an air powered DA the difference was amazing and there was just no comparison to the amount of work accomplished in the same amount of time. These were Craftsman and B&D and are the only brands I tried so there may be some better ones out there but I would recommend trying out the model you are considering first to make sure it will do the job for you, I was really disapointed with the ones I tried.

Thanks guys.....sounds like I need a bigger compressor then. I dont want to mess with electric ones if thats the case

I've had an electric random orbit sander for maybe 8 years. I didn't buy it with bodywork in mind but it does a fairly decent job anyway. For woodworking it's fine with 36 grit but i don't use rougher than 60 for bodywork. It has held up great though. I burned up 2 6/7" sanders and a orbital sander in the same day. Only the RA survived.

An orbital (square) is more aggressive than the RA, a belt sander even more so.
If i'm sanding filler i get it close with the RA and finish with a block. The block feathers better for me.

If my compressor would support a DA i'd have that and use them like this:
Bodywork=DA
Woodwork=RA

hope this of use