I have an inexpensive no-name brand belt/disc sander combo.  I like it and use it constantly (not only for model building).  Maybe the best way to help is to point out some of the things I don't like about mine.  Mine is 6" diameter and most of the time I wish it was larger.  If you use a support table you can only use 1/2 the diameter, 3" ain't much.  Mine also has a guard around the outside edge.  It can get in the way if you have an inside corner or radius.  Make sure you get one that has a dust collector/shop vac connection.

Paul

I have a smaller version of the one shown above ( 1" belt and 5" disk) and wish I have bought a stand alone 8" disk sander 

The Grizzy tool is so so, I use it a lot BUT I am not a fan of the tables of these smaller tools as they are a royal PITA to get exactly 90 degrees and STAY there

Same with the version from Harbor Freight...both very useful tools but Chinese quality of hardware, tables, and fences suck for precision work

Now if you want to stick on a 80 grit disk-- they will turn most balsa to dust in 0.9 seconds....Grin

I plan on adding a 8 or 10 inch disk sander to my shop this year

Power tools just help me make mistakes faster.  For critical jobs I use hand tools, because it helps my poor slow brain keep up with my nimble fingers.

I am not sure what I was thinking when I bought this sucker, I guess I was feeling super studly at the time, heh heh. It's big, it's heavy, and it is absolutely awesome! It will make balsa disappear at an alarming rate!

Yes, I have free handed roughing out wingtips with it, but...

All I can say is, when holding small pieces up close, hold on to them tight, and keep one side down against the bed tight, because if it gets it out of your grip, it's going flying, and FAST, like a bullet!

Hopefully not through the wing of another plane or something valuable across the shop.

I am thinking I would like to try it with my variac in front of the plug, or getting an actual speed controller for it... one of these days.

     That's a useful size but, as you note the direct drive versions are WAY too fast for wood processing. Probably 1725 RPM, possibly 3450 since its appears to be an AC synchronous motor. Putting a variac on the front probably won't do anything to slow it down no-load - it might just burn up the start windings.

    I think you need a good-sized disc but at relatively low RPM. Otherwise, for wood, it just burns the wood on contact. My dad made one with about an 18" disc with with a 1/2 horse motor and it just flambe'd everything that touched it.  It *was* really fast and you could cause the lights to dim if you really forced it.

 I changed it to run on separate shaft, driven by a v-belt reduction drive. It was something like 4:1 reduction, and then it worked very well, and was ver controllable.

      Brett

I have an old 10" Black and Decker combo belt disc, a 4" Jarmac  and a Foremost miter sander. The B&D and the Foremost get the the most use.

Norms 2 cents

Larry,

Have you tried these?  http://www.olsonsaw.net/scrollsanders.html  Sanding belts for your scroll saw.  Indispensible for doing the inside of that big hole in a profile fuse to fit the wing.  If you have a variable speed saw you can slow it right down for fine detail work.

Paul

    Hello George:

    May I make a few suggestions.

    I use a disk sander that is is 9.5" in diameter and powered bu a 1/3 h.p. motor. This is an old washing machine motor that turns the disk at 1725 rpm.  I have used it for many years on both hard and soft woods with 80-100 grit paper disks attached.  Never had any problems using it in this manner

     Kindly permit me to make a few suggestions:

     Look for an older American made machine like Oliver, Rockwell. DeWalt Milwaukee etc. and other machines that have been made from CAST IRON.  These are great machines that will last for many many years and do very accurate work.  Where does on find these oldies? Look on line,local newspapers,Craigs List etc.  Be prepared to travel and pay a bit more but you will get much more than what what you can buy that is presently made today.  Avoid the imported stuff!!!!  Oh yes, a dust collector connection is a great feature.  Often times the seller will throw in additional items that are great to have.  Keep looking for quality machines.

      I was educated with a sander that had about a 30" disk powered by a 7.5 hp motor.  One could feed a 2x4 into it and it would reduce the 2x4 to sanding dust a about as fast as one could feed the monster! Of course this was done when the teacher had left the building! I saw a guy get his hand caught between the disk and the table while doing something very stupid.  All of his fingers were then the same length!  The teacher warned us not to %*$# with this machine!

     Buy quality! You only cry once!
                           
                                                                      Good luck,

                                                                      Frank McCune