Well, any machine is only as accurate as its setup be it a sander, router, or saw (table, band, scroll) even the less expensive tools can be adjusted to make square cuts if they are carefully used. What I'm not sure of is what you mean by corner, are you talking about making the edges square with the surfaces, or the corners of the square? Any of the tools mentioned can be made to produce square edges or corners, it just depends on how you adjust it before you start. I know people with the best equipment that can barely build things of crate quality, I also know people that do exquiste work with low cost and minimal equipment.

Now before the flame job about "NEVER BUY CHEAP TOOLS!!!!" You have to decide what you're willing to pay and how much you'll actually use it. I have some very good equipment that hardly gets used, so basically I wasted some money. I have less expensive equipment that I do fine work on because I just can't justify the high price of the equipment I'd like to have. Its not the tool that necessarily assures quality, its the guy using it and his ablility properly adjust and use it.

All that said, a 10 or 12 inch disc sander is probably your best bet, but I've made sanders using a piece of old Formica counter top and a piece of 1/2" aluminum angle I got at Home Depot or even just some scrap wood. I use adhesive backed sandpaper I buy for my T bar sanders. At the corners you'll see I relieved them so the sanding dust will clear the part being sanded.

Well Gene, many guys here and many techniques, myself, if I were building such a fixture, would use a disc sander, carefully adjusted to produce a square corner. On the other hand, a well adjusted table saw could cut you long pieces that you could then slice off into jig uprights. Watch for a while and see what the other guys suggest and pick the one you feel most confident in. In the end, there's no necessarily right or wrong way to do it as long as you get the result you're looking for.

Looking to buy an "ACCURATE" sanding device that would yield absolute accurate 90 degree corners (as in a 6 inch
square piece of 1/8 inch plywood) - hand held device or a super accurate disc sander ?  ...... what are you using ?
Thanks in advance.
    Geno

EDIT:  Sorry, I did something wrong.   The photos all appear at the bottom rather than being inserted into the text.


Gene,

It's a little unclear as to what you are trying to accomplish.  It sounds like you would like to construct a fuselage jig, and fabricate the parts yourself.  In my shop, I have a combination 6" disc and  3" belt sander.  The disc sander, with careful use, can create the final dimension on model parts that exceed what our requirements are.  It's probably the second most used tool in the shop.  

In the first photo, I created a new table base for the disc sander, using a small piece of melamine board.   A stringer was epoxied to the bottom of the base to keep it in a constant position.  The melamine table does two things for you....it gives you a very smooth surface to work from, and brings the point of the sanding above the center of the disc, where no sanding takes place.  This allows one to use the full 6" of the disc surface, realizing of course that the right hand portion will try to lift your work up from the table, so materials have to be held securely, cuts have to be made slowly, and the sandpaper has to be sharp.



Now with the table located on the original surface, you can made a guide which will be an accurate 90 degrees to the disc.  I was only making a weight box in this photo, so extreme accuracy wasn't needed.  You can use a large piece of wood as the guide, and use more clamps to insure that it doesn't move after you have established the 90 degree angle.



As you can see in the third photo, I was construction a fuselage jig.  The accuracy of all of those parts was finalized using the setup on the disc sander.




And the last photo shows the completed fuselage jig, with the accuracy of the "barn doors" established with careful setup and use of the disc sander.   This simple tool can easily fabricate dimensional parts that exceed what is needed for our balsa and plywood models and the supporting tools like this fuselage jig.



I hope this is what you were looked for.   If not, I just wasted a half hour+ typing when I could have been in the shop doing some sanding of parts.    :-)

Lets us know how you make out with your project.

Cheers.

Warren Wagner

Me too, Warren, so ya didn't waste your time as far as Randy and I are concerned.

I built the same fuse jig.  Did not have to use a sander to get the parts square.  By keeping your fence and miter guage properly aligned, the parts are square right off the table saw.