Split Mandrel Flap Drum Problems

Hi. I was hoping that some of you guys who have been using the split mandrel and sandpaper as a flap wheel could give me some help. There doesn't seem to be much written about how to go about it. I found one piece of information that said to fold the sandpaper in half lengthwise and insert it into the slot in the mandrel. But it didn't say how long the strip should be. I started with a strip of sandpaper 1" x 4" and started on the tang of a broken blade for practice. I was using 320 grit, but it didn't really seem to be very aggressive. I put a little more downward pressure on the Dremel and I guess the sandpaper must have wrapped around the tang, because the shaft of the mandrel was bent at a 45 degree angle and vibrating like crazy. I realize (now) that the shaft was too long (1 1/8") which made it easily bent. I had the motor at its lowest rpm (5000) and had a firm grasp on the on heavily taped blade. How long should the sandpaper strip be? How much should protrude from the non-working end? Should it be spiraled around the mandrel before you begin sanding? How much pressure should be used? If you could answer any of these questions and maybe add some words of wisdom from your own experience, I know it would really help me and a few others as well. I plan to cut about 5/8" off the shaft to give it more stability. Thanks guys.

Regards - Walt
http://s464.photobucket.com/albums/r...dd/mandrel.jpg

here is what I do.. I cut a strip about two inches long and fold it up... taping the two cut ends together with some slight overlap.. for a large wedge, I'd use a final strip length after folding of about 3/4 to 1" max (for hollows I do about 1/2 of that, with a smaller width also). Also, I would never use more pressure... I actually like these because of the light pressure... the scratches are easier to take out moving from grit to grit. Also.. the tang can be a dangerous place to start (if you get on the wrong side of the dremel rotation you are done for).

Yes, that is a rubber band holding the paper in place... works like a charm, but the smaller the band the easier (less times you have to wrap it around the shank).

Maybe my pics will do a better job explaining.


Oh yeah... a flex shaft really helps for any dremel resto jobs!

Thanks for your advice. I tried your system and it worked very well except that the flaps kept tearing apart. That could be because of the brittle paper or, more likely, a heavy impatient hand. Does your flex shaft attach to your Dremel or do you have a dedicated motor for it? What speed do you normally use when you are sanding? Do you use a circular motion, go parallel to the blade or"across the grain"? I hope you don't mind me asking a lot of questions, but I do value your, or anyone else's, advice.

Regards - Walt

I'll post a tutorial with pics, and I'll send you a PM so we can do this in a way that lets you ask tons of questions

Dave