Thickness sander scorching

[Stray Feathers]

I have a Delta 18-36 thickness sander which I bought used several years ago. It has been a wonder generally. But lately it has been scorching some of my wood. Rosewood (which is oily) seems the worst. I clean the sandpaper well, don't take large bites (1/16 turn on the adjustment wheel max). Belt is installed correctly. It may be worse with 120 grit (I also use 80). The 120 paper I am using most recently is Klingspor; the old 120 belts are not branded but say aluminum oxide, and are the same brick colour as the Klingspor. I have recently increased feed speed (the adjuster seems to vibrate to a slower setting). I have been thinking a slower feed would make the scorching worse but can try that. I will also try a new belt. And the Delta has two settings on the drive pulley, which has been always set at the faster speed. I can't find any information on whether a slower drum speed would reduce scorching, or anything at all on scorching. Any suggestions appreciated. Bruce W.

[tippie53]

you using too fine go to 60 or 80 turning the feed speed is also not a good idea this is a thickness sander
not a finish sander.
the finer the grit the more burning you will get and once the paper gets warm it glazes over and magnifies the problem.
how much are you trying to take off on a pass? .010 is plenty

[Stray Feathers]

Thanks John. And sure enough, after I posted, I did find some helpful stuff online, including a Dan Erlewine video that showed a) that belts can get messed up with oily wood and b) using a blade cleaning solution to clean glazed sanding belts. What I am seeing may not be the belt scorching the wood, but the heated oily residue doing it. I have not experienced this in the past, and I have done oily woods before.Your point about finer grits being worse confirms my suspicions, and yes, I do take very little off with each pass - that's partly why I couldn't understand why it was happening. But I have several things to try now.

[Bob Gleason]

Taking smaller bites is necessary in those oily woods, but also passing the wood through a second time on the same height setting can really help clean up any burn streaks. I almost always do the final pass 2 or 3 times on the same setting if I want a really smooth, even surface. You can buy belt cleaner sticks and wide cleaner boards, but they are just like just crepe rubber. If you can find an old pair of crepe rubber shoes at the thrift store, they will last for years as a belt cleaner,even if they are not your size! No matter, you will have limited success cleaning burnt, loaded belts. Go easier on the sanding, bite the bullet, and change belts more often.-Bob