Preventing Burn Marks on a Drum Sander
My drum sander starts out working well, but after I use it for even a short time, a burn streak appears in the sandpaper, and eventually the wood. I'm only taking off 1⁄64 " at a time, as the manufacturer suggests. But, regardless of grit or wood type, it always happens. How do I correct this?
—Claude VanVooren, Louisville, Ky.
Claude, the usual suspects for burning are improper depth of cut or feed rate for the grit being used, loaded abrasives, and overlap in your abrasive strip, all of which build up heat. Here are a few things you can do to counteract the excessive heat that causes burn marks:
Finer grits require a reduced depth of cut. If you need to remove more material, switch to a coarser grit. Also, at slow feed rates, finer grits could start to burnish the wood, causing heat buildup. Try speeding the feed rate a bit when using finer grits.
Sawdust-loaded abrasives generate hot spots which will quickly lead to burning. Clean the paper often with a gum-rubber abrasive cleaner, and connect a dust collector to reduce the chances of loading.
Finally, make sure that your abrasive strip isn't overlapping. A new belt will often stretch some as it heats up, causing slack that leads to overlapping. After several passes on a new belt, re-tension the belt to work out any slack.