Preventing gluelines on drum sanders?

[Scott]

I ran some oak table sections through my new Performax drum sander, and after a few passes I began to get some burned grooves in my work. Dang! I then searched the archives, and learned I was not the first to discover this . . . Question: how does one prevent the buildup of glue/dust that causes the damage? Surely the commercial builders use drum/belt sanders on their glued tabletops. I was using #150 paper; would a slightly courser grit prevent the glue build-up? Will waiting a week (for the glue to fully cure) help? I used Titebond, and waited

24 hours. I also scraped all excess glue off before sanding.

I did find (after the fact) that using the rubber sandpaper cleaning stick between each pass solved the problem, but I wonder what the commercial builders do?

Thanks,

Scott

[Mike G]

If possible try not to run the glue line through the exact same spot every time.

[Preston Andreas]

With a drum sander, heat buildup causes the burning. The drum diameter is only about 5" which doesn't give the sandpaper time to cool before it is in contact with the wood again. With a belt sander, the belt has time to cool and clear the sanding dust before the same spot on the belt contacts the wood again. If you take very light passes, the finer the grit, the lighter the pass, and clean the drum off before it gets clogged, you are less likely to get burning.

On my Delta sander, with 150 grit, I take probably 1/128" off at each pass and every few minutes, I clean off the belt with one of those rubber thingees.

[Leon]

You are using a dust collector with your sander... right?

[markm]

Is that what that is? I just saw that this weekend for the first time and never associated it to glue. I cranked up the feed speed and it went away.

[bob]

I'm going to regret asking this, but what is a rubber thingy and where can I buy one?

Bob

[Doug Brown]

[Scott]

Interesting . . . I guess I'll try that next time. I suppose the faster speed prevents the glue from softening from the heat. I'll do that, plus keep the rubber cleaner thingie handy (reply to a previous question, I bought mine at Woodcraft for about $11).

But I still wonder what the commercial furniture makers do with their glued pieces; maybe feed speed is the main trick?

Cheers,

Scott

[Preston Andreas]

Actually Scott, the faster speed generates more heat and softens the glue, which leads to burning. Before I run a glue-up through the sander, I scrape off all surface glue I can get at. If you can, skew the piece slightly so the glue line doesn't line up on one spot of the drum. Also, start with

80-100 grit for the first couple of passes. The rougher grit generates less heat while you are sanding any surface glue off that you couldn't scrape off. Use the rubber thingy often. If you let sanding dust build up on the drum, it holds heat and burns itself to the drum and gives those burn marks on the wood.