Luthier Community Advice
January 9, 2011
I posted the following question on a Luthier Community Forum.
I use an 18″ Grizzly Drum Sander to thickness backs and sides. I use 100 grit paper, keep it clean, advance mere micro millimeters for each pass yet still can’t avoid burning. Any suggestions? The feed rate has been tested from slowest to fastest, yet it doesn’t seem to make a difference. The harder the wood, the more prone it is to burning. Must
I accept burning as part of the process (I can scrape it off in the end)?
- My first thought is that the belts are moving too fast. Can you adjust the speed of the belts?? I assume that the feed pressure is appropriate given that you are able to adjust the thickness w/o difficulty. 100 grit is fairly common in this application.
- Are you sanding with the grain? Sanding with the grain on high resin woods can cause burning. Try sanding at an angle against the grain. The greater the angle the better.
- I have a Performax 16-32 and found out early on that you need to use a heavy grit (80 or lower) to take the initial pass. After you have removed a bit, go to 100 or higher. This works very well for me. Also, with high resin woods, the paper will not gum up as quickly. If you try to remove the wood with a higher grit, it will burn and gum up. Use a heavy grit to remove the bulk of it, and go to a higher grit to smooth it out.
- A dust collector of adequate CFMs is a must. That would be the first thing I’d look at. You have to get the dust out of there efficiently as the sanding is happening in order to prevent clogging of the abrasive. If you have a good dust collector on there, then the problem could be the design of the sander – how well it’s designed to maximize dust removal. I have a Woodmaster, which excels in this regard.
- I use the little Performax (10-20) so I have to pass on each side to thickness a plate. I have never had a problem with burning, but I keep my sanding belt really clean (I have a sanding “eraser” next to it and use it about every 4th pass) and use a Grizzly product that comes in 10′ or 30′ rolls for about 4 bucks. It fabric backed and doesn’t loat much anyways. I get 3 out of the small one, if I’m really careful cutting. Also, when wrapping the drum I don’t go right up tight to eachother, but leave a little gap of about 3mm. I find that any dust not pulled into the hose lodges in there rather than the grit. I’ve done Sitka and Englemann spruce, and the hardwoods from mahogany to ebony, no issues. Hope this helps.
Jim on 09 Jan 2011 at 10:24 pm #
Some of these ideas seem impractical (running the material through at an angle, changing the sandpaper grit back and forth). The one idea that I’d try is the dust collection. I wonder if hooking a shop vac up to the dust port and running it during operation would help?
Jim on 09 Jan 2011 at 10:45 pm #
Misc notes.
“Feed rate too slow?”
“As for the wood burning problem, I figured out that the hollow sanding drum will eventually become loaded with dust. This dust acts like an insulator and does not allow the drum to cool properly, thus burning the wood and ruining an expensive piece of sandpaper. So now I frequently shut the sander down and blow the dust out of the drum and haven’t burnt a piece since.”
“I have been using the 1 1/2 horsepower Grizzly dust collector with my Delta
drum sander. I recently bought a much larger dust collector and discovered
that the additional air volume and static pressure the new dust collector
provided make a noticeable difference in how well the Delta drum sander
works. It picks up the sanding dust off of the drum much better, the
sandbelts are not as prone to cloging/burning, and the finished work is not
as prone to burn stripes on the work surface. The sawdust residue that the
smaller dust collector left on the work surface seems to be the cause of the
problems I have described. I would advise you to buy the largest dust
collector you can afford and to connect it up to the Delta drum sander with
the shortest hose connections you can so as to maximize dust collection
airflow around the rotating drum and work piece. The 1 1/2 hp Grizzly will
work and provide adaquate performance. I am just saying that I was suprised
at how much better the sander worked when connected to a larger dust
collector.”
http://forums.finewoodworking.com/fine-woodworking-knots/power-tools-and-machinery/scoring-drum-sander-roll
I’d work the dust collection angle, that has popped up in a couple of places.
Jim on 09 Jan 2011 at 10:48 pm #
Sorry if I’m covering ground you’ve already been over.
http://americanwoodworker.com/blogs/tips/archive/2009/11/04/7-tips-for-better-drum-sanding.aspx
Jim on 09 Jan 2011 at 10:53 pm #
And with this, I sign off. He recommends the drum sander only for finish sanding, not thickness sanding. That sounds to me like more passes, lighter passes. I’d look at the dust collection, that has to help all the way around.
http://thewoodwhisperer.com/proper-drum-sander-use/
Brian Riley on 10 Jan 2011 at 6:39 am #
Hi Steve,
We currently use a homemade sander with about an 8 inch radius on the MDF cylinder. The 18″ Grizzly that I just Googled has a much different configuration as it has a flat deck and so the paper is in contact with the wood for a longer period of time. (Don’t know if that is the same as yours.) Burning is one of many issues that have happened with our unit. We’ve felt that one can’t see or feel what is left after a cleaning so changing the paper has been our answer.
We’ve found that working with rosewood is absolutely the fastest way to use up sandpaper.
Now, if this is something that is recurring even with paper changes, I’m not sure what could be the problem. You mentionned that you only take micro depth changes, so the compression of the wood under the cylinder can’t be too high and therefore the friction created by that would be very light. So, that doesn’t leave many other factors to be creating the friction responsible for the burning.
About the other comments:
1. We do have a shop vac hooked up and it is necessary for our closed-in unit. That said, I just recently noticed that if I leave the vacuum off I can pick up some patching sawdust for later use in a real hurry. And, when we do use the vacuum at the same time, I need to plug it in to a second circuit in the house so I don’t trip the breaker and with teh incerased noise, I wear my earmuffs.
2. I really like the suggestion about leaving the gap. The sawdust needs to clear from the wood asap. But that suggestion will work with our unit and not with the Grizzly Googled.
Good luck,
BR
Jim on 10 Jan 2011 at 11:02 am #
The suggestion of the gap didn’t really register the first time through. But, it doesn’t sound unreasonable at all. Maybe that and dust collection together?
Brian Riley on 10 Jan 2011 at 2:27 pm #
I now see that you describe yours as a drum sander. BR
Brian Riley on 28 Jan 2011 at 2:52 pm #
Hi Again Steve,
Just read this in the GAL Big Red Book of American Lutherie, Volume 3 page 218. It was reprinted from GAL #31 1992. The article concerns a circular thickness sanding disk for a drill press.
Nevertheless, here’s one more idea for a solution:
“Resinous woods like cocobolo require slower speeds and lighter cuts along with an abrasive lubricant such as beeswax or dry teflon spray. Some people use a silicone spray, but this poses the potential for problems in finish application.”
I’d never heard of an abrasive lubricant, but there you go.
BR