Official Luthiers Forum!

Hey guys

I am having problems thicknessing a set of Cocobolo with my Delta drum sander. The sandpaper clogs up within a few runs, so much that it becomes totally unusable.

I have heard and read about luthiers who use acetone on Cocobolo to remove the oils. Any thoughts on that?

Any other tips on this subject would be appreciated.

Cheers

Pat

I might be a bit misguided here, but wouldn't acetone just cause cocobolo to become more oily?

If all else fails, you can always plane and scrape it.

There is no way to stop this, but you can slow it down.

1) 80 grit or coarser. Best is use 60, then take a final pass with 80.
2) put the drum on its slower speed
3) put the feed on its fastest speed
4) take very light cuts--on the order of 1/8 of a turn of the wheel or less. More like 1/12 of a turn.
5) If at all possible, do not feed with the grain parallel to the direction the sandpaper is cutting. Any amount of crossing the grain with the cut helps.

6) Unless you have LOTS more time than money, throw away the clogged wraps and put on fresh ones.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

The paper can be saved by removing it, spraying it with oven cleaner allow to set for a couple hours. then take a wire brush and scrub it lightly, rinse well with water. stretch out and allow to dry out.

As far as how to thickness. Howard is dead on here light cuts slower drum speed if you have that option and faster feed rate. The real key here to remember is light cuts. The heaver the cut the more the resin build up per pass. this is good thumb rule for any resinous wood or easy wood to heat score like Maple.

Anyone ever tried any of that non-silicone dry spay lube on the drum? It works to keep Cocobolo from gumming up bandsaw blades.

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http://www.chassonguitars.com

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Everything already said. It's a stinker.
I use an abrasive cleaning stick (looks like a hush puppy shoe sole) with the hood open and drum spinning on my Woodmaster. Probably violates every known safety rule on the subject... I usually have to clean after every pass.
-C

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Freeborn Guitars
and home of BeauGuard©

I build almost exclusively with coco, and as others have said nothing can do about the clog thing. I can get 4-6 full sets done on a strip of abrasive. I do start with 60 and go down to 120 and use the eraser thing about every 3-4 passes. I use a griz 18" open end drum sander and Griz abrasive (mostly because of cog problem) It is cheap and can get I think 3 strips off of a roll and at about if remember right $3.50 a roll cheaper than using expensive stuff. Great wood, just at times a pain in the rear. I change it to do the tops, might not have to, but do.

They make those in sheet form for drum sanders Woodcraft, Rockler and I think Grissly caries them. Just run it through like a pice of material but at slower speed. However Coco's resin is hard to remove with these. In perticularly if it got hot and cooled down. Then it is like cured epoxy

I know this sounds odd, but I use Pam (vegetable oil spray) on my Delta drum sander. In combination with a light cut and fast feed, it does wonders. (I also tried extra-virgin olive oil in a pump sprayer, but my wife vetoed any further experimentation!) In the past, cocobolo would sometimes ruin the sandpaper before I got a single set to thickness. Now the sandpaper lasts until the abrasive wears out. I spray lightly and check regularly for resin accumulation. As soon as I see any accumulation, I use a crepe (rubber, not pancakes) cleaner on the drum and spray it again.

Sometimes on the first pass after oiling, there wil be some signs of oil on the wood, but by the second pass it is gone. I've not had any trouble with finishing (z-poxy or nitrocellulose lacquer).

Stan

Thanks guys

I will try just about anything before I revert to the hand plane and scraper. This is why I spent $1500 on a drum sander in the first place!!!

I use 100 grit. I will try it with 60 and 80.

The Pam and spray lube are worth a try also. I am already using the rubber thing, but it can only remove so much.

I'll let you guys know how it turns out.

Cheers

Pat

Like I said It wont help while you using it but once through do the oven cleaner and wire brush thing and you will get more use from the wrap. But don't do it on the drum

You need to add a lubricant. I have the same problem when I sand Coco. I wet the wood with a light coat of mineral spirts before each feed. This will keep you paper from clogging. I've done it for years without a problem. Only issue is the dust collection. I usually add the dust to my garden... but if I use Mineral Spirts I bag it and throw it away.

I used to sand floors in my youth... and this was a constant problem (clogged paper) on old "gummy" varnish finishes. We used 4 grit paper (yes I said 4). Even that would gum up and clog. Someone told use to wipe the floor with turpintine and then try sanding. Works like a charm.

When I saw my drum sander clogging with Coco I knew exactly what to try. It works! Been doing it for years. Any oil will work and I suspect PAM is less toxic.

Great suggestions guys - I've also been having this problem, with ziricote as well.

What I've done is to revert to using a thickness planer - I run the coco (or ziricote) through on a planed sled that has 100-grit paper stuck down on top. With sharp knives and a good setup I can get almost as much fine adjustment to the thickness as I can with a drum sander, and the surface is almost as good as scraper quality. I've taken stuff down to 0.080" with no tearout, no problems.

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The member formerly known as erikbojerik....