next »

[Robert Yarger]

I cut all pieces for my next box and am now in the process of assembling them.  Cocobolo is not the worst wood for warping that I have run across by any means, but some of the panel pieces I cut have a very slight bend to them.  In most projects, it would not even be an issue, but these particular pieces have to fit together perfectly.  Normally, I would just apply glue and clamp them into place and once dried the slight warp would be fixed by the gluing, but on this application, gluing and clamping would offset the exact fittings of other pieces.

My current approach is to stick a piece of paper under the slight bulge, lay it on a flat board surface and clamp it down for a day so that I force a bend in the opposite direction.  If anyone else has a different technique, I would love to hear about it.

[Canuck]

I've stayed away from Cocobolo because of it's oily nature but have made some pens with it   Robert my big concern with your technique would be that your panels will return to their 'bowed' state eventually   Will that ultimately affect your box mechanishm?  If so maybe it's not too late to switch to another wood type   The other thing I was thinking was perhaps when you clamp the bow out you might want to exagerate the bend so that it returns to flat   I know I'm grasping at straws, just disregard, if nothing I said helps, but had to try

[Robert Yarger]

We think along the same lines as far as the overbend, but yes it is too late to cut new pieces.  Besides, it is about $100 of cocobolo that I can't use for anything else.  Scott sent me the wood for free, but I simply refuse to waste it.  I am just frugal that way.

The warp really is extremely slight, and is not on every piece.  I think that once stright, the adhesion of glue to other parts will easily keep it from warping again.  Also, it will eventually be laquered, and that would help resolve future warping problems.  In fact, I would normally just glue and clamp it without a second thought, but a clamp applys too much pressure in this particular instance and would cause other glued pieces to move before drying.

I think I will just slightly overbend them as you mentioned.  I have used that technique before with very good results.  Just wondered if any one else had a different method.  Oh, by the way, if anyone else ever has this problem and needs to bend back warped pieces, they should slighly wet both sides of the piece before clamping, and not unclamp them again until all moisture has evaoporated.         

[Canuck]

You do know that Scott has a bad history with Cocobolo, so it's likely he put a 'hex' on the wood before he sent it to you

[Scott Peterson]

The only bad history with Cocobolo is health related for me personally, nothing that has to do with the wood itself!

Sorry to hear of your troubles, Robert.  Sonds like a tricky problem - I hope your wetting and clamping technique works out.  Parafin wax is supposed to be the most effective in preventing moisture transfer between the wood and the environment.  Not sure with your application if you can coat with parafin after you get it straightened out...

The only other thought I had was somehow machining it flat after it warped.  This can be hard to do sometimes - since a planer or drum sander tends to flatten the piece during planing - especially if i the piece is thin.  However, sometimes you can find a way to support the warped piece on a sled that you run the piecte through the planer on - so that it doesn't get flattened during planing.

 

[Robert Yarger]

The clamp method seems to be working.  In the past, I have liberally rubbed pariffin on box parts and put them in the oven at 130 degress to absorb the wax, then wiped off the excess.  That method works very well, but you have to give extra attention to glue joints because glue does not stick to wax, and genrally, you have do any lacquering first or the lacquer will not stick well either.  However, the wax method does not seem to apply well to cocobolo, as they are already so oily that the wax does not absorb.  You would think as oily as they are, it would not be a problem in the first place.

Really it is not much of a problem, and the pieces seem to have strightened out and are going together quite well.  What I should have done was clamp them all flat the same day that I cut them so that they would have no where to go.

[Robert Yarger]

Scott, I will tell you the same thing that I told John Devost when it came to working with spaltled myrtle.  Both woods may be a booger to work with, but they are definately worth it in the end. 

[Eric Fuller]

I have been storing flat panels in double wrapped ziplock bags forever.  If you leave them laying around they always warp since usually one side will tend to get more moisture than another.  Just an idea to prevent the issue in the future.  I bought a big bag of surplus plastic bags and keep EVERYTHING wrapped up while work is in progress.  Never have any more warping issues.

[Robert Yarger]

An excellent idea.  I usually keep my stuff in 5 gallon square buckets with "supposedly" airproof lids.  This time I left pieces out overnight prior to a storm when I really knew better.  Some woods really don't have a problem with warp, and for some reason I just assumed that cocobolo was one of them, so I did not give it as much protection as I needed.  The leopardwood pieces I left out at the same time had no problems at all.

I have also noticed that warping can take place when you plane off one side of a board, but not the other, or when you are gluing (since glue applies moisture to only one side).

This time, I think it was not as much a humidity issue as it was the fact that I had cut a maze in only one side of the pieces.  The fiber tension on one side of the panel was then different from the other.  Humidity probably compounded this, but the minute amount of warping I had were all in the opposite direction of the maze panel side and only on the pieces that I cut the pattern into.

Still, if I had heeded your advise and just packaged the wood pieces up, I probably would not have had any problem.