Help with Cupped Bloodwood

[Raymond Fries]

I have two pieces of bloodwood that was resawn for one board. They are 3/8" thick 7" wide and 7' long. They have become cupped by about 3/16" in the center. :mad:

Any thoughts on how to flatten this wood and keep it flat?

It will not make very nice boxes in its present form.

[Mark Rios]

Does It HAVE to be 7' long? If not, cut it into shorter pieces, appropriate for the job/project and then joint and plane.

[Peter Quinn]

Does It HAVE to be 7" long? If not, cut it into shorter pieces, appropriate for the job/project and then joint and plane.

Most planers have a minimum length around 9"-12", and 12" is a thumbnail minimum on a jointer. I assume you are suggesting using hand tools?

I think you can attempt to flatten and plane with hand planes, but given 3/16" cup on a 3/8" board, you may need to get more wood. I would screw these to a wall in a prominent place as a reminder of the capricious mature of wood as a medium. Do not pass any pieces this short through or over machines.

When resawing exotics, leave room for jello, and flattening, and warping, and cupping, and release of spastic tension you weren't considering, and moisture differences, and Murphy's law, and...oh, lets face it, as wood workers we're doomed to this sort of thing.

[Ed Sallee]

I'm with Mark..... find a project that requires shorter lengths, then cut it in to shorter lengths.

[David DeCristoforo]

Try wetting the "bottom" (as oriented in your picture) and then putting the pieces in the sun or heating them with a heat gun. The idea is to swell the fibers on the concave side. If possible overcorrect a bit then clamp the pieces between cauls to keep them flat until they dry. May work, may not

[Eric Larsen]

Why fight it? Make a curved box!

[Mark Rios]

Most planers have a minimum length around 9"-12", and 12" is a thumbnail minimum on a jointer. I assume you are suggesting using hand tools?

I think you can attempt to flatten and plane with hand planes, but given 3/16" cup on a 3/8" board, you may need to get more wood. I would screw these to a wall in a prominent place as a reminder of the capricious mature of wood as a medium. Do not pass any pieces this short through or over machines.

When resawing exotics, leave room for jello, and flattening, and warping, and cupping, and release of spastic tension you weren't considering, and moisture differences, and Murphy's law, and...oh, lets face it, as wood workers we're doomed to this sort of thing.



Sorry, I meant 7'. I've changed it in my first post. thanks

[Narayan Nayar]

Forgive me if I've got something wrong here, but cutting the board into shorter pieces isn't going to help with the cupping problem.

Raymond, you're not going to get that cup out across the width of the board by jointing and planing. You'll be left with a 7' long toothpick.

You can, however, rip it along its length once or twice. you'll have a smaller radius cup to deal with. I don't know what thickness you'll be left with after flattening the resulting pieces, but you might glue those up and get your box sides that way if the grain patterns match alright.

I definitely wouldn't throw the board away (maybe that's my problem). There's a lot of wood in there that could be used as detailing pieces or as a contrasting line in a glued up panel or something like that. Speaking of which, you can also use this situation creatively--rip the bloodwood into 2" strips, joint a square edge on them, then run a strip of some contrasting wood like birch or a dark wood like ebony and get your box sides that way. Not the same look as a solid piece of wood, I understand, but you can still get a box out of it.

[Frank Drew]

Don't be surprised -- this is a very common occurrence when resawing. You've got to have extra thickness for insurance because as often as not the resawn boards cup to some extent.

[Mark Rios]

Forgive me if I've got something wrong here, but cutting the board into shorter pieces isn't going to help with the cupping problem.

Raymond, you're not going to get that cup out across the width of the board by jointing and planing. You'll be left with a 7' long toothpick.

You can, however, rip it along its length once or twice. you'll have a smaller radius cup to deal with. I don't know what thickness you'll be left with after flattening the resulting pieces, but you might glue those up and get your box sides that way if the grain patterns match alright.

I definitely wouldn't throw the board away (maybe that's my problem). There's a lot of wood in there that could be used as detailing pieces or as a contrasting line in a glued up panel or something like that. Speaking of which, you can also use this situation creatively--rip the bloodwood into 2" strips, joint a square edge on them, then run a strip of some contrasting wood like birch or a dark wood like ebony and get your box sides that way. Not the same look as a solid piece of wood, I understand, but you can still get a box out of it.

Aaahhh, your right, sorry. I thought I was looking at the side of the board, the edge grain. I see now that the pic is of the end grain. (I am a bonehead :D) Therefore, as you mention, ripping would be my suggestion as well.

[Raymond Fries]

There is a lot of great ideas here and I will probably try a few different ones to see what works the best.

This was my first resawn wood that layed around for a while and I did not expect this. I had a board of canary wood the same size that was resawn the same time as the bloodwood. I just used it up first. I suppose the canarywood could have cupped just like the bloodwood given some time.

Hopefully it will flatten for the original plan (Thanks David)
Hmmm - Curved might be interesting.
Hmmm - Mixed colors might be nice as well

OK now there is overchoice - Thanks alot! LOL

I'll post some pics of what I do.

[Peter Quinn]

Wow, I'm finally seeing that picture right, and have my glasses on, 7' length, not 7"! Can you cross cut your parts a bit over on length (or the length of several if the parts are short), rip each piece in thirds on the BS, joint the edges and reglue then flatten? Might have the minimal impact on the grain lines. You will lose a bit of of thickness but may still be thick enough for a delicate box.

[Mark Ball]

If it was mine, instead of just trashing it, maybe cut the 7' into two 3', face glue them together with the cups facing each other, and plane down. I know, you now only have half the material, but better than none.

[Karl Sudar]

Bloodwood is notorious for being unstable, especially when cut to thin and wide dimensions. If it was quartersawn, you might have a chance, but 7" is pretty wide for that thickness. I would think a 3/8" x 7" wide board has about the same chance of staying flat as a 3/4" x 14" wide board. Most of us would get the 14" by edge gluing 2 or 3 boards.

[jim gossage]

This is just thinking outside of the "box" (bad pun - couldn't resist), and might not even work, but if the flattening attempt fails, you could make veneer. face glue your bloodwood to a sacrificial board of the same length and width, but about 1.5-2" thick. this will flatten your board. then, resaw it into 2 or 3 slices of 1/32-1/16" veneer. i wouldn't think that cupping would matter on veneer that thin.

[Ralph Barhorst]

Take advantage of the curved wood by making a round box.:)

[Per Swenson]

Wow,

Didn't anybody listen to David D'C?
This method works, but I would like to add a few things.
Don't use a heat gun, it's to localized.
Saw horses in the Sun. (Sound like a Hemingway novel?)
This process happens fast, so don't walk away.
Wood has a memory, so we apply a little amnesia.
Once the board is decupped, (No misogynistic jokes fellas)
Seal it temporarily with shellac.
I may not be quite able to dress my self, but I ain't half bad at dressin lumber.

Per