Cupping problem

[myxpykalix]

This started out as 1" thick walnut and was kiln dried but like in Randalls other thread I wasn't looking for an exotic fix like carbon fiber rods but something simple.

Am i asking for disaster if i just make a shallow kerf cut on the bottom and try to push it down flat?
I thought along with that i might make a rail and stile frame for it to help keep it flat?
It is going to be a lid for a jewely box.

Also i thought of chucking it and starting over and doing it in mdf...any thought?

6680

[bcondon]

It will not flatten.

I have had luck screwing in the outside corners but leave the cup in it and take a surface planing bit and take a little off to get rid of the center cup. There is now no stress in the board. Flip over and flatten the entire bottom.. you probably just lost 2/5 of the board though...
but in the end, you will have a board that is flat on both sides and without inner stress.

[ghostcreek]

My only success with these issues have been:
1) Rip cut the board, glue-up panel, Plane. But you lose thickness and any grain figure.
2) Using the spoilboard cutter on the Bot, try flattening the cup, but like Bob said, you will lose a lot of material.
I too would like a method other then what has worked for me. I hate loosing a grain figure, hate to waste material, especially in the Z dimension. Lets hear from other Cabinetmakers and all. Happy Holidays

[mhmslm]

Jack,

I haven't tried this yet but it sounds reasonable:
In an article from an old issue of The Woodworker's Journal
(March/April of '89) there were instructions on making a tripod tilt-top tea table. This project involved creating a round tabletop out of some good furniture grade hardwood such as walnut (or maybe Mahogany). The problem of cupping was discussed. Solution was to rout or thickness plane small amounts of surface at a time, then sand freshly thicknessed area before proceding to another small area. Must have worked for them, the table they completed was very beautiful. Might be worth a try anyway.

[myxpykalix]

I (had) a uncut border around it after it was done carving and i did what you suggested and ran it thru the planer to try to flatten out that bow. I came in here to ask the question then went right back out (not thinking) and cut the border right off!

Well unless i get some good advice i may start over with mdf.
We are in the midst of getting about 12-24" of snow so i got nothing better to do!
(global warming my A**!)

[cnc_works]

Jack, it may raise the grain a little, but if you dampen the carved side then place it carved side down on concrete overnight, it may expand the cells in the concave side and give the convex side a chance to further dry and pull it straighter. Good luck!

Donn

[dlcw]

Jack,

When I've worked with wide boards over the years one of things I've done with it is to gang rip it into about 4" wide strips. I then make sure each of the strips has a flat face and perfect 90 degree edges to that face. Then I glue it all back together making sure the grain matches back up. Since the glue joint is long grain to long grain, the only need for biscuits is to align the boards. Another way to align the boards is to put culls - on top and bottom of the glue up to keep the edges aligned. Just make sure that wherever a cull passes over a glue joint that you use waxed paper so the cull doesn't stick to the squeeze out.

Following the process described above, I haven't had a board cup again.

Don
www.dlwoodworks.com (http://www.dlwoodworks.com)

[dmidkiff]

Jack,
I agree with Donn since it is already carved. After it is straight you might want to apply a "Z" brace to help keep it from cupping again. In the future I would try the other Don's suggestion.

[dlcw]

Another process I've used is to place the board, cupped side down, in the grass on a sunny day.

The concave side of the board will absorb moisture from the grass, causing it to expand, while the sun will dry the convex side of the board causing it to shrink. It may take awhile for this to happen but it has worked for me many times. It has even worked on a 1" thick by 40" wide by 10' long piece of highly figured bubinga.

Don

[michael_schwartz]

Rough mill stock oversize a few weeks ahead of a project, and then let it cup, twist, bow etc... Since you left extra material you can mill it again to final dimension and have a much more stable board.

Removing material equally from each face during milling helps as well. Same thing goes with finish.

[myxpykalix]

Hey Don...
That might be a good technique, that is if you can see some sun or for that matter some grass!!! lol

6681

6682

Is it just me or are you starting to feel the effects of cabin fever?

[dlcw]

Yeah Jack, maybe in the spring. :-)

It looked like that here last week. Now rain. Last year at this time we had one storm come through and dump 36" in 24 hours. 72 hours later we had another storm come through and dump another 16". 48 hours after that we had our third storm come through and dump another 14". Needless to say, it took awhile to dig out of that one. Lots of collapsed roofs also because of the snow load (I was busy at the fire department getting people out of collapsed buildings). Snow berms finally went away in mid May just in time for old man winter to dump his final storm load of about 8". Then we were done. Winter 2008-2009 was the same way. We're praying we don't get a 3-peat.


6683
The roof line is a little over 12'. My daughter, at the time, was about 40" tall.


6684
Berms ended up being over 12' tall that year!

Stay warm and safe in the white stuff.

Don

[navigator7]

@ Don,
Yep...you guys got kicked last year thats for sure!
My sister lives in Cheney....cabin fever set in around 12".
I wish I could replay her phone calls as the snow load built up.
It got downright x-rated near the end.

I like your comment to Jack about grass and a hot sunny day.
That made me think about this:

@ Jack
What about steam, clamps and a stout fixture to hold things straight after the deed is done?
Maybe even a possible recurve or an over-curve?

[rcnewcomb]

Years of exhaustive scientific research have determined that, if properly dried and stored with care, carefully selected pieces of high grade wood in an environmentally controlled workshop will do pretty much as they darn well please.

[navigator7]

@ Randall,
That must be why they call it wood despite the conundrum...your description meets the definition of a teenager.

Hence heat and pressure should work!
;-)