Qx - Straightening a Cupped Panel

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Background:
Doing some volunteer work for one of our senior lady clients. Changed out a faucet seat and washer, leak stops, all done. Then I get the famous "One more little thing you could look at ...". Here we go again!
She has this pretty, kinda old writing desk, French escritoire style, where you let the front down to a horizontal to open the desk interior, the inside of the front panel becoming the writing surface. The outside of this panel is carven, some oriental scene.
Situation The panel in question is in a rail and stile frame. It's about 32 X 15 in a frame that's about 36 X 22. The frame is held together by through tenons. The panel rides about 1/4" deep in the grooves in the rails and stiles. It is not removable without getting the frame apart, and there's no good way I can see to do that. The panel wood is fairly heavy, fine grained, may be mahogany or another tropical hardwood.
The panel is badly cupped, warped side to side along its length. The cupping has broken out part of the edge of the framing at the tops of the sides. One side is broken free for about 5" and the other side is split for about the same length. I have removed the inner panel that forms the writing surface. It was glued to the carved panel but had largely broken free from the cupping, so I just eased it off by hand.
Question I'm looking for bright ideas on getting the panel "unwarped". I can't just glue the broken/split edges back where they came from as the cupping is so extreme it'll just break them out again, I think.
I re-read my decades old copy of The Furniture Doctor and have the framed panel out on the concrete patio up on wooden blocks at the panel corners, concave side down, with a wet towel under it (not touching the wood) and a 25 lb barbell weight on cauls on the top. I'm hoping that 95+ Dallas heat will create a bit of a steamer to bend the wood back.
Posting some pics to a.b.p.w
Any thoughts?
Tom
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On 7/8/2012 11:24 AM, Tom wrote:

Hmmmm ... where are the "through tenons"?
IOW, it looks more like the door frame is joined with miter joints in the photos?
If so, the question then becomes whether the miter's were done with some type of spline, biscuit, etc.?
Is that a bow in both stiles from the panel warping, or is that camera distortion?
Just a SWAG, but considering the doors warped, and if the stiles are indeed bowed ... something which would not have happened with a properly designed "frame and panel" ... then the entire construction method may be suspect, and perhaps to your benefit.
Are you positive that what to appear to be miter joints in the photos are reinforced in some manner (I see no evidence of "through tenons" or a spline, although it may just be the photos)?
My point ... applying some heat to an inherently weak, un-reinforced, miter joint, joinery put together by someone who obviously does not appear to have been an expert in joinery from the current state of thing, might actually allow you to get that frame apart?
Just a thought, and a long shot, but something to consider ... hard to troubleshoot from photos alone.
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The photos do not show the through tenons. The joints are, as you note, mitered, but there are tenon ends that show in the sides of the stiles (short sides). Whether they are floating tenons or solid ones I can't tell, but it really doesn't matter, the frame isn't coming apart short of destructive surgery.
The frame is flat and true in all dimensions. The panel is floated in the rail/stile dadoes (I can move it a tad horizontally and vertically). The stiles are not bowed, just the panel, that's why the interior edges of the stiles split out, the panel bow put too much pressure on the thin edges above the dado.
Yeh, it's almost impossible to diagnose from the photos and my lousy descriptions, but I'm pretty sure I've got to get some of the cupping out of the panel. Then I can shave down the panel edges where the panel would go in the stile dados enough (maybe??) to get pressure off the stile edges and glue them back together - hope springs eternal. She's a sweet 80+ year old lady and seems to treasure the desk, so I'd like to get it looking at least OK.
Thanks.
Tom

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On 7/8/2012 12:49 PM, Swingman wrote:

Got an opportunity to download two of the photos and can faintly make out what appears to be, judging from its position, possibly an angled spline?
The only one I can see, if that is what I'm seeing, appears to be the wrong place with regard to the joint to be a "through tenon", but is also in a location that would rule it out as decorative, therefore it could indeed be a method to reinforce a miter joint?
Is this piece Asian? Saw a lot of carvings like that in Hong Kong years ago, and the joinery is not necessarily what we would see in a European piece.
If there is one in each corner, than all previous bets about getting the frame apart are off.
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Yep, what you think you see is it. It may well be, as you say, a spline, though it appeared to me to be a tenon. There is one at each corner, all in the same relative location.
I too believe that the frame is NOT coming apart - it's damn solid. No give or twisting movement in any direction.
The carving depicts an oriental scene, or at least the figures, clothing and upswept hairdos look oriental in nature. I suspect it was acquired in the Phillipines. I saw similar carved items for sale in the 'Nam many years ago, generally sourced out of the Phillipines or Hong Kong. Never bought one 'cause they wouldn't go with the decor in my bunker.
Tom

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On 7/8/2012 4:29 PM, Tom wrote:

Knew I'd seen a similar looking miter joint before. This appears to be similar to what you have and what I can see in the photos. It is typical of what you would see in Asian crafted pieces of the highest craftsmanship:
https://picasaweb.google.com/111355467778981859077/EWoodShopJigsFixturesMethods#5762919506017095330
You may now know what you are dealing with?
Not to mention that I apologize to the woodworker, where ever the hell he is, for doubting his joinery! And that's an understatement. :)
BTW, the only thing I ever saw in 'Nam from the Phillipines was copycat Rock 'n Roll bands, and guys dancing with a strange, foot mounted puppet/doll. ;)
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On 7/8/2012 5:56 PM, Swingman wrote:

https://picasaweb.google.com/111355467778981859077/EWoodShopJigsFixturesMethods#5762919506017095330
An idea from some one who never did this before.
With the panel being so thin, could you work something out so the panel could be put into a piece of aluminum channel and then the channel hidden in the frame?
It is a dumb idea but maybe you could work something.
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I would suspect the panel is air dried wood (best/easiest carved when still some greenness to it), not kiln dried.
The back side seems to be unfinished. Is this correct? If so, then I would try dampening the back side (and leaving the damp cloths laying on the panel) and see if the panel straightens, on its own, a little, after a period of a few hours of dampness only. Place some moderate dead weights in position to straighten the panel. If there is a hint of straightening, after a few hours, then I would reapply some dampness and gently shoot some *heat onto the panel while applying some dead weight pressure to straighten the panel more..... Possibly rigging up a dead weight press, first, to assist while warming/heating the dampened panel. If the wood is air dried, it should respond to some dampness and/or some heat with pressure, similar to steaming wood for bending. This may be easier and safer than trying to cut relief kerfs (as a last resort?).
*Note: Do not apply high heat with this procedure. Good warmth, ~150, not too hot, at all. Also, when applying heat, don't apply too much initial dead weight pressure. Place small pressure and gradually increase, if need be.... but first, see if the panel responds to just dampening the back side, with no heat assistance.
Sonny
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wrote:

Wouldn't adding moisture on the back cause those fibers to swell, increasing the cupping?
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Yes. Art
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Yes, maybe, but will allow the panel to be compressed on the back side by the pressure. The panel dried more (and probably faster) on the carved side, likely causing the majority of the cupping in that direction.... and possibly enhanced by natural tension of the wood.... and/or volume of wood on the back side relative to the carved side. You want moisture to penetrate the panel, but not to the extent is reaches the finish on the carved side. The panel has likely cupped all its going to cup, not much more. You don't want to bend it back into proper position too fast or the carved side might crack, form check type cracks. Same with cutting kerfs on the back side... you don't want to bend it back, too fast, into too flat of position or else the carved side might (likely, IMO) develope cracks, because of the extent it has cupped. That panel is not quarter sawn wood, i.e., easier to compress than quarter sawn wood.
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Sonny:
I concur with your guess that the wood was likely air dried. The piece is 50+ years old, came from Asia, so kiln drying seems unlikely.
The back side (convex side) is unfinished, just some dried glue which I plan to scrape off anyway). I just learned from the owner that the whole piece got wet some years ago during a move - probable source of the warping. If that's the case then the back side (unfinished except for bad glue) would absorb more moisture than the finished front side, causing the cupping, or at least that's my theory.
Dampening the convex side is counter intuitive, but WTH, I'll give it a shot. I am concerned about cracking of the panel if I do relief cuts. Its varying thickness, due to the relief carving, would make depth of cut pretty critical and hard to determine.
One maybe good, maybe bad thing is that the grain is not straight along the panel width, but at a slight angle, maybe 15 degrees. The cupping is almost dead straight along the width. IMHO this could reduce the potential of a split running the width of the panel as it tries to un-cup. Wishful thinking in progress.
Thanks for the ideas.
Tom
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On 7/8/2012 11:24 AM, Tom wrote:

Some thoughts. It appears that the frames too are in bad shape. IMHO they may need to be replaced. As for the warped panel I would thing that perhaps some length wise relief cuts in the back side might ease the bow such tha a new frame would keep everything in check...
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The frame is structurally sound and true. It has not warped to any discernible degree. There's no give to any of the joints.
Relief cuts on the back side of the panel are definitely a reasonable idea. I'd just have to be real careful with the depth of the cuts as the relief carving on the front seems to leave, in places only about 1/16" of thickness. Overall the panel is ~5/16 thick but some of the relief areas are cut almost 1/4" deep.
Thanks for the idea.
Tom
wrote:

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It's possible that the frame may come apart by using a multi-tool to saw thru 2 of the miter joints to get one side off. You may not have to saw all the way thru, just enough to cut the tenon. Once the frame is open the panel can be removed and lengthwise cuts made in the back side to relieve the tension. These will be covered by the writing panel anyway, no? Once flattened fill the kerfs and reassemble. Art
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Art
I could use a multi tool or fret saw to cut through the splines, or tenons, or whatever they are. I coud then, as you say, get the panel out, I think. Relief cuts on the back are a good idea (2 votes, you and Leon) but see my response to him above regarding depth of cut..
I can make relief cuts without getting it out. Thought to use a palm router with a V bit set REAL shallow, then complete to the edges with a V chisel. That would help, I hope, flatten it out enough to get the pressure off the edges of the frame where the dados are, so I can repair the breaks and splits.
Net/net, I've got to reduce that warp induced pressure to get the front repaired. If the panel stays a bit cupped, no worries, no one will notice.
Thanks.
Tom
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[This followup was posted to rec.woodworking and a copy was sent to the cited author.]
snipped-for-privacy@REMairmail.net says...

Would someone be so find as to share some information with me as to:
a) Full name of a.b.p.w
b) How to access this site
c) What reader tool needed to access binaries
I happen to use the MicroPlanet Gravity reader and would like to see Tom's pictures.
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Michael Karas wrote:

alt.binaries.pictures.woodworking

The rest should be the same as the way you access the rec.woodworking newsgroup, as long as your newsgroup provider subscribes to the newsgroup.
If they don't, there may still be another way--but try first!
Hope this helps!
Bill

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[This followup was posted to rec.woodworking and a copy was sent to the cited author.]

First off, thanks for the info.
When I look at the list of available news groups to which I can subscribe I find that "alt.binaries.pictures.woodworking" is not one of them. Is it possible that my news service, Eternal September, is not collecting input from that group?
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wrote:

I didn't think Eternal September carried any binary newsgroups (my Usenet provider doesn't either).
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