Howdy folks, mostly retired old coot broadcast engineer here, in the process of building an entertainment center that is about 95% solid cherry. The design has an equipment box mounted between a pair of planks bolted into the ends of the base cabinet, about 4 feet long and 18″ deep, with a bottom, weight bearing shelf of cherry about 1.1″ thick, edge glued with biscuits to help alignment, out of 4 narrower planks. To be mounted at the top of the side posts about 6 feet up.
Progress of sorts can be seen at <http://gene.homelinux.net:85/gene/GenesWebPages.html> and click on the E-Center link.
So 2 months ago when I glued it up, sanded it flat, stained and put a coat of polycrylic on it, was flat. I put it aside, standing on end against a flat surface in a corner of the shop after milling sliding dovetail grooves to take the end panels of this box and fitting those but not gluing it yet as I wanted to be able to get at it with an air brush, my favorite method of laying on a thick but level finish.
When I went to assemble it a couple of days ago, I found my nice flat board now had about a 3/8″ wind in it. This wood has had several years to dry since I purchased it in the overhead of an outbuilding and should be very well dried. So that amount of wind in just a 45 day lay around surprised me.
I can rig some 2×6’s on edge so that I can draw it with a pretty heavy pull to take the wind out of it, and did so last night but only pulled it about 1/8″ past flat, and left it sit overnight. I believe its actually worse today when I take the pressure off it.
So the question is:
How brutal do I need to be, and for how long, to restore it to flat at least long enough to glue up the lid, itself an assembled cherry plank but only 1/2″ thick which should pretty much lock it flat forever?
Or until it pulls the Tightbond-III apart from the sheer in the sliding dovetails anyway. 🙂
I’d like to get this done before I fall over the last time. I tell folks that at 74, my warranty expired decades ago. 🙂
Thanks all.
—
Cheers, Gene
Replies
Gene,
Water under the bridge now, but I wonder how long it was in your shop before you worked it? If it was in an unheated shed, and you brought it into a conditioned area, and worked it up pretty quickly, that might have prompted the movement. Alternatively, if it was standing tightly against another surface, with air only circulating around one side, that might have been the problem.
Anyhow, you ought to be able to get by if you clamp the offending plank flat, assemble the case, then remove the clamps after the glue has set. A well fitted sliding dovetail ought to hold it, at least on the end where the dovetail is...
Ray
The shop isn't well heated at all. An uninsulated garage I built last summer, now with 2 little 1500 watt heaters whose job it is to keep it above freezing is the only heat. They can raise the temps about 20F, no more, and of course the breeze of the spinning electric meter can be felt. And it probably stood around in there for a week before I even cut it off from a larger glueup.That particular piece was actually laid up & glued about 4-5 years ago, when tv's were tube type and deeeeep, had been stored on edge at floor level, about 15" above ground level in the same outbuilding I had the rest of the wood racked up on the rafters of.So I cut it in half a couple of months ago when I restarted this project and used one piece for the top of the base cabinet, and intended to use this other half as the bottom of the overhead box for the tuner/amps etc. FWIW, the half I cut off and used for the base cabinet top, where the tv will be sitting, had to have 3 pieces of cherry 1.25x2's glued crossways across the bottom of it to stop it from cupping about a 1/8" a week. I was running out of board trying to sand it flat. :)Now this piece wants to wind up like an airplane propeller. :(I've got a couple of 2x6's so I'm going to set them up in an X shape, lay it across one at an angle that puts the low corners on it, and the other one under that one arranged so a clamp can pull down on the high corners, and pull it down about 1/2" past flat & leave it that way for a few days just for effects. I was hoping to have this done by Christmas, but not at this rate.Where it was standing, it did have air all around for the most part. The doors were behind it, so there was at least 1/2" of air behind it.I don't have a flat surface (other than the concrete floor) I can spare without everything coming to a halt or weights to stack on it, so clamps will have to do.Thanks.--
Cheers, Gene
As you have posted. A tight fitting sliding dovetail (or two) 'cleat' has saved me a few times. A lot of work but it does work! Usually...
Gene,
All wood, no matter how long it has been dried, and no matter whether it was air dried or kiln dried, will gain and lose moisture from the air forever and at least change in dimension and possibly also cup or twist depending on the features of the wood's grain. Every time the humidity in the air changes the boards will move again. Some finishes will slow the process a bit but won't stop it.
Wood should be brought into the shop and allowed to acclimate to the shops environment for a few weeks before you start to work with it. If the shop swings from hot to cold, and dry to damp, because it isn't regularly heated then there is no good way to get the stock to settle down and keep it that way while you work with it.
Wood cannot be twisted like metal to permanently take out warpage, it will return to its original shape as soon as you remove the clamps or weight.
John White
You are no doubt correct to a large degree, so generally I try to cut and get it glued up on the same day, but I have found with white ash for instance, that I can clamp it to a steel frame that is somewhat springy but is generally flat, and I'm referring to a nominally 2.5" thick by 7" wide native sawn board that went on that frame 3 years ago with a 2" bow & a little wind in 7 feet of it, now has, if the clamps are released, about a 1/8" bow & unmeasureable wind. That steel tubing frame may sag with the pressure from 3 stacked pieces of such white ash, but it never stops pulling.What I've done today is make plans & cut stock for another piece but I'm running low on suitable cherry stock so the individual sticks will be narrower, if the wind doesn't come out of this one long enough to get it glued up solid. But I'm not just pulling it back flat, it is sitting with a couple of 1" thick blocks under what would be the low corners, with a 2x6 under the sawhorse beam the blocks are sitting on, with a couple of 30" clamps connecting the high corners with the bottom of that 2x6, and pulled tight enough that its pulled about an inch and a half opposite to the wind it had. That popped the glue in one end of one of the sliding dovetail joints holding the end panels into it, it was rather sloppy anyway, so I'll need to run some more glue into that when I can get it up on edge and pour the TB-III into the end of the dovetail groove & exercise the joint to get better coverage than I did have. I figure on leaving it pulled that way till it gets the hint, then glue it up as its coming back through flat. I've also left the heaters on out there, so it will be about 15-20 degrees warmer overnight, and I'll unscrew the clamps tomorrow evening to check progress. If its actually gone the other way, then I'll get busy and get it glued into the box shape as its coming back flat or in the neighborhood of it. If not, then I put the pressure back on it for the weekend as the next 3 days are gonna be busy anyway, a friend died yesterday & we'll need to put in an appearance at the visitation at least.The sliding dovetail is sloppy because I didn't make any two of them with the same method when making the tail on the end panels edge, finally winding up with a knife edge opposite the bit in the table saws router holder aux table, mounted to the fence and a ball bearing running above the bit and behind the edge by the amount the cutter needed to penetrate the side of the board to make one side of the tail. I need a ball bearing on both sides for easier feeding, and some means of adjusting it more accurately than I have now. Someone should invent a gismo that fits on the the base of a good router to do this. I have something in mind too, and it would auto compensate for the thickness variations of the board if I do it right. I have a small table top cnc mill that could make it I think. Would there be a market for such a router accessory? Hummm, definite maybe IMO. However, my vision of how to do it falls apart at the ends of the board. Like a planer that snipes.Necessity being the mother of invention is the applicable phrase at this point. :)If I succeed at this, I'll post & let folks know there is yet another tool in the wood fighting arsenal.Thanks John.--
Cheers, Gene
Gene, Maybe this is a dumb question. Did you put finish on both sides of said board?
Another culprit could be the dovetail grooves sitting unassembled. Just guessing, hope it all works out.
Finish? More or less. Several well rubbed out coats of min wax's cherry gel stain, and a coat of polycrylic that has been about half sanded, it gelled (temps in the mid 60's at the time too) in the air brush and the can at the same time, preventing me from laying on a nice level coat so it got leveled back out with 220 grit and a RO sander. Then it got stood on end with a piece of 2x6 between it and the concrete) and leaning against a sheet of mdf for about 3 weeks while I waited for minwax to send me another can like they promised when I called the 800 number on the can and squawked. Maybe 10 minutes of open time when it turned into 10% strings of rubber cement that would not remix, I closed the can and hung it crossways on my little lathe, and left it turning end over end at about 1 turn per second for about 36 hours before giving up on that & calling Minwax. They said they would send me another can. That was 29 or 30 October IIRC.Never happened (thanks Minwax), so I bought another, this time semi-gloss, a week ago, which hasn't been opened yet, been fitting drawers and making pulls. And the drawer fits still need some fine tuning. :(A bit warmer about 3 days ago, I figured I'd get this upper box assembled and finished, and it was when I was putting the top on that I noted the wind in the heavy shelf board. I've pulled the wind about 2" in the opposite direction and left it overnight now, and haven't checked it yet today. Being almost retired, I just now got up but won't get to do that, other obligations, funeral, part time doing maintenance at the tv transmitter in the wee hours of Sat morning, till tomorrow afternoon now.I take a couple of pix now & then and post them on my web server here, right on this machine at:<http://gene.homelinux.net:85/gene/GenesWebPages.html>cabinet (E-Center) link clear at the bottom of the page. The page isn't fancy, but it works for me. And its on this machine so verizon doesn't get to load it up with all their commercials. Someday I'll see about making thumbnails to click on. Someday. I have an "Html for Dummies" book laying around here, but there always seems to be more interesting things to do. Like mutilate some more wood. :)Thanks.--
Cheers, GeneEdited 12/5/2008 12:34 pm ET by Gene1934
Edited 12/5/2008 12:36 pm ET by Gene1934
Gene,Sorry to have to repeat what's already been said, and to add more bad news.First, you can't "undo" wood movement that's a consequence of its responding to humidity and temperature changes by applying a counter force. Despite what you think you accomplished with your ash samples. It sounds like the cherry has moved due to released tension in the board and your (very much) less than ideal shop conditions. It won't work, no matter how much you insist it should.Second, Minwax finishing products are junk. It sounds like your first batch was old. Using any finish in a shop with the temperature in the mid 60's is asking for trouble. But even fresh Minwax products will give you grief of one kind or another. Bad choice.You are working under poor conditions with problematic materials. That's a formula for failure.Rich
I have to admit that other than the stain, I'm less than impressed with them, and have seriously considered opening a gallon of leftover Man-O-War Marine spar varnish. I used that a year ago to varnish the paneled ceiling I put in one room, and I've got nothing but ooohs, and ahhhs from the visiting frogs over that. Putting that up with a short nap roller was a PMIA though. As for the temps, I may just have to wait for warmer weather as the breeze from the electric meter isn't helping to heat it. 3kw of heat raises the temps about 18-20 degrees is all. Or stop this, and spend a kilo+ insulating and finishing it. If I do, with 2x6 walls, I'll put 4" of blue stuff between the studs and on top of the ceiling I'll have to put in. With that stuff at circa $40 a sheet here, that alone will be close to a kilobuck.There is no ceiling up now, the soffets are open as usual, and a full length ridge vent was put in last fall when I built it. And if I put up a ceiling, I'll lose access to the rafters for lumber storage and there is quite a bit of leftovers up there now. Obviously I have a malady known commonly as PackRatitis. DIIDo, DIIDon't. :)Thanks, we'll see tomorrow if its going to be usable or firewood, it got glued up yesterday, and pulled a hair past flat, so hopefully it will be usable when I remove the clamps. If not, then it rests till warmer weather & I find some more cherry to make a new one. Unforch, here in WV, that isn't easy to find, too much of it gets cut for firewood! So I've been getting mine from a little shop near Ithaca NY, we have kin there we visit from time to time.And if I wait, the better half will probably remind me of it from time to time too. :(Thanks Rich.--
Cheers, Gene
Gene,Good luck. There's nothing like having a comfortable work shop. Here in Florida, my major problem is cooling and dehumidifying in the summer. But winters are quite cool and it's been known to get into the teens over night. This summer we insulated the "attic" of the garage and had a "mini split" heat pump system installed which cools or heats as the need be. 70 degrees all the time. Wonderful!Rich
I have been considering drilling a couple of wells and putting a heat pump between them, but I find it hard to get a decent estimate of payback time. In the summer here, unless I needed the extra cool coils for dehumidifying, I might be able to just run the well water straight through the A-coil in the furnace. Thats the rub, summer humidity can be pretty high.I have a tank type kerosene burner stored in an outbuilding that I'm thinking about bringing in, but then I recall the last time I fired it up in my older workshop building and all my steel tools turned bright red in 30 minutes from the rust due to the condensation. If I could actually use it to feed a 30 foot U-run of stovepipe for a radiator, and pipe the used combustion gases outside, it may be a plausible way to heat it as long as I can truck the kero to it. I may look at that possibility after I take a nap. I've been up since yesterday due to an employee who had to put his woof in the shop last night, ruptured appendix they said and none of the others were answering the phone to about noonish when I finally reached my successor, so we split the day shift at the transmitter. Probably the only still manned transmitter in the tv broadcasting business. I was supposed to go to a funeral 30 miles away that should be in full swing right now, but while I feel I should, I don't need to take my cold into a crowd of similarly aged people and pass it on.I think all of you are right, and that before I start another project in there, there will have to be some sort of climate control in a space that is climate controllable. It certainly isn't right now.In the meantime I'm hoping to get this done well enough to move it into the house by Christmas. And there goes the budget then cuz I'll have to go buy a 42" Sharp Aquos to put in it. :)Thanks all.--
Cheers, Gene
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