I’m making Norm’s blanket chest. Made the top last Saturday and set it aside.
Did the glue up for the front, back and sides yesterday.. reached for the top.. and it was cupped. Great for a steamer trunk.. but not for this.
Put a wet towel on the concave side.. an oscillating heater on the convex side overnight.
It flattened some.. but still not flat enough to use. Any advice?
What I’m debating is whether to go buy more white pine 1X6’s and try again.. or just buy a sheet of birch plywood and take no further chances.
I’m making this for a friend who wants to paint it but hasn’t decided on the color.. but I could do another glue up and prime it to try and limit movement.
What do you think?
TIA,
Bill
Replies
This is just a flat glued up panel, no frame, no cross pieces to help stabilize it? Is there a site where we can see the design?
Priming and painting won't solve the problem no matter what the primary cause.
John W.
John, it's just a flat, glued up panel, roughly 44" X 22", which serves as the lid to a blanket chest. You can see it on the New Yankee Workshop webpage.. plans/category/chests.
It does have breadboard ends. Will that be enough to stablize the top? Norm tongue and grooves them to the end.. will biscuiting them suffice?
Thanks,
Bill
Bill;
This won't help you now but in the future but you should let the wood adjust to your shop environment before working with it. Assuming the wood has equalized, when you unclamp the glue-up piece, stand them on end or sticker them to let the sides equalize in the air unless you are immediately attaching braces to the piece.
Doug
This chest is made from kiln dried white pine from Home Depot.. already s4s. I assumed you could use this stuff right away. No?
It might have been kiln dried, but how/where it was stored afterward would affect its moisture content. Needed to acclimate to your shop before building. Also, what type of "cut" did you get? If they were cut from close to the center of the tree, as much of that "appearance pine" is, you're struggling uphill. How wide were the boards?forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
No! The crap they sell at Home Depot is notoriously prone to cupping, one because it's not dry and two because it's from a species of pine that moves a lot. If you buy the stuff from Home Depot let it dry a good long time before using it.
Once warped, it's hopeless. You can add moisture to the concave side and it will flatten, but when the board comes to equilibrium moisture content with the environment the warp will return.
It's not worth fighting it. I'd make a new top.
Thanks. That's what I'm learning. It just keeps cocking one side to the other.
I had a similar problem a few years ago with a blanket chest I made for one of my daughters. The top developed a slight "twist" (one corner raised about 1/4") and nothing I tried straightened it out. I made a new top from 3/4" birch ply banded in pine and it's been dead flat ever since.
I recycled the old top into a coffe table top for the other daughter and when I attached it to the legs and frame it sucked right down. Someday, I should take it off and see if it still wants to twist or has finally flattened out. - lol
I had a similar problem with a lid to a large toy chest. I used regular HD white pine 1 x 6 and alternated the grain pattern. After a few days it turned into a corrugated panel! Seriously, if I had not spend the time to make it I would have had a good laugh at the sight. But I was not going for a cool modern curvy look. I added two battens on the inside to draw if flatter, and planed/sanded the top side flat and since it was a painted child's project it was acceptable in the end. I fear the shortcoming is in your white pine which has too strong a tendance to cup. If you insist on sticking with that construction, try again, but pick through the pile to get only boards that are quartersawn (end grain is short stripes that pass perpendicular to the long edge of the board). Those will not tend to cup as much as the flat sawn boards (end grain pattern is a sweeping curve). I agree with the suggestions to let the board acclimate to your shop, but also then select out only the least cupped boards, and cut them into smaller widths, and re-joint the edges before glue-up. That will minimize overall cupping resulting from movement in a particular board. If you do not re-joint the edges, then even a small cup will transmit into a big one on the glued up panel because the edge itself will be out of square. I believe that was a large part of my problem.
Quarter sawn lumber is unlikely to cup unless there's a large humidity gradient betweeen the inside and outside of the chest. That may be one of the reasons why QS is more expensive than plain sawed.
Thanks to all of you for your advice and wisdom born of experience.
I agree that my problem likely resides with my HD white pine boards (1x6x8) which, according to a sticker on the side, are radiata from New Zealand.
Before reading your replies I dropped by HD today and bought two more boards for the top.. thinking I would let them acclimate in the shop for a couple of weeks.
When I get home from work I'm going to see if they are flatsawn or quartersawn and try to exchange them if they are flatsawn. If I can't do that, I'm going to make the top out of birch ply and band it with the pine as one of you once did.
If the box was going in my house I would go to the hardwood place here in Houston and buy some nice (no doubt expensive) quartersawn pine boards.
But this blanket chest is for a friend who asked me to make it as a toy box for the child she is expecting. And she's having someone paint it.. so a ply top will be okay.
I did enjoy making the box because it was my first frame and panel project and I got some serious schooling in.
Thanks again all. I really and truly appreciate the guidance.
Bill
Edited 1/17/2005 5:13 pm ET by bill
Another alternative is that you can sometimes find pine veneer plywood. You could make the top of several "boards", with all but the two edge boards made of plywood. Since you will be using breadboard ends, the ends of the plywood won't show.
I've been thinking of another alternative. I have enough s4s 1x6x8 cherry to make the top. Just a shame that it's going to be painted, though.
But I bought those cherry boards back before I had a jointer and planer and they've just been sitting there gathering dust.
Everything I buy now is 5/4 (or thicker) rough and I mill it myself.
This discussion is one of four or more going on currently in Knots about the "mysteries" of wood movement with a fair number of dubious pieces of advice being given.
There is absolutely nothing mysterious about wood movement, cupping, shrinking, bending, and cracking are all as predictable as the sun coming up in the morning and they can all be avoided using well known techniques that have been around for centuries.
Everybody, please, go find a copy of "Understanding Wood" by Bruce Hoadley and just read chapter 4, "Water and Wood" it is only 23 pages long. If you read that chapter, you will never ever be unpleasantly surprised by what a piece of wood does when you make a piece of furniture out of it.
To quote the opening paragraph from that chapter:
"Someone once said that more than 90% of all problems with wood involve moisture. For those that ignore basic wood-moisture relationships, that is probably a conservative estimate."
Truer words were never written about woodworking.
Rant's over, have a nice weekend.
John W.
Bill
Your white pine will most likely be plantation grown Monterey pine (Pinus radiata), It grows like a weed here & is used extensively for house framing, ply, MDF manufacture & general construction. The mills process this timber as a low cost product so it is invariably gang bandsawn, shoved thru a kiln, machined, bundled & put on sale before it looks like a boat keel. That usually happens when the pack is broken open. It is best avoided for any furniture making because unless you are able to hand pick the one or two boards sawn thru the centre of the tree, then cut the pith out (to give you quarter sawn boards) you are going to need to refer to Ch 4 John refered to above.
Having said that some really excellent Monterey (or Radiata) pine coming out of New Zealand. It's pretty incongruous that there is a mill within 45 minutes of here but I have been getting any I need from the land of the long white cloud.
Don
"...put on sale before it looks like a boat keel." Too funny, DDU, too funny. To really get an eyeful of this phenomenon, folks can take a look at the 1x2's that are usually stacked on the end-caps in the lumber section. Much of it looks like it's been steam-bent, LOL!!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
I had this problem with two cabinet tops made of poplar. A breadboard edge solved the tendency of the wood to cup. The edge is easy enought to apply. Norm has a technique in which he uses cuts a #10 biscuit slot, which he fills with a #20 biscuit that is pinned. I dowled mine and it has worked just fine without spliting.
Good Luck
Rick
Rick, in the technique you described as being Norm's, you say he puts a smaller biscuit in an oversize hole? Is this to allow for seasonal movement?
Also, what do you mean by "pinned"?
In the plan of Norm's I'm using he tongue and grooves the breadboard ends. If I can get away with biscuits I'm anxious to go that route.
TIA
Edited 1/17/2005 5:15 pm ET by bill
Your item made me remember a refectory table I made in 1975. It had a 5/4 thick top of radiata pine. a few days after assembly it warped from corner to corner to the extent of 2 inhes. There was no way I could restore it. However, I screwed the base down to the floorboards and into the joists. This pulled it pretty flat. It was amusing to ask visitors to test the weight of the table. When we moved house some years later i unscrewed the table and it imediately sprang back to its warped condition.
This is my first post to this very interesting site.
Woodsy
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