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Cedar Box Maker
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Discussion Starter · #1 ·
Bring you up to date. Question Later.
My wife and I are retired and we build cedar boxes for an Indian Trading Post. So far we have built 18 " X 6" X 5" and 22" X 6" X 5" (LXWXH) and a lot of them. The boxes are always made of areomatic cedar, that is what they want. This cedar has a tendency to warp, so we are very careful to take equal amounts off each side as we are planing it.
About 2 months ago my customer came up with a new box size. He said make it the same way just bigger 26" X 7" X 8" with a tray on the inside. So we made one and they liked it. About a month ago he gave us an order for 10 of the new boxes. We have made them but the tops are warping very bad.:censored: so much so that I have had to recut the bottom of the lids just to make them fit well enough to put the hinges and latches on them. :blink:
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Question;
What can I do to keep this from happening next time?
Staves under the Lid?
Double check moisture content of wood?
I just don't know. Need some experienced help here.
Oh, and none of our other boxes ever warped, but they were shorter.
Thanks in Advance,
 

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Cedar Box Maker
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Discussion Starter · #2 ·
OK, 41 views and no replies.:icon_redface: Maybe I didn't explain myself well enough. Do I need to explain the way I make the box or attach the top or cut the lid? Someone give me some feed back of what I need to do.:confused1:
Thanks,
:whistling2:
 

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The lack of responses may be the fact we (US) are gearing up for a holiday weekend.

But your problem is peculiar! As for natural wood movement - that only happens across the grain so rule that out. The single major factor you have changed is the length of the boxes, so lets focus on that issue. The 1st 2 photos show that the whole box (body and top) are bending. In the 3rd and 4th photos, I see the lids or tops bending, but the box seems to be straight.

Understand that wood will do what nature has told it what to do. In this case, it will bend along a the length and this becomes easier as you increase the length. The only remedy I know is to clamp both the box and lid straight and the glue a thin ply (luan board) along the inside of th box and cover.
 

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I haven't had much trouble with cedar warping. At one time I made a lot of cedar chests where the lid was just a 3/4" thick slab with just two pieces of 1x3 screwed to the underside to stabilize it. I did apply a finish to both sides of the lid where the rest of the chest was finished on the outside only. My guess is your lumber isn't seasoned well enough. You might look to a different supplier and see if that helps the problem. I sure don't see anything wrong with the way you are building the boxes.
 

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The only thing I see in the pictures makes me have a question for you.

Is the lid made from one piece of cedar or is it three pieces edge glued to make a panel?

If its three pieces, have you glued them with the grain in different directions? Let me explain that. Looking at the end of the board the growth rings should be arranged in an up, then down, then up again manner. That will help prevent the warp.

Also, it looks like you just glued the top rather than setting it in a dado. The wood must have some place to go when nature tells it to move otherwise it will warp and twist you entire lid just as your pictures show. The bigger the panel, the worse the problem.

Your smaller boxes wanted to do the same thing, but the wood didn't have enough mass to pull anything apart. The bigger box has plenty of mass in the panel to turn a nice straight lid into a pretzel.
 

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where's my table saw?
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agreed

When gluing up a top from separate individual boards, alternate the "cup" in the end on every board ...cup up, cup down, cup up, like that.

Glue up the tops, then let them stand around for a while before adding the sides. Make a rabbet either on the sides, or all around the top to support the sides.

IF the top boards have been resawn from a thicker piece, they probably will tend to warp. Resawing releases the internal stress in wood and it is often unpredictable what will happen. All you can do is stack and bind or clamp the pieces with spacers in between them to allow the air to circulate.

As johnnie suggested you may want to look for a different source for your wood, or if they can resaw, have them do it and then sort through the pieces for the straightest ones. I haven't worked with Cedar for a long time and don't remember it's characteristics.
 

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The edging around the top looks fairly thin and provides little strength from warping once the top is glued on. And who knows what the glue is doing to promote warpage.

Why not dado the top in place? You could use a half-lap cut on the top so it ends up flush with the boarder. This would allow for some movement of the top. Then beef up the corners of the boarder pieces.
 

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You are using lumber with wild grain and knots. When you cut the top off, it's the same as ripping the wide side boards. Quite often, when you rip a wide piece of lumber, it can react, meaning it may twist or warp. People use all kinds of explanations for this, sometimes blaming the kiln drying process. That can be a reason but for the most part, when the board was cut from the log and then dried and milled, it became an individual. Cutting it creates two individuals and either piece can react but it's usually the smaller piece.

One tactic would be to rip your sides and ends before you make the box. See what they do. If the pieces stay straight and flat, you can glue them back to the wider sides and ends. If they react, hopefully you have about an extra 1/2" so you could joint that warped piece straight, rip it width and glue it back on. When you cut the top off later, have the saw blade hit that glue joint. Some pieces may warp so badly, even correcting them by joining and ripping may not stop future movement. It would be your eye and experience that determines if those particular pieces should be used or discarded.
 

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Cedar Box Maker
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Discussion Starter · #10 ·
The lack of responses may be the fact we (US) are gearing up for a holiday weekend.

But your problem is peculiar! As for natural wood movement - that only happens across the grain so rule that out. The single major factor you have changed is the length of the boxes, so lets focus on that issue. The 1st 2 photos show that the whole box (body and top) are bending. In the 3rd and 4th photos, I see the lids or tops bending, but the box seems to be straight.

Understand that wood will do what nature has told it what to do. In this case, it will bend along a the length and this becomes easier as you increase the length. The only remedy I know is to clamp both the box and lid straight and the glue a thin ply (luan board) along the inside of th box and cover.
All the photos are of the same box. The 1st 2 photos show the lid and how it is bending. The lid is standing up on its edge on the side of the box. In the 3rd and 4th photos, I lightly clamped the lid to the box so that you could see the difference between the lid and the box. The boxes did not warp.
In the construction of these boxes, I make the sides and ends with dovetails on each corner. I dado the sides and ends to accept the bottom. Then I use Titebond III glue up all 5 pieces except no glue on the bottom. It is in the dado. After sanding the corners I recut the bottom on the table saw. Cutting off 1/16th to form a true and square bottom. Next I recut the top of the box 1/16th to form a true and flat top.
I use Titebond III glue to glue the top board to the box. The top board is cut with 1/16th over lap on all sides so I can use a flush trim bit to cut it to fit after the glue is dry.
Next I cut the Lid. Using the TS and cutting in the center of a dovetail, I cut the Lid off the box. Up until now the top and lid is straight. Over the next couple of days I made the trays that go in the box. The Lids were stacked so that nothing would fall on them or damage them. When I started to put the poly on them 7 out of 10 were warped, so bad I had to recut the mating surface to the box to take some of the bow out of them.:thumbdown:
The only remedy I know is to clamp both the box and lid straight and the glue a thin ply (luan board) along the inside of th box and cover.
BernieL, I'm not sure what you ment here and what is a luan board? :smile:
 

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Cedar Box Maker
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Discussion Starter · #12 ·
I haven't had much trouble with cedar warping. At one time I made a lot of cedar chests where the lid was just a 3/4" thick slab with just two pieces of 1x3 screwed to the underside to stabilize it.
These boxes have to be 3/8 areomatic cedar. I buy sawmill cut lumber and plan it to size.
[/QUOTE] I did apply a finish to both sides of the lid where the rest of the chest was finished on the outside only.[/QUOTE]
The finish on mine is polyurethane and can only be on the outside.
[/QUOTE] My guess is your lumber isn't seasoned well enough. You might look to a different supplier and see if that helps the problem. I sure don't see anything wrong with the way you are building the boxes.[/QUOTE]
Thanks Steve on the construction. There are getting to be less and less sawmills that cut cedar in Texas. Seems like the younger generation doesn't want to do that for a living.
Thanks,
 

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Cedar Box Maker
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Discussion Starter · #13 ·
A piece of luan plywood, the same stuff used as the surface of hollow core doors. Should be available at the big box stores.

Lightweight but would add some stiffness.
Oh, yes I know what you mean.:wallbash: As a matter of fact I thought of the same thing on the next batch of boxes. That seems to be the next thing I'll try.;)
Thanks,:thumbsup:
 

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These boxes have to be 3/8 areomatic cedar. I buy sawmill cut lumber and plan it to size.
I did apply a finish to both sides of the lid where the rest of the chest was finished on the outside only.[/QUOTE]
The finish on mine is polyurethane and can only be on the outside.
[/QUOTE] My guess is your lumber isn't seasoned well enough. You might look to a different supplier and see if that helps the problem. I sure don't see anything wrong with the way you are building the boxes.[/QUOTE]
Thanks Steve on the construction. There are getting to be less and less sawmills that cut cedar in Texas. Seems like the younger generation doesn't want to do that for a living.
Thanks,[/QUOTE]Your not that far from Dallas. If you would buy your cedar from Brazos Forest Products it would be kiln dried and I don't think you would have any more problems. I don't know what their delivery range is but if I buy a minimum of $300.00 they will deliver to me in Terrell for about a $28.00 delivery fee. They are located in the neighborhood of Six Flags so it's cheaper for me to have it delivered. It would probably take $28.00 gas for the trip.
 

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I read through the other replies to see about the kiln drying, application of finish to both sides, and any other clues. One thing you might consider is the way lumber "cures". When lumber is stickered and kiln dried or air dried, it is forced to stay flat by the stickers and weight of the pile. I have sent boards that were perfectly flat through a rip saw or planer and watched them come out the other side in all kinds of "non-straight" shapes. I am guessing that the machining relieves a lot of stored up internal stress that is in some boards.

There is no way to know by looking at a board, other than grain pattern, that it will stay straight or "spring" into a new shape when milled. If you build the box over with another board (make sure it has been kiln dried to 6-8%) it probably won't bow.

Using a wider skirt (edging) on the lid may help prevent the bowing.

One more thing...If you lay boards flat without finish on them, they will absorb or give off moisture on the open side and bow or warp in that direction. An extreme example, which I have actually done to flatten boards, is to lay a board on the lawn in the sun with the cupped side down. In a short time the sun will heat the top side and "shrink" it. The moisture from the lawn will absorb into the underside and expand it. Warps across the grain will change dramatically this way. Bows along the length of a board are not as predictable, but do respond to moisture variation.

Bows along the length or twists are due to memory from the tree where branches or other factors have shaped the log.
 
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