Bowing Box Top End

[Patrick Rose]

Hello all,
I have been browsing the forum for some time now and learning a little all along. I have been woodworking for many years off and on during my military career but never for any extended period of time. Since retiring I have really started to build up my wood shop and in 2019 finally bought a place that has a large enough garage (not attached to the house) to put my woodshop together in. So, to quit babbling about what got me here and to get to my question

I built my father a certified coin box to hold 100 certified dollar coins, most PCGS but some NGC. It is built out of poplar and the dimensions are
13 7/8" L x 11 7/8" W x 5" T
The 4 main walls of the box are 1/2" thick and the top and bottom panels are 1/4" thick panels made from the same piece of poplar glued together. So, a basic box more or less, the bottom panel sits 3/8" from the bottom of the box and the top panel sits 5/8" down from the top of the box.
The deeper top gives him a place to bring out coins and place on the top to look at them or sort through new ones or whatever else he wants to do on the top without a coin sliding off of it. To answer another possible question, why all the 1/8" measurements? well certified coin cases are 3/8" thick and it just worked out for everything to come out to 1/8" measurements because of it.
So, to continue on, the box was assembled and left to set overnight for the glue to dry. The top was then separated from the bottom using the table saw. The top is 2" deep and the bottom 3" deep.
Another side note, this was left in the shop, which is unheated, so the temp is what it is based on outside temps. This I think is going to be an important factor in what is happening with the top.
After separating the lid from the box, I decided to bring it in the house because it would not be done before Christmas, and it was supposed to be his Christmas present. I did sand it all up on the outside and showed it to him on Christmas eve when he came over. I noticed that one end of the top had started bowing in, not enough to stress the mitered corners but definitely noticeable. I took the box back out to the shop and left it, fast forward a week. The lid was now not bowed, and it looked as if I had just cut it from the box. I started working on the liner that would hold the top in place, this was a 1/4" thick and butt jointed then glued to the bottom part of the box. Once the glue dried it was a perfect fit for the top, well after I chamfered the edges a bit the top slid right on and had air lock resistance when taking it off. Back on track no warping.....
I then made the inserts that would separate the coins in groups of 5, long story short, there are 3 dividers length wise and 4 dividers width wise. Almost irrelevant at this point. Now I just needed to put a finish on it, I didn't want to add any kind of oil or finish to the inside as I didn't want to take the chance on it reacting with the coins being sealed up with them. So, I only used mineral oil to finish the outside and decided to use a butcherblock wax to top it off. Everything is now going great, bring it inside and have it ready to take to him once he gets back from his trip.

WELLLLLLL
In the house for 1 day no change, by day 2 the lid and only the one end of the lid started to bow again. I thought that if this were to happen again that the inserts would help keep it at a minimum, NOT the case. So, that end of the box which was originally 1 piece of wood when the box was all glued up and then separated only has the lid piece (2" piece not the 3" bottom piece) bowing.

Finally, you made it to my question
Why is the bottom 3" piece not bowing like the top piece, and how do I go about fixing the top piece to stop bowing, or at least reinforce it so that it doesn't bow so much?

Just so you know where my mind is on it, I was thinking that I could run a saw kerf 1/4" deep along that piece and using the same wood but different grain orientation and glue an inlay into it and just call it the front of the box with a decorative inlay. I would of course leave it in the garage for a few days to see if it straightens back out like it did the first time. But if I do that inlay then the sides would look a bit odd with the end of the inlay showing through part of the miter. I really don't know I am just running through ideas, and that is why I decided to post here to get others' opinions.

Thank you for the answers and ideas in advance, I am signing off to go to RDU to pick my pops up from his trip tonight at 1240, and I am 2 hours away from there. This is not a fun trip for an old person and probably even less fun for my pops in his later 70's.

 

[mdbuntyn]

Even with your thorough description, a picture will be helpful

 

[Patrick Rose]

Not sure what my limit is on uploads but I will start with the bowed top, and then show the bottom part of that same board. Not sure if you will see the file names but I think you will get the picture when you look at them both. Remember before I separated the top this was one board.

 

[Patrick Rose]

Ok so that worked ok, at least from what I can see. Here are a few more just to see the box as a whole.
Yes the box itself is poplar, the inserts are also poplar and look more like regular poplar as where the box doesn't look like your typical poplar. The only other wood involved is the handles are sycamore.

 

[John Jimenez]

From the picture it looks like the one side of the lid bows in a little less than 1/8”? When it bows in does it prevent the lid from closing?

 

[Patrick Rose]

From the picture it looks like the one side of the lid bows in a little less than 1/8”? When it bows in does it prevent the lid from closing?

While no it doesn't stop the box from closing it does cause it to be very difficult to take off. When it straightens back out the lid slides off and on with a slight air suction resistance. The lid also closes all the way down to not show much of a seam where the top and bottom meet, if you look at the second set of pics you will see a slight gap between the lid and the bottom while that part of the lid is bowed.

 

[mdbuntyn]

The humidity in your house is lower than in your shop, and it looks like the drier air is causing the top panel to twist. I've never made a box like that, so I wouldn't know to advise you on correcting it.

 

[Patrick Rose]

I kinda figured it had to do with that, but aside from a way to fix it, what puzzles me the most is that the four boards that make up the box were obviously all one board before I cut them into the four boards that now make up the box and on top of that the one little 2" tall section of that one board is the only piece that is being affected. That is what doesn't make any sense to me. I understand warping but usually if you have a board that is warped and you cut it, it releases stress through the whole board and not just a small section of it.
I mean that was an 8ft board originally and out of all 8ft only that 2" piece is warping, isn't that rather strange?

 

[bainin]

Did that particular board get more attention than the others...ie sanding, jointing/planing?

Additional operations compared to the other boards would be a different heat/stress load which could cause it to warp more than the others.

b

 

[Patrick Rose]

That board as a 5 1/8" board before cutting got no more than the other three, and once cut only that top 2" of just that one board warped.
I don't mean to sound aggravated with anyone, I appreciate all the thoughts you are sharing, It just baffles me that only that one piece is doing that. And then there is the how to fix it issue as well. It is back in the garage so that it can straighten back out and I am thinking that I will cut a piece of walnut so that the grain is going a different direction from that piece and use it as an inlay, just a deeper than usual inlay, maybe that will help keep it from bowing again.

 

[DSWalker]

Couldn't the construction/joints of the box provide enough 'structure' to keep those boards straight? The top, without any permanant joints to help hold it straight, could twist naturally as the wood moves with humidity changes.

 

[JGregJ]

Does the 1/4 in panel for the top float and is free to expand/contract within the frame?

 

[Patrick Rose]

Couldn't the construction/joints of the box provide enough 'structure' to keep those boards straight? The top, without any permanant joints to help hold it straight, could twist naturally as the wood moves with humidity changes.

The only joints are the two miters (one on either side) that hold that board to the other two boards for the long sides of the top. Nothing else structural for that piece, that said the same thing applies to the bottom half of the box, the only difference is that the top piece is 2" and the bottom piece is 3" Tall, again it was one piece until I cut the top from the bottom.

Does the 1/4 in panel for the top float and is free to expand/contract within the frame?

Both the top and bottom panel is free floating and was cut just to size to fit in the dado. So, while it could expand and contract it would have to do so left to right across the grain of that panel if that makes sense.
It took several cuts to get it to fit without any visible space at the miters before glue up. Now that said I would think that if that panel was going to affect that part of the top, it would push it out and not bow it inwards towards the panel.
I will take closer look at this now that you brought it up to see if that panel is moving when the end board bows. I am thinking put a mark on the panel and a mark on the long sides to see if the panel is moving when the short side bows.

 

[John Jimenez]

While no it doesn't stop the box from closing it does cause it to be very difficult to take off. When it straightens back out the lid slides off and on with a slight air suction resistance. The lid also closes all the way down to not show much of a seam where the top and bottom meet, if you look at the second set of pics you will see a slight gap between the lid and the bottom while that part of the lid is bowed.

Patrick, I should have mentioned this is a beautiful box and I bet your father will love it! One of the hardest things I have found about woodworking is appreciating and being proud of my work when I know where all the mistakes and imperfections are. If it was me, I’d sand the inside of the bowed lid to make sure that it can open and close with ease and just consider the bow to be one of many things that make your gift to your father a one of a kind, hand crafted treasure. Keep up the good work!

 

[smallboat]

Patrick, I should have mentioned this is a beautiful box and I bet your father will love it! One of the hardest things I have found about woodworking is appreciating and being proud of my work when I know where all the mistakes and imperfections are. If it was me, I’d sand the inside of the bowed lid to make sure that it can open and close with ease and just consider the bow to be one of many things that make your gift to your father a one of a kind, hand crafted treasure. Keep up the good work!

100% what JJ says here.

I do, however, understand wanting to get to the bottom of these “mysteries”. I can tell myself it’s so I can prevent it in the future, but really it’s just not being able to let go of something I don’t understand.

That box is sure work to be proud of and a well thought out gift for someone who will appreciate it.

Put the mystery on the back burner. If it does happen again, you’ll have two data points and maybe the answer will become clear(er).

 

[Patrick Rose]

Patrick, I should have mentioned this is a beautiful box and I bet your father will love it! One of the hardest things I have found about woodworking is appreciating and being proud of my work when I know where all the mistakes and imperfections are. If it was me, I’d sand the inside of the bowed lid to make sure that it can open and close with ease and just consider the bow to be one of many things that make your gift to your father a one of a kind, hand crafted treasure. Keep up the good work!

100% what JJ says here.

I do, however, understand wanting to get to the bottom of these “mysteries”. I can tell myself it’s so I can prevent it in the future, but really it’s just not being able to let go of something I don’t understand.

That box is sure work to be proud of and a well thought out gift for someone who will appreciate it.

Put the mystery on the back burner. If it does happen again, you’ll have two data points and maybe the answer will become clear(er).

Thank you both for the compliment, for me those are sometimes hard to accept being prior military.
I do have a habit of logging things that sometimes, later don't make a lot of sense, especially if I can't remember what it had to do with, ok that's poking fun at myself, but the point of that is I have made notes about what is happening with this box. Hopefully it never happens again, but if it does, I will have something to compare it to provided I remember what I mean by the notes I have taken. LOL

As for fixing the problem, I think I have come up with a solution that will work. My original idea of using an inlaid piece of walnut or harder wood didn't really appeal to me but I was trying to give that piece some rib type structure. My new idea is using a piece of the same wood (poplar) and placing it under the lid but making it a half a mm longer than it needs to be and gluing it in place about middle way of the box top. This should keep the lid from being so hard to get off even if it warps again. It shouldn't warp enough to pinch the inner liner making it stick so tight when trying to remove it. I will also take the advice of sanding the inside of that end of the lid to also help out with the sticking.

I did learn from my grandfather many years ago that woodworking is never perfect, and that a perfectionist should not even attempt it, but learning to fix the imperfections is a woodworker's greatest skill.

I will come back and add some finished pics of the box, and maybe include some of the coins that will be kept in it.

 

[Patrick Rose]

So I finally got this thing finished. Here are the pics as promised.
I did end up adding a piece of Padauk for the rib under the lid. I was going to add walnut but after talking with my dad, he asked me about that piece of padauk that we bought a few years back when we were visiting my sister for Thanksgiving. So a piece of that got used instead of the walnut. You will see IT STANDS OUT, lol.

 

[HITCH-]

Your Dad will appreciate that piece of padauk

 

[Craptastic]

Stands out in a very nice way.

 

[NYTransplant]

Nicely done. It's a great touch with the Padauk having functional AND sentimental value.