chess board round 2

[Charlie Fox]

finally got to a decent point with this project - i have literally been on vacation photographing grizzlies. the real ones :). ok so i have 1/4" walnut/white oak over 1" mdf, hoping the thickness of the wood is not going to move the mdf. can i glue a simple frame to the edges - 2 of course would be with and 2 cross grain with the 1/4". maybe an inch wide, 2 walnut and 2 w.o. should i glue only to the mdf so there is no wood on wood xgrain ?

509026

[Kent A Bathurst]

Same issue as has been following you through your prior related threads. If your cross-grain concern is a legitimate issue, then that means you anticipate the top to be expanding and contracting, So the 2 sides "with the grain" will be pushed away from the MDF and open gaps with the cross grain sides. At this point, I believe you are over-driving your headlights.

With the construction as is - 1/4" thick top glued to 1" MDF base, "the die is cast" as Caesar said when he crossed the Rubicon.

He did not mean that the die was on the table and the future was now known. Rather, he meant the die was just now thrown, and is in mid-air and yet to land, so you are past the point of no return, there is no turning back, there is no way to reverse the decision, and there is no way to influence the outcome.

So just strap it on and go to Rome to learn your fate. Or rather, glue it all up because it no longer matters.

As for me, I have a pretty good idea what awaits in Rome, and it's different than that which Caesar found.

[Kevin Jenness]

finally got to a decent point with this project - i have literally been on vacation photographing grizzlies. the real ones :). ok so i have 1/4" walnut/white oak over 1" mdf, hoping the thickness of the wood is not going to move the mdf. can i glue a simple frame to the edges - 2 of course would be with and 2 cross grain with the 1/4". maybe an inch wide, 2 walnut and 2 w.o. should i glue only to the mdf so there is no wood on wood xgrain ?

509026

I would suggest reducing the thickness of the face material to <1/8" and gluing a balancing veneer face on the other side. Or take your chances. As is you have the potential for cupping and gaps between the frame and the long grain edges. I doubt it matters whether you glue the frame to the "veneer" edges.

[Steve Jenkins]

I’d run the whole thing through a sander to reduce the thickness of the solid stock to 1/8 or less, use a backer then edgeband with no concern

[Charlie Fox]

so basically y'all are saying the 1/4" is too thick and its movement will move the mdf. one person told me before that 1/4" max, and it is a little under that so i thought i'd be ok. i have regular paper back veneer on the bottom, walnut - i figured the glue and the veneer would somewhat seal the bottom - and i know its never a perfect seal but it should pass a whole lot less moisture than if left bare, especially in a controlled environment such as an a/c home and with 3 coats of poly.

oh well, guess i have no choice but to finish the disaster and tell the recipients to never let the chess board go outside. i always see people claim they did the same oir similar 8 yrs ago and its still fine, and they are told to just wait another year or two. so i guess its a gamble if i outlive them or not.....lol

[Kevin Jenness]

so basically y'all are saying the 1/4" is too thick and its movement will move the mdf. one person told me before that 1/4" max, and it is a little under that so i thought i'd be ok. i have regular paper back veneer on the bottom, walnut - i figured the glue and the veneer would somewhat seal the bottom - and i know its never a perfect seal but it should pass a whole lot less moisture than if left bare, especially in a controlled environment such as an a/c home and with 3 coats of poly.

oh well, guess i have no choice but to finish the disaster and tell the recipients to never let the chess board go outside. i always see people claim they did the same oir similar 8 yrs ago and its still fine, and they are told to just wait another year or two. so i guess its a gamble if i outlive them or not.....lol

You do have a choice. You can fix the problem now by making a balanced panel with maximum 1/8" thick veneer on both sides or you can deal with it later. Maybe you will die first, but what will they be saying about that chessboard at your funeral? "Nice guy, but he didn't understand wood movement." :)

[Michael Burnside]

so basically y'all are saying the 1/4" is too thick and its movement will move the mdf. one person told me before that 1/4" max, and it is a little under that so i thought i'd be ok. i have regular paper back veneer on the bottom, walnut - i figured the glue and the veneer would somewhat seal the bottom - and i know its never a perfect seal but it should pass a whole lot less moisture than if left bare, especially in a controlled environment such as an a/c home and with 3 coats of poly.

oh well, guess i have no choice but to finish the disaster and tell the recipients to never let the chess board go outside. i always see people claim they did the same oir similar 8 yrs ago and its still fine, and they are told to just wait another year or two. so i guess its a gamble if i outlive them or not.....lol

Honestly none of us know in this circumstance. Hell, I've seen people with dresser tops glue 3/4" material right to the plywood and it's fine. Crazy, but fine...sometimes. It is probably fine as what you have is generally a good idea, though I do think a thin veneer on the bottom would help and look better as Kevin pointed out. Is 1/8" better than 1/4" in this circumstance? Probably. There is a reason why veneers are thin and can be glued directly to panels without too much risk to movement. I'd go with what you have, and be sure to spline the miters on the perimeter.

[Charlie Fox]

You do have a choice. You can fix the problem now by making a balanced panel with maximum 1/8" thick veneer on both sides or you can deal with it later. Maybe you will die first, but what will they be saying about that chessboard at your funeral? "Nice guy, but he didn't understand wood movement." :)

lol...good one but after surfing around the world and photographing grizzlies solo the last thing i am worried about is mourners trashing my woodworking skills - just a later age hobby... ;-)

[Kent A Bathurst]

so basically y'all are saying the 1/4" is too thick and its movement will move the mdf..

No. Nothing of the sort. The MDF will not move. The glue will not move. The 1/4" of wood above the glue WILL move, and fracture in some pretty impressive ways.

Saddle up. Cross the Rubicon.

[Charlie Fox]

this is the comment that made me think i would be ok:
"The "trick" is to use very thin pieces of the various contrasting material, no matter what the grain and put it on a stable substrate. The thickness shouldn't be more than .25" but preferably thinner so it's more of a veneer than blocks of wood and it should be a lot less prone to seasonal movement issues."

what i am missing is if it is even 1/8" thick, would it not still move and therefore crack?

[Michael Burnside]

this is the comment that made me think i would be ok:
"The "trick" is to use very thin pieces of the various contrasting material, no matter what the grain and put it on a stable substrate. The thickness shouldn't be more than .25" but preferably thinner so it's more of a veneer than blocks of wood and it should be a lot less prone to seasonal movement issues."

what i am missing is if it is even 1/8" thick, would it not still move and therefore crack?

It's not going to crack IMHO, I think the wood is too thin for that and the pieces not wide enough. This, of course, if used like a chessboard and treated accordingly. Don't go setting a beer on it. What it might do at 1/4" is cup the whole board slightly. If it were 1/8" it still might, but far less. That said, once you button up the sides, it might not be enough to matter. Honestly if you built 10 of these, maybe 10/10 would be fine and maybe a few wouldn't. Thinner just gives you a bit more insurance is all. Overall I think the design looks reasonable. No idea what Cesar or Rome would say about it though...

[Kevin Jenness]

For argument's sake, run the numbers. Guessing that the chessboard is 16" square and the face "veneers" are quartered white oak and walnut Woodweb's shrinkulator projects expected seasonal movement of 5/32" on a swing of 5-10% moisture content. That's not at all out of the question in a (air)leaky non-air-conditioned house in my climate. If the recipient's home has minimal humidity changes the chessboard should stay reasonably flat, but if the conditions are more challenging it is quite likely there will be significant, perhaps unacceptable cupping, despite .020" of paperbacked veneer and maybe .005" of polyurethane film on the backside. MDF, even at 1" thick, is not a strong material and it will often bow with even a thin veneer on only one side. Moreover, at 1/4" thick the face veneer will be restrained at the glueline and trying to move to its full potential at the face, inviting checks. In my experience 1/8" is a safer bet and I stay under that thickness when veneering a man-made core.

I am not predicting failure, but I have seen problems with similar constructions. I would be surprised if a border frame did not show open joints at the corners over time unless the service conditions are quite stable. Personally, I like to design and build conservatively so known principles of wood movement are in my favor. Making a balanced panel is the first rule of veneering. One can sometimes get away with breaking the rules but it is a good idea to understand them first.

[Charlie Fox]

For argument's sake, run the numbers. Guessing that the chessboard is 16" square and the face "veneers" are quartered white oak and walnut Woodweb's shrinkulator projects expected seasonal movement of 5/32" on a swing of 5-10% moisture content. That's not at all out of the question in a (air)leaky non-air-conditioned house in my climate. If the recipient's home has minimal humidity changes the chessboard should stay reasonably flat, but if the conditions are more challenging it is quite likely there will be significant, perhaps unacceptable cupping, despite .020" of paperbacked veneer and maybe .005" of polyurethane film on the backside. MDF, even at 1" thick, is not a strong material and it will often bow with even a thin veneer on only one side. Moreover, at 1/4" thick the face veneer will be restrained at the glueline and trying to move to its full potential at the face, inviting checks. In my experience 1/8" is a safer bet and I stay under that thickness when veneering a man-made core.

I am not predicting failure, but I have seen problems with similar constructions. I would be surprised if a border frame did not show open joints at the corners over time unless the service conditions are quite stable. Personally, I like to design and build conservatively so known principles of wood movement are in my favor. Making a balanced panel is the first rule of veneering. One can sometimes get away with breaking the rules but it is a good idea to understand them first.

with all this considered, what finish would you use to keep the most moisture out?