Lazy Susan Checkerboard

[Coop]

Las weekend I took some 8/4 rough cherry and milled it to 2” square. I took two pieces of rough 4/4 walnut and laminated them and milled them to 2” square. I glued the two pieces together and ran them through the drum sander and cross cut them into 3/8” slices. My goal was to maker a checker board for my young nephew. I took each 2” x 4” piece and glued them to some 1/4” bb ply, them trimmed the whole thing with a 1/4” wide maple boarder and sanded it all down to 220. It has been sitting on my ts ever since, waiting on some finish. Today I go out and I can spin that sucker like a Lazy Susan. So what you’re seeing is end grain. Where did I screw up? Both boards are kiln dried from a reputable dealer. 

[treeslayer]

Well you screwed up when you didn’t pay attention in school and become a doctor instead of a woodworker and my best guess is maybe sitting on the TS for so long caused it to warp, have you tried some wood blocks under the corners and some weight on it? very nice work Coop, don’t give up on it

[Chet]

I think Dave is right.  Cast iron can be a bad place to leave wood for a period of time.  I am guessing that your cherry and walnut bowed and because the ply was only a 1/4 inch thick it was pulled along for the ride.  You could try wetting with a sponge or spray bottle the concave side with warm water and then lay it on a flat surface (shop floor) concave side down.  Worst that can happen is nothing. 

[Coop]

Never thought about stickering  a project, just the boards. Thanks you two and I bet you’re right. I’ll put the reverse whammy on it tonight. Glad it’s not cold enough for a fire as that’s where it would have gone! 

[Ronn W]

Another possible explanation could be:  1) The glue used on t he end grain pieces (moisture) caused the grain of the pieces to swell just a little.  Then you glued the assembly to the pywood.  As the glued (and fibers next to the glue) dried, they shrank a little while the plywood did not.  2)  When doing veneer work, it is always a good idea to veneer both sides of the panel to keep things in balance.  I think you assembly was "out of blance".  Hope you have luck straightening it out.

[Chet]

4 minutes ago, Ronn W said:

I think you assembly was "out of blance".  Hope you have luck straightening it out.

Ronn could be on to something.  Plywood is always made in an uneven number of ply's to keep it stable and when you added you checker board it made it an even number.

[Coop]

I guess now I will have to shim the playing pieces ! 

[houstonjc]

I've made chess board patterns before and have experienced the same thing when glowing them to a substrate.  I think that your primary issue is that you glued solid wood (which wants to expand and contract) to plywood, which can't.  

 

Last weekend here in Houston was wet and humid, and our lumber therefore had more moisture and was expanded.    This weekend is dry, and the wood is contracting. Since the squares are glued to the ply, it is pulling the wood inward from all four angles.  It may flatten back out when the humidity strikes us again.

 

I found that I needed to get the hardwood down to under 1/8 inch (nearing veneer thickness) to make sure that the expansion / contraction was contained by 1/2 plywood.  If you want to use 1/4" ply, I would shoot for 1/16" thick hardwood.

[Coop]

Yeah, humidity was super Las Vegas type low and I suspect you are right! 

[Brendon_t]

Unfortunately bud, you done broke the rules. Remember when Steve said what you do to one side, you do to the other side?  THIS is why. 

[Coop]

I laid this thing on edge on the shop floor waiting for a coolish night to build a fire. I picked it up Sunday night and it was flat as a pancake so I set it back on edge untilI had a chance to put a finish on it. Tonight it has cupped in the opposite direction. I’ve stickered it, hoping for it to go back flat again. If and when, I will slather it with ARS! 

[treeslayer]

Sounds like a good plan Coop, let’s hope it works, that’s a great looking piece

[Coop]

Thanks for saying but up close there are a couple of gaps that will get an epoxy fill as I couldn’t figure out how to clamp the pieces together and not spend a day doing so. 

[Chet]

Sounds to me like you may be fighting a losing battle Ken.  I would probably start a fire and toast some marshmallows to go with your beer.

Live and learn.

[Coop]

I’m betting on the come! We are headed to Louisiana tomorrow for a little R&R and when I get back, if it’s not back to flat, I will epoxy the whole thing and make a bird bath out of it 

[wtnhighlander]

Coop, I did a similar board, with similar problems. 

Sacrifice the border, make another 1/4" end-grain checkerboard, and glue it to the back of the plywood, once you catch it in a flat state. The add a new border. 2 plies will never stay flat, but three has a fighting chance. The new bottom layer should probably be end grain to balance the top, but it doesn't have to be pretty. All poplar, alder, whatever is cheap there, should work.

[Coop]

Hmmm. Unfortunately I dadoed the trim to fit on top of and surround the edge of the ply and pin nailed it into the board. Probably best to just start over and do as you guys suggest. The little nephew is a brat anyway so I may just go to Walmart and buy him a cardboard board. 

[difalkner]

When I make cutting boards, even 2" thick boards, I have to be careful how I store them while they're in the process and stages of construction.  At night or if I move on to other projects while glue is drying on the cutting board(s) I stand them on edge and out of the way.  My table saw extension is unfinished MDF and I have found that it's safe to leave a cutting board lying flat on that surface but I still don't like doing it for more than a few hours. 

Our shop is climate controlled so I don't have huge humidity swings and don't usually have issues with end grain work cupping but if it has just been glued and not yet surfaced it's still subject to the moisture in the glue and will likely move, so that's why I stand them on edge.

David