# Miter Shrinkage



## bwad40 (Oct 18, 2015)

I have made several chess boards out of solid lumber with mitered borders and I keep having issues with the joints coming apart. As you can see in the photo, I have loaded the corners with glue and biscuited them but I still have this issues. Is this unavoidable due to cross grain gluing? If anyone has a solution, I am all ears!


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## Kazooman (Jan 20, 2013)

The problem is not shrinking miters, it is more likley the expansion of the field of the board forcing the miter joint apart. From the grain orientation shown in the picture, the field is going to expand and contract along the left to right direction with changes in humidity. The long grain piece of the frame at the bottom of the picture is not going to expand along its length to any significant degree. No amount of glue in the corner is going to hold the joint together against the expansion forces. A good way to prevent this is to have the edges of the playing field set into dados in the frame with room for expansion.


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## bondogaposis (Dec 18, 2011)

Your miters aren't shrinking, the squares are changing in width with every change in humidity. This type of failure is well known and called the "panel of doom". You need to allow for wood movement in your construction or use a stable substrate for your squares, like plywood.


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## bwad40 (Oct 18, 2015)

Alright, thank you guys for the help. Another questions would be then, what if I put the chess board on top of the mitered frame? So you have sort of a concave look underneath the playing surface?


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## wood2woodknot (Dec 30, 2012)

If you alternate the grain direction of each tile (whites one way, darks at 90 degrees) expansion should cancel out. Notice the vinyl tile on your floor - always rotated for the same reason. It's not just for visual aesthetics. Also using two wood species with similar expansion characteristics.


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## geekwoodworker (May 27, 2014)

One way to avoid this is to have the chess board floating inside the frame and the board should be 1/8" smaller than the frame to allow for expansion and contraction. Make it similar to stile and frame doors where the panel floats.

Another way to avoid this is to use quarter sawn wood for the board. Quarter sawn wood expands and contracts through its thickness and not its width.


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## Cooler (Feb 3, 2016)

Take it apart. Add a 1/2" thick stable substrate. Wrap the substrate with a mitered frame and allow the squares to rise proud of the substrate and the frame.

CornerWeld glue was specifically designed for picture framers. I tested it many years ago when I had my frame shop and it outperformed everything else out there for mitered joints.

Since that testing Titebond II and Titebond III have come out so I don't know if it still is top dog for corner glueing. It is still the standard for the picture framing industry.

http://www.thegrumble.com/index.php?threads/corner-weld-glue.76544/


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## BinghamtonEd (Nov 30, 2011)

> If you alternate the grain direction of each tile (whites one way, darks at 90 degrees) expansion should cancel out. Notice the vinyl tile on your floor - always rotated for the same reason. It s not just for visual aesthetics. Also using two wood species with similar expansion characteristics.
> 
> - wood2woodknot


I don't think that alternating the grain direction would cancel out expansion, at best it would cut it approximately in half. And, it would potentially introduce cracks showing up between the tiles as they're now trying to expand in a different direction than the adjacent ones. Vinyl tile will expand/contract to some degree with heat fluctuations, however, unless the substrate is solid wood, the tile will expand evenly across the length and width, making the orientation an aesthetic decision, not a functional one.

I like geek's suggestion of floating the panel inside the board. You could make the tiled portion a raised panel, with a decorative chamfer, cove, etc. around the edges, that way as the panel expands/contracts, the gap between the tiled portion and the frame looks more like a design element, and less like a plain old gap.


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## splintergroup (Jan 20, 2015)

Yep, expansion. That is one of the things I designed around in my latest cutting board project (by avoiding it all together!).

You center tiles will expand much more than the frame allows, no way around that. If you do what ajh suggests, you can at least make the expansion equal in both directions, but it will still move and you run the risk of separation of the joints between the adjacent tiles for the same reasons (cross grain glue joints).
Others have suggested placing the board into a dado in the frame, much like one would do with frame/panel door construction. You could also put the board on top (outside) of the frame was you surmise. A third alternative is to rabbet the center board and place the frame into that rabbet (with the necessary clearance).


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## 000 (Dec 9, 2015)

Check out the board I made 38 years ago.
Miters are as tight as they were when it was made.
The wood squares are 3/4" thick glued to a pc of 1/2 particle board. 
My only explanation is the the squares are sealed real good and that I live in a dry climate. 
(The oak inlay between squares is only 1/8" deep)


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## a1Jim (Aug 9, 2008)

I agree with all the others comments about your problem being wood movement.I also agree with the idea of treating your top like a raised panel. You're not the first person who has overlooked wood movement cross grain situation.
Here is a PDF I give to all my students on the subject of wood movement.

http://toddpartridgedesign.com/sr_pages/documents/UnderstandingWoodMovement.pdf


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## JAAune (Jan 22, 2012)

I'd personally use veneer to do a chessboard. It would allow for all sorts of artistic license and eliminate the movement issue.


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