Removing cup from chessboard

[RichardM]

I have made a hardwood chessboard which is just under 10mm thick, it has cupped by about 2mm in the middle. I have tried just putting weight on and it flattened it but as soon as removing it the cup returned. Don't really want to glue mdf backing board. Any suggestions as to whether gluing hardwood strips diagonally after weight flattening might work. Cannot put through planner as too wide. Did see suggestions of applying heating to crown which thought about but think it will affect the glue and could end up with lots of 50mm squares

Any suggestions.

 

[Yojevol]

So are the squares thick veneers applied to the top side only? If so you need to apply similar veneers to the underside to balance it up.
Brian

 

[RichardM]

So are the squares thick veneers applied to the top side only? If so you need to apply similar veneers to the underside to balance it up.
Brian

Sorry should have said, solid wood squares so assume veneer will not work

 

[Phil Pascoe]

Have you polished both sides equally?

 

[RichardM]

So are the squares thick veneers applied to the top side only? If so you need to apply similar veneers to the underside to balance it up.
Brian

Sorry should have said, solid wood squares so assume veneer will not work

 

[RichardM]

Have you polished both sides equally?

Not applied any finish yet

 

[RichardM]

Have you polished both sides equally?

Not applied any finish yet, good suggestion though

 

[Yojevol]

Sounds to me as though there were small errors in the individual squares which have eventually caused the distortion. I think you've got 3 choices:-

1. Remove material by hand planning
2. Heat up (assuming glue is PVA) whilst keeping it all flat and square . Now there's a challenge.
3. Put it down to experience and start again.

Brian

 

[recipio]

Assuming it is cupped concave side up your suggestion of glueing in hardwood strips on the convex side should work. You need to clamp it down to a true flat surface while the glue sets. Usually done with parallel lines in boards that have cupped I don't see why it won't work with diagonal saw kerfs.

 

[RichardM]

Sounds to me as though there were small errors in the individual squares which have eventually caused the distortion. I think you've got 3 choices:-

1. Remove material by hand planning
2. Heat up (assuming glue is PVA) whilst keeping it all flat and square . Now there's a challenge.
3. Put it down to experience and start again.

Brian

Thanks for the advice, not sure which is worse . Made from strips not individual squares not that it changes anything.

 

[RichardM]

Assuming it is cupped concave side up your suggestion of glueing in hardwood strips on the convex side should work. You need to clamp it down to a true flat surface while the glue sets. Usually done with parallel lines in boards that have cupped I don't see why it won't work with diagonal saw kerfs.

Thanks for that, are you suggesting cutting shallow trench or. Table saw kerf, then fill with hardwood strips, they could only be about 5mm deep. Also what centres would they be. Sorry so many questions.

 

[alex robinson]

Sorry should have said, solid wood squares so assume veneer will not work

If it is solid, how about a router sled? stick / clamp it firmly, flatten the top, flip over flatten the other side? Then just sanding to remove the marks where the individual passes line up (though if you made a perfectly flat sled, these would be tiny)

 

[paulrbarnard]

Best option would be to make it double sided. Put another set of blocks on the back.

 

[RichardM]

Best option would be to make it double sided. Put another set of blocks on the back.

A good option but I have already cut the box sides to hold the pieces so won't fit

 

[recipio]

Thanks for that, are you suggesting cutting shallow trench or. Table saw kerf, then fill with hardwood strips, they could only be about 5mm deep. Also what centres would they be. Sorry so many questions.

I have done this with sheet goods which I don't want to waste. Usually a single saw kerf per 300 mm on the underside does the trick. 5 mm deep should work - it is the glue line that holds the board flat . To make diagonal lines on a chessboard you would obviously need to make a jig to hold it while you pass it over the saw. Not ideal on a nice piece of work but it might just salvage the piece from the scrapheap.

 

[RichardM]

I have done this with sheet goods which I don't want to waste. Usually a single saw kerf per 300 mm on the underside does the trick. 5 mm deep should work - it is the glue line that holds the board flat . To make diagonal lines on a chessboard you would obviously need to make a jig to hold it while you pass it over the saw. Not ideal on a nice piece of work but it might just salvage the piece from the scrapheap.

Thanks, that is helpful. My current plan is to route a 5mm trench across the back, place in a stainless steel bar in resin and then place a lot of weight on the top and , fortunately I have some bar from another project so if all goes wrong I am no worse off. This is my first post I have been blown away how helpful people are

 

[Fitzroy]

Thanks, that is helpful. My current plan is to route a 5mm trench across the back, place in a stainless steel bar in resin and then place a lot of weight on the top and , fortunately I have some bar from another project so if all goes wrong I am no worse off. This is my first post I have been blown away how helpful people are

We all love a problem to solve, you can even make a post without a problem to solve, and we'll find the problem in it to solve.

 

[hlvd]

I have made a hardwood chessboard which is just under 10mm thick, it has cupped by about 2mm in the middle. I have tried just putting weight on and it flattened it but as soon as removing it the cup returned. Don't really want to glue mdf backing board. Any suggestions as to whether gluing hardwood strips diagonally after weight flattening might work. Cannot put through planner as too wide. Did see suggestions of applying heating to crown which thought about but think it will affect the glue and could end up with lots of 50mm squares

Any suggestions.

I suspect you’ve left it uncovered with the dished side on top?

This has the effect of unequal drying with the side on top drying more than the underside, causing this cupping.

If you turn the chessboard upside down leaving the underside exposed for a few days with some stickers underneath it should go back to flat. You’ll have to monitor it otherwise you may have the exact same effect as you started with.

Keep your wood covered and it’ll stay flat indefinitely.

 

[hlvd]

Thanks, that is helpful. My current plan is to route a 5mm trench across the back, place in a stainless steel bar in resin and then place a lot of weight on the top and , fortunately I have some bar from another project so if all goes wrong I am no worse off. This is my first post I have been blown away how helpful people are

Overkill, try my method first and once flat cover it all with your desired finish.

 

[RichardM]

Overkill, try my method first and once flat cover it all with your desired finish.

Thanks, I will try your suggestion and see if it works