# Steel channel to prevent cupping



## Hawkdriver (Sep 15, 2016)

Looking for your thoughts here. Im getting ready for a lived edge kitchen table build consisting of 3 boards edge joined spanning approx 40in. I have seen an a few instagram feeds that companies are using steel channel routed under the slab to prevent cupping obviously with elongated screw holes to allow movement. I like the idea if i can prevent any cupping im ok with doing it however i cannot easily find the channel short of paying a crazy price from a few specific companies. Is it worth the investment or if dried, glue up and finished properly is it overkill? If you think its worth the effort any source of the channel online?


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## Steve Neul (Sep 2, 2011)

It's possible the steel would help however it would have to be sufficient for what ever thickness of top you make. I wouldn't route a channel in the bottom for it though. Generally what ever you do to one side of wood you should do to both sides. By routing a channel on the underside you would weaken that side of the wood and cause the top to warp where it might not without the grooves. Most of the time warpage is caused by a imbalance in moisture content from one side to the other. We often have a member make a table top and leave it laying on their work bench for a couple days and find out it warped. By doing that moisture in the air can get to one side and not the other so the side facing up swells up. It's the same with a finished table if you only put a finish on the top and leave the underside raw wood. The underside needs a finish too for this reason.


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