Why did my 3/4" plywood bent and how do I fixe it??


JTWoodworks

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I recently made a cabinet using 3/4" furniture grade walnut veneered plywood. I bought the plywood pre-finished from a local plywood distributor. The cabinet is mounted in a corner of an office and holds a computer router, wifi box, and things like that. The door to the cabinet is 18" x 58" and is mounted with a piano hinge on the left side. The issue is that the bottom right corner of the door has warped out, away from cabinet, about 3/4" - 1". The door is solid plywood with pvc trim covering the edges. 

Why would the plywood bend like this? And more importantly, how can I fix it? This cabinet isn't in direct sunlight, close to a heater or anything like that. The computers in the cabinet get a little warm but the entire top of the cabinet is open. I thought about routing a groove on the back of the door and gluing in some steel c-channel. It would be 1/2" x 1 1/2" channel. Would this work and what other ideas do you have? Thank you/ I need some help figuring this one out!

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I recently made a cabinet using 3/4" furniture grade walnut veneered plywood. I bought the plywood pre-finished from a local plywood distributor. The cabinet is mounted in a corner of an office and holds a computer router, wifi box, and things like that. The door to the cabinet is 18" x 58" and is mounted with a piano hinge on the left side. The issue is that the bottom right corner of the door has warped out, away from cabinet, about 3/4" - 1". The door is solid plywood with pvc trim covering the edges. 
Why would the plywood bend like this? And more importantly, how can I fix it? This cabinet isn't in direct sunlight, close to a heater or anything like that. The computers in the cabinet get a little warm but the entire top of the cabinet is open. I thought about routing a groove on the back of the door and gluing in some steel c-channel. It would be 1/2" x 1 1/2" channel. Would this work and what other ideas do you have? Thank you/ I need some help figuring this one out!
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http://www.finehomebuilding.com/2002/11/01/fixing-warped-doors


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The door is 3/4”? If you don’t care what the inside looks like, I would attach some 3/4” by 1.5” to 2” hardwood horizontal strips to the inside of the door, with the edge of the strip against the door. Maybe taper it down to 1” on each end so you won’t have as much to drill thru for the screws. 

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Constant heat on the inside of the door isn't helping but if there is a hole in the bottom convection should make it workable. I've found that almost all commercially made flat slab veneered doors are made with a particleboard core.  I don't love the stuff but it stays flat much better than plywood does. Long plywood doors do have a tendency to twist.

https://www.kjmagnetics.com/products.asp?cat=173

Look at BC82CS -S and BC82CS-N if you get one of each the combined power is 26 lbs of pull.  That should be plenty to hold the door shut & flat if shimming the top left back corner doesn't work.

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  • 2 months later...
On 4/20/2018 at 7:31 AM, wdwerker said:

Constant heat on the inside of the door isn't helping but if there is a hole in the bottom convection should make it workable. I've found that almost all commercially made flat slab veneered doors are made with a particleboard core.  I don't love the stuff but it stays flat much better than plywood does. Long plywood doors do have a tendency to twist.

https://www.kjmagnetics.com/products.asp?cat=173

Look at BC82CS -S and BC82CS-N if you get one of each the combined power is 26 lbs of pull.  That should be plenty to hold the door shut & flat if shimming the top left back corner doesn't work.

That site is a gem. Thank you!

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