Isaiah Barker Posted March 22, 2021 Report Share Posted March 22, 2021 Hey community, I'll try and keep this to the point. I've made a table top for a client out of hard maple. For about a week and a half the top had been sitting out of clamps and unfinished, basically not being touched as I worked on the base. The client changed her mind with the top, not liking a dark vein along one of the edges of one of the boards. So we decided to rip the table to remove the 1.5" wide vein and re-glue. So to me, I didn't think there was a problem with this approach. 2 weeks later the table was finished and delivered. 1 week after, the top had bowed up as much as 3/8" in the middle, right on the seem of the re-glue. Not sure if this is the reason so I turn to you guys. Additional info: I've oriented the faces of the top so the rings run in the opposite direction to combat this exact issue. Up Down Up Down. Never had a problem in the past. Both the top and underside were stained and finished within the same days. The top is being secured in place with Z-clips (from Rockler). So plenty of room for expansion, but that should only be for the movement along the width and not really have anything to do with the top bowing or cupping. I had the client leave the table in place and wait a week to see if it just needed to acclimate to the room... An embarrassing attempt of not knowing the cause or a solution but it bought me a week. The bow remained the same. Any ideas on the problem? Solution? Sorry, no pictures :( Thanks! Link to comment Share on other sites More sharing options...
Chestnut Posted March 22, 2021 Report Share Posted March 22, 2021 What are the dimensions and how is the top mounted to the table? I see Z clips but is it just fastened along the long edge or all edges? It it secured in the middle of the long and short edges or just the corner? What does the base look like? Is the bow going up in the center or down in the center? I don't think the glue has much to do with this. unless you cut out material in the middle and glued in a different board creating 2 new glue lines. Odds are the lumber acclimated to the new house and moved. If you can hide a brace under the table you could use a brace with elongated holes on the ends to restrain the top back to flat. Depending on the size it may make 2-4 braces. Think of it like an apron that just runs under the table. This picture shows the flat. For more strength I'd turn them on edge and use 6/4 material. This should bully most tops into submission. elongated holes are critical for expansion and contraction. Link to comment Share on other sites More sharing options...
BillyJack Posted March 22, 2021 Report Share Posted March 22, 2021 How thick is the top? Link to comment Share on other sites More sharing options...
wtnhighlander Posted March 23, 2021 Report Share Posted March 23, 2021 Some details of the construction would help. I will say that I made a thick-topped table for a friend some time back, with lumber that measured well within the acceptable moisture range for MY house. But he keeps a large de-humidifier running 24/7, which I didn't know about. Within 6 weeks, the 2" thick top had bowed down where it overhung the sides of the base by 3/4". When I checked moisture content, it had lost half of what was present at delivery. My solution was to rip, re-glue, and refinish, then extend the top rails of the trestle base to reduce the overhang. The extension was a 4" angle, tapered at the end and painted to match the walnut accent pieces. Link to comment Share on other sites More sharing options...
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