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Forum topic by lew posted 1460 days ago 1040 views 0 times favorited 10 replies Add to Favorites Watch
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lew

10006 posts in 2391 days


1460 days ago

Topic tags/keywords: question cherry straighten a panel

Glued up some 7/8” cherry into a 62” x 22” panel to make a table top. The moisture content was less than 7%. It is made from 4 boards. Because of the sap wood, it was not possible to alternate the growth rings. One of the boards had a slight bow from end to end. Used biscuits to aid in aligning the edges. All seemed to go perfectly until it was removed the clamps and placed the panel on the workbench. The panel had bowed in the middle (from end to end) of over an inch!

So far, have tried weights in the center of the panel with the ends raised on 2x stock and wetting the underside of the panel. Seemed to help but not enough. Flipped the panel over and now have the center sitting on the 2x and the ends weighted.

Could anyone please provide some ideas about what went wrong? And maybe another way to fix it. Man, I hate to think of wasting 10bdft of cherry.

Thanks in advance for any and all ideas!

Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.


10 replies so far

View Dan'um Style's profile

Dan'um Style

12937 posts in 2619 days


#1 posted 1460 days ago

I’d find some 8/4 seasoned quartersawn hard maple and screw it to the bottom
...
another thought is to make a table with a skirt around the top and add a bunch of screws to hold it flat. Let it set screwed together for a month to normalize and give the screws another 1/4 turn. Plane the top as flat as you can. Hopefully the highest spots will be less then an 1/16” to remove

-- keeping myself entertained ... Humor and fun lubricate the brain

View glassyeyes's profile

glassyeyes

136 posts in 1965 days


#2 posted 1460 days ago

I’ve been struggling to make two table tops out of white oak, slightly larger than you describe. On the three-board panel, One was nice and flat; the other two weren’t. I put them on the outside, and did the bad thing; I kerfed them at four points, part-way across the width, and about two-thirds the depth. Inelegant, but with enough biscuits they were flat enough. The underside is pretty ugly, though. For my sins, they’ve bowed a little across the grain. Some strongbacks and clamps have corrected enough of it to put the tables together. I don’t have a meter, so I don’t know what the moisture content was. The wood seemed well-seasoned, but how knows? This is a much larger project than I’ve ever tackled, and it’s taxing my limited skills.

-- Now, where did I put those bandaids?

View lew's profile

lew

10006 posts in 2391 days


#3 posted 1460 days ago

DaN- The top is going onto an existing “buffet” style cabinet- I guess I was a little misleading when I called it a table top. Unfortunately, the existing construction prohibits the addition of a long cleat. I think I can add enough scab blocks around the inside of the cabinet to secure the top but I am worried about the pressure required to bring the top flat and keep it there.

Glassyeyes- I have considered cutting saw kerfs across the underside. My concern there was the cuts would have to stop short of the “front” of the top- so as not to be seen- and when the top is pulled flat the cuts would split through to the front.

This is the first time I have had this experience and it is quite perplexing.

Thanks for the suggestions. Maybe a combination of both might do it.

Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

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lew

10006 posts in 2391 days


#4 posted 1459 days ago

shopguryl- Thanks for the drawing! I hadn’t thought of the edge banding idea. This could work!

Thanks
Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Hacksaw007's profile

Hacksaw007

591 posts in 1825 days


#5 posted 1459 days ago

Lew, not knowing how you are attaching this top to the base, your fear of too much stress from pulling that top down, might be the way to straighten it out. Hopefully you are using some type of expantion contraction rigging to hold the top so that it can still float….. You can use that rig to pull the top straighter a little at a time, not putting the full stress on it. I have seen people “wet” the top by wet rags and place the top in this stress mode and have pulled the top straight, especiall if your base comes out to the outside edges closer. Did that make any sense? If not I can do better explaining maybe…. Seen this done at Pennsylvania House and at the kitchen cabinet company that I worked for, they tried this from what I told them about PAH…. Good luck and let us know what happens.

-- For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. John 3:16

View lew's profile

lew

10006 posts in 2391 days


#6 posted 1459 days ago

Hacksaw007- The weights, water and setting over night seems to have lessened the bowing. I am hopeful that with enough anchor points the top will be flat after installation.

I think I will allow it to set for a day or so to see if it tries to re-bow.

Thanks for the suggestion.

Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Beginningwoodworker's profile

Beginningwoodworker

13337 posts in 2309 days


#7 posted 1459 days ago

Lew, maybe you had the boards clamp to much.

-- CJIII Future cabinetmaker

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lew

10006 posts in 2391 days


#8 posted 1459 days ago

CJ- I thought of that, too. But, the bow was along the length of the boards. I’ve always had trouble with clamping pressure so recently I made some clamping culls and they have really helped reduce the bowing of panels, across the width.

I, just checked the panel and it is still holding at about a 1/8 to 1/4” bow. Much better than the 1”+ I had yesterday.

Thanks CJ for the thoughts.

Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Jonnyfurniture's profile

Jonnyfurniture

59 posts in 1463 days


#9 posted 1459 days ago

Hey lew,

I’ve had some good success by tossing the panel on the lawn in the sun. Just keep an eye on it every 20 mins. Then attach it to your table base right away.

View lew's profile

lew

10006 posts in 2391 days


#10 posted 1459 days ago

Jonnyfurniture- Thanks for the idea. Due to the location of the buffet. I’d have to put the finish on the top before I tried this, but it may come to that.

Lew

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

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