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Thread: Quandry

  1. #1
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    Quandry

    I have been working on a white oak trestle table for a long time. The top sat against the wall for a few years. I finally broke it out and find that there is a crown in the center the length of the table. I was ready to cut it up, but thought I'd try to persuade it to come back some. I built a level table out of a couple sheets of 3/4 plywood which I the screwed to my heavy sawhorses. It is all level and good on the base. I laid some thin cardboard on the ply and sprayed it with water, laid the top one that. Laid waxed paper across the top and with 4- 2x2x.019 steel clamped them across the table. The table has flattened out nicely over a few days. I am leaving it in the clamps right now. I'm afraid it will explode Anyway, I achieved the goal and now, the quandary is...where do I go from here? The top is 32x74x1 1/8". It is a six board top with mahogany strips on the glue joints. Full length Wh oak splines in the joints and oak breadboard ends. Plans are good, but these things need to be thought through

  2. #2
    Join Date
    Sep 2016
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    Modesto, CA, USA
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    Where in the world do you live? what is the temperature humidity now and seasonally? You may get better responses if you change the title so it has some relationship to your question.
    Bill D.

    PS: 17% today at 4:36 PM
    Last edited by Bill Dufour; 11-04-2018 at 7:37 PM.

  3. #3
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    I'm in Nevada City, CA. Elevation 3000'. Humidity 32%. We got just over a 1/2" of rain in mid-Sept and as you know in Modesto, it hasn't spit at us otherwise since mid-May, so dry dry. I can edit the post but the title seems to be uneditable. Another quandary!

  4. #4
    Jack

    You seem to have done the right things based on the theory that different equilibrium moisture content (EMC) is what bowed the panel. The side that was against the wall is the side that was convex, right? All you really needed to do, probably, was dry the convex side a bit. Maybe you managed to get both sides to equal EMC by wetting the concave side -- I can't tell. I would never try to flatten a glued up panel with clamp pressure but you seem to have gotten away with it. Put the table in a dry place where air can circulate around both sides and give it a chance to stabilize, acclimate, i.e., equalize EMC on both sides. If the glue joints are still intact you are ready to move forward.

    Once it is stabilized, I would give both sides two coats of a film finish, preferably dewaxed shellac. Shellac is a good barrier against water vapor. Opinions will vary about what kind of finish to use, but apply equal amounts of finish to both sides so that it won't tend to warp again.

    This is guesswork based on what you wrote but may be worth considering

    Doug

  5. #5
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    Jun 2014
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    One of the several reasons why the table top is the last piece to be made and fastened for a project. When I make a top, I won’t start milling the boards unless I have the time to get it in clamps that day. Furthermore, I won’t do all that if I don’t plan on sanding it and finishing it within the next few days to a week. My lumber and shop are in a climate controlled basement, but as you experienced, it’s easy for things to get away from you when they are left to their own devices.

    Few things. One, how much was the bow over what length? If it wasn’t substantial, then I wouldn’t worry much. If it was substantial then I would sticker it and watch it for a week. You may need to repeat what you just did. I once took 3/4-7/8” bow over 6’ out of an end grain island top. Contractor Was beyond negligent with storing and transporting it, but I was able to mitigate most of his stupidity. In that case, it took a few sessions of wetting one side to get it back to a stable 1/8” bow. Finally, after a few days if it stays mostly flat then I would finish that sucker(bottom and top) and get the breadboards on and attach it to the table base. The base and breadboards should allow you to straighten out any remaining bow.

    I know it sucks for people with busy lives(myself included), but I’ve found most projects benefit from being completed in a short period of time. This was mostly a result of you storing the table top poorly, but really, storing the unfinished table top for years was asking for trouble.

  6. #6
    So far so good.

    I think your next step should be remove the barriers to air circulation and re-clamp the top flat. That should include adding stickers on top of your reference surface. I would leave it clamped as long as you can.

    You could use a fan to speed things up - since you live in a fairly dry climate you need to lose the water you added, then get finish on all surfaces as quickly as possible.

  7. #7
    Join Date
    Sep 2016
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    Lucky you to have some rain this season! Nothing here yet. I would remove the cardboard and install some cauls so air can circulate on both sides then let the moisture stabilize for a week or so and remove the clamps. You could even screw on some angle iron across the bow and leave then on permanently.
    Bill D.
    Last edited by Bill Dufour; 11-04-2018 at 7:39 PM.

  8. #8
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    Thank you all for taking the time. Patrick, too right on pinning the tail on the donkey. Here is what I have done and what I plan to do. The bow, or crest, was right down the middle of the top, approx. 5/16" and it had a bit of a twist. It has flattened out nicely. No sign of splits or cracks, so far. I removed the top from the clamps, flipped it finish side up, put 2" steel above and below and re-captured it. Air can circulate both sides now. I covered it with a moving blanket for the night and will check it out again in the morning. I'm going to bring this down slowly.
    A thought I have had is to get some 1/8-3/16 angle iron and cut it leaving only 1/2" to fit the dado x 1/4 or 5/16. Rout the dadoes 12" from the ends of the table where the trestles will go and one in the center. The legs will cover the angle and the center cross piece will cover the other. I am not sure on the dimensions of the cut angle, but that will be apparent once I get into it. Once screwed down that might help stabilize the table. Given the history on this I am afraid that if someone bumps into the table it will start walking around the room, so I think the steel might help. Thoughts?

  9. #9
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    If you do the steel, or any other cross pieces, The screws will have to have slotted holes for the wood to move or the top will split.
    Bill D

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