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Thread: jatoba tabletop

  1. #1

    jatoba tabletop

    Hello: this is my first post to the forum, but I have been benefiting from many threads with good advice. I am making a large dining room table (44x 60, extendable to 9 feet) in jatoba. I've noticed that after jointing and planing, some boards do spring back to the original bow, as I had read it would. Would using loose tenons (instead of buiscuits or just plain edge-on-edge gluing help to prevent warp/bow/convex problems after glue-up? Is it overkill? Thank you all for any advice

  2. #2
    Join Date
    Dec 2007
    Location
    Minot, ND
    Posts
    558
    When you joint a board you should be cutting off the cup/bow in the board. There shouldn't be any spring back as such. Once the board has been jointed, it is then thickness planed to a uniform thickness. Again, no spring back. If you're trying yo do everything with a thickness planer, without jointing one face grist, then springback can occur as the feed rollers will press the wood flat as it passes through the planer. Are it exits the planer, it can then revert to its previous form, seeing as how the cup/bow was not cut off by jointing.

    You our can, however, joint and then plane a board, and have it re-bow through wood movement. Internal stress in the wood will sometimes cause this. Or warping can occur as the moisture content in the piece changes, but this usually will only happen after it has sat for a while. If either of these occur it is best to re-machine the board till all bowing and cupping are removed. If it would then remove too much wood, best to replace it with a new piece.

    In response to your question, adding loose tenons won't add anything to your glue up other than helping yo align the edge of the boards. You want,(and need), your lumber to be flat and square prior to gluing it up. Especially if this is for a tabletop.

    Good luck

    Clint
    Last edited by Clint Baxter; 05-11-2014 at 7:01 AM.

  3. #3
    Join Date
    Dec 2008
    Location
    Northern Michigan
    Posts
    4,973
    Ok, Jatoba is a different animal. It will screw with you every step of the way. It moves a lot more than one would think a wood with that specific gravity would. Unless its very thin, it not the planer pushing it down its just the nature of the beast. With Jatoba it is always best to sneak up on the finish size, as every time you make a cut it does something else to screw with you. Very beautiful when done, but to give you a clue I double my labor bid when on a Jatoba project.

    I have done several desk tops, and it is always a lot of work. The figured material I was using was stubborn, laughed at a hand plane, so had to be sanded out. I used auto body straight line and air boards, and it still took me 8 hours for each top. I say if its for yourself embrace the imperfections. It acts like case hardened wood in many ways, but less predictable. The upside is you will never dent the table.

    Allow for a lot of movement seasonally across the grain when you fasten the top if you are in a climate that changes with the seasons. By the way you should have your location in the header, makes a lot of difference in solutions because of climate.

    I have a 42" wide by 9' long slab I am saving for my own desk.

    Larry

  4. #4
    Join Date
    Feb 2003
    Location
    Bellingham, WA
    Posts
    1,933
    I have found that if I want straight and flat jatoba parts, I need to start with flat and straight rough boards. It is very sensitive to moisture changes, like you get when removing uneven amounts of material via jointing and planing. The skin of the board will have a different MC than the core, so trying to flatten a warped board creates more problems as it re-adjusts. With some boards, you can almost watch it change from flat to potato chip in the space of minutes. So select carefully and don't try to polish any turds.

    It can be quite striking - out of many thousands of BF of jatoba, I've only seen a few curly boards. I saved a couple and eventually made a small table with them.

    Last edited by J.R. Rutter; 05-11-2014 at 1:23 PM.
    JR

  5. #5
    "tenons (instead of buiscuits or just plain edge-on-edge gluing help to prevent warp/bow/convex problems after glue-up? "
    ************************************************** *********
    A tough challenge to outsmart the future of milled Jatoba, alright.
    But I would T&G the stuff, glue it in a press that has equal air flow on both sides and whence fastening, allow plenty of slop in the slop mechanism.
    Moreover, don't over tighten the hardware. The screws, even in sloppy holes or slots, may dig into the wood and prevent its seasonal slip/slide.
    This slab is cupping up, not randomly.

  6. #6
    Thank you for all the replies and advice. I am in Portland, OR. Yes I have jointed one face and edge before planing the boards, and the springback effect happened in 3 of 8 boards. To Pat: you lost me with "T&G". What is it? tenon and glue?

  7. #7
    Join Date
    Nov 2007
    Location
    Hendersonville, NC
    Posts
    331
    I believe he meant "Tongue and Groove". That style of glue joint will force the boards to align, but the milling must be accurate.
    ______________________________
    Rob Payne -- McRabbet Woodworks

  8. #8
    Join Date
    Feb 2008
    Location
    Northwestern Connecticut
    Posts
    7,149
    Oh, Jatoba. You'd think it would be more popular. Great advice from JR. Pick straight boards. Get straight boards. I made a few tops from it last year, real joy. One i left really long, made it at the start of a mud room build, staid reasonably flat, pretty wide boards, in the 13" wide plain sawn range, so a top almost 30" deep in two pieces plus a little slice at the back edge. But they started reasonably flat, I turned a lot of boards to get the one I used. The other was a book case top for my son, quarter sawn, has remained perfectly flat since the day I milled it, still in the shop 2 years later, waiting for a round tuit and a free day. I finished the top quick to stave off checking......The mudroom bench checked bad on both ends, was in a climate controlled shop with both ends sealed with shellac, and wrapped, kept vertical so air was all around. Nearly had to resort to butterfly keys to control the checking.

    Oh yeah, thats the other nice feature. Not only does it often move a lot and fight the normal flattening process.....it checks too. Sometimes months or years after your done! Possibly right in the middle of thanksgiving dinner....please pass the HEY WHERE DID THESE CHECKS COME FROM.......Sure is pretty though. And tough. Enjoy that, and know, its not just you.

  9. #9
    Thank you again for the advice (and the good-natured commiseration) I know I am not alone in my troubles, as I had researched in different woodworking forums before I started, but I did not want to alter my client's first choice of wood (stepdaughter) plus believing of course that somehow I would be able outsmart-out-tough through plenty of sweat this tough, challenging wood.

  10. #10
    Join Date
    Nov 2010
    Location
    Anchorage, Alaska
    Posts
    1,617
    Enrique,

    One good technique, if you have the time, is to rough-mill the wood to near final dimensions and let it set for a few months to see if it's going to go crazy on you. If it moves very little, then you can clean up the movement when you bring it to final thickness / size.

    Jim
    One can never have too many planes and chisels... or so I'm learning!!

  11. #11
    Don't be too worried about using jatoba. Yeah, it might move a little bit more than other wood, but it is still within the ballpark of normal wood movement. If you start with quality materials (generally straight boards) and use quality build methods that account for wood movement, you can do normal high-quality woodworking procedures and still end up with a perfect product. I recently made a 3'x8' jatoba table in 8/4 and it is still just as flat a year later (this particular one has endured severe humidity changes) as it was the day it was wide belt sanded. If you build it right with the right wood, it doesn't matter what happens in the air around it, regardless of the wood.

  12. #12
    Join Date
    Jan 2009
    Location
    Detroit, MI
    Posts
    1,661
    Having just finished a jatoba dining table last weekend, I feel your pain. Good luck!

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