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Thread: Need help on jointing/planing large subassembly

  1. #1
    Join Date
    Dec 2018
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    Washington DC
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    Need help on jointing/planing large subassembly

    Hi folks,

    I'm working on building my first laminated workbench top after reading the Schwarz books and advice on this forum. I have already glued up four 7.5" wide subassemblies of my top. The individual boards in each subassembly are pretty well aligned since I used dominos to guide the glue-up. The edges are also still pretty square to the faces, and the faces are pretty clean of glue because I scrubbed pretty hard right after the glue up.

    I'm wondering how best to prep the subassemblies before gluing them to each other. Schwarz recommends jointing and planing each subassembly before the final glue up. I can see how that would be smart, but I'm a little intimidated since each subassembly is already pretty heavy and I am not eager to lose too much more thickness (they are currently just over 3" thick each). Should I:

    1. Go the whole way by face-jointing, edge jointing, and planing each piece, then squaring the other edge up by running through the TS? I have a solid 8" jointer but I'm not at all sure I can keep a 50# subassembly totally square to its fence or the TS fence. (I have a 12" dewalt planer) So I'm worried I'm going to lose a lot of thickness this way. (You can just tell me that losing 3/16 of thickness is no big deal in a 3" thick maple top) Plus, if I rip one edge in an effort to get it square it will end up less clean than the jointed edge I have now.

    2. Trust that the edges are still pretty square, and just face-joint what will be the top face and glue?

    3. Just glue it and go?
    Last edited by Sam Shankar; 02-27-2020 at 10:28 AM.

  2. #2
    Join Date
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    If the glue ups are pretty flush, which they should be if you used Dominos, then you should be able to flatten the final bench top w/o huge effort using a handplane. But if you have obvious variations or, even worse, any twist in the assemblies, then face jointing and planing are going to be a lot easier. And no, I would not worry about losing 1/4" of the top if it's 3" thick. My bench top is only 1/2" thick in the center section; only the perimeter is really thick.

    FWIW, 50 lbs should not present a major problem to face joint or edge joint. Just use roller stands to help support it going into and out of the jointer. Same with planing.

    John

  3. #3
    Just a few thoughts: If the what will be the top surface is already quite flat and even you can probably forgo planing the sections, but remember the only way you will have to flatten the top once glued up is by hand planing or building a huge router flattening sled. (or taking the whole top somewhere with a wide belt sander). Running a long, heavy sub-assembly through a lunchbox planer is no picnic though, you will need solid infeed and outfeed support, but in the end it may be easier than a lot of hand planing (although you'll still need to do some). I would not be concerned about sacrificing a little thickness in favor of flatness. You also don't need to worry too much about the bottom surface being perfectly flat and even, just the top.

    Regarding jointing the edges: try clamping pairs of assemblies together with strips of notebook paper or the like between them, every foot or so along the length. When clamped, if you cannot easily pull out any of the strips, *and* if the top surfaces are still in line and flat across the joint, then you can forgo any further edge jointing. If the paper doesn't come out, but the top isn't flat across the joint, you can try flipping one of the sub-assemblies; you may get lucky and find that they now are flat or flatter across the joint.

    Don't stress if things aren't perfect; it's a bench. You're going to have do final flattening after glue up no matter what, all this other effort is to just minimize the work involved in that step.

    Having said all that, there are folks here with way more experience doing this than me, but those are my suggestions. Good luck!
    --Certainty is the refuge of a small mind--

  4. #4
    Check if you live near someone who will rent time on a CNC router or widebelt sander. I recently found a "maker space" with a 36" widebelt that charges $0.50/min. So $8 later, I had a very flat bench top.

  5. #5
    Join Date
    Apr 2013
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    Okotoks AB
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    My hard maple top is 28.5" wide x 3.5" thick x 72" long. I first glued up 3 sections, each 9.5" wide. Those were then jointed on one face & planed on the other to the same thickness. I then squared up the glue faces by joining one with the top face registered against the jointer fence and then running through the planer with the unjointed face up. When I glued up the 3 sections I used cauls to meticulously keep them lined up. After glue up I just did a little hand planing to do a final flattening.

    My jointer be is only 54" long & those sections were pretty heavy, so I build in feed & out feed bed extensions which made handling much less stressful. I made the mistake of trying to turn over the complete top myself & did a number on my shoulder. That was a dumb mistake.

  6. #6
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    Thanks all. Iím not eager to get outside help because, as Paul said, itís just a bench, and because this is a skill building exercise as much as anything else. In that vein, Iím leaning towards jointing the top faces, skip planing the bottoms, dry fitting, and edge jointing only if necessary.

  7. #7
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    Quote Originally Posted by Sam Shankar View Post
    Thanks all. I’m not eager to get outside help
    But please do get some help handling the complete top. When I turned my top over my thought was "I don't need any help with this"

  8. #8
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    I take things like that to a local shop (one of my hardwood suppliers) and have them run them through their wide sander to level everything after final assembly. It's never cost me more than $25. And yes, that includes workbenches. "Just a bench" still has to be absolutely flat...wink, wink...nod, nod...
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #9
    I didn't face joint mine when I assembled my workbench. I just edge jointed, and glued up with the reference face (top) down on a reasonably flat surface and cauled them to it. After that, I just planed the top flat after glue up. The bottom was flat enough that it didn't cause an issue with connection to the trestle base.
    ~mike

    scope creep

  10. #10
    Join Date
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    My bench top is about 22 x 60 ash, around three inches thick. At the time I made it I only had a 15" planer so I couldn't plane the whole thing. The ash lumber was all 4/4 and I face planed everything so it was nice and flat, then glued it up into two 11" wide pieces. I used white glue for the open time. After it was dry and the glue scraped off, I ran the two pieces through the thickness planer to flatten them, then glued the two halves together using regular yellow glue, a LOT of bar clamps and a couple of cauls to keep the two halves as flush as possible. Once it was dry I did the final flattening using winding sticks and a #5 1/2 with a heavily cambered iron for the initial flattening, then a #6 and a #8 for final finishing. As I recall it took between 1 and 2 hours to get it flat, not hurrying. I didn't use dominoes, biscuits, splines, or anything else between the boards and it's held up fine for well over ten years and a major move and climate change.

  11. #11
    Join Date
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    I would joint and plane all 4 faces then glue together.

    Once glued they be so flat you'll be just using a card scraper to finish it off............Rod.

  12. #12
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    Quote Originally Posted by Rod Sheridan View Post
    I would joint and plane all 4 faces then glue together.
    And, to be clear, by that you mean face-joint, edge-joint, plane the other face, then run the other edge through the TS.

  13. #13
    Don’t rush this last step. Take your time to assure you’ll have a flat work surface. I’d make sure each 7-1/2” segment is flat and the glue edges are square to the top face, sliding a square along the entire length and using a hand plane for adjustments. The better job you do here, the less thickness you’ll lose in the end.

    I would definitely hand plane the entire top to flatness. You’ll have to do this to periodically reflatten it also. Unless you oriented the grain direction for each board, you may have to plane some in the opposite direction as others to avoid tear out. If that is the case, power planing is likely to create tear out. I always seem to take off more with the power planer than with hand planes.
    Last edited by H. Gregory Porter; 02-28-2020 at 6:06 AM.

  14. #14
    Join Date
    May 2007
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    Florida
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    Prepare each sub assembly as if it was a rough cut individual board. Don't worry about losing thickness or width too much, but don't take off any more than necessary either. Once they are dead flat, they can be glued together carefully enough that the top will be very flat and co-planar.

    Dan

  15. #15
    I would make sure all is square, and do the dry run for sure.
    Check for light between the slabs, this is definitely best done when they are standing on edge.
    Two jointed battens to aid alignment for the face sides might be a good idea, just to be safe.
    Good luck with the bench.



    Just a bench... Them's fightin words

    Tom

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