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Thread: Really struggling, need help with table top glue ups

  1. #16
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    I make glued up panels every day (I make a lot of cedar blanket chests). Everybody above has made very valid observations, and provided excellent solutions to your possible problem. In my own case, I use alternating top/bottom clamps, every 10 - 12". I don't use biscuits, but I have the luxury of being able to run my panels through a 24" drum sander - so perfect vertical alignment is not vital to me.

    Personally, given that you state when you check your jointed pieces they are flat and square ("perfect" was your description) I think the most likely problem is that you're over tightening the clamps. Try not tightening them so much on your next glue-up. If the problem remains, then move on to the next solution, etcetera.
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  2. #17
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    Quote Originally Posted by Scott Brandstetter View Post
    Time for glue up, my process........
    I use bisquits (I realize there is a debate about strength) and match the boards up for this process.
    I would not debate the strength of biscuits; I'd debate their usefulness in alignment. Biscuits have too much tolerance on the flats (to permit glue to enter), and thus aren't very good at alignment (on their own) on the flat surfaces. I use dowels. A proper fluted dowel is firm at the high flute points against the inner walls, yet the flutes permit glue to flow. They are also stronger than biscuits, although the face glue surface should be sufficiently strong.

    Others have mentioned their techniques. If properly milled (and dried), with grain altered, you should be able to get flat glue-ups with cauls+clamps on a flat surface.

  3. #18
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    First off, what you are describing is fairly common. I do not think its reasonable to expect that the glue-up will be perfectly flat, even under the best conditions. I also think its typical to have to do some work on the top and bottom surfaces after the glue-up to level the boards to each other although there are tricks to minimize that such as cauls, dowels, biscuits, and the like. I think that small amounts of bow can be managed during assembly.

  4. #19
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    The first thing you should do is check your jointer fence to make sure it's dead on perpendicular to the bed. If not 90degrees, then you're already starting in a deep hole.

    I don't use biscuits and rarely use cauls. I use quick grip clamps to align the boards at the panel ends. I alternate clamps top and bottom and avoid over tightening. I've never worried about alternating the grain (not convinced it helps, and it would often interfere with the desired face grain pattern).

    On extra wide panels I do the glue up in sections, e.g. if it's 6 boards I'll glue up 3 pairs of 2 boards, joint and plane each before doing a final glue up of the 3 sub-assemblies. I've found that doing this improves my chance of flatness.

    Even with the best practices, it's darn near impossible to get all panels dead flat. I don't worry about minor deviations; most of my panel work gets attached to an apron which makes it easy to pull flat.

    Hang in there and keep tweaking your process...you'll get it figured out.
    Scott Vroom

    I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.

  5. #20
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    Quote Originally Posted by Prashun Patel View Post
    Another trick people use is to joint boards 'bookmatched'. Line up the boards in order of assembly, then fold up adjacent pairs (face to face on boards 1, 2, then bottom to bottom on boards 2,3, then face-face on 3,4, etc.). Clamp and joint them as a pair. Again, this way any error is cancelled.

    Also, it really helps me to glue one board at a time. It allows you to work cooler, and neater. It's also easier to nudge boards into vertical alignment and to add more clamps to remove any gaps. If you are a hobbyist like I, you may not mind the sacrifice in throughput.
    Do these. The "bookmatched " final edge joint has proven critical for me.

    I do one joint at a time, so I can focus on that one thing.

    I disagree re: pipe clamps. That is what I use exclusively - up-down-up-down.....but - I do use cauls religiously.

    It is all "doable". Took me a while, but my joints require nothing more that [a] junk card scraper dedicated to glue removal, and [b] good card scraper to even the joint - there is no difference that cannot be taken care of by a card scraper.

    Biscuits add nothing in terms of structural or alignment. A waste of time, IMO.
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  6. #21
    I'm with Kent on the pipe clamps. Cheap and effective, and honestly easier for me to manipulate than cab clamps.

  7. #22
    Dump the biscuits and use cauls to keep things flat as others have said. If the glued-up panel is < width capacity of your planer don't plane before the glue-up. Joint one face & both edges, make sure all jointed faces end up on the same side and glue that sucker up. Light pass through the planer either side post glue-up and as long as the edge mis-match is less than what the planer is removing... you can't goof it up (as they said in the navy "sailor-proof")

  8. #23
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    Quote Originally Posted by Erik Christensen View Post
    Dump the biscuits and use cauls to keep things flat as others have said. If the glued-up panel is < width capacity of your planer don't plane before the glue-up. Joint one face & both edges, make sure all jointed faces end up on the same side and glue that sucker up. Light pass through the planer either side post glue-up and as long as the edge mis-match is less than what the planer is removing... you can't goof it up (as they said in the navy "sailor-proof")
    This is another excellent solution.

    If your glued-up panel is > width capacity of your planer, do it in sections that DO fit in your planer, then glue the sub-assemblies together to form the final product.
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  9. #24
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    You guys are way to hard on BISCUITS. I have never had a glue up fail because of biscuits, (and I used them for many many years) on the contrary they have been immensely helpful as an easy alignment tool. YES, you can use them improperly - to close to the top face or misaligned - but when used correctly they are great. As I noted above, the Festool Domino is more precise and just as easy but the biscuits are more than useful even with consideration to their limitations. Even used with cauls or other top/bottom flattening clamping systems, biscuits help a glue up by getting the top surfaces in very very near alignment prior to clamping. Glue up failures occur for lots of reasons but biscuits are not at the top of the list.

    Just sayin'
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  10. #25
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    I've done quite a few larger glue ups and my experience mirrors a lot of the advice above. Alternate faces against the jointer fence so any error on the edges is cancelled out. Alternate clamps top/bottom about 8 or 10 inches apart. Don't overclamp. I always clamp on my flat work table and then when the clamps are tight I lean the glue up against the table or wall. I use cauls when necessary, but a lot less since I got my widebelt. My cauls are just 2x4s ripped down the middle and faced with blue tape.

    I have a biscuit jointer. It's a Freud I got when I didn't know any better and all the WW'ing mags said you HAD to have one. I haven't used it since the 90s.

  11. #26
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    Quote Originally Posted by Sam Murdoch View Post
    You guys are way to hard on BISCUITS. I have never had a glue up fail because of biscuits, (and I used them for many many years) on the contrary they have been immensely helpful as an easy alignment tool. YES, you can use them improperly - to close to the top face or misaligned - but when used correctly they are great. As I noted above, the Festool Domino is more precise and just as easy but the biscuits are more than useful even with consideration to their limitations. Even used with cauls or other top/bottom flattening clamping systems, biscuits help a glue up by getting the top surfaces in very very near alignment prior to clamping. Glue up failures occur for lots of reasons but biscuits are not at the top of the list.

    Just sayin'

    Yeah, yeah, yeah..........yawn....
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  12. #27
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    Is your jointer set to perfectly 90°?
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  13. #28
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    Quote Originally Posted by Judson Green View Post
    Is your jointer set to perfectly 90°?
    Key point, Judson:

    If you do the bookmatched edge jointing, you can be off dead-nuts by a few degrees and you are groovy. But - you gotta be using cauls to keep it all copacetic.
    When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.

  14. #29
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    Quote Originally Posted by Sam Murdoch View Post
    You guys are way to hard on BISCUITS. I have never had a glue up fail because of biscuits, (and I used them for many many years) on the contrary they have been immensely helpful as an easy alignment tool. YES, you can use them improperly - to close to the top face or misaligned - but when used correctly they are great. As I noted above, the Festool Domino is more precise and just as easy but the biscuits are more than useful even with consideration to their limitations. Even used with cauls or other top/bottom flattening clamping systems, biscuits help a glue up by getting the top surfaces in very very near alignment prior to clamping. Glue up failures occur for lots of reasons but biscuits are not at the top of the list.

    Just sayin'
    I drink beer when I am doing my glue ups. I have never had a glue up fail when I drink beer during the glue up! Everybody should drink beer during their glue ups if they don't want their glue ups to fail!


    My apologies for being such a smart a$$.

  15. #30
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    True, the edge jointing can be off by many degrees and still make a flat panel but the boards need to be glued in the proper way. Those of us in the hand tool camp know this all to well and often joint for panel glue up two boards at a time, so any angle inconsistencies are corrected automatically.
    I got cash in my pocket. I got desire in my heart....

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