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12 posts 1 2

Gluing up large panels

#263589 by algale » Sat Oct 12, 2019 7:08 pm

Hey folks! I am trying to glue up a panel, which, when finished, is about 24" x 24" x .75". The panel is made up of 8 pieces of wood, each of which is about 3" wide by 24" long.

I thought this was going to be a snap using the Shopsmith double bar clamps but when I go to dry fit, I'm getting some twist in the panel. And obviously a panel this big isn't going to be run through a jointer or planer. And I'm not a wiz with hand planes.

I've never glued up a panel this large. Any tips or hints on what I should do to get this panel nice and flat?

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Gluing up large panels

#263591 by BuckeyeDennis » Sat Oct 12, 2019 7:43 pm

I’m thinking that your edges must not be perfectly square. Maybe just a tad helical. What did you use to joint them?

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Re: Gluing up large panels

#263592 by sehast » Sat Oct 12, 2019 7:44 pm

I assume the 3" pieces have been jointed flat and planed parallel. If you have the thickness to spare you might glue just two together so you have four 6" pieces. Then run them through the jointer and planer. Hopefully that will get rid of some of the twist when your do the final glue up of all four.

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Re: Gluing up large panels

#263594 by algale » Sat Oct 12, 2019 8:20 pm

BuckeyeDennis wrote:I’m thinking that your edges must not be perfectly square. Maybe just a tad helical. What did you use to joint them?


I used my jointer. Everything seemed flat and square but I think a couple of pieces ended up with a little post jointing movement. I may not have enough thickness to joint them again but I may be able to replace them.

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Gluing up large panels

#263595 by algale » Sat Oct 12, 2019 8:21 pm

sehast wrote:I assume the 3" pieces have been jointed flat and planed parallel. If you have the thickness to spare you might glue just two together so you have four 6" pieces. Then run them through the jointer and planer. Hopefully that will get rid of some of the twist when your do the final glue up of all four.


I may not have the thickness ...

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Gluing up large panels

#263597 by BuckeyeDennis » Sat Oct 12, 2019 8:41 pm

My modern Shopsmith jointer has a bit of twist in its fence. Which means that it can impart a bit of twist to jointed edges, even if the boards are flat. When I need jointed edges to be dead on, I use a tall flat auxiliary fence, with hot-glue shims between the aux. fence and the jointer fence.

But if your boards twisted after you face-jointed them, that’s a different problem.

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Re: Gluing up large panels

#263600 by masonsailor2 » Sat Oct 12, 2019 11:33 pm

One of the issues you may be facing in the very small differences between your jointed edge and absolute 90 degrees. As you joint them mark the side that is in contact with the fence. When you go to glue up make sure each piece is opposite orientation to the other piece you are gluing it to. Otherwise one mark up and one down. That way any small differences in angle cancel each other out. The next issue is clamping the piece up and keeping the piece flat. Normally you would glue it up extra thick and then use a surface sander to flatten it out. To do it without a surface sander just takes a few more steps. You have to be able to press the panel down to a flat surface as you edge clamp it and let it dry. You can press it down to the flat surface in various ways ie clamping it down or just put a bunch of heavy objects on it. I can elaborate on how to make a press using a workbench and 2X4’s if you want to go that method. A lot depends on just how flat you need the end product to be. If it need to be absolutely flat then I would glue it all up extra thick and then use a router sled setup to flatten it.
Paul

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Re: Gluing up large panels

#263601 by algale » Sun Oct 13, 2019 7:30 am

masonsailor2 wrote:One of the issues you may be facing in the very small differences between your jointed edge and absolute 90 degrees. As you joint them mark the side that is in contact with the fence. When you go to glue up make sure each piece is opposite orientation to the other piece you are gluing it to. Otherwise one mark up and one down. That way any small differences in angle cancel each other out.
Paul


I'll give it a try. I did mark the side that I face jointed, which was then held to the fence to edge. During my test fit, I didn't alternate.

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Gluing up large panels

#263603 by algale » Sun Oct 13, 2019 9:39 am

I did another dry fit this morning using Masonsailor's advice about alternating the orientation of the faces that were jointed (and which served as the reference surfaces when the edges were jointed, and I got a MUCH better result! So I glued up the panel and am cautiously optimistic that it is flat enough! I'll report back after the glue dries and the clamps are off.

It makes sense that tiny errors in the angle between the jointer bed and the fence would stack up in a panel of this size made up of eight pieces.

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Gluing up large panels

#263620 by edflorence » Sun Oct 13, 2019 4:23 pm

Glad to hear the panel straightened out. Masonsailor's idea seems to have done the trick, and I think it is probably the only way to take care of any gaps in the joints that result from a situation where jointing leaves a face and edge that are not perpendicular.

I just wanted to follow up on your reference to Shopsmith's double bar clamps. I have done a number of multi-board panels using them, and I really like the way they work. What I have found to be helpful is to do the glue up in sections rather than all at once. If the panel is four boards, for example, I glue up two sets of two and then do the full panel in a third glue up. Each time making sure the two bar clamps are snugged down to the faces of the boards. And sometimes I add a caul to the very ends of the boards to be certain they are in the same plane as the rest of the panel. I have never had to do it as a regular thing, but setting dowels or biscuits along the edges of each board will also help greatly with the alignment.

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Ed
Idaho Panhandle
Mark 5 of various vintages, Mini with reversing motor, bs, dc3300, jointer, increaser, decreaser

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