Any tips on gluing up thin stock (1/2") panels and keeping them from popping out of alignment under clamp pressure? I'm making a small 20" square cherry panel (out of some boards I rescued from the burn pile because they were horribly twisted with my newfound jointer knowledge, but the twist was so bad that I could only salvage 1/2")
I'm using one clamp above and two below (pipe clamps), and it keeps wanting to pop out of flat... any tips?
I just used a method where I cut mortises in two scrap strips and slipped them over the ends of the strips I was clamping, parallel to the clamps. Worked fine on 1/8" thick material, so it ought to work on 1/2".
Lionel
hm good idea! thanks :)
I just glued up a panel that was also 20" square. I put two clamps below and one clamp above. Then I wrapped each end (parallel to the clamps) with wax paper and clamp another board using C-clamps along the edge to keep everything in alignment. Even then, it is hard to get it absolutely perfect.
Bill
Hi tmbg,
Get a piece of flat thickish ply or mdf, a few inches larger than the panel all round. Nail a couple of parallel cleats to it, the cleats being exactly the same distance apart as the panel width, less 1/32 or so. Put a strip of polythene sheet between them to prevent the glue sticking the panel to the ply/mdf. Glue up the edges of the boards, assemble the panel and put it between the cleats. If you've got the distance apart correct, the panel will almost fit between the cleats, but not quite, looking like a very shallow tent, with the joint at its apex . Put another sheet of of poly over the top, and weight the whole lot down with sandbags/pile of magazines etc. The panel will be forced down flat and will bear hard against the cleats, forcing the joint tightly together and keeping perfect alignment.
This is similar to the method used by some guitar-makers to joint 1/4" stock for backs and soundboards. It works pretty well for 2 or 3 piece panels, but might be a bit awkward for a larger number of boards.
You may need to experiment a little with the distances apart, using a dry fit.
HTH
Frank
Or just wax the ply/mdf. Glue will pop right off it when you're done.
The way I've done it is leave the cleats far enough back to slip a couple wedges in to snug things up. Allows for fine control of the pressure.
Several.
Are the edges of the boards precisely square to the faces? If you didn't use a true precision square to align the fence on your jointer, they might not be. (Note: if your square doesn't say "Starrett" or "Incra" it might not be as square as you think.) A slight variations from dead-on-square in the jointer alignment can be compensated for by jointing the edge of one board with its top face against the fence, and the mating edge of the next board with its bottom face against the fence, so that (for example) an 89-degree edge on one board will mate against a 91-degree edge on the other, still producing a flat joint.
Your clamping pressure may be too high. I've successfully edge-glued 1/2" stock without any problems -- but never into panels quite that wide.
Are you trying to glue up the entire 20-inch panel at once? That's a lot to try to do in one shot with stock that thin. It will probably work better if you glue it up in stages, e.g. glue up two 10-inch panels, wait for the glue to cure, and then glue them up to make the full width.
Lastly, lay cauls (straight pieces of stout lumber) across the glued-up panel at each end, and hold them in place with C-clamps. Use waxed paper in between the cauls and the panel to prevent the cauls becoming attached to the panel.
Hope this helps...
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
Another idea seen on David Marks' show is to place foil-wrapped bricks over the joints to provide some weight to hold the boards down.
That weren't "foil", dude ... that be ITWDFYHTSALFYH duct tape. I have a pile handy in my shop also, all the way up to cinder block size.
Ahh, of course, that makes more sense. Even got some of that here too :-)
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