Gluing up panels is a must-have skill in woodworking. From table tops to raised panels there are plenty of times you’ll need to glue boards edge to edge. When you do you want the panel flat, with rock solid glue joints. Here’s the recipe for making that happen in your shop.
Rough cut to length. As you crosscut material for the panel leave it 1” – 2” longer than the finished panel needs to be. When cutting up long boards it’s often easiest to cut them with a jig saw. It’s much easier to accurately joint short boards than long boards, so it pays to get them close to their finished length.
Joint one edge of each board. The edges must be smooth, straight and square before gluing boards together. If you don’t own a jointer, or need more info on using a jointer, be sure to see the related stories we’ve listed at the end of this article.
It makes the two edges parallel, which makes clamping easier. If the boards you’re clamping are wedge-shaped they tend to slide past each other when you apply clamp pressure. Wedge-shaped boards also result in a funky shaped panel that can be hard to square up later.
Ripping makes the next round of jointing go faster. If the board has a rough edge it’s faster to straighten it on the table saw than on the jointer.
I shoot for boards that are 4” – 6” wide in my glue ups. The wider a board is, the more prone it is to cupping. That’ll sure mess up making a flat panel. If you want to use a 12” wide board it may seem counter intuitive but what you need to do is cut it down the middle, and then incorporate the two narrower pieces in the glue up.
Your edge to edge glue up should be 1”-2” wider than what is required for the finished panel.
Joint the sawn edge. Note the position of the pencil mark from the first jointer pass. The face that was against the fence on the first cut is away from the fence on the second cut. Mark the second edge, making the mark near the jointed edge and on the face that was against the fence. For more info on why it’s important to alternate faces against the fence check out the sidebar at the end of this story.
The joints should easily close with hand pressure. If you have any gaps go back to the jointer for another pass. Excessive glue and clamp pressure do not compensate for lousy joinery.
Mark the faces. Once you’ve worked out the joints and orientation of the boards, make a face mark. A big triangle will show you how the boards go together. You shouldn’t be guessing at this while you’re working with glue and clamps. The bigger the glue up, and the more pieces you’re working with, the more important a face mark becomes.
As I’m working with the boards I go for the best looking face, a function of grain and color. You do not need to alternate growth rings, provided your material has been properly dried.
Prep your clamps. If you’re using pipe clamps made up with black pipe, put masking tape on the pipe. If you don’t, glue squeeze out can loosen up the black coating and allow it to migrate into your panel. It can take A LOT of sanding or planing to remove those black marks.
What about biscuits, dowels or some other joiner? No need, as far as strength goes. With good joinery the joint will be stronger than the surrounding wood. Need proof? Watch this video http://www.wwgoa.com/video/000330_strength-of-glue-joints/ On large glue ups you may want to add biscuits, or something similar, simply to help keep the faces aligned so you don’t have to work so hard to level the panel as you’re clamping it up.
Clamp the panel. Use an equal number of pipe clamps above and below the panel. Having clamps above and below the panel, with equal pressure on all the clamps, helps keep the panel flat. The pipe clamps on top were made using galvanized pipe, instead of black, so masking tape isn’t required.
Don’t over tighten. As soon as you see the joint close, you’re done with clamp pressure. No need for clamp pads because the panel is oversized and the edges will get cut off later.
Check alignment. As you tighten the clamps you’ll need to manipulate the boards to make sure the faces are aligned. Near the end of the panel you can bridge the seam with a small clamp. As you tighten this clamp it will pull the faces into alignment.
Don’t wipe the squeeze out. Wiping wet glue with a damp rag just pushes the glue around and makes an even bigger mess. Allow the glue to dry until it’s rubbery, about 10-15 minutes, and slice it off with a chisel. If you don’t wait long enough it’ll be too wet and make a big mess. If you wait too long it’ll get too hard and you won’t be able to cut it off. Check the squeeze out frequently to see if it’s hit the right consistency yet. When it’s ready it’ll peel easily.
Make glue ups easier. If you want to simplify gluing up panels, consider upgrading to parallel jaw clamps. There’s no need to put masking tape on the beam and, because the jaws are parallel to each other, there’s no need to clamp from below and above. You’ll find parallel jaw clamps at woodworking specialty stores, from a variety of manufacturers. A warning, these clamps aren’t inexpensive, but they make clamping panels (and doors) so much easier, they’re worth the price.
Why Alternate Faces on the Jointer?
When setting up the jointer your goal is to make the fence perfectly perpendicular to the table. That’s a great goal, but it doesn’t always happen. If the fence is off a little you’ll joint a slight angle onto the edges of your pieces.
In this picture the jointed boards are lying on a table with the face that was against the fence down on both boards. You can see that because of the angled edge the joint won’t close unless I rock one of the boards up off the table. That’s fine if you’re making a barrel, but no good for panels.
If you know that your jointer fence is perfectly perpendicular you can ignore this aspect of the panel sequence.
Glue brushes #04Z51 Woodcraft www.woodcraft.com (800) 225-1153
Jointing on a Router Table http://www.wwgoa.com/edge-joint-on-a-router-table/
How to Master the Jointer http://www.wwgoa.com/master-the-jointer/
Jointing with a Router http://www.wwgoa.com/jointing-with-a-router/