You can’t always depend on your free hand to secure wood when cutting it with a handheld tool. Apply glue to the edges of the boards being joined and lay them in position on the bottom cauls, the edge of the panel against the end of the cauls closest to you. You want to see some glue squeezeout, but you don’t want to completely squeeze the glue from the joint. Be sure the corner of the block is square, or your precisely- cut 45-degree joint faces won’t be flush when you clamp them together.
Bar clamps: Quicker and easier to use than pipe clamps, light-duty bar clamps are perfect when you need a long reach and moderate pressure. Cauls are usually used in a glue up so you need to make sure the cauls do not get glued to the project by the glue squeeze out. The parallel clamp has two faces that provide parallel force and plenty of it. The long bar on this clamp supports the workpiece at a 90 degree angle so the joint comes out flat and strong. Pipe clamps are especially well suited for this application because their clamp pads can rotate 90 degrees to engage one another. Includes: 2 PC 50 x 250 Heavy Duty Screw Handle F Clamp Wood Metal Work Quick Action Glue Floor.
I did not think that this post was of as much interest as it should be when I posted a few months ago, but at the Woodworking Shows people are fascinated by the fact that I generally don’t use dogs so I thought it was time t do a more in-depth one because it’s important for people to know that for little money you can have a good system. Tighten the nuts just enough to be sure the cauls are in contact with the wood. He also found that the force of an individual clamp can differ by a factor of two depending on the strength of the operator.
Irwin also makes larger varieties if your woodworking project calls for it. The Irwin 24 inch Quick Grip Bar Clamp is a great example at about half the price of similarly sized high-end brands. There is essentially no limit to how large of an object you can clamp with the pipe clamp. The cauls force the boards into alignment, and hold the panel flat while the glue sets. When planning your clamp buying, consider three general categories of assemblies. That’s similar to the superior three-point pressure provided by a double-headed clamp.
Apply a continuous strip of 2”-wide packing tape to the contact surface of each caul and rub it down to be sure it is fully adhered to the wood. Bessey makes a H-style pipe clamp that can stand on it’s own two legs (literally). I’ve used these clamps more often than not to clamp something to a table to keep it from moving. This solid-wood edging on plywood, for example, would have required a clamp every few inches.
The force will radiate sideways in both directions the same distance as the clamp is from the glueline. Check your work using a square on the outside of the new 45° corner – if necessary, loosen the clamps very slightly and tap to make adjustments. The cauls also keep the panel flat during glue up and minimize the amount of work (and lost wood) to get it flat later.
Apply strips of tape along each joint, pressing the tape firmly onto the wood, then flip the boards and apply glue. I usually plan my glue ups for during the week so that I have to leave the clamps on until I come home from work the next night. Both the wood species and the grain orientation affect the clamping pressure required for a strong glue joint.
You can make clamps for this job cheaper if you buy some threaded rod from the hardware store (I’d get the thinnest available because you only need enough pressure to hold all the boards flat against each other while the glue dries). The jaws of woodscrew clamps can be angled in relationship to each other to finesse the application of pressure on out-of-parallel surfaces.
Clamps come in various sizes and shapes, and while some are spring-loaded, most have a fixed jaw and a moveable one attached to a screw with a handle. First, it overcomes the viscous resistance of the glue and forces it into a thin, continuous film in contact with the wood, which is necessary for a strong joint. These are some simple wood joinery methods that you’ll be glad you have in your basic woodworking repertoire. Now we’ll clamp our boards with these pistol grip clamps, making sure to clean up any glue squeeze-out with a damp rag. I think a key question is whether you want to get to that glue squeeze out before it hardens.
This is a really good blog for you to look at because he utilizes some nifty homemade ideas into his work including a cool twisted rope clamp. Surprisingly, the instructions on my Titebond III Ultimate wood glue say that you only have to clamp for 30 minutes, and then don’t stress the joints for 24 hours. Thrust and vibration are more pronounced when cutting small or thin pieces of wood, and you must usually clamp these to cut accurately and safely. When routing a tabletop, for example, I can rout all the way around without stopping and shifting clamps.
Clamping cauls are a great tool to help produce flat panel glue ups but they cannot remedy every situation. It worked quickly and perfectly and I think it saved the project – dowels would’ve required too much perfection in the wood (and my sawing skills). Put a chunk of scrap over the joint, drive the screws through the scrap to pull the glued case together, and remove it all after the glue dries. Place the parallel clamps over the wood to be glued and simply tap the pillow blocks to create an evenly distributed pressure along the glue joint.
Armed with the pressure data included in the article, I can do a clamp pressure test of my own with one or two of the clamp styles shown and calculate just how many clamps are needed for the glue-up based on my grip strengh. Second, the linked clamp pads may mar the surface of the panel, so slip a square of cardboard under them. To avoid the wiggling pad problem altogether, use bar clamps that feature clamp pads specially designed to stay parallel under pressure (photo D). I have to say that at first I wasn’t sure about the locking mechanism on this clamp.
Namely, you can twist their two threaded screws independently to angle the jaws for less-than-parallel surfaces, or to apply extra pressure at the jaw tips. Woodworkers discovered early on that by cambering a caul to create a belly at its center, it’s possible to increase clamping pressure between the clamps that are positioned at each end of the caul. That way you’ll know all the clamps you need are at hand and there won’t be any nasty, unexpected misfits in your joinery to ruin your glue-up and your day.
The Irwin Quick Grip 6 Clamp Set is a great place to start because it gives you various sizes and for the price of one high-end clamp (around $40). Now draw the joint closed by clamping the handscrews together with bar clamps on top and bottom. On big things like table tops, legs or other projects where there is a lot of glue I always leave it overnight. Joint one edge of the glue-ups (with the glue seam) to make it flat and straight. But the barracuda-like jaws leave nasty scratches on the wood, so tape or clamp softwood strips on the corners to shield the project pieces. If we put a clamp on each end, we can pull the cauls together easily – too easily.
To speed up drilling the holes for the spring pins, I make two holders out of scrap wood – one for the fixed jaw and one for the adjustable jaw. Moisture in glue triggers a reaction between iron and chemicals in wood (called tannins”). Specialty clamps: Band clamps include a ratcheting mechanism that makes them good for clamping round, odd-shaped or multi-sided assemblies, ranging from boxes to chairs. Extend the reach of your hand screw clamps with a couple of lengths of scrap wood.
When your clamps are too short for a project, link two pipe clamps by hooking their lower clamp pads together (photo below). Use web clamps to tightly hold the joints together, and wipe the squeeze-out from the inside corners. Check in every weekday for news, information, projects, and answers to questions from Fine Woodworking readers everywhere. Parallel-jaw bar clamps: These bar clamps have jaws covered with non-marring, non-stick plastic faces that are designed to remain parallel when the clamps are tightened.