A double-leg clamp is the tool of choice for doing panel glue ups as it equalizes the force over both workpiece surfaces and therefore resists cupping. This one is very light in weight, compared to its cast iron and black pipe rivals, yet is no less useful and is largely made with wood scraps. You may use several of these on a panel glue- up project and still move it about the shop with ease. In addition, since its not made of ferrous metal, it won’t react with tannous woods like oak or cedar and leave a black stain upon contact with glue squeeze out, so standoffs or spacers are not needed. It is also an effective carcase clamp due to the oversized ram and anvil bodies. It has a maximum width capacity of 28” (711.2mm), and 3-½” (88.9mm) in stock thickness.
Quick adjust is made by bringing the anvil to the nearest dimension needed and inserting the anvil pins. Final clamping is transmitted to the work via the 9” (228.6mm) acme threaded veneer press screw. Coarse dimensions of 10 (254mm), 14 (355.6mm), 19 (482.6mm), & 23 (584.2mm) inches are provided, with the maximum of 28 inches (711.2mm) being set by the tailstock bar itself.
In use, rotating the clamp so that the legs straddle both surfaces closely will facilitate alignment of adjacent stock edges. Lay the project down on a bench top, and finish by applying a downward force upon the top leg. A light mallet rap will help ensure the finished (up) surface edges are flush. End by a final tightening of the clamp.
Tip: Remember that bone crushing force is not needed to create high quality glue joints, just some careful stock preparation.
Step 1: Video Showing Clamp in Use
Tool is shown in actual use; advance to 06:02 minutes, or better yet, watch the whole thing.
Step 2: Plans and Procedures
The following instructions tell how to construct the components for the clamp. Once again, apologies to my metrified friends, please convert dimensions as needed.
Step 3: Headstock
Bore a through hole as indicated for the press screw's t-nut and check the fit. Although the manufacturer specifies a 1” (25.4mm) hole, it is a casting, and some hand work needs to be done finessing the hole for a proper fitment. Do not drive it in or the headstock may split under the force of use. Also, bore two stopped depth holes for the 1” (25.4mm) diameter, 36” (914.4mm) long dowel rods that serve as legs. Layout & center punch the locations of the six- 3/8” (9.5mm) dowels that will be used to secure the legs to the headstock.
Step 4: Anvil and Ram
Locate and bore two 1-1/16” (27 mm) through holes for the legs. 1-1/8” (28.6mm) holes may work but too large a diameter may result in a “camming” action of the components. If an adjustable hole bit is not available, grind down the sides of a 1-1/8” (28.6mm) spade bit.
Step 5: Anvil Only
Locate and bore two- 7/16” (11.1mm) diameter stopped depth holes. Be as accurate as possible, as this component will also be a drilling jig for the four leg stop stations.
Step 6: Assembly
Insert legs into headstock holes, ensuring they are seated all the way. Slip on the anvil as shown in the drawing. Attach the tailstock with ¼-20 (M6 x 1) x 1- ½” (38.1mm) long flat head machine screws. Carefully bore the six- 3/8” (9.5mm) diameter stopped hole locations previously marked in the headstock operation. Install 3/8” (9.5mm) diameter dowels, using glue. Glue only the pins in place. Gluing the rods is not necessary for strength.
Move the anvil to the first hole station location (10” (254mm) capacity), as shown in the drawing. Clamp the project to a workbench surface to prevent components from shifting while drilling. Using the anvil as a drill guide, bore two- 7/16” (11.1mm) holes clear through the rod only. Unclamp the anvil and move to the next location, 4- ½” (114.3mm) away, re-clamp and bore as before. Repeat two more times, for four stations in total.
Remove the anvil from the project, and re- bore (enlarge) only the two anvil pin holes to ½” (12.7mm) diameter. Do not bore clear through the anvil, as this feature keeps the anvil pins from slipping through the other side.
To finish the anvil component, cut two pieces of 3/8” (9.5mm) dowel rod to 2-3/4” (69.9 mm) long. Cutting a shallow depth head groove (quirk) around the pin diameter about ½” down is optional, but looks professional. Slot that end of each, & glue in a 9” (228.6mm) long piece of string. Wrap the center of the string around an upholsterers tack and drive it between the pin holes as shown on the drawing.
Prepare the press screw by drilling four clearance holes for a #6 (M3.5) screw in the removable pad casting. This will allow the ram to retract upon reversal of the screw and keep it from sliding about. Insert the t- nut into the headstock, and secure with two #6 (M3.5) flathead screws. Run the press screw into the t- nut, attach the clamp pad & lock its set screw.
Now slide on the ram & anvil, and fasten the tailstock in place. Bring the anvil up to the first station and insert the pins. Clamp a piece of scrap between the ram & anvil and check to see if the pad is centered. If so, screw the clamp pad to the ram. Remove the stock and check for smooth ram travel the length of the screws throw. Finish the panel clamp with a clear sealer and paste wax. This will give excellent resistance to glue drippings and allow for a clean looking, smooth operating, hard working shop tool you will prize for many years to come.
Step 7: Parting Thoughts
Alternate means of driving the ram can be done by a simple threaded rod, 3/8" (9.5mm) or larger, fashioned in the style of a press screw. Having access to metalworking tools will also be an asset if shop- making the screw system, but is not mandatory.