Intro: Infinite Band Clamp
A band clamp lets you clamp many different shapes for gluing that would be difficult to pull together with just standard bar or pipe clamps. Want to make a picture frame? Use a band clamp!
You can easily and cheaply make your own band clamp to use on rectangular frames, furniture, circular objects, hexagons, octagons, n-gons …. and clamp anything of practical size!
You will need a 4" by 10" hardwood board 3/4" thick, a 5" by 20" piece of 3/16" (tempered) hardboard, a 1/4" and 3/8" hardwood dowel (e.g. oak, don't use poplar or pine), a 4" long 3/8"-16 hex bolt (or rod) fully threaded, a 3/8"-16 T-nut, a #8 hex nut, ten or more feet of 3/4" heavy Nylon webbing, four 3/4" triglide sliding buckles, and wood glue. For tools you need a table saw, a band saw, and a drill press.
Step 1: Construct the Corner Jaws
The band clamp consists of a number of jaws, a band that wraps around the jaws, and a tensioning mechanism that pulls the band around the jaws to tighten them on the work piece.
For a rectangular frame you need three jaws to hold three of the corners, and a fixed jaw and tensioner for the fourth corner.
To make these corner jaws, cut out a 4” diameter circle from ¾” hardwood. Drill a 1/8” hole through the center. Cut two 5” by 5” squares from 3/16” hardboard (actual thickness is less than 3/16") , and also drill 1/8” holes through their centers. Use nails to line up the hardboard centers with the hardwood circle, and glue the block together. The hardboard edges should line up as shown in the pictures.
After the glue dries, print and cut out the drilling template 1 and stick onto the square block with rubber cement. Then drill the ¼” and 3/8” holes as shown all the way through the block.
Use a band saw to cut the block into quarters, and cut out the jaw corners (1” square) on each piece. You will cut through the 3/8” holes, its part of the design. Finally trim off the diagonals on each piece.
Cut eight pieces 1-1/8” long off a 3/8” hardwood dowel. Use an oak dowel; pine or poplar is too soft. Glue these dowel pieces into the 3/8” inch diameter half-holes. The dowels will function like ‘swiveling’ jaws to accommodate clamping joints that are not at 90 degrees.
Cut eight pieces 1-1/8” long off a ¼” hardwood dowel and glue into the top/bottom holes in the hardboard. These dowels will retain the band for the clamp. There should be enough space between these dowels and the circular edge of the hardwood to thread the band through.
Lightly sand and clean the edges and faces on the four corner jaws you just made. Set aside.
Step 2: Construct the Fixed Jaw and the Tensioning Mechanism
Start with a 3” by 4” piece of ¾” hardwood. Trim off ½” on each side along the 4” dimension. Cut one of the trimmed pieces in half - use the band saw or hand saw, its too small for the table saw! You will use these three pieces of ¾” hardwood: one piece of 3” by about 2-7/8” (depending on the kerf of your table saw blade), and two pieces ½” by about 1-1/2”.
Cut two pieces of 3/16” hardboard to 3” by 4”.
Now glue together a block (hardboard – hardwood – hardboard) as shown in the diagram and pictures. I used pennies stacked and taped together during the glue-up to create the slot for the clamping band. Remove the penny spacers after about 15 to 20 minutes before the glue completely dries.
After the glue dries, attach template 2 to the top and side of the block; and drill holes in the top and into the side as indicated.
On the band saw notch out the fixed jaw, cutting through the 3/8” holes as in step 1; then cut the block in half along the line indicated on the template. Mark the two pieces as to how they go together, you really want the side-holes to line up! You now have the fixed jaw and the moving slider for tensioning.
On the fixed jaw glue in four 1-1/8” long dowel pieces (2 each 1/4" and 3/8") similar to step 1. Sand the edges clean and the dowels flush.
Cut two 5-inch long pieces of 3/8” dowel. The dowels should be able to slide back and forth smoothly through the moving piece. If necessary, sand the dowels (you can do this with a drill press, see picture). Glue the dowel pieces into the fixed jaw piece. Use the moving slider to keep the dowels aligned while gluing.
Step 3: Install the Tensioning Bolt
Install a 3/8”-16 T-nut in the center hole of the moving slider on the side that is facing the fixed jaw. You will have to drill a shallow 7/16" recess around the center hole to accommodate the T-nut. Insert a 3/8”-16 threaded rod (or 4” long bolt threaded all the way) through the T-nut. As you screw in this rod/bolt it will push against the fixed jaw and push the moving slider outward. Press-fit a #8 hex nut into the center hole of the fixed jaw so the rod/bolt turns against it, protecting the wood at the bottom of the hole; see picture. You can make a handle for the hex bolt to tighten the clamp, or you can use a 9/16" wrench to do it.
Step 4: Finish All Parts
Finish the corner jaws, fixed jaw, and moving slider with varnish or polyurethane so that wood glue won’t stick to it, and will be easier to clean off. Do not paint the dowels and the holes in the moving slider; it might stick if you do!
Step 5: Install the Band
Get a 10 foot (or more, up to infinity!) length of ¾” wide heavy Nylon webbing (the band) and four ¾” triglide buckles. Thread the webbing through a buckle, the left side of the fixed jaw, another buckle, then through the left slot of the moving slider, the left side of the fixed jaw, the first buckle, and three corner jaws. Complete the same arrangement on the right side. The pictures show how its done.
There are probably better ways to adjust the length of the band, i.e. cam levers, compression screws, spring loaded buckles, etc. The simple triglide buckles I am using are cheap, easy, and they seem to work well. Feel free to improve and then share your design.
Step 6: Use the Band Clamp
Always adjust the band length before applying glue to the work piece and do a dry-fit. Wrap the band clamp around the work piece, and align the jaws with the corners. Pull the band taut on the left side and adjust the sliding buckles. You may wish to use masking tape on the jaws to prevent glue from sticking to it. Be sure you don't get any glue on the sliding/tensioning dowels and mechanism. Turn the bolt with a 9/16" socket wrench to pull the jaws tight against the work piece. Make sure your work piece is flat and square, and let the glue dry.
For rectangles, use 3 jaws plus the fixed jaw. For six-sided work pieces, use 5 jaws plus the fixed jaw. For n-sided work pieces ….. well, you get the idea!
Yes, you can buy clamps like this, but where is the fun in that?
Key Words: Clamp, Band Clamp, woodworking, glue up, frame, hexagon, octagon, furniture making, assembly