Any time you’re building a cabinet, a box, a frame, or anything that has four 90° corners there is always a need to ensure there is equal pressure and the structure remains perfectly square. I admit, I have tried clamping things square with regular bar clamps, pretending to get “equal” pressure on all of them. Having a strap clamp is such a better option in most situations. Sometimes the length of the strap just isn’t long enough for the job at hand, or they wear out and it is hard to get enough pressure. These DIY strap clamp jig plans are a cheap and effective option for another tool (or clamp) in your tool chest (clamp chest?).

You should be able to quickly build four of these to pair with a thin endless ratchet strap and then have another option that has the flexibility to clamp larger pieces. I two sets of these from the scrap I had laying around my garage workshop. It probably took me under 90 minutes to build both sets, and that is including glue up because I used CA glue for everything except the back dowels (which I am not counting that drying time in the 90 minutes because I glued them in and let them dry after everything else was already done.

Materials Needed

• 2 – 5″x5″ pieces of 3/16″ hardboard
• 1 – 1×6 at least 5″ long
• 1 – 3/8″ dowel at least 20″ long
• wood glue or CA glue if you want to speed up the build
• endless ratchet straps

Tools Needed

• Jig saw or bandsaw (table saw is optional)
• Drill / Driver with 3/8″ drill bit
• 4″ hole saw or small circle router jig (and router)
• Tape measure
• Clamps

Step 1: Cut your hardboard and hardwood to size

To build a set of four of these, start by cutting two pieces of 3/16″ hardboard to 5″ x 5″. Then use a 4″ hole saw (or router and small circle router jig) to cut a 4″ diameter circle from your 1×6. Next, I like to find the center of the two pieces of hardboard and drill a hole the same size as the one in the center of the circle (this can vary depending on the hole saw you used or if you used a different method to cut the circle). Then I glue the three pieces together, with the holes as an alignment guide. If you’re using CA glue, I recommend using a dowel pushed into the center of the circle as an alignment guide.

Once the glue is dry, cut the assembly into four equal pieces. Each square should wind up being 2 1/2″ x 2 1/2″, minus the kerf of the blade you used to cut. I used my table saw to cut mine, so each piece is about 1/16″ less than 2 1/2″. Now use a jig saw or band saw to cut a 1″ x 1″ square out of the inside corner of each piece. Then mark 3/4″ in from each back corner, mark a line, and cut on the diagonal. It doesn’t have to be precise, you just don’t want that square corner hanging out in the way.

Step 2: Cut the top board

The last steps in building these DIY strap clamp jig plans is to put in the dowels. The inner dowels help prevent denting in your project boards while also allowing the clamping jig to pivot slightly around the corner. They also compensate if you you’re 1″ x 1″ cutout isn’t exactly square. The back dowels provide a guide to hold the straps in place while you’re putting them around your workpiece.

Using the guide below, drill four 3/8″ holes into each piece. Then glue your dowels in place and trim them flush with a hand saw.

I hope you enjoy these plans and find them useful. Please check out our other jig and workshop plans. If you have any questions, leave us a comment below. And don’t forget to submit your build if you use these or any of our plans to build something of your own.

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