Introduction: Modify Strap Clamp for Extra Corners
I bought a standard band clamp (also called strap clamp) which is very useful for boxes and frames with four corners. I wanted a strap clamp for hexagonal (six-sided) frames and octagonal (eight-sided) frames, so I decided to modify the strap clamp.
Please remember that safety must be first when using any power tool, such as a band saw, table saw or router. No final product will be satisfactory if you cut yourself while making it. ALWAYS, SAFETY FIRST.
3/4" birch plywood
Step 1: Make a Pattern for the Corner Braces
Shown here is a pattern for the corner braces for a hexagonal brace.
The angle for hexagonal braces is 120 degrees. I made the pattern to be about two inches on each 'leg'.
The angle for octagonal braces is 135 degrees.
Please note that one of the braces must fit against the main brace on the original strap clamp. That main brace is attached to the handle that takes up the slack. Therefore that brace cannot be removed unless you destroy the handle. So there must be a corresponding main brace for the hexagonal set and for the octagonal set of corner braces which fits up against the main brace on the original clamp.
In the second photo above please note that one of the hexagonal corner braces is shaped a little odd so that it will fit over the main brace on the handle.
Onto the 3/4" plywood draw six corner braces with one of them designed to fit over the main brace.
Step 2: Adjust Thickness of Plywood.
Each of the corner braces should be 1.5" thick, so cut another piece of 3/4" plywood and glue to first piece. Clamp and allow to dry.
Step 3: Cut Corner Braces
I cut the corner braces on a band saw. Then hand sanding is required to smooth the inside edges and verify that the angles match the pattern. I also rounded the sharp corner on the outside of all the braces except the one brace which will fit against the main corner brace. Rounding that sharp corner makes the next step a lot easier.
Step 4: Put a Groove in Outside of the Corner Braces
I wanted a groove in the outside of the corner braces so the strap will fit and not slip out. I want to make the groove with a router, but I absolutely do not want to hold the corner braces against the router cutter. That would put my fingers too close to the cutter. Very unsafe.
Using scrap wood, I made a holder into which the corner braces fit. The holder accepts one corner brace at a time and it is large enough to accept a hexagonal corner brace and an octagonal corner brace. Using the holder, I could hold the brace against the router with my hands at a safe distance from the router. Remember, safety first.
Since my router cutter is not thick enough for a 1.5" brace, I cut the brace then turned it over and cut the other side.
Step 5: Hexagonal Strap Clamp in Use
The first photo shows that the main corner brace of the original strap clamp is covered by a matching hexagonal corner brace. The second photo shows a hexagonal strap clamp in use to hold a hexagonal frame while glue dries.
Step 6: Octaganal Strap Clamp in Use
The first photo shows that the main brace on the original strap set is covered by an octagonal corner brace which is cut to match. The second photo shows an octagonal strap clamp in use to hold an octagonal frame while glue dries.