Making The Power Wedge Bar Clamp Homemade Woodworking Tools
At this point I’m not sure just how many wooden clamps I’ve designed and made, but it’s safe to say this one is a very big step forward. It pretty much leaves most of the others behind, in fact.
The problem when designing a wooden clamp has always been the need for notches in the bar itself to anchor the moving jaw, and that adds extra machining work plus it also weakens the bar substantially. The spacing of these notches also meant that you would have to do a lot of cranking on the handle to adjust and tighten the clamp. This new design eliminates both of these problems with the use of a simple wedge to lock the moving jaw to the smooth bar. It’s infinitely adjustable – just slide it closed and start tightening.
While it’s a good idea to use suitable scrap wood for a project like this, since all of the parts are fairly small, I chose to use a nice piece of straight grained ash. Much like the longer bar clamps I made before, I want these to look as good as they work:
I ripped it into three strips and then resawed those on my homemade band saw to get the thicker and thinner parts for the clamps:
Worth pointing out that although the best choice for this is a strong hardwood, you can also use a clear, straight-grained softwood. Fir or spruce construction lumber would be good, but you might want to avoid soft pine and especially anything with a lot of knots and defects.
I then got to work cutting out the individual parts for four clamps:
It makes sense to do the assembly in two phases, getting the major parts put together on day one, then letting the glue dry overnight before finishing assembly the next day. This allows the glue to come up to full strength before putting any stress on the joints.
PLAN CORRECTION NOTE: In the plan (PARTS 2 page), the fixed jaw parts are listed as 9/16″ (14MM) thick, these need to be 1/2″ (13MM) or the same thickness as the bar. Only the moving jaw parts are 9/16″ (14MM) thick.
The plans have now been revised to correct that mistake.
Among the first day parts to put together is the wedge. The sanding belt needs to be cut to size and glued on with epoxy (I used polyurethane construction adhesive) and left alone until the glue cures.
You’ll want to use a coarse grit (I recommend 60 grit) and it must be cloth backed sanding belt – regular sandpaper may not be durable enough.
After spreading the glue and putting on the strips, I just set the wedges down like this and let them dry. Unless the sanding belt is extra curly, there’s no need to clamp:
The fixed jaw was next, and I used masking tape to hold the parts inline while gluing them:
I could then get one side glued on and clamped that for about an hour before gluing on the other side:
Yes, you need clamps to make clamps, but they don’t have to be good clamps, or expensive. And if you are handy enough to be here reading this, you might already have some homemade ones to use.
The moving jaw is assembled in the same way:
I used regular wood glue for these parts. It produces a bond that’s stronger than the wood when used this way – long grain to long grain.
The pad is glued next. I could have made this in one piece with a 3/4″ counterbore, but I like how the jaw pad projects out and better concentrates the pressure:
Spring clamps are handy for clamping small parts like this.
I made the handles from ash as well, although any type of softwood will work as well. The 3/8″ hole was drilled before I shaped them:
Another must have tool is a step drill, and I’m using it here to enlarge the hole in the retainer slightly:
I then glued the threaded rods into the handles. I flattened one side of the rod (seen in the video below) to key the rods to the handles:
I used polyurethane construction adhesive to glue in the rods and let them dry overnight. Epoxy is also a good choice.
I drilled the holes for the lead screws after the glue set on the moving jaw. I started by drilling in about 1/2″ with a 7/16″ bit before switching to a 3/8″ bit to finish:
Alternatively, you can just drill all the way through with the 7/16″ bit. That size is needed for the t-nut to fit properly.
The tangs on the t-nuts will split the wood, so holes need to be drilled for them. I’m using a 3/16″ bit for plenty of clearance:
The tangs mainly keep the t-nut from turning, and can’t be counted on to keep the t-nut in. For that, I like to use a single small screw:
It doesn’t have to be big – I used a #4 x 1/2″.
To fix the nut on the end of the threaded rod, I squashed it onto the rod (shown in the video below). Another, less violent way is to use epoxy or drill it out for a pin. Pounding it is the fastest, though.
Want to make sure you have the retainer in place before peening on the nut, though.
Trimming the fixed jaw at an angle like this is optional, but does make the clamp look less bulky. It also allows it to get into tighter spaces and doesn’t affect the overall strength:
Though detailed in the parts in the plan, it’s better to make this cut after the fix jaw is fully assembled.
Gluing the pad to the retainer completes the moving jaw assembly:
Setting it up
The metal shim that goes on top of the wedge serves two purposes. First, it makes that surface more durable and reduces the friction over the bare wood only. Second, it holds the wedge in place on the clamp:
That’s done by bending the end up to create a hook:
To position the shim correctly, you need to assemble the clamp with the wedge in place:
The hook should be about 1/4″ past the front of the moving jaw this this (yellow arrow):
That provides enough slack to freely move the moving jaw back and forth.
To get the length, tighten the clamp moderately and mark it about 1/2″ past the back of the moving jaw (yellow arrow):
That mark will be the end of the shim and you can cut it off there.
A hole needs to be drilled beside that mark for the screw that will hold the shim in place on the wedge:
With the shim cut to length and fastened to the wedge, I used some handy sized round things to layout the finger groove and end:
I used the first one to mark the other three:
Here’s how it looks finished, with the end shaped and the tip trimmed off:
The rust on the metal doesn’t affect the performance, and again the screw used is small, a #4 x 1/2″.
The finished quadruplets:
I consider a project like this to be one of the nice things we woodworkers deserve, a gift to ourselves in other words. I know most end up using their hobby to make stuff for others, to give away, and it’s nice to make something nice that just for yourself. If carefully made, these will last a very long time. I still have and use clamps that I made ten years ago.
I said as much at the end of this video that covers the build from start to finish: