How To Make A Parallel Jaw Bar Clamp Homemade Woodworking Tools
Another clamp build? Yes! I consider this one to be a direct replacement for my most recent long wooden bar clamp design and also a big step above any other homemade clamp design. And I’m not bragging here, it’s that good.
It is based on the same wedge lock mechanism design as my smaller wooden bar clamps, but these are sized to be longer – typically 18″ and up (capacity). The bar is thicker and the moving jaw pad is held parallel to the fixed jaw with a pair of struts that reach behind the moving jaw.
The prototypes for this clamp were made from softwood and they performed surprisingly well. So, while hardwood is the best possible (wooden) material to use, I think these will be just fine made from the softer wood. There are some major advantages as well, with lower cost being the biggest one. Clear, straight grained hardwood is not cheap and we all probably have better things to make with it. Softwood is also substantially lighter than hardwood making these easier to handle.
The build video:
NOTE: The materials list in the plan gives the length of the threaded rod as 6-1/4″ (159mm) when it should be 7″ (178mm).
I bought three 2×8’s that are reasonably straight grained. Most of the defects (knots) are small. Of these I picked the best one to make the bars and cut it to 72″ long before ripping it into six pieces:
My goal was to make four long clamps, picking the best of the bars from the lot. But I decided to up that to five after planing them down to final size. Only one bar had a major defect (a knot hole pictured below) and these can always be cut shorter if I find that I don’t need that many.
I also took the time to mark the “up” side on the bars after carefully looking them over. The bar will be under two forces when in uses: tension (pulling) and compression (crushing). The up side of the bar is under tension and therefore I put the best side up:
Defects that are close to the edge weaken it when it’s in tension, while they don’t on the compression side.
This is the knot hole in the rejected bar:
It didn’t go to waste, though. I used it to make other parts for the clamps, specifically the fixed jaws.
The sides for the jaws is cut from half of the second 2×8. These are strips that were cut and planed down to 1/4″ thick:
This looks like a lot for five clamps because I’ll ultimately be making at least six more and figured I should cut the material needed now. That saves going through all of the machining steps again. If you are going to make these clamps, I recommend doing the same.
The other half of the second 2×8 was cut into stock that’s the right thickness for the moving jaw parts:
While softwood will work for the wedge, I decided to use some scrap oak instead and cut them using my precision miter sled:
Whichever way you cut these, the important thing is the angle: 10 degrees.
I did use softwood for the handle and made a quick and dirty jig for trimming them down to my trademark shape:
I drilled the 3/8″ hole for the lead screw while they were still square:
And smoothed them out on the belt sander platform:
The glue that holds the threaded rod in has to dry overnight, so I did this toward the end of the first day:
Eleven, but I have enough handles for ten more.
The bond between the sandpaper and the wedge needs overnight to dry as well:
This is a 60 grit sanding belt that I cut in pieces. Actually, the one in the picture above wasn’t flat enough – it was a belt that fell on the floor and got stepped on and kicked around and I figured I use it for this. Nope, it needs to be flatter and free of bends and kinks.
The glue has enough of a grip when it’s still wet that clamping isn’t needed. I just put the wedges with the sandpaper side down while drying and that worked well:
The parts for the moving jaws:
And for the pads:
And all of the sides of various widths:
And cut into pieces:
The rub plate is thin sheet metal that has a hook bend on the end. I made a crude bender from a block of hardwood to make the bending easy:
Feel free to use metal that isn’t rusty on yours.
The strut has a stylish taper that’s easy to cut when you make a simple fixture:
I’m cutting two at a time.
Another quickly made fixture for drilling the finger groove:
This could also be done with a band saw, but the drill makes short work of it.
Rounding over the end of the wedge is a good idea, since it’ll save your knuckles when tightening the clamp. I used my homemade belt / disk sander:
With many of the same parts to drill counterbores in, it’s a good idea to set up a fence and stop block to quickly and accurately position the parts:
The 1″ counterbore on the moving jaw for the t-nut is optional, but I think it looks better:
Here’s a lesson on where not to drive the screw. Putting it on the other side where there’s more wood will stop it from splitting:
And yes, I did drill a pilot hole. Although it’s incredibly strong for its weight, spruce splits easily.
Here’s something you need to know: put the sides onto the pad temporarily and measure the distance:
This is how long the strut block needs to be. Mine is a full 1/16″ bigger than it’s supposed to be.
Here’s a mock-up of the guts of the moving jaw with the wedge put in:
Yours should look like this if you did everything correctly. If not, make adjustments or make new parts.
Assembly starts with the fixed jaw, gluing the top and bottom to the end of the bar:
And before that dries, getting the sides put on and clamped:
Next is the moving jaw. I used 23 gauge pins to hold the parts in line and spring clamp to put the pressure on:
Usually I prefer “real” clamps, but plenty of glue and lots of glue surface area means a lot of strength. I think the side would tear before the glue joint would fail, and that’s well beyond the operating range of a woodworking clamp.
The pad sides are glued to the struts next. Note that a pair of these (as in the same but opposite) are needed:
Waiting for glue to dry is the name of this game, and scheduling things to do while it’s happening. After the moving jaw dried I sanded it pretty and installed the t-nut. I then threaded in the lead screw, slipped on the retainer and threaded on the hex nut. The nut is locked onto the end of the lead screw by smashing it with a hammer on my anvil so that it looks like this:
That’s an ibuildit original, right there.
The crushed nut plus the washer and a smear of grease go into the counterbore in the pad and the retainer is glue on:
And then wait for that to dry…
…and when it does, glue on the pad sides plus struts that were glued up earlier:
I know, it’s hard to see the wooden clamp for the wooden clamps on the wooden workbench. But look closer… it’s there.
The video shows how to make the rub plate the right length before fastening it to the wedge. It’s a really good idea to cut the plate long, then trim off the extra after for a perfect fit:
It needs to stick out at least 1/4″ to allow the wedge to loosen properly:
Here it is actually clamping something:
And it shows how the strut mechanism keeps the pad at 90 degrees, even when the stock is near the bottom.
It’s a good idea to drill and drive screws into the strut block to reinforce the end grain joint:
A single one on both sides is enough.
All done and lined up for the glamour shots:
Watch for these and the shorter version of these in upcoming projects. They work great and what I love the most is how there’s no cranking of the handle to make up the distance between notches. The wedge locks quickly and firmly and is infinitely adjustable.
Get the plans for this project here: