As usual, click any photo to bring up a larger version.
This project is inspired by, and heavily based on, the long reach clamps that were designed and made by Matthias Wandel of Woodgears.ca, and also the long reach clamps from John Heisz of ibuildit.ca. I had been planning on making some of these "someday", however last fall Matthias and John got together and compared and tested their clamps (see video on Matthias' page linked above) and that prompted me to finally get to building these for myself.
If possible, I recommend reading their articles and/or watching their videos, which will provide a lot more information, and a different take on the build process.
A conventional clamp, such as the one in the inset picture, has a fairly shallow throat depth. So you can only apply clamping pressure a few inches from the edge of the workpiece.
A long reach clamp is a homemade DIY "C" clamp. Since it is homemade, you can decide how deep you want to make the throat. This allows you to apply pressure several inches in from the edge of a project.
There are three pieces of wood in each clamp. (I'm making two, plus a prototype) The arms are 2" tall, 12" long, and a bit under 1" thick. The back/spine is 2" tall, 9" long, and around 1-3/16" thick. This is where the strength is, so I made the spine a bit thicker.
I have a woodgears-design box joint jig, so I used that to make finger joints to connect the arms to the back. I normally make 1/4" thick finger joints, but for this project I used an ordinary combination saw blade which is .127" thick. Using a thinner blade will result in more fingers in the joint, and thinnner fingers as well. This should make a really strong joint, as there is a huge amount of glue surface.
It took a lot of experimentations, and a bunch of math, to figure out the settings for the box joint jig. I don't really want to get into the mechanics of how to configure this jig in this article. Matthias has several articles about it on his website.
The end result was some really nice and tight joints, with a lot of fingers. (This is just a dry fit at this point.)
For the next step I need to drill some holes to accommodate the nuts that the threaded rod feeds through. I first drilled a shallow hole with a forstner bit, to hold the nut, and then I drilled a 1/2" hole all the way through the arm.
The hole from the forstner bit is not quite big enough, as I want a tight fit. So I traced the nut and then chiseled out the hole so that the nut could snugly fit into the hole.
I used epoxy to glue the nut into it's mounting hole in the lower clamp arm. I used two nuts (MORE ON THIS LATER), one on the top and one on the bottom of the hole. I then immediately threaded the rod through BOTH nuts and set it aside for about 7-10 minutes until the 5-minute epoxy had set up, before removing the rod. I wanted to make sure that both nuts are properly aligned such that the threaded rod would feed smoothly through both nuts.
Speaking of the threaded rod... I bought some 1/2" threaded rod along with matching nuts from the local big box hardware store. I used a hacksaw to cut off a length of threaded rod for each clamp. It needs to be long enough to reach from one arm to the other, through the lower arm, and extend out enough to fit into a handle.
After cutting the rod I lightly ground off the rough edges on the belt sander so that the nut would easily thread onto the rod.
And here is a cool dark moody photo which I made just for fun.
We need a way to mount a pad on the end of the threaded rod. Matthias goes into this in great detail on his article -- linked above. I chucked the threaded rod into the drill press, turned it on, and used a cutting disk in an angle grinder to smooth down a section of the rod about 3/4" long at the end of the threaded rod. I then cut in a recess about 1/8" deep to make a notch -- there is a close-up photo below which shows this. The notch will be used to lock on a wooden pad.
I found some scrap oak and drilled partway through with a 3/8" drill to make a recess for the end of the rod. I then cut out a small circle of wood to make a clamp pad.
I then got some scrap 1x1 pieces of oak and drilled a 1/2" hole into the end to make handles. I sanded and shaped the handles on the disc sander I then used the angle grinder again and cut a small notch across the threads at one end of the rod. I then used 5 minute epoxy to glue the rods into the handles.
I painted the clamps black, and the handles + pads a light orange. (Leftover paint from painting my shop walls)
The final step in assembling the clamps is to insert the threaded rods, and mount the clamp pads onto the ends. There is a small hole drilled into the sides of the pads, but angled to be off center.
I did have a problem with one clamp. The threaded rod would just not engage properly in the second nut. I think that one of the nuts must have shifted slightly during the glue-up process after I removed the threaded rods. I had to cut out one of the nuts in the affected clamp, which you can see in this photo. I'm not totally certain that two nuts are necessary, so I'm leaving this clamp as is, for an experiment. I still have two strong clamps, and one "weak?" one, and I can always make more!
I inserted a small nail (cut down from a longer one) into the hole and tapped it into place. The nail should slip into that notch that I cut into the end of the threaded rod. This locks the pad onto the end of the rod, while still allowing it to spin and turn on the end.
Thanks for reading!