February 11, 2012
I've always wanted some hand screw clamps but never had any, for the simple reason that I wanted to make them and not buy them. So many times I planned to make one but got sidetracked on other projects. Recently, I found some time to get started on making a few to have around the shop. They are made with commonly available materials and are fairly easy to build.
Before going into the build details, here's a brief video showing the features of the clamp:
This is part one of four videos covering many of the build details:
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The problem I had in previous design attempts was what to make the barrel nuts from. Looking around my workshop, I saw that ordinary steel pipe (the type used for pipe clamps) would be a pretty good option.
I laid out eight barrel nuts and marked for pilot holes, double sided taped it down to a v-block and drilled through with a 3/16" bit:
I then enlarged the holes to 11/32":
11/32" is slightly oversized for a 3/8" tap, but still giving good thread depth. I ground a flat spot on the side of the tap so that it would not spin around in the drills chuck. I do this with every tap I own, since I don't use anything other than the drill to tap holes.
A little oil makes the tapping more efficient:
I'm holding the drill as vertically as possible:
And run the tap through both walls of the pipe.
Four of the eight barrel nuts get 3/8" threading, while four others are drilled out larger. Here I'm using a step drill to do this and checking to make sure the 3/8" threaded rod slips easily through the hole:
With the holes finished, I mark the nuts for cutting:
A good way to draw a straight line around the pipe is to drill a hole through a piece of wood and use that as a guide.
Cutting the nuts to length with a zipcut blade:
And cleaning up the cut at the belt sander platform:
It's a good idea to get rid of the sharp edges. I used a round file to clean out the inside as well.
Cutting the wood down to size for the jaws:
I'm using regular framing lumber - spruce 2" x 6" that has been drying for a while in my shop. This is a good choice, I believe, as it is low cost and easy to work. Traditionally, these clamps are made with hardwood, but I think that softwood will perform well for the duties this clamp will have.
The wood, cut down to 1" thick, ready for planning:
A few passes through the thickness planer bring it down to 7/8" thick.
These are then cut to the finished length of 14", trimmed to 2-1/4" wide and screwed together in pairs:
Each jaw is made up of two pieces that will be glued together later. For now, the screws hold them temporarily for the machining operations.