Third Hand Splice Clamp style.


Well-Known Member
Jul 22, 2019

Western Colorado, USA
So I started working on the Constitution cross section I started about 20 years ago and got to the rigging portion. I quickly grabbed a 2X4 and drilled some holes in it and blued some clamps on dowels for a third hand. Then got to work and remembered all the fun I had years before. The alligator clips ate the tiny blocks, the little blue clamp shot blocks across the room like a bb gun, the thin alligator clips wouldn't hold, and the board slid around on my steel workbench. etc.

So I decided to build a third hand on steroids. I'm usually reading these threads jealous of the guys that seem to have an entire home improvement store lying around their garage; however, this time I'm kind of that guy. From my machining hobby I had the following material in the corner and chopped it up into this. Even had the handles left over from when I converted my Mill.

The aluminum plate is 6 inches by 12 inches by 1/4" thick and initially I thought about cutting it down, but I think it's actually big enough to use as a keel clamp if I want too. I'll show a photo of the whole thing at the end.

The real reason for this post is I have a splice clamp from Micromark, and I was messing around with it and it seemed like it help thread and about anything else pretty nice so I basically copied it.

I bought all of this from the local hardware store for about 27 dollars us. It's just a gasket kit a couple pieces of the K&S brass and basic hardware.

The screws and nuts are 8-32 threads. The brass rectangle is 3/16 x 3/8 and the brass strip is 0.090" x 1/2".

I cut the brass rectangle and flat bar into 4 pieces. I took some 3/8" rod and machined a flat on it (Could skip that step and it would work fine it just looks a little better), then drilled and tapped it along with the flat brass plate. I drilled a hole through the rectangle and then bolted it all together like the photo below and drilled a second hole to line everything up.

I then assembled it as shown below.

So basically it's the same as the micromark clamps with one addition, which is a small spring in the upper bolt so when you back off the thumb screw the clamps open and stay open so you don't have to use two hands to put something in the clamp.

I epoxied the gasket material to the jaws. The red is just rubber and the brown is kind of a cork rubber mixture. The one other note, that isn't obvious, is there is a nut inside the brass rectangle hat sets the distance at the back of the clamp.

It took me about three hours to build these four clamps. Like the third hand pictured below I didn't get carried away making all this stuff really accurate. A person could build this with a drill press if they just skipped milling flats on the rods.

Here's the beast with the clamps on it.

I have the parts to attach the two center arms the same as the outer arms. Here's 4 of my wood clamps hanging on a .2mm thread suspended between the cork clamps.

Here's a photo of a block I siezed in one of the clamps with a rubber side. These clamps really grab and hold, without a ton of pressure because of the friction from the gasket material. I expect to make different clamp as I go along for various purposes but wanted to post this because I hadn't seen anyone using this style of clamp.

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