Beta project 15 (Lapstrake Clamp)



I started messing with this idea quite a while ago. I was clamping something and needed a bit more reach than the standard Jorgensen clamp I was using could provide. A bit of googling uncovered a wooden boat building rabbit hole at the bottom of which was the lapstrake clamp. Look it up if you are curious, some people make simple ones, and some make really beautiful ones.
I made this one.

Of course I first had to make these two…

I thought I needed the holes to keep the layers aligned but instead I made a little jig with pins.
Here are a few in progress shots.

I needed a bunch of clamps to make my clamps. The jig was two pieces of plywood with holes to match the outline of the clamp half. I stacked them so the kerf would essentially cancel out and the pins would not wobble.

The layout is a bit tricky to get all the parts to fit and move as they should but the final SVG looks like:

Of course the post would not be complete without a video of fascinating cam clamping action.

Box hinges

Fascinating as always. Why did you settle with the jig instead of through holes? As to adjustability, why not use notched straps? Or if that would be too weak, straps with multiple holes?


Great project as always! I have several hundred clamps in various styles and still end up with unique situations where, what I do have, still needs additional modifications to work.Having the GF to expedite the process will be handy.


Ooo they look great. I think I can find a use for some of them.
Going on the GF list.


Josh, you have yet again demonstrated why you were a fabulous choice for First Beta.


I was wondering about that.


I love it! Tools making tools so you can make tools!


Another great project and video. I can see me needing a few of those. lol


I was just thinking the same thing about the notched straps. I think it might have to be made from s thicker material to hold up to the stress but worth a try.


I couldn’t agree more. I always come away from his post with a ton of ideas to try.


I love books. I love tools. A book tool? Awesome!

Thanks for describing the clamp’s action as “it squishes.” :upside_down:


A call out to the engineers of the forum. I have never had to calculate cams and how to figure around them. How do I design one? I know its basically a circle with an offset pivot or attached off the centre, but beyond that… shrug. Any good tutorials or advice?


@markevans36301 @pomwah I tried exactly that (I can’t find the other strap at the moment because I think I used it as a glue scraper).

It worked fine with a couple caveats. It means the cam is completely separate from the body of the clamp (and in my shop will get lost). It also makes setup a little too fussy since you have to hold all the pieces together until the tension grabs them.

I just used some 3003 Aluminum sheet because it was easy to prototype (and I had a convenient size scrap), but if you were making these you would need something with much higher strength. Either a less ductile Al alloy or brass or even steel. You could also drill holes and use wing nuts instead of the notches.

I gave up on the through holes because I did not like having the screws sticking out, they did not contribute anything, and with the jig it was actually quicker to assemble!


Very cool project. Great work!


What did you make them out of? Looks like a wood veneer over MDF. Also, is the middle board on the cam larger for a reason? I am amazed at all of the unique things that you are making. @dan made a good choice when he chose you for the beta forge. :grin:


I think this is perfect! I’ll probably be making something like that when I get my glowforge


The center lobe rides in a corresponding notch and centers and helps retain the cam on the clamp.


BTW Josh, nice work!
Thanks for that!


One of my very large R&D ideas with the pro model is to attempt using it to cut out parts for a kayak. I think the GF precision will be very useful for small boat building. There are even plans on the interwebs for such a thing.


Interesting, Keep up the great ideas.