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12 March 2016

How to make wooden C-Clamps

The title of this post sounds like madness of the highest order. Can it really be a good idea to try and make clamps out of wood? Surely not.

I had to give this a go!

Let me start by showing you what I made: 2 x deep-throat c-clamps. In this picture I've clamped some wood to my workbench from either side to give you a better look at the top and bottom of the finished clamps. It's taken me about a week to put these together, but that was mainly because I was experimenting along the way. How about I explain...

I got the idea for making wooden clamps whilst I was researching ways of making a c-shaped frame for an up-coming digital caliper project.

I came across a number of posts on the internet where people have been making clamps very similar to the plan I mocked up above. In my last post I showed you my experiments with comb finger-joints created on my table-saw. Rather than to jump right into my caliper project, I figured that I'd explore the concept a little more by making some clamps. The clamps I ended up making are pretty much to the spec in my plan above.

I had misgivings right from the start of this project over the choice of wood for making the clamps. Everyone I've seen doing this has been using Pine. Pine is a very soft and bendy wood prone to splintering, splitting and generally falling apart when you least want it. Despite my misgivings, I figured I would follow the herd and perhaps learn something in the process.

For the handle and the vice part of the clamp I elected to go with some off-cuts of mahogany. At the very least, I figured that these need to be hard-woods.

I took inspiration from other people's projects, but my idea for the bolt is one - I'm surprised to say - that I haven't seen anyone else try. I took a long carriage bolt and built a cap for the bolt end.

It's not a super-technical solution, but it has worked out really well. I made the bottom part of the cap by drilling out the inside with a forstner bit and cutting around the outside with a jigsaw. Inside I placed a washer to spread the load of the bolt head. The cap is simply a thin bit of wood with a hole drilled in it. Once glued together around the bolt-end I'd pretty much finished. The only downside to this approach is that I needed to fit the bolt to the pine body prior to gluing the pine together. Not a big deal.

Here I am gluing the pine body. You'll see in the picture that I haven't actually glued the cap on the bolt at this stage, just fitted the top onto the bolt and fitted the bolt into the top arm.

The bolt runs through a hole in the top arm which I've counter-sunk two nuts (one on each side). This was a bit fiddly to do. One clamp worked straight off the bat; the second required a bit of faffing about to get the bolt to ride cleanly.

Having glued the frame I was feeling pretty good with myself. I sanded and rounded the edges but soon the doubts were starting to bubble up over whether the clamp joints would hold under pressure. I succumbed and fitted hardwood dowels to further strengthen the joints. If you look closely you'll see that the pine has splintered in places. Yep, I reckon my paranoia is well-placed.

I don't have photos of me doing it, but I coated the pine with z-poxy. I'll explain more about using z-poxy another day. I wanted to experiment with using z-poxy as a lacquer because I intend to use it to finish my archtop guitar. All I've read on z-poxy suggests that I'll be able to create a tough smooth surface. From what I've seen so far, I think it will do the job. I haven't tried sanding it down and buffing yet... that will be the true test.

The handle looks pretty basic doesn't it. That's because I never finished it; I fitted it on to get the hole right and couldn't get it back off again. Ha ha. I'd intended to round it, but took the resistance as a sign. It'll stay like this until it falls off. I can't see this happening anytime soon.

One last shot of the clamp in use. When I tightened it up for the first time it made a cracking noise which I think was just the z-poxy flexing. I haven't tried to push it to it's limits but it is easily applying enough force to hold this plank in place. The exciting thing is the potential this clamp has with it's long reach for helping out with those really awkward jobs.

Will it stand the test of being used in anger over a prolonged period? We'll just have to wait and see, but I have high hopes.

In other project news, I thought of a little innovation to improve my spool clamps. Look at one of them here fitted with a fat straw over the bolt. I don't know what you call these type of straw, but I've seen them go by "bubble straw" and "boba straw". The key is that they're wide enough to fit over the bolt to protect whatever you're clamping from coming into contact with the bolt thread. I don't know how good this will work, but there you go... the mind never stops thinking ;-)

I finish with a teaser shot of me ripping some wood by hand. This is me two days in and I still haven't got half way through the bloody thing! Ha ha. I'm determined to get it done if it kills me. This block was billed as "West African Mahogany" (Khaya Ivorensis) when I bought it. It's a lovely bit of wood. I hope I get the best out of it.

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