Tag Archives: roubo panel clamps

Roubo-Style Panel Clamp Tweaks

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After I made my panel clamps, I’ve now used them several times and have been able to work around some of the issues that came up. Here’s a partial shot of the latest project getting its final glue-up (this is big–roughly 7×2 feet (2130x610mm) in area:

I have four clamps–three long ones and a shorter one that I made earlier as sort of a prototype. I used all of them on this project.

Let’s address the the two comments that on speculation of “stuff that might go wrong” that I got last time.

First, Lionel asked if glue squeeze-out is a problem; can you glue the work to the clamps? The answer is yes. I said that if this were a problem, I’d just wax the insides, and that’s exactly what I did. The wax eliminated the problem.

Then, Matt asked if I used a single wedge, would it tend to wear/dent stuff into the pegs? I tried it, and it does indeed mush into the pegs (especially when they are southern yellow pine).

On that note, I wasn’t terribly happy with the way that the single or double wedges were working. In particular, all sorts of things can happen when you try drive them in:

  • The force of the mallet blow can shift and tilt the entire clamp over just a bit.
  • On double wedges, it can be tricky to hit one wedge without loosening and dislodging the other wedge.
  • On double wedges, it’s pretty easy to hit them so that they go askew of each other, and then they can slip out.
  • If the clamps are too close together, it can be difficult to find enough room to get your mallet strike started.
  • Fussing around with the wedges during glue-up (especially when you don’t have anyone to help you) takes precious time. The liquid hide glue that I use gives me a little more time, but still.

One of the speculative ideas that I had last time was I could add a hook to the upper wedge, so that I’d only need to hit one end of it. I did this, with one other change:

I planed a groove into the top and a matching tongue into the bottom with some old wooden match planes I picked up in Alameda many years ago. (Note to self: regrind those plane blades, they’re in awful shape.) This eliminates the slipping askew and generally makes it much easier to get the wedges set up.

With that in place, it was much easier, but I still had some difficulty finding the room to set the wedges at times, and didn’t really have a feel for how much I was tightening the joints. So I came up with this dumb hack to do the final tightening:

Even though using a little F-clamp like this might look like it could back the hook off of the peg, it hasn’t happened to me in practice; it just shoves the lower one into place. In any case, this made the job a lot easier.

In addition, I made new pegs out of ash to discourage dents from forming in them. I suppose that I could do that with the upper wedges as well, but that hasn’t caused any problems (after all, the upper wedges aren’t supposed to slide).

So now what do I think of using them?

Overall, I’m pretty happy. One of the things that I like the most is that you perform glue-up against a wall with the work sitting on its side. This makes it a lot easier to get things in place, and it’s also relatively easy to do a dry run of the glue-up and clamping, or at least get a good idea of what’s going to happen. Once you have everything in place, you can easily check both sides by just tilting it one way or the other. And because it’s already against a wall and not on a bench or anything, you don’t have to move it afterward to reclaim your space.

The Roubo-Style Panel Clamp

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This was going to be my year for getting enough clamps: I was to troll the tool sales and estate sales to get what I’ve been lacking. Then you-know-what came around, and that plan whimpered and died. As fate would have it, I’ve got an upcoming project that requires more clamps than I have.

Perhaps I was fortunate that I was reading the Roubo translation from LAP recently, and of course Roubo talked all about clamps. He described a panel clamp made from two boards that he called “twins.” He said that “the use of these tools is excellent,” and his recommendations are not to be taken lightly. OK, whatever, it looked reasonable, so I wondered if anyone in the 21st century had made them. I should have guessed that Don Williams had done it; here’s his blog post. There’s a snippet of the Roubo plate in there. Also, keep in mind that even though we’re calling them “Roubo clamps,” we don’t really know how the form evolved over the years to the form he described.

The construction of these is simple enough that it was definitely worth trying. I grabbed some southern yellow pine 2x4s and put a bunch of holes in:

Hand tool disclaimer: I used my drill press. Sure, I could have used my brace, but it would have taken a lot longer, and this is one thing that a machine actually does really well.

The holes are alternately offset like Williams did. It seemed like a good idea at the time. He used a mortising machine to make 1/2″ square holes. I planned for 3/4″ pegs, and I didn’t like the idea of using round pegs, so I needed to square up the holes. With no mortising machine of my own, I just went at it with the biggest mortise chisel that I own:

Thankfully, these don’t need to be appearance-grade. And yes, I chopped halfway in from each side, and yes, there’s something underneath the wood to keep from putting (any more) nicks into my bench.

This was something of a chore, but not awful. After that, it was simply a matter of resawing, making the pegs and wedges, and before long, I had three twins:

I tested them on some boards that were lying around:

These seem to work well. I pounded the wedges in pretty hard. Using them requires some acclimation, so I guess another reason to use liquid hide glue is so that you have enough time to put them on. Although I’m using double wedges here, I might change to single ones for the simplicity.

Being southern yellow pine, I think they’ll be strong enough. Roubo describes beefier things: roughly 4-5 inches wide, and 2 inches thick (but is this per side or for both twins?). His described mortises and pegs are 1.5 inches wide–four times the volume profile. But from what kind of wood would he have seen these made? Oak would be very strong for the pegs, but its tendency to split cleanly might be something of a concern for the twins. Beech wouldn’t have that kind of problem. Or what if it were a wimpy sort of thing?

Oh well, I don’t think that’s something I need to concern myself with that until I manage to break these.