I’ve received a lot of questions about clamps, and specifically, how they clamped things in the 18th century, so I thought I’d do a post on it. While I don’t know for sure everything that they used clamps for 250 years ago, I can offer a somewhat educated guess based on some historical information and my own work habits in the shop. It’s an interesting topic indeed, since today, we tend to have the mentality that he who has the most clamps wins. However, 250 years ago, it may not have been so.
There is historical evidence that clamps made of iron and or wood have been used since at least the 17th century (I haven’t researched the topic any further back than that). Several 17th, 18th and 19th century texts and images speak of or picture some kind of clamp. It is, however, unlikely, that clamps as we know them were as heavily relied upon as they are in today’s modern shops. At least not for the tasks they tend to be most used for today.
From what I can gather from the few hitorical sources I’ve had the opportunity to browse, clamps were used more for work holding and gluing panels rather than assembling pieces. Hand screw clamps like the one pictured above are invaluable in the shop for myriad work holding tasks. They’re capable of exerting bone crushing pressure and hold abnormally shaped pieces well as the jaws may be angled some. If you notch the jaws, they also hold round work very well, and they can also be held in a bench vise for shaping or carving tasks.
Traditional joinery, such as drawbored and/or wedged mortise and tenon, and dovetails, make the use of clamps unnecessary for assembly tasks. In fact, these types of joinery can essentially be assembled without glue (and typically were in 17th century joined work), if they are well fit, and will stay tight indefinitely. This is because the mechanical advantage of these joints is their primary strength. The glue is just a secondary measure.
By contrast, many modern joinery methods have no such mechanical advantage. Joints like dados, biscuits, dowels, and cope and stick have no mechanical advantage. These joints rely on the glue alone to hold things together, which creates the need for dozens of clamps to hold things together until the glue cures. The problem is, when the glue fails (and one day it will), these joints will fail as well as a result.
In my own experience, I have found this to be generally true. On occasion I may use a clamp as a third hand to help steady a long or complex assembly until I can drive the pegs or wedges, but for the most part, I rarely use clamps for assembly tasks in my own shop. In fact, I’ve sold most of my clamps as I found having so many of them unnecessary. All they did was take up valuable space in my already tight shop. I haven’t missed them at all.
Where I do use clamps more often is for panel glue-ups. Small, two board panels and edge joints are easily joined with no clamps using hide glue and a rub joint. However, longer panels, and those glued up from more than two boards, benefit from a few clamps to hold things in place. The purpose of the clamps, however, is simply to hold the boards in place, not to close a bad joint. If your joints have gaps when dry fit, clamps won’t solve your problems. The joinery must fit well.
The simplest of these clamps is the iron staple or pinch dog, pictured above right. When they were mentioned at all in a period inventory, they were typically referred to as staples (at least that’s my interpretation). The wedge shape of the pointed legs serves to pull the two adjacent boards tightly together when driven into the end grain. These are best used on shorter panels or in conjunction with a different kind of clamp as they only serve to hold the ends of the boards and do little at the center of a long panel.
Roubo pictures several other types of clamps in his 18th century treatise. While I cannot read a lick of French, I can understand the picture, which pretty much speaks for itself. I would hazard a guess that the top clamp would be made of iron by a smith, and tightened with a tap of a mallet, similar to using a holdfast. The bottom clamp would be made of wood by the joiner/cabinetmaker, and tightened using wedges. Roubo even pictures a panel glued up from four different boards in this clamp. I’m not sure, but the middle engraving may be a close up of the shaft of the top clamp? Then again, it could be something different altogether. If anyone who can read French knows for sure, please chime in.
Des Principes de L’Architecture pictures clamps almost identical to those in Roubo’s work, on the shelf above the workbench. Again, the one on the left would be made of iron and the one in the middle of wood. The one on the right bears strong resemblance to the double screw pictured and described in Moxon. The rear jaw of this appliance would be fastened to the bench top with a holdfast or two, as per Moxon’s description. However, there is no obvious way of attaching this appliance to the front edge of the bench, as it is pictured and described in Moxon. Perhaps the Moxon engraver got it wrong? I think of this double screw clamp as the precursor to today’s hand screw clamps. Peter Follansbee just wrote about this in much more detail. My special thanks to Peter Follansbee as well, for graciously allowing me to “borrow” his image of Felebien’s plate.
The cabinetmaker’s shop in Williamsburg has yet another type of clamp. This kind of clamp is probably the most familiar looking to most of us as it’s basically a wooden version of a bar or pipe clamp. I’m not sure where they found the reference to this style of clamp, but if it’s in their shop, it was likely available in some form in the 18th century. I personally find these clamps particularly appealing as I think the wooden screws just have a high coolness factor. I think I’m going to need to make myself some of these.
The last picture I have is a painting called “The Carpenter’s Shop” and was painted by John Hill in 1813. At first glance, it doesn’t seem to show much in the way of clamps. The picture is a little dark, but look at the enlarged version, at the extreme lower left corner. Leaning up against the window is what appears to me to be a panel clamp with a screw, similar to the ones used in the Williamsburg cabinetmaker’s shop.