Those engaged in the art and mystery of joining pieces of wood together to make a chair, a table, a case of drawers, a cupboard, or any other useful piece of furniture, architectural feature, or household accessory, have a wide choice of “joints” suited to making such things strong and beautiful. Shaker woodworkers, like their counterparts in the outside world, demonstrated their mastery of mortise and tenon, rabbet, half-lap, dovetail, dado, miter, spline, finger, and tongue and groove joints. For a few specific purposes Shaker woodworkers used a particular method of joining pieces of wood that, while not unknown in the outside world, was not common. That method involved turning the common round mortise and tenon joint – that is inserting a round peg in a round hole – into a stronger joint by cutting threads inside the mortise and on the outside of the tenon and screwing them together like iron nuts and bolts. This joint, because it did not require glue, had the advantage of being relatively easy to take apart.
There are three common examples of Shakers using this joinery technique to great advantage – the pulls (or knobs) on drawers and cabinet doors, the omnipresent pegs (or pins) mounted in boards circling the interior of nearly every Shaker room, and window screws.
Pulls. Drawer pulls with glued unthreaded mortises and tenons tend to loosen over the years as wooden drawer fronts expand and contract year to year from summer to winter. The heavier the drawer the more the stress put on the pull every time the drawer is opened. The threaded mortise and tenon is a mechanical joint that relies on the interlocking of the threads rather than glue. Alternatives to threading the pull – used more in non-Shaker pieces – were to either leave the tenon long, protruding into the drawer, and put a pin through it so it could not pull out, or cutting a slot in the tenon and driving a wedge into the slot, flaring the end of the tenon so it was too big to pull out of the hole.
Pegs and Peg Board. Could anything be more annoying to the Shaker than grabbing his or her wrap from the hallway peg board and half-way across the door yard finding the peg on which it hung still tangled in the collar? Threaded pegs, like pulls, did not accidentally come loose from the board. Peg board was made in two parts – one piece of rough wood nailed to the studs that supported the plastered walls and a finished piece of wood that covered the rough board and the joint between that board and the plaster. The rough board had threaded holes to receive the pegs while the finished board had a slightly larger hole through which the peg could pass on its way to the threaded board beneath. In cases where this technique was used, the pegs actually held the finished peg board on the wall. Removing the pegs and peg finished peg board allowed rooms to be painted without having to worry about getting paint or whitewash on the peg boards.
Window Screws. In a number of Shaker buildings the windows were designed such that there was a thin board that overlapped the movable window sash. This board, much like the finished piece of peg board, could be tightened against the sash by turning a thumbscrew that passed through it but tightened into a board beneath. This feature made it possible to hold the sash open without using a stick or counterweights.
Making wooden threads was done with two tools: a tap for cutting the threads inside the mortise and a die or “screwbox” for cutting the threads on the tenon. These tools would not have been common in every toolbox but specialized woodworkers may have invested in or made these specialized tools. For example, making spinning wheels, which Shakers in a number of communities did, required threaded tensioning screws for keeping the cord that connected the large drive wheel with the spindle where the fiber was twisted tight. Toolmakers made hand screws for clamping pieces of wood together that required long threaded wooden rods and threaded mortises and some woodworkers specialized in making large, one and one-half to three inch diameter wooden screws and nuts for large vises on cabinetmakers’ workbenches.
In the collection of Shaker Museum|Mount Lebanon is a purpose-made tool for threading the tenons on pegs for peg boards that also has a changeable cutter for doing the same for drawer pulls. The tool is thought to have been made at the Church Family at Mount Lebanon by Brother Isaac Newton Youngs, a clever mechanic and woodworker. Faced with the task of making tens-of-thousands of threaded pegs, it seems a worthy project for a clever brother.
There is one example in the Museum’s collection where one unidentified cabinetmaker used the “treaded mortise and tenon joint” in a less common way. Two tripod stands – candlestands – were made with their tops joined to their pedestal bases with wooden screws. Round cleats, screwed to the bottom of the stands’ tops have threaded mortises that screw on threaded tenons protruding from the tops of the stands’ pedestals. The Shaker cabinetmaker was probably thinking of the mechanical strength of the joint and not taking the stand apart for shipping – but it is a design worthy of consideration by Ikea.