Bowsaw Making Class
Class was held Saturday, February 15, 2003, at John Wilson's Home Shop. Each class member built a turning saw. A turning saw is a type of bow saw; bow saws, in turn, are a type of frame of frame saw. A bow saw consists of two arms held apart by a central stretchers. A blade (in this case, bandsaw blade stock) is attached to the lower end of the arms by slotted brass rods. A pin, which goes through the rods and through a hole in the blade, holds the blade in place. The rods are glued, threaded, or pinned to knobs that bear against the outside of the arms. These knobs can turn (hence the name turning saw), thereby changing the orientation of the blade in realation to the frame, much like a coping saw. Turning saws are very useful, performing tasks that are usually performed today by power tools, such as the scroll saw and the band saw.
Turning saws, as well as bow saws, can be made in a variety of sizes. The saw made in class has about ten inches of usable blade. The arms, stretcher, and paddle were made from birdseye maple, the arms and stretcher from 3/4 inch stock, the paddle from 3/8 inch stock. The stretcher was one-inch wide and measures 12 inches from shoulder to shoulder. The arms are 1 & 1/4 inch wide at the lower end and measure 12 inches long. The arms taper in thickness from 3/4 inches just above the mortises to 3/8 inches at the upper ends. The knobs are about 1 & 1/8 inches in diameter. The smaller one is about 2 & 3/4 inches in length; the longer, about 4 & 1/4 inches in length. The distance between the middle of the blade and the bottom of the stretcher is 5 & 3/4 inches. These measurements can be varied succesfully according to taste and application. Please see these webites for more ideas about bow saw design and construction.
With exception of the drill press, which was used to drill the "pin" holes in the brass rods and the blades, the class used hand tools to make their bow saws. Among the suggested tools the students were asked to bring were: Hacksaw (to cut 5/16 brass rod stock), small combination square (6-inch blade), folding (zig-zag) rule, marking knife or jack knife or utility knife, back saw (around 14 points per inch), mortise gauge, 3/8 inch chisel (to chop mortise), 1/4 & 1/2 inch chisels, mallet, 5/16 brad point drill bit, brace ( to hold bit), spokeshave, smooth plane (#4 or #3), coping saw with new blades , mill file (to smooth ends of the brass rods after they are cut to length), half-round rasp (the Nicholson #49 and #50 cabinet makers rasps work very well), round rasp (3/8 inch diameter), and a cabinet scraper.
Of course, if you already have a turning saw, you'll find it works better than a coping saw for this project.
A bit and brace was used to drill a one-inch deep hole in the center of the knobs for the brass rods. The 3-inch long rod is held in place by cyanoacrylate (super) glue. Drill the pin holes in the rod and cut a grove in the rod with a hacksaw before gluing the rods to the knobs. The very thin glue was applied with the rod already in place; it seeps in between the rod and the side of the hole. It holds surprisingly well. Holes are then drilled in the base of the arms for the rods to pass through. You will notice in the adjacent picture that a scrap is being used to backup the arm while it is being bored. This prevents the wood from splitting out when the bit passes through the arm.
Here is John Wilson sawing out stub tennons on his stretcher. The tenons are only 3/8 of an inch long, hence the term "stub" tenons. Anything longer would actually weaken the joint. The tenon is 3/8 of an inch thick and 5/8 wide. The joint is held together by compression only; no glue or fastener is used.
The mortises were chopped into each arm by hand. Because they are so small and shallow, the chopping goes quickly.
Please contact Gil Chesbro for your questions & comments.
