Wooden frame saws, also called bow saws, are built with two arms, with a bar or beam mortised into the center of the arms, forming an "H" shape. The saw blade is attached across the bottom of the H, and a tensioning system across the top. The beam mortised into the centers of the two arms provides the fulcrum around which the blade is tensioned. Because the blade is in tension, it can be significantly thinner than an ordinary hand saw blade, which must be relatively beefy so as not to buckle. Traditionally the tension was provided with several loops of hemp string in a Spanish windlass, but today it is more common to use a rod tightened with a wing nut at one or both ends.
Frame saws can be used for almost any job: cross cutting, rip sawing, crosscutting wet wood, cutting curves, and cutting shapes within a board. By cross cutting we mean cutting across the grain of a board to shorten it. Rip sawing is cutting along the grain to straighten or narrow a board. Because the blade of a frame saw is easy to release, one can drill a pilot hole, undo one end of the blade, put it through the hole, and then re-attach the blade and cut out almost any kind of shape inside the board, a long through mortise, for instance. Every task demands its own kind of blade for optimal performance. Rip cutting needs a blade with relatively large, flat filed teeth. Crosscut blades have finer teeth filed at an angle. The turning saw uses a narrow blade with fine teeth set for a wider kerf to enable it to cut curves. A big advantage of frame saws is that the blades are relatively long and so permit faster cutting than other types.
Many people enjoy building their own frame saws. They are fairly easy to make, and can be very inexpensive without sacrificing any quality relative to a manufactured product. A nice bonus is that one can give free reign to fantasy in the design and ornamentation of the saw. With a blade, a few bits of hardware, and wood from the scrap pile, one can also knock together a serviceable frame for a special job in a few minutes. But be careful: we have seen, for example, a saw built with thin, elegant arms and an even thinner center beam. Lovely saw, but the builder soon found that the frame was no where near stiff enough to offset the blade tension needed, and the arms were too thin in section to provide a good grip. So one needs to pay attention to the strength and ergonomics parameters. For those interested in this end of woodworking we offer not only spare blades, but also steel blade holders, and twisted hemp cord. It might also be worth having a look at our short section on sharpening saw blades, or better, the directions from Friedrich Kollenrott, which are comprehensive, but unfortunately only in German. We find that the many of the ordinary frame saw blades offered today often have too much set in the teeth, and have not been very well sharpened. This does not need to be a problem if one knows how to fix this. Alternatively one can buy Japanese frame saw blades, which are optimally set and sharpened, but which cannot be re-sharpened.
Important: One should not leave frame saws under tension after work is finished, as this exposes the components to too much stress and can damage the saw.
These photos compare the different types of frame saw blades, rip, cross, wet wood, and turning saw blades more or less in their relative sizes.
|Rip cut blade||Cross cut blade||Farmer's saw blade||Turning saw blade|
The saw blades for the ECE saws can, when they are the same length, be easily exchanged to match the task at hand. The saw arms are in red beech. The beam is in a flexible, light tropical wood, and the frame is tensioned using a wing nut on the threaded end of a 5 mm steel rod. These bow saws show a very good level of fit and finish.
With all ECE bow saws the distance between the saw blade and the beam is about 110 mm, but if you pivot the blade 90° this becomes 130 mm. The length given for the ECE saw blades is the entire length of the blade, and not the distance between the mounting hole centers.
Using a Japanese blade can substantially improve the quality of cut and general ease of use with frame saws. The saw teeth are laser hardened, which means they will remain sharp much longer than with conventional blades, but also means that they cannot be re-sharpened. Depending on how they are mounted, they can cut either on the push or pull stroke. If you hear or feel a light clattering while sawing, change the angle at which the blade enters the wood, which will help you to obtain a finer cut. Experiment with different blade angles, and you will be surprised at how much improvement you can expect in the speed and accuracy of the cut.
Japanese saw blades are thinner than the normal European types, and so a little bit more demanding. So be careful for instance to keep the blade lined up exactly in the cut. This will avoid kinking the blade. The listed lengths are for the total blade length! These blades fit easily into the saws from ECE and Ulmia, but not into the frames made by Wilhelm Putsch. If you would like anyway to use the Japanese blades in a Putsch frame, you will need to alter the mounting system using two of the blade holders listed near the bottom of the page, and you will also need to extend the middle beam a few millimeters or perhaps more simply make a new one.The distance between the mounting holes in the same nominal length can be a few millimeters different. One must be aware of this when changing from a standard blade to a Japanese blade. See chart!
Aside from a saw blade you need only 2 blade holders and some (recommended) specially produced hemp string to build your own saw! If you are looking into these saws, we are sure you have enough wood lying around to build something beautiful!