A bow saw is a useful frame saw for work that falls between the fine control of a backsaw and the reach of a full-size panel saw. Its replaceable blade can be changed for curved work, crosscutting, or light resawing, while the wooden frame remains simple enough to make with ordinary workshop tools.
The essential parts are two upright arms, a central stretcher, a flexible tensioning cord, and a blade held between the arm ends. The frame should be light but not springy, and the blade should be held firmly without being forced beyond its natural tension.
This version uses straight-grained hardwood and a cord-and-toggle tensioning system. Make the frame to suit the blade you have; blade length and pin spacing are more important than following a fixed set of dimensions.
What you will need
Materials
- Two straight-grained hardwood pieces for the arms, roughly 30–45 mm wide and 18–25 mm thick
- One hardwood piece for the stretcher, roughly 25–35 mm wide and 18–25 mm thick
- A bow saw blade with suitable end holes and pins
- Strong, non-stretching cord or braided line
- Two wooden or metal blade pins, if the blade is not supplied with them
- A small wooden toggle or winding stick
- Wood glue
- Sandpaper or a cabinet scraper
- A little wax or light oil for the blade, if desired
Ash, beech, oak, maple, and similar close-grained woods are suitable for the frame. Avoid boards with knots near the ends, short grain, splits, or pronounced run-out. The arms carry the tension from the cord, so sound grain matters more here than decorative appearance.
Tools
A handsaw, brace and bit or drill, chisels, a spokeshave or plane, a marking knife, square, mallet, and clamps are enough. A rasp is useful for shaping the arm ends and cleaning the blade slots.
Photo by Dominik Scythe on Unsplash.
Plan the frame around the blade
Begin with the blade. Measure from the centre of one end hole to the centre of the other. This is the working span between the arm ends. The stretcher should be shorter than the blade span so that the arms can lean slightly inward and hold the blade under tension.
For a general workshop bow saw, a blade between about 400 and 600 mm long is manageable. A narrower blade is useful for curves; a wider, coarser blade is steadier for cutting across thicker stock. The frame can be made deeper for resawing, but extra depth also makes it heavier and more awkward in tight curves.
Lay the arms side by side and mark their intended length. Keep them equal. Mark the blade slot at each upper end, and mark the cord attachment points near the lower ends. The stretcher should meet the arms roughly in line with the lower third of the frame, leaving enough room for the blade and for the cord to be tightened without striking the work.
Do not make the stretcher a tight permanent fit. It needs to keep the arms apart while allowing the frame to be assembled and the blade to be changed.
Shape the wooden parts
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Prepare the stock.
Plane or sand the three pieces until their faces are reasonably flat and their edges are straight. Mark the best-looking, straightest grain on the outside of each arm. Round only the edges that will be held; leave the joints and blade slots crisp.
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Taper the arms if desired.
The arms may remain rectangular, but a slight taper toward the upper ends reduces weight. Leave plenty of material around the blade slots and cord holes. A modest taper is safer than a narrow, elegant arm with weakened ends.
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Cut the blade slots.
At the top of each arm, mark a slot aligned with the centreline of the blade. The slot should be deep enough to receive the blade end and its pin, but not so deep that little wood remains above or below it. Saw the slot, then pare it clean with a chisel or narrow file.
The blade should enter without force and should not twist when the frame is assembled. If the blade has a shoulder or fixed pin arrangement, copy its shape carefully rather than assuming all blades use the same fitting.
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Drill the cord holes.
Drill a transverse hole near the lower end of each arm. The cord will pass through or around these points and be tightened with the toggle. Keep the holes well away from the end grain and from any visible weakness. Their positions must be equal so the tension pulls evenly on both arms.
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Fit the stretcher.
A simple method is to cut shallow open notches in the inner faces of the arms and form matching shoulders on the stretcher ends. The stretcher then drops between the arms and resists their inward movement. It should seat positively but still come apart by hand.
Another option is to use small tenons on the stretcher ends fitting into mortises in the arms. This is stronger and more finished, but it takes more careful layout. Whichever joint you choose, keep the stretcher square to the arms so the frame does not rack under tension.
Assemble and tension the saw
Set the stretcher between the arms. Fit one end of the blade into its slot, insert the pin, and then flex the arms together just enough to fit the other end. Do not bend the blade sharply. The frame should provide the spring; the blade itself should remain straight.
Pass the cord around the lower ends of the arms, or through the prepared holes according to your chosen arrangement. Tie it securely, leaving a loop or space for the toggle. Insert the toggle and turn it gradually to draw the arms together and tighten the blade.
The cord should become firm, and the blade should no longer sag or shift when the saw is lifted. It does not need to be pulled to the absolute limit. Excessive tension can split the arm ends, distort the frame, or damage a thin blade. If the frame creaks, the cord binds, or the arms bend dramatically, release the tension and inspect the fit.
The blade should sit in the same plane as the frame. Sight along it from the end. If it points off to one side, check that both slots are centred and that the pins are seated evenly. Small errors are best corrected by careful paring of a slot rather than by forcing the cord tighter.
Photo by Austin Ramsey on Unsplash.
Finish the frame
Once the fit is sound, take the frame apart and soften the hand-contact edges with a spokeshave, file, or sandpaper. Keep the blade slots, stretcher shoulders, and cord holes clean and square. Sand through a few grades until the wood feels pleasant but not slippery.
Glue is useful for a permanent stretcher joint, but do not glue parts that must be removed to change the blade. If the stretcher is a loose drop-in piece, a small shoulder or shallow notch will usually hold it in place. The goal is a frame that can be repaired rather than one that is difficult to dismantle.
A thin coat of oil, wax, or another suitable finish will reduce the absorption of workshop dirt and moisture. Keep finish out of the blade slots and allow it to dry fully before fitting the blade. The cord is a working part, so inspect it regularly rather than burying it beneath a heavy finish.
Fit the saw to the work
For straight crosscuts, fit a blade with teeth suited to the thickness and hardness of the stock. For curves, use a narrower blade and turn the frame gradually as you cut. A bow saw cuts most cleanly when the blade is allowed to do the work; forcing it sideways can twist or break it.
To begin a cut, rest the blade against the waste side of the line and make a few short, light strokes. Once a kerf is established, use the full length of the blade where the work allows. Keep the frame moving steadily and support the timber so the closing cut does not pinch the blade.
When cutting curves, rotate the frame rather than bending the blade around the curve. For a tight turn, relieve the curve with several changes of direction or use a narrower blade. If the saw binds, stop, withdraw it carefully, and correct the support or the line of the cut. Do not twist harder against a trapped blade.
A bow saw can also resaw small stock, though it is slower than a dedicated frame saw with a deep throat. Mark both faces when accuracy matters, start square, and check the cut often. The open frame gives useful visibility, but it does not prevent a wandering blade.
Useful mistakes to avoid
- Using short-grained wood for the arms: the ends may split when the cord is tightened.
- Making the blade slots too loose: the blade can rattle and wander. Fit them closely, but leave enough clearance for easy removal.
- Tensioning before checking alignment: cord tension magnifies small errors in the frame.
- Making the stretcher too long: the arms cannot draw together, and the blade remains slack.
- Making the stretcher too short: the arms may close unevenly or place too much load on the cord.
- Over-tightening: firm tension is sufficient. More tension is not a substitute for accurate slots and sound joints.
- Leaving sharp corners: rounded edges make the saw easier to control and less tiring to use.
- Cutting with a damaged blade: replace a bent, cracked, or badly dulled blade rather than compensating with force.
Photo by Brett Garwood on Unsplash.
Keeping the bow saw in service
Release the cord slightly when the saw is stored for a long period. This reduces constant stress on the arms and cord. Keep the blade dry and lightly protected from rust, and store spare blades flat where their teeth cannot damage other tools.
Before each use, look for splits at the arm ends, loose pins, frayed cord, and a stretcher that no longer seats properly. These are simple parts, and each can be repaired or replaced without discarding the whole saw.
A well-made bow saw should feel balanced in the hand, hold its blade without fuss, and invite a measured pace. Its value lies in that directness: a few pieces of sound wood, a replaceable strip of steel, and enough tension to turn a quiet stroke into a clean cut.