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A backsaw is defined by its spine. The brass or steel strip along the top of the plate stiffens a thin blade, which lets the saw carry fine teeth without buckling. That explains why backsaws are the joinery saws: they cut straight, start easily, and leave a shoulder line clean enough to show.
The family is broader than most woodworkers expect. Dovetail, carcass, tenon, and sash saws share the spine but differ in length, tooth count, plate thickness, and filing. Choosing among them means matching pitch and length to the joint and the cut direction.
The names are not standardized across makers, which adds confusion. A saw sold as a carcass saw by one company may be called a tenon saw by another. Ignore the label and check the numbers: length, tooth count, and rip or crosscut filing.
What the Spine Actually Does
The spine stiffens the plate in the vertical plane. Without it, a thin plate would buckle under the push stroke and the cut would wander. With it, the plate can be 0.018 to 0.025 inch thick, thin enough for a narrow kerf and fine teeth but rigid enough to track straight. The added weight near the top helps the saw sit in the kerf.
The spine is not a handle for the off hand. It is a structural member, and it should be tight against the plate along its full length. A loose spine lets the plate flex and the saw will not cut true. On older saws the spine is often folded brass; on newer ones it may be slotted steel. Check it by holding the handle and tapping the spine; a rattle means the spine needs tightening or the saw is not worth buying.
The plate is usually taper-ground, thicker at the tooth line and thinner toward the spine. That taper lets the saw clear its own kerf without excessive set. A plate that has been hammered flat or ground unevenly will bind no matter how well the teeth are filed.
The Backsaw Family Tree
A dovetail saw is the smallest and finest of the common backsaws: 8 to 10 inches long, 14 to 20 points per inch, filed rip. The plate is thin, often 0.018 to 0.022 inch, with minimal set. It is built for dovetail tails and pins in stock up to about an inch thick, where a fine kerf and clean baseline matter more than speed.
A carcass saw is larger, usually 12 to 14 inches with 12 to 14 points per inch, normally filed crosscut. It cuts tenon shoulders, lap joints, and the crossgrain cuts in carcass work. The filing leaves a cleaner shoulder than a rip saw would, and the extra length gives a longer stroke across a wide board.
A tenon saw is larger still, typically 14 to 18 inches with 10 to 12 points per inch, filed rip. The deeper plate and heavier spine suit cuts along the grain in thick stock, especially tenon cheeks. The length gives enough stroke for a 3- or 4-inch cheek, and the coarser pitch clears waste faster than a dovetail saw.
A sash saw sits between the carcass and tenon patterns: about 16 inches, 12 to 14 points per inch, often crosscut, with a narrow plate for sash bars and muntins. A gent's saw is a miniature backsaw, 6 to 8 inches with 15 to 20 points per inch. These patterns cover most furniture tasks.
Tooth Count, Pitch, and the Feel of the Cut
Tooth count is usually given in points per inch, which counts the tips. Teeth per inch is one less: a 20-point saw has 19 teeth per inch, a 12-point saw has 11. The difference matters when comparing makers, because a saw described as 15 tpi may be 16 ppi.
Finer pitch means a slower cut and a cleaner surface. A 20-point dovetail saw takes many small bites, which gives the user time to steer and leaves a kerf narrow enough to hide in the joint. A 10-point tenon saw takes bigger bites and clears waste faster, which is what you want in thick stock where the saw is buried most of the time.
The length of the tooth line also changes the feel. A short saw accelerates quickly and is easy to control in small work, but it runs out of stroke in thick stock. A long saw carries more teeth through the cut and cuts faster, but is harder to start precisely. Use the shortest saw that completes the cut without bottoming out.
Rip vs Crosscut Filing in Backsaws
Dovetail saws are almost always filed rip: small chisels with zero fleam and a rake of about 8 degrees. The rip filing cuts efficiently along the grain on the tails and across the end grain on the pins, and it leaves a straight wall that pairs well with a chisel. A crosscut dovetail saw exists, but it is a specialist tool for veneered or fragile stock.
Tenon saws are also usually rip filed, because the long cuts on the cheeks run with the grain. A tenon saw used on the shoulders will leave a rougher line than a carcass saw, which is why many woodworkers keep both: the tenon saw for the cheeks, the carcass saw for the shoulders.
Carcass and sash saws are crosscut filed, with 20 to 30 degrees of fleam and a rake of 10 to 15 degrees. The knife edges sever the fibers at the shoulder line and leave a clean surface. The same geometry is described in more detail in crosscut versus rip saws, and the filing angles carry over directly.
Handles, Hang, and How the Saw Meets Your Hand
Most backsaws have a closed handle for a full grip and precise control. Some dovetail saws use an open handle, which is lighter and encourages a lighter grip. Shape matters less than fit: the handle should fill your hand without forcing your wrist into an awkward angle.
Hang is the angle between the grip and the tooth line. More hang encourages a forward and downward stroke, suiting ripping; less hang sits more level, suiting crosscutting and fine joinery. The difference is subtle, and most woodworkers adapt within a few cuts.
Handle material matters for balance. Beech and other dense hardwoods absorb vibration and keep the saw steady; too light a handle feels top-heavy, too heavy a one feels sluggish. Check for cracks around the saw nuts and a loose fit against the plate. A cracked handle can be repaired, but one crushed around the nuts has seen hard use.
Matching the Saw to the Joint
For dovetails, use the finest saw you can control. A 20-point saw leaves a kerf of about 0.020 inch, narrow enough to leave the pins strong and wide enough to clear the saw. Mark the baseline with a gauge or knife, cut just to the line, and remove the waste with a chisel. The technique is covered in dovetail saw technique, and the layout angles are worth settling first.
For tenon cheeks, use a tenon saw with enough length to make the cut in one pass. The saw should be rip filed and the plate deep enough to span the cheek. Cut just outside the line, then trim to the shoulder with a shoulder plane or a chisel. The shoulder is a crosscut, so a carcass saw is the better tool for that part of the joint, as described in through mortise and tenon work.
For half-laps and bridle joints, a carcass saw works well because most of the cuts are crossgrain. For sash work, a sash saw's narrow plate fits into the confined space between the bars. For small trim cuts, a gent's saw is easier to control than a full-size backsaw. The joint dictates the saw, not the other way around.
Buying, Setup, and Care
Used backsaws are plentiful and often better value than new ones, if the plate and spine are sound. Check the tooth line first: it should be straight and free of broken teeth. A few short teeth can be jointed and refiled, but a crack running from the tooth line into the plate is fatal. Check the spine, handle, and plate for tightness, cracks, and pitting near the teeth. Sight down the plate; a saw hammered flat will not clear its kerf.
New and used backsaws both benefit from a tune-up. Joint the tooth line, check the set, and file the teeth to a consistent rake and fleam, as described in sharpening a hand saw. Backsaws take less set than panel saws, often 0.002 to 0.003 inch per side. Too much set makes the saw wander; too little makes it bind.
Keep the spine tight and the plate oiled; a light coat of camellia or mineral oil prevents rust without attracting dust. Store the saw hanging or flat with the teeth protected. If it binds, check the set; if it wanders, check the tooth line and plate for a kink.
A properly set up backsaw will cut a joint that needs almost no cleanup. That is the point of the tool: not speed, but control. Dovetail layout and trimming with a shoulder plane both depend on a shoulder line that was cut cleanly in the first place.
Frequently Asked Questions
Can I use a dovetail saw for tenons?
You can cut small tenons with a dovetail saw, but the short plate and fine pitch make it slow in thick stock. A tenon saw is better for cheeks; a carcass saw is better for shoulders.
What is the difference between a carcass saw and a tenon saw?
A carcass saw is usually shorter, finer, and crosscut filed for shoulders and crossgrain cuts. A tenon saw is longer, coarser, and rip filed for cheeks. Some makers blur the line, so check tooth count and filing.
How many teeth per inch should a dovetail saw have?
Most run 14 to 20 points per inch. A 20-point saw starts more easily and leaves a finer kerf; a 15-point saw cuts faster in thicker stock. For dovetails in 1/2- to 3/4-inch stock, 16 to 18 points is a practical middle ground.
Why does my backsaw bind in the kerf?
The set is probably too small, the plate may be kinked, or the saw may be dull. Check the set first, then sight down the plate for a bend. Wax helps, but it will not fix an under-set saw.
Do I need more than one backsaw?
For furniture work, two saws cover most tasks: a fine dovetail saw and a larger carcass or tenon saw. A single 12-point crosscut backsaw does a surprising amount of work, but it is a compromise at both extremes.
See Also
- Japanese Saws vs Western Saws: Which Cut Belongs to Which Saw
- Sharpening a Hand Saw: Jointing, Rake, and Fleam Explained
- Crosscut vs Rip Hand Saws: Tooth Geometry and When Each Belongs
- Scroll-Saw Blade Sizes Demystified: Pick the Right # for Intarsia, Inlay & Fretwork
- 2026 Handsaw Showdown: 8 Premium Hand Saws Ranked for Speed & Smoothness