Backsaw

How it works

The blade is too thin to be pushed without bending, and the back supplies the stiffness that a frame or a thick plate would otherwise supply. Moxon, writing in 1703, states the reason in a single clause: the tenon saw, being thin, has a back to keep it from bending. Disston’s 1916 history says the same of the type used for very fine cutting requiring a straight or even saw cut, adding that the blade is so thin that a back of steel or brass is necessary to prevent buckling.

The teeth are fine, so each stroke removes little wood and the cut is controlled. Disston’s 1926 catalog lists a miter box saw usually with 11 points to the inch, a No. 1 back saw in 14 points to the inch in the 12-inch size, and a No. 3 back saw with 13 teeth to the inch.

Anatomy

Blade: Thin steel plate. Disston’s 1926 catalog calls its miter box saw blade quite thin and its dovetail saw blade extremely thin.
Back: A folded strip of steel or brass along the top edge. Disston’s 1926 catalog gives blued steel for its miter-box and No. 3 back saws; Disston’s 1916 history names steel or brass.
Heel: The butt end of the toothed edge. Disston’s 1916 and 1926 texts say the heel of the larger miter-box saws is shaped, or the tooth edge made shorter than the back, so that the heel does not catch in the work.
Teeth: Fine, in points to the inch. Fine Woodworking’s Kenney recommends about 19 tpi sharpened for rip for a dovetail saw and 12 to 14 tpi crosscut for a larger carcass saw.
Handle: Closed pistol grip or open straight (gent’s) form. Kenney prefers the pistol grip; Gochnour’s 2006 test covered both pistol-grip and gent’s saws.

Variants

Tenon saw: The 1703 name in Moxon’s text and the name on the Science Museum Group record of a Sheffield saw of 1750–1770.
Dovetail saw: A small, fine backsaw for dovetails. Disston’s 1926 catalog lists a No. 70 dovetail saw with an extremely thin blade.
Carcass saw: A larger crosscut backsaw with a taller, longer blade than a dovetail saw (Kenney).
Miter-box saw: The larger backsaws, 20 inches and longer, called miter-box saws in Disston’s 1916 history; the 1926 catalog lists them in 20 to 32 inch lengths.
Movable-back saw and gauge saw: The Disston 1916 history describes a movable-back saw whose back detaches so it works as a backsaw or an ordinary handsaw, and a gauge saw with an adjustable depth stop.

Specifications

Blade length · in: Disston’s 1926 No. 1 back saw is listed in sizes up to 18 inches; its miter-box saws from 20 to 32 inches. No single typical value is sourced.
Points per inch · ppi: 14Disston’s 1926 No. 1 back saw is 14 points to the inch in the 12-inch size; Kenney recommends about 19 tpi for a dovetail saw and 12 to 14 tpi for a carcass saw.

Safety and care

Safety

Hold small workpieces firmly; Kenney recommends a sawhook, a board with a fence that both the user and the saw press the work against.
Wear eye protection and keep the work supported (CCOHS).

Tips

Start the cut between the fingernails
Kenney’s method: after marking with a knife or marking gauge, place the nails of the forefinger and thumb in the knife line, set the teeth of the saw against the nails and push lightly. The nails guide the first strokes of the kerf.1
Chisel a groove on the baseline to start a shoulder cut
Kenney recommends chiseling an angled groove along the scribed baseline and using its vertical wall to start the saw. The saw then falls naturally down the baseline, leaving no waste to pare.1
Use a sawhook for small parts
A sawhook is a flat board with a square fence and a cleat that goes in the vise. Because the backsaw cuts on the push stroke, it presses the part against the fence while cutting. Kenney adds kerfs at 90 and 45 degrees in the fence to support the work on both sides of the cut and prevent tearout.1
Choose the pistol grip for control
Kenney prefers a pistol-grip handle on a dovetail saw because it makes the saw easier to push and control. Western backsaws are made with either pistol-grip or straight handles.1
Match tooth pattern to the job
Kenney uses a dovetail saw of about 19 tpi sharpened for ripping for dovetails and other fine cuts, and a larger carcass saw of 12 to 14 tpi set up for crosscuts for cutting small parts to length.1
A shortened back lets the saw cut close to a wall
Disston’s No. 3 back saw has its back cut three inches shorter than the tooth edge so that it can cut close to walls when hardwood flooring is laid. The catalog says the tooth edge of the miter-box saw is made two inches shorter than the whole blade so the heel does not catch in the work.1

History

Earliest documented

1703 (earliest document read); c. 1750–1770 (earliest object read)

England

Moxon’s Mechanick Exercises (1703 edition) describes the “Tennant-Saw” among the saws for a single man’s use and says that, being thin, it has a back to keep it from bending. The Science Museum Group holds a tenon saw of 12 points to the inch, of cast steel and hard wood, made in Sheffield in 1750–1770 and used by Samuel Crompton; the record does not describe the back. Earlier evidence has not been located.1 2

The back is the answer to a specific problem: a thin blade cuts with little effort and a narrow kerf but will not hold a line when pushed. Moxon in 1703 names the thin tenon saw as the one that has a back to keep it from bending, and Disston’s 1916 history says the same of the saw for very fine cutting. The open handsaw solves the problem differently, by a thicker plate and a tapered grind, and the frame saw by tension.

The Science Museum Group records a Sheffield tenon saw of 12 points to the inch made in 1750–1770, although the record does not say how its back was made. The evidence read for this entry therefore establishes the name and the purpose of the saw but not its place or date of origin.

By the early twentieth century the backsaw was made in several sizes. Disston’s 1916 history names the 20-inch and larger saws as miter-box saws and records saws of the same pattern in special steel for cutting metal. The 1926 catalog specifies the miter-box saw as a thin blade usually of 11 points to the inch, tested in a miter box before leaving the factory, with the tooth edge shortened so the heel does not catch.

Kenney argued in 2013 that a handsaw is often the better choice for crosscutting or mitering delicate moldings, because a table saw or miter saw would need a jig to hold the part and the spinning blade could damage it. The Japanese dozuki is the same idea carried out differently, with the spine and the pull stroke, and Gochnour’s 2006 review notes that both Japanese and Western-style saws have advocates, himself preferring the Western style for its sturdier construction and thicker steel.

Timeline

1703
Moxon’s Mechanick Exercises (1703 edition) names the Tennant-Saw, for a single man’s use, and says it is thin and has a back to keep it from bending; it is used to saw down to the gauged lines of a tenon.1
1750–1770
A Sheffield tenon saw of 12 points to the inch, 510 mm long, is made; it is now in the Science Museum Group collection.1
1916
Disston’s The Saw in History describes the back saw as the type used for very fine cutting, with a back of steel or brass to prevent buckling, and the larger saws of 20 inches or more as miter-box saws. It also describes the movable-back saw, the gauge saw and the use of tenon saws of special steel for cutting metal.1
1926
Disston’s Saw, Tool and File Book lists a miter box saw of 10 gauge in 20 to 32 inch lengths, the No. 1 back saw, the No. 3 back saw cut so the tooth edge is three inches longer than the back, and a No. 70 dovetail saw.1
2006
Chris Gochnour tests 11 Western-style pistol-grip and gent’s dovetail saws priced from $10 to $125 for Fine Woodworking issue 183, judging speed, ease of starting, smoothness and tracking.1
2013
Matt Kenney, in Fine Woodworking issue 231, names a dovetail saw and a carcass backsaw set up for crosscuts among the four handsaws a shop needs.1

Gaps in the record (6)

The date and place of the first backsaw have not been established. Moxon’s text is the earliest document read, and Moxon’s first edition date and the Science Museum record’s description of the back were not checked.
Early maker histories (Spear & Jackson, Sheffield) and patents for backs and folded backs were not located.
Care has no sourced entries.
No standard has been located that governs backsaw dimensions; standards is empty.
Gochnour’s 2006 test is cited for what he tested; its rankings were not reproduced, and no independent failure data has been located, so buying is null.
Disston’s 1926 catalog text is an OCR scan; the dovetail saw gauge, the miter-box blade thickness and widths, and the smallest No. 1 size were not legible and are omitted.