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The Bandsaw Store

Bahco, Morse and Lenox

Bi-metal bandsaw blades

An HSS tooth edge on a fatigue-resistant alloy backing: the blade fabrication and engineering shops fit as standard. Choose your width and pitch and we weld the band to your machine's exact length.

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Two steels doing two jobs

A bi-metal blade solves a contradiction. Teeth hard enough to cut steel are too brittle to survive flexing around a bandsaw's wheels, and a band springy enough to flex all day is too soft to hold an edge in metal. The construction answers both at once: a narrow strip of high speed steel, commonly M42 or M51, is welded along a fatigue-resistant alloy steel backing, and the teeth are then milled so only the tips are high speed steel. The edge keeps its hardness at the temperatures steel cutting generates, while the backing absorbs the constant bending that would crack a through-hardened band.

That split is why bi-metal is the default in fabrication and engineering workshops. One construction covers aluminium, brass and copper, mild and structural steel, stainless and tool steels and cast iron. Wood and softer materials are the ground of carbon steel blades. The choices that remain are the edge grade and the tooth pitch, and both are dealt with below.

M42 or M51: choosing the edge

Bi-metal blades pair a high speed steel edge with the same style of alloy backing. M42 covers most workshops; M51 and similar premium grades exist for the work that wears M42 out. Each product page states the edge as its manufacturer publishes it. When even a premium edge struggles, the next construction up is a carbide-tipped blade.

M42 against premium HSS grades such as M51, drawn from the manufacturers' published positioning. Both weld to the same kind of backing; the difference is the edge.
ConsiderationM42M51 and similar premium grades
Edge materialCobalt high speed steel.High speed steel carrying more tungsten.
Behaviour under heatKeeps its hardness at the temperatures generated when cutting steel, so the edge cuts rather than rubs as the work heats up.Holds hardness further into hot, abrasive cutting; the margin tells most on long cuts through large solid sections.
Wear behaviourOutlasts carbon steel teeth on ferrous work.Wears slower again on tough, abrasive ferrous material where M42 edges dull early.
Typical workThe everyday fabrication mix: steel, alloy steel, stainless steel, iron and non-ferrous metals.Tempered steels, larger solid sections and some exotic alloys.
When to choose itStart here. It is the default edge for general fabrication and engineering.Step up when M42 blades wear quickly on tough ferrous material rather than failing from fatigue.
In this rangeBlades their makers name M42, for example Production M42 Bandsaw Blade, Rx+ M42 vp Bandsaw Blade and Rx+ EHS M42 Extra Heavy Set Bandsaw Blade.Premium lines, published for special and difficult alloys and tool steel, for example 3854 Sandflex King Cobra PQ Bandsaw Blade and 3858 King Cobra P9000 PQ Bandsaw Blade.

What bi-metal blades cut

The materials below come from the manufacturers' published ranges for this construction. The guidance is general: section size, machine condition and feed discipline matter as much as the material name. Steel cuts best with coolant, and our cutting fluids guide explains what it does.

Typical bi-metal workpieces with general cutting guidance. Material names link to our dedicated guides where one exists.
MaterialCutting guidance
Structural steelBox, angle and beam are interrupted cuts through thin walls. Choose a finer variable pitch so several teeth share each wall, and keep the feed steady where the blade breaks through a face.
Mild steelSolid bar wants a coarser pitch with gullet room for a full chip. Feed positively so every tooth bites; a blade allowed to rub polishes the cut face and dulls itself.
Stainless steelWork hardens the instant a tooth rubs instead of cuts. Bite from the first pass, never dwell in the cut and keep the coolant generous.
Tool steelAnnealed grades saw respectably on premium bi-metal with a firm feed and an unhurried band speed. Hardened material is carbide territory rather than a job for HSS teeth.
AluminiumFast cutting but gummy. A coarse pitch keeps the gullets clear of packed swarf, and a sharp blade with a steady feed stops the soft alloy smearing onto the tooth face.
BrassUsually free cutting with short chips. A medium pitch and moderate feed give clean faces; ease the feed on thin sheet so the teeth do not snatch.
CopperSoft and gummy rather than hard. Keep the pitch on the coarse side for the section and change the blade while it is still sharp: a dull edge tears rather than cuts.
Cast ironThe skin is harder and more abrasive than the core, so feed firmly through it rather than easing in. Expect powdery swarf and follow the machine guidance on cutting dry or with coolant.

Picking tooth pitch and width

Width first: fit the widest band your machine will tension properly for straight, deep cuts, and only go narrower when the work curves. Pitch then follows the section you cut, not the material's name.

  1. Measure the section

    Measure the metal the teeth actually pass through: wall thickness on tube and box, full width on solid bar. The thinnest part of the cut governs the pitch.

  2. Apply the teeth-in-cut rule

    Aim for between 4 and 24 teeth in the cut at any moment. Fewer and each tooth takes too big a bite and can strip; more and the gullets fill before they clear, so the blade rubs.

  3. Coarse for solids, fine for walls

    Big solids run coarse, with variable pitches in the 2/3 to 4/6 TPI range, so the gullets can carry a full chip. Thin wall tube and profiles run finer, such as 8/12 or 10/14, to avoid tooth strippage.

  4. Mixed work runs variable

    A variable pitch band covers a spread of section sizes and breaks up the vibration a fixed pitch can set off, so one blade handles a varied cutting list without constant changes.

Each product page lists that blade's published width and TPI options. If you would rather answer questions than read a chart, the blade wizard applies the same rules for you.

The bi-metal range

16 blades from Bahco, Morse and Lenox with published widths from 13 to 67mm, every one welded to the length you order.

Shop all bi-metal blades

Industries that run on bi-metal

Where this construction is the first blade on the saw, and where it works alongside carbide for the hardest jobs.

Material guides for this range

From the blog

Frequently asked questions

What does M42 mean on a bandsaw blade?

M42 is a cobalt high speed steel grade used for the tooth edge of bi-metal blades. It holds its hardness at the temperatures generated when cutting steel, so the edge outlasts carbon steel teeth on ferrous work.

When should I step up from M42 to M51?

M51 carries more tungsten and suits harder, more abrasive work such as tempered steels, larger solid sections and some exotic alloys. If M42 blades are wearing quickly on tough ferrous material rather than failing from fatigue, M51 is the usual next step.

What TPI should I choose for solid steel bar?

Aim for between 4 and 24 teeth in the cut at any moment. As a rule of thumb, larger solid sections need coarser pitch: variable pitches in the 2/3 to 4/6 TPI range suit big solids, while thin wall tube and profiles need finer pitches such as 8/12 or 10/14 to avoid tooth strippage.

Do bi-metal blades cut wood as well as metal?

Some do. Wood-cutting bi-metal blades pair the durable HSS edge with wood tooth geometry, and are chosen where carbon blades blunt too quickly, for example abrasive hardwoods and high-output resawing. Check the cuts line on each product page for what the manufacturer rates a blade for.

Tell us the length your machine takes and we will weld your bi-metal blade to match.

Order a custom length