What are metal hand planes made of?
Some types of metal plane – for instance, some block planes and some types of specialist plane – are made entirely of metal.
However, most metal planes actually have some parts made of wood, notably their handles and, in the case of some specialised planes, their "fences" or guide rails which keep them moving in a straight line at a fixed distance from the edge of the wood as a groove or decorative shape is being cut.
The totes (rear handles), and knobs (front handles) of most metal bench planes and metal scrub planes are made from wood.
Others have handles made of impact-resistant plastic, which is less likely to mark or split if, for instance, the plane is dropped onto a hard floor.
Ductile cast iron
The body of the average metal hand plane is made of ductile cast iron. Although their shapes vary, this applies generally to scrub, bench and specialised planes.
Ductile iron is less brittle than other types and so is unlikely to break or go out of shape if the plane falls onto a hard surface such as a concrete workshop floor.
Bronze and brass
Some metal planes have bronze or brass bodies, which makes a plane both heavier and costlier.
Bronze is an alloy (a mixture) of copper and tin, and brass is an alloy of copper and zinc.
While the extra cost of these may be a drawback, some woodworkers like the extra weight they give to planes, claiming that it gives more momentum and thrust.
Another advantage of bronze and brass is that they will not corrode, while cast iron bodies may rust if left for long periods, especially in damp conditions.
The tops of some cast iron bodies – but not the cheeks (the sides) or the sole – are often finished with "japanning" or stove enamel.
Japanning is the application of a heavy, black lacquer, almost like enamel paint. Ironware is japanned or covered with stove enamel for decorative reasons and to make it rustproof.
Older planes that lose their gloss are sometimes re-japanned.
Hardened carbon steel
The irons, or blades, are usually made of hardened carbon steel, including high carbon steel (HCS) and what is known as ‘tool steel’.
A2 and O1 tool steels are extremely hard, resistant to abrasion, and have the ability to retain a sharp cutting edge for longer than most other steels.
O1 is not quite as hard as A2. While this means that A2 retains its sharp edge for longer, as a consequence it is a little more difficult to sharpen than O1.
Tool steel is said to respond well to cryogenic treatment in which the temperature of the steel is reduced to -196 degrees C (-320 degrees F), which gives increased wear resistance without any increase in brittleness.
However, some experts question the claimed benefits of cryogenic treatment, dismissing it as propaganda from from the cryogenic industry.
Another type of steel – chrome-vanadium – is resistant to abrasion and corrosion, and is even harder than A2. However, while irons made of this material hold a sharp edge well in woodworking applications, their increased hardness means it's difficult to hone them as sharply as plain high-carbon steel ones.
Adding chrome to steel increases its resistance to corrosion. However, corrosion is rarely the big issue with plane irons as long as they are kept in dry conditions.
The two major considerations are retention of the sharp cutting edge and "sharpenability" – how easy or difficult it is to sharpen the iron.
Overall, it seems that irons made of A2 tool steel are the best bet based on current research and experience. They retain their sharpened edge longer – but have the disadvantages of higher cost and being a little more difficult to sharpen because of their hardness.
Totes and knobs
Hardwood and aluminium
While the totes and knobs of scrub and bench planes are usually made from hardwood – such as rosewood, cherrywood or beech – or from plastic, there was a time when aluminium was a popular alternative.
Some planes with aluminium handles are now collector's items.
Plastic is an alternative to wood and it is very durable, but many woodworkers prefer wood for aesthetic reasons.
Stainless steel bolts and screws
The bolts and screws that hold totes and knobs in place are usually made of stainless steel.
Some bolts have a single-piece design with a slot in the head to take a flat-bladed screwdriver.
Others have a brass nut at the top – again with a screwdriver slot – which screws onto the thread at the top of the bolt to secure the tote.
Cast iron, bronze and brass
The frog – to which the blade, chip breaker, lever cap and adjusters are attached – is usually made of the same metal as the body of the plane. This means it is usually cast iron, but can be brass or bronze.
Chrome-plated steel screw
The frog adjustment screw – which moves the frog backwards and forwards to adjust the position of the blade in relation to the leading edge of the mouth – is usually made of steel, and often chrome-plated.
Lever cap and chip breaker
Steel, bronze and brass
Lever caps on metal planes are usually made of steel, and are often nickel- or chrome-plated to make them more resistant to corrosion and give them a smart, shiny appearance. They can also be bronze or brass to match the body of the plane.
The screw that holds the cap in place is usually steel and sometimes chrome-plated. It can also be made of brass.
Steel lever caps that are not chrome- or nickel-plated are often made of stainless steel.
Chip breakers, also known as cap irons, are usually made of plate steel.
While the quality of the steel used may not match that of the iron, the chip breaker needs to be firm to help keep the iron from flexing, which can lead to "chattering", or juddering of the plane.
The chip breaker screw, or cap iron screw, that fastens the iron and chip breaker together is made of steel or brass.
The blade depth adjustment wheel, which is a feature of most bench planes that follow the Stanley Bailey design, is usually made of brass, but can sometimes be plated steel. It turns on the thread of an iron or steel shaft.
Brass is an excellent material for machining (grinding and cutting to shape) accurately, and runs easily on iron or steel threads without binding. This is because brass is a tensile material with the ability to bend, making it suitable for bearings and moving parts. However, it is more expensive than iron or steel.
Yoke or "Y" lever
The yoke or "Y" lever – the wishbone-shaped lever that transfers the forwards and backwards movement of the iron depth adjustment wheel to advance and retract the blade – is usually an iron casting.
Lateral adjustment lever
The lateral adjustment lever, which is a feature of most bench planes, is made of mild steel and is often chrome plated.
Different types, but similar materials
In outlining the materials from which metal planes are made, Wonkee has concentrated mainly on standard Stanley / Bailey pattern bench planes. There are other plane designs – for instance, low-angle planes – with different body shapes and different adjusters, but the materials used for the parts are similar.