Aluminum block planes are the odd ducks of block planes. The problem with early cast-iron planes was the fact that were they to be accidentally dropped on the floor, they likely would not survive due to their brittleness. Pressed-steel block planes helped alleviate this problem, however there is still the issue of rust. So for a period of time, manufacturers turned towards building aluminum planes. Aluminum as a metal was first isolated by Danish physicist and chemist Hans Christian Ørsted in 1825, although in a impure form. German chemist Friedrich Wöhler furthered this work, isolated aluminum in 1827. French geologist Pierre Berthier discovered aluminium in bauxite ore. However, large scale production of aluminum was not possible until the development of the Hall-Heroult process – American chemist Charles Martin Hall and French chemist Paul Héroult developed the process simultaneously in 1886. Their process extracted aluminum from aluminum oxide, however it consumed a substantial amount of electricity. In 1888, Austrian engineer Karl Josef Bayer developed a process by which alumina could be extracted from bauxite.
The 1890s saw the production of the first aluminum boats, and 1899 saw Karl Benz present the first sports can with an aluminum body. By 1915, the first all metal plane, the Junkers J1 had appeared, made of Duralumin, an aluminum alloy which included copper, magnesium and manganese. After WW1, the use of aluminum in consumer products increased. By the mid-1920s, Stanley began production of its bench plane series using aluminum – the A4, A5, and A6. The Stanley A18, an aluminum version of the No.18 knuckle-cap block plane was produced during the two world wars from 1925-1935. In the bench planes, the bodies and frogs were made of aluminum, whereas on the A18, only the actual body of the plane was aluminum, with the remainder constructed of nickel-plated metals.
The core benefits of aluminum planes are: (i) they are light weight, (ii) they don’t rust, and (iii) they don’t crack or break when dropped. However they have an equal number of limitations. Firstly, when they appeared, they were 30% more expensive. In 1926, the A18 sold for $3.50, while the No.18 sold for $3.00. This was likely one of the factors of their limited success, that and their introduction before the Great Depression. Next, because aluminum oxidizes, when the planes are used, they leave black marks on the wood, discolouring it (the same thing happens with aluminum ladders). Finally, because aluminum is a soft material, its sole is susceptible to scratching, and denting. Aluminum is often thought of as being rust-resistent, however corrosion can actually be a big problem in aluminium blocks. One reason for this is that contact between aluminium and steel can cause galvanic corrosion.
The aluminum block planes include the following:
- BOSTON No.1
- BOSTON No.2
- BOSTON No.2A
- UTIL Plane (Chicago)
- Foster Mfg. Co. No.1(?) (1 Kinsey, Buffalo NY)
- Stanley No.A18
For some of the planes, such as the UTIL, and Foster, there is little information. Foster Mfg. Co. sold woodworking machinery for the home user in the late 1940s (the company was gone by 1953), and so this hand plane seems to be a one-off? Maybe a give-away? They didn’t manufacture any of the tools they sold.
There were also a couple of planes from the Stanley Model Shop, aluminum versions of the No.110, and No.220 (they were never put into production). Stanley may have produced the greatest number of aluminum planes in total, also producing A4, A5, and A6 bench planes and the A45 combination and A78 rabbet planes.
P.S. I wanted to post some images of aluminum degradation, but none of my aluminum block planes have any!