Was 1/40 a box scale size ?

not too many kits were made in this scale. this subject would have made a great 1/35 diorama subject.
what's the history behind 1/40 and its incompatibility with 1/35 and 1/48 ?
Craig

I think Revell's first armor kit, the mismash M4A1E8 was a larger box scale kit, maybe 1/30 or so. Then they hired Adams to design their line of 1/40 scale armor. For some reason, when Adams left Revell, he was able to take some of the molds he designed with him and released them as Snap Adams kits. The rest stayed with Revell. Why 1/40? Who knows, probably the same reason why 1/35 was selected by others.

This brings up my theory on modeling scales. Seems like there are two origins.
One is architectural scales. These long predate plastic models, and were used by architects. These are typically common fractions of an inch to the foot- say quarter inch to the foot (1:48) or half inch to the foot (1:24), etc.
The second grew out of box scales, and were ones folks found convenient so other mfgs picked them up. When there was the push to common scales, these survived.

Revell issued many of their early kits in Box Scale. An aircraft carrier and destroyer would be the same size. Their sherman tank "Black Magic" was the first of their military vehicle kits. It was in 1/40 and not some weird fraction like 1/67. They actually stuck to the 1/40 for the rest of the releases as opposed to the war ships so looks like there was a little more coordinated planning here. Next to come were the M4 tractor with 155mm Long Tom, armored scout car etc. They issued a figure set which also kept with the same scale. I have to assume 1/40 had some advantage like small, yet the figures would be large enough for detailed weapons etc. The molding technology at the time may not have allowed the required details in 1/48, and they may have found 1/32 too large. Some time later I remember a hoby shop owner saying the Revell rep told him they couldn't do cost effect detail like Tamiya in 1/48th.
ADAMS originated with Revell and continued in 1/40.
A the same time Monogram was coming out with a constant scale military set - unfortunately in 1/32 - standing the figures sid by side clearly shoed the incompatability.

That Black Magic Sherman may have been advertised as 1/40th scale, but that kit is larger than the Tamiya 1/35 scale M4A3 Sherman but smaller than the old Tamiya motorized M4A3E8 Sherman.
Many of Monogram's armor kits were labeled as 1/35 originally. It wasn't until their later kits that they started labeling them as 1/32.

There was no standard scale in the 1950's. Most early kits were "fit the box" scale (i.e., we need an airplane model ten inches long, so what scale will that work out to be?). It soon became clear that offering collections of models in a common scale would be a useful marketing decision, but there was nothing inherently obvious about what scale would be "right." Some scales were logical within the Imperial measurement system, though they seem nonsensical to the metric world. 1/32nd is 3/8th of an inch to one foot, for instance, and 1/48th scale is a quarter inch to a foot, while 1/72nd is one sixth of an inch to a foot (so a six foot man stands one inch high, conveniently). These scales can be converted using household rulers, so they are easy to work with, at least in the US and the Commonwealth countries. Scales that end in zero or five make more sense to metric countries, so some car kits were offered in 1/25th instead of 1/24th scale. In armor kits, Renwal offered models in 1/32nd scale, which was a logical choice, and one compatible with existing car and aircraft kits. Revell and Adams went smaller, with 1/40th scale, joined later by Midori in Japan. Monogram decided to split the difference. There had been a range of 1/36th scale metal recognition models designed during World War Two that had a postwar life as popular toys, so the size was familiar to the customers, but Monogram opted for a more "metric" scale, so their 1950's vintage products were released in 1/35th. It's a convenient size, and a 5'10" man in that scale stands exactly two inches high. In Japan, about the same time, Mr. Tamiya records that he wanted a Panther tank kit that was a particular size, and the box scale worked out to 1/35th. He insists he wasn't copying Monogram. In any event, that was one of the scales that Tamiya standardized in the Far East, and they were followed by Nitto Kagaku in the 1960's, and Nichimo in the 1970's. In Italy in 1972, a new start-up company, Italaerei (now Italeri) offered a new Hetzer tank destroyer kit and opted to follow Tamiya's lead. In 1975, Heller followed suit, and pretty much everybody since then has adopted 1/35th as the "medium" scale. Nichimo in Japan tried to launch a new scale, 1/30th, in the early 1970's but only Ogonek in The Soviet Union joined them, and that scale never caught on. Ironically, Monogram zigged when the rest of the industry zagged, switching to a line of 1/32nd scale armor kits in 1969. Only Airfix joined them and the larger scale sank into obscurity. The smaller scales have been more chaotic. Aurora offered a range of popular but fairly inaccurate armor kits in the 1950's and 60's, while Tamiya and Bandai offered a better range of models in the 1970's, though Tamiya's were compromised as motorized toys with rubber band tracks. Only recently has interest in that scale revived. The "Braille Scale" scene was split during the 1960's among HO scale (1/87th, usually) offered by Roko Minitanks, and 1/76th scale (a bizarre mixed scale, where four millimeters equals one foot) offered by Airfix and later, Matchbox. In the 1970's Esci and other continental makers switched to 1/72nd, though today, many old 1/76 scale molds are boxed as 1/72nd, just to aggravate the customers. Big scale kits have varied between 1/24th and 1/25th, and the motorized model community has had a few kits in 1/15th or 1/16th scale to choose from. Gerald Owens

Gerald has most of it captured. I think the reason was basically that Renwal and Monogram were doing "3/8th Inch" scale (1/32) and that Revell wanted to stake out their own scale, e.g. you have to buy their kits in order to have them compatible. Adams cut their molds which is why "competing" items from Adams were not really competition per se. SNAP had some sort of relation (not sure what it was) and eventually all of the molds went to Life-Like (I guess unless they unloaded them technically Walthers now would have them as they bought out Life- Like).
But the Sherman as noted was 1/35 as were Monogram's PM kits (their military line) in the 1950s so things did not always work out.
It really wasn't until 1969 that 1/35 really started to catch on and we do have to credit that to first Tamiya, who started their "Military Miniatures" series in a relatively close 1/35 scale (as comparted to their early 1960s offerings like the more-or-less 1/33 scale M4A3E8). Revell did not compete although they did later import Italeri kits under their brand name.
Cookie Sewell

1/40 was a "compromise" scale half-way between the 1/32 of Renwal armor and the 1/48 of Monogram (?) aircraft. It allowed the display of armor and aircraft together. Revell made at least two aircraft kits (Skyraider, Bell X-5) to go with their armor, and Hasegawa and Midori also made 1/40 armor.
KL

...plus a goodly number of their missile kits -- TALOS, Terrier, X-17, Dart, Little John, Aerobee, Corporal...
Cookie Sewell

1:72 (i.e. 1"=3D6'0") is and old engineering scale that was used by surveyors (like me 8~P) in map-making for smaller parcels. I have also seen it in detail drawings for bridges and tunnels, although most everyone uses metric nowadays. I haven't seen too many household rulers that had a 1/6" designation.

The story goes that Tamiya chose 1/35th scale for their Panther (the first kit in that scale) because at that scale the kit motor they had available was a perfect fit inside the hull.
If that story is true, it's a shame they didn't decide to fit the motor in a slightly-more-roomy 1/32nd scale hull -- that would have had an enormous impact on the future of the hobby ... imagine civilian vehicle kits, Tamiya's armour kits, Airfix's infantry sets and soft- skin vehicle kits, all at the same scale ....
Oh well ....
Bruce Melbourne, Australia

...or better yet actually stick to one or the other (1/35 or 1/32) rather than the "sort of scales" of their early kits -- compare the new Matilda (sans motor) to the original one (with motor option) or a scale size Sheridan to the Tamiya behemoth!
Cookie Sewell