# Was There a Scale of Measurements Based on Tenths of Inches? **URL:** \ **Category:** Factual Questions\ **Created:** [May 13, 2020, 1:42pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711 "2020-05-13T13:42:25Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [May 17, 2020, 9:13pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/21 "2020-05-17T21:13:02Z")
> [@bump](#): > > Surveying is still done in decimal feet (feet & tenths of feet), or at least it was back when I was in college. Makes the math easier. Can confirm, still is ('round these parts, anyway). ---
**Author:** ![E-DUB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/e-dub/32/403_2.png) [@E-DUB](https://boards.straightdope.com/u/E-DUB)\ **Post date:** [May 17, 2020, 10:52pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/22 "2020-05-17T22:52:22Z")
I’ve got a ruler that has 1/10’s of an inch on one edge (the other is conventional halves, quarters, etc). One side does say (Faded) Engineering division. Can’t recall where I got it. I use it for scale model work. It makes it easier when a measurement from the prototype comes out as 6.37 inches to just go in on the high end of 6.3 rather than converting to English. ---
**Author:** ![Bonum\_Legatum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bonum_legatum/32/6183_2.png) [@Bonum\_Legatum](https://boards.straightdope.com/u/Bonum_Legatum)\ **Post date:** [May 21, 2020, 9:03pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/23 "2020-05-21T21:03:28Z")
To the OP: If you go to [www.archive.org](http://www.archive.org) and search for “shop theory henry ford”, one of the responses will be a book titled “Shop Theory by Henry Ford” (and that should be “Shop Theory by the Henry Ford Trade School”. Download the book and you will see a decimal ruler on Page Number 35, along with a discussion of how it was to be used. The decimal system would work well with the very precise and accurate shop measurement system provided by Johansson blocks, manufactured in decimal inches. ---
**Author:** ![Some\_Call\_Me.Tim](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@Some\_Call\_Me.Tim](https://boards.straightdope.com/u/Some_Call_Me.Tim)\ **Post date:** [May 22, 2020, 12:55am UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/24 "2020-05-22T00:55:28Z")
Centuries before that, Thomas Jefferson’s 1790 proposal of a [Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United\_States](https://en.wikipedia.org/wiki/Plan_for_Establishing_Uniformity_in_the_Coinage,_Weights,_and_Measures_of_the_United_States) included a decimal system of measure in which a tenth of an Inch would be called a Line. (This wasn’t quite the same Inch, though, being 1/10 of what it was using as a Foot) While the US did adopt its radically innovative decimal coinage system (the ‘dollar’) based on this proposal, we did not adopt decimal measurements as was recommended. A few years later the French adopted a similar decimal based system of measures, but called it the “metric system”… you might have heard of that one. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 22, 2020, 2:46am UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/25 "2020-05-22T02:46:43Z")
> [@friedo](#): > > What ever do you mean? Everybody knows that DIP pins are spaced exactly 2.54mm apart! No inches to be seen here. 🙂 Reminds me of “Plotter units.” Whenever I see the number 1016, I am reminded of HPGL, where the original unit was 1/1016 of an inch, or 1/40th of a mm. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [May 22, 2020, 11:48am UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/26 "2020-05-22T11:48:36Z")
> [@Horatius](#): > > Canadians would love it if they became more wide-spread. They [Robertson screws] are great, but now in decline, I believe. Torx fasteners are taking over - they have some advantages, including anti-cam-out. ---
**Author:** ![bubba001](https://avatars.discourse-cdn.com/v4/letter/b/f17d59/32.png) [@bubba001](https://boards.straightdope.com/u/bubba001)\ **Post date:** [May 22, 2020, 12:23pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/27 "2020-05-22T12:23:25Z")
Ford used Johansson blocks. Now, all these reference blocks are called Jo blocks. They were so prevalent in the Detroit area that I’ve seen Jo block sets with a Ford logo on them, in independent shops, even at Cadillac Motor, a division of GM. Ford might have even bought Johansson. And to a toolmaker, a tenth is 1/ 10000 of a inch. Ford really created the standards, not just set the standards for industry. Not only autos, but aviation and virtually all manufacturing in the world. I had the pleasure of working with a lot of graduates of the Henry Ford trade school. This was to my knowledge, the only Europeon style training school in this country. With that level of training, Ford could do anything. ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [May 22, 2020, 3:33pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/28 "2020-05-22T15:33:50Z")
> [@bob\_2](#): > > > [@Hampshire](#): > > > > All our manufacturing tooling drawings are spec’d in inches and then decimals after that. So in essence tenths, hundredths, thousandths of an inch. A typical depth may be noted as 1.027 +/-.005 > > Only in the USA. Everywhere else uses millimetres. Indeed, though at the level we are talking about the advantage of metric is no longer present– machinists work in decimal portions of a base unit on both sides of the pond; working in thousandths of an inch or hundredths of a millimeter. Now, if you want to ridicule the less savory part of imperial units, note how all American machinists intuitively know the fractional sizes in thousandths of an inch–0.1875" is 3/16", for example. So our micrometers have a tiny list of fractional/decimal conversions engraved in the side ([example](https://www.amazon.com/Starrett-T230XRL-Micrometer-Graduation-0-00005/dp/B0006J4RTK/ref=sr_1_5?dchild=1&keywords=starrett+micrometer&qid=1590161402&sr=8-5)). A tangent to my tangent: at the inch level, the fractional system is pretty cool in itself because instead of being base-10 like metric, it is base-2: half, quarter, eighth, sixteenth, and so on. That has a certain elegance, until someone tries to mix fractional with decimal. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 22, 2020, 7:45pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/29 "2020-05-22T19:45:08Z")
dp ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 22, 2020, 7:43pm UTC](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711/30 "2020-05-22T19:43:52Z")
What would that be, .067 smoots?: [Smoot - Wikipedia](https://en.wikipedia.org/wiki/Smoot) [Previous page](https://boards.straightdope.com/t/was-there-a-scale-of-measurements-based-on-tenths-of-inches/853711.md?page=1)