Was There a Scale of Measurements Based on Tenths of Inches?

As a child I recall being told Henry Ford, that nut, developed the “Ford Scale” that used parts (and so tools) based on tenths of an inch. (No quarter inch nuts, but you could have 2/10 or 3/10.)

A Google turns up nothing. Was I lied to?

I’ve never heard of a “Ford Scale”, but people do use tenths of inches – I’ve seen rulers scaled in tenths of an inch rather than the more traditions 1/16", 1/8", 1/4", and 1/2" divisions.

And, of course, machinists routinely use decimal fractions of an inch, and characterize uncertainties measured in thousandths of an inch.

Tenths of an inch ruler:

https://www.amazon.com/Tenths-Ruler-12-Inch/dp/B003G5CLZS

You can get an engineering ruler, it has six different scales on it, 10, 20, 30, 40, 50, and 60 of an inch. I don’t use them any more, but I have a couple at the office. Our CAD programs will also do most things in tenths of an inch.

Printed circuit board layout commonly uses .1” and .001” grids.

A "mil"is 1/1,000 of a inch and is not uncommon. As you say, it is used on circuit boards, but also in some measurements of paper thickness.
But in this case, I was told you needed special tools to work on old Fords, as well as parts (nuts & bolts) only Ford produced.

I’ve used and still own some Engineering scales (tri-edged rulers). As mentioned above they us 1/10 scales. I also use to use 1/10th inch graph paper for almost everything that needed graph paper.
Scale ruler - Wikipedia has some pictures.

You’re not thinking of Ford’s short use of Robertson (AKA square drive) screws are you?

CMC fnord!

Well, it was long ago and on the edge of memory. I appreciate your link, but in my mind’s eye I imagined nuts, bolts, and spanners. Funny how little half-memories get stuck in your head.

My goodness, I just read up on Mr. Robertson’s wonderful screws. It seems Ford widely used them in the Good Old Days. Yes, I am pretty sure that is the truth that somehow got twisted in the telling. Thank you all.

Once, in an instructional lab I was teaching, one group kept getting answers a little bit off and we couldn’t figure out why, until we finally noticed that they were using a ruler that was marked in 32nds of a foot, instead of centimeters.

There are certainly special parts that you need special tools to work on - trim, oil filters, spark plugs etc.

I’ve got a vague memory that the very very first Fords had a single suspension or drive nut that was not a standard dimension, but I could be wrong.

A lot of the Ford tools actually have “Ford” written on them, but that’s just branding. The original Ford adjustable wrench is sometimes called a “Ford wrench” – I think that’s because adjustable wrenches like that weren’t (aren’t) very common.

Also, the threads on early bolts and studs won’t exactly match modern nuts. The thread profile is different. Sometimes this matters.

Specific question: did Ford ever use 5/10th nuts? Dunno.

Canadians would love it if they became more wide-spread. I just finished building some frames for a raised bed garden using them. They’re way better than most other screws.
As for the OP’s question, the Japanese “shaku-sun-bu” measurement system is a powers’ of ten system, where a shaku is very close to a foot in length. Of course, the only use I’ve ever seen of that system is measuring sword lengths, and the naming of the “Shaku-hachi” flute, so named because it is 1 shaku, 8 (hachi) sun in length.

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.

Canada’s a mixed bag, though, and not 100% on the mm train.

It’s a scale thing. If you’re working on paper plans where 1"=60’, it’s easier to grab the 60 ruler with it’s adjusted 10ths of an inch, and measure how far that bench is from that planter. On it, one mark’s length equals one foot. You don’t even have to calculate, the way you would if you had to calculate "well it’s 1-7/32nds of an inch, so . . . "

“Borrowed” at some point from my dad, I have a late 1950s small T-square with one side in 16ths of an inch, and the other side in 10ths. It looks to have been a giveaway promo for General Electric tubes and television components, though I don’t know whether that’s relevant (maybe tube-era electronic chassis were laid out in 10ths of an inch). Because this was probably the first straightedge or ruler I ever saw, it never occurred to me that it was unusual. But I don’t remember ever seeing another ruler showing 10ths of an inch. By the time I was in school, they all had metric on one side—and later, working as a typesetter, they had picas.

What ever do you mean? Everybody knows that DIP pins are spaced exactly 2.54mm apart! No inches to be seen here. :slight_smile:

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.

I remember using a transit with a measuring stick graduated in hundredths of a foot. That happens to be very close to eighths of an inch, which is interesting but coincidental.