Best screw drive ever. It was also invented before the Phillips.
Disadvantage: Won't cam out. Hard on your wrist and drives.
Advantage: Won't cam out and doesn't require magnetic force to retain the screw on the tip.
Henry Ford was one of the first big users but because Robertson wouldn't license them to him, Ford didn't know about supply and restricted their use. Big mistake on Robertson's behalf.
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Since the patent expired decades ago, there are many knock offs and they remain the #1 drive here in Canada.
The imperial length measurement units come from body parts partly. At least this is what yo have at hand literally being out in the middle of nowhere with your bandwagon.
Here you find a good overview for reference:
Edit: Source of the image and further background:
https://whydoesitsuck.com/why-does-the-imperial-system-suck/
Here you find a good overview for reference:
Edit: Source of the image and further background:
https://whydoesitsuck.com/why-does-the-imperial-system-suck/
I had hoped for metric units when I moved from the USA to Canada, but no such luck. Unfortunately, as planet10 said, both systems of units are hopelessly mixed here in Canada (and in the US, too)
The construction industry is its own weird world, where "2x4" lumber isn't actually two inches by four inches, and a "half inch pipe" doesn't measure anywhere near half an inch (neither ID nor OD).
At a Canadian gas (petrol) station you see a mess of both units. The pump dispenses gasoline in litres (metric), while the air compressor for your tyres has a pressure gauge that reads in pounds per square inch (imperial).
The same sort of confused mess of units is built into the way tyre sizes are specified. A 255/60R17 has a nominal width of 255 millimetres, a nominal aspect ratio of 60%, and a nominal wheel diameter of 17 inches. One metric unit, one dimensionless ratio, and one imperial unit, all combined into a revolting mess.
The mish-mash of units is confusing (particularly to children starting to learn math and develop basic concepts), and expensive (you need to own multiple sets of tools).
Imperial measurements still use fractions rather than decimals, and I think this may be a significant factor in the poor math skills of the average North American person. Trying to work out (3 5/16) + (2 1/4) is so much harder than 3.3125 + 2.25.
I think this business of being forced to work with fractions puts children off arithmetic when they are still young, and that leads to permanent confusion and dislike of all forms of higher math as they grow up.
The nonsensical state of measurement systems in North America used to annoy me, but given the rapid ongoing collapse of global climate and global politics, we all have much bigger problems now. In the summer of 2022 alone, extreme flooding made some fifty million people in Pakistan and Bangladesh homeless climate migrants. There were millions more spread across the rest of the globe.
That's more homeless people created in one single summer, than the entire population of Canada, Poland, Ukraine, or Spain.
-Gnobuddy
The migrants should be back home by now.
Happens every year in India and Bangladesh, Pakistan was the surprised one this time, and as usual some people there tried to blame India.
The Brahmaputra river system is the one more prone to dramatic floods, the Ganges river system also has floods, and both rivers flow into the Bay of Bengal through Bangladesh, which has floods every year, the country is barely above sea level.
There is climate change everywhere, but the effect seems less to us here, maybe more awareness is needed.
Not too political, I hope.
Happens every year in India and Bangladesh, Pakistan was the surprised one this time, and as usual some people there tried to blame India.
The Brahmaputra river system is the one more prone to dramatic floods, the Ganges river system also has floods, and both rivers flow into the Bay of Bengal through Bangladesh, which has floods every year, the country is barely above sea level.
There is climate change everywhere, but the effect seems less to us here, maybe more awareness is needed.
Not too political, I hope.
Most of us that attended school in the '60's & 70's learned both systems, so it's really no big deal. Kinda like speaking two languages. 😉
jeff
Don't know. I had HO & N scale as a kid. A friend here had a giant Hornby layout. The track was about the same size as HO. It was all imported from the UK.
jeff
jeff
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The weirdest, but still actively used measire is shotgun gauge, which is the number of round bullets, equal to bore diameter, that can be cast out of one pound of lead. So, 12 ga is bigger than 16 ga.
I spent four years in a machinist apprenticeship, starting in 1984. Most of the manual machine tools had dials with metric and non-metric units. Since we didn't have metric and English/American measuring tools in our tool boxes (you could get metric calipers, micrometers, etc in the tool crib), anytime we got a metric drawing we multiplied millimeters by 0.03937" to convert to English units. Since our micrometers were accurate to 0.0001" that gave us the discrimination (that's what it's called) we needed to work to ten thousandths of an inch. Today, most machined parts are designed with CAD, and CAD models are supplied by the designer/engineer to the machinist instead of paper drawings. BSME students in the US don't take blueprint drawing anymore, now they take CAD classes. It became my mission before I retired to ensure that no one graduated without knowing something about fasteners and I never saw anyone graduate from the university who dimensioned a fastener such as: 1/2-13 +/- 0.005"
Should be: 1/2-13UNC-2B, for example. The tolerance is stated by the -2. 1/2" nominal diameter, 13 threads per inch (pitch=1/13) United National Coarse. -2 is the tolerance of the diameter and B indicates an internal thread. To get the tolerance for a class B thread, look in Machinery's Handbook, online calculators. Many CAD/CAM programs have these tolerances in the software.
Not unusual since most of the profs went from grad school to teaching, but there was no chance of graduating from the university as a BSME student and going into the real world without knowing this before I retired.
The American thread system is also documented in US Department of Commerce National Bureau of Standards Handbook H28- Screw-Thread Standards for Federal Services.
Should be: 1/2-13UNC-2B, for example. The tolerance is stated by the -2. 1/2" nominal diameter, 13 threads per inch (pitch=1/13) United National Coarse. -2 is the tolerance of the diameter and B indicates an internal thread. To get the tolerance for a class B thread, look in Machinery's Handbook, online calculators. Many CAD/CAM programs have these tolerances in the software.
Not unusual since most of the profs went from grad school to teaching, but there was no chance of graduating from the university as a BSME student and going into the real world without knowing this before I retired.
The American thread system is also documented in US Department of Commerce National Bureau of Standards Handbook H28- Screw-Thread Standards for Federal Services.
12ga. wire is bigger than 16 ga., too.
And it’s log like dB. 16 is 4dB down from 12, or divide cross section by about 2.5.
And it’s log like dB. 16 is 4dB down from 12, or divide cross section by about 2.5.
A pound not a pound. You would need to mention which kind of pound there is.
Reminds me of copper thickness in oz for PCBs. A special kind of ounce (forgot which ounce) flattened onto a square feet of area gives a certain thickness of material and this caveman unit is still used to define copper thickness in PCBs.
Edit again: https://en.wikipedia.org/wiki/Pound_(mass)
I can remember old engineering handbooks that would have a list of about 30 different gauges and conversions, Birmingham wire gauge, different sheet gauges, what a mess; but then there was lists of different screw threads, bike threads are sometimes left handed, just to spice things up a bit more (well actually to stop them unscrewing).
The shop I worked for wouldn't make parts without drawings. Unfortunately, some drawings were not much more than a sketch on a napkin. 🙂
CAD models could be sent to both the machinists and QA.
jeff
Back in the 70's I drove my 1970 Plymouth Duster to a tire shop for two new tires on the rear. I returned at the predetermined time for my car only to find it still on the rack wearing its original tires. Upon asking the manager what was up, he replied that the rookie mechanic had snapped off two of my wheel studs trying to get the lug nuts off. Now I knew that the lug nuts on the driver's side were "backwards" since my first car, a 1949 Plymouth was that way as were most Chrysler products through the mid 70's. The manager agreed that everything would be fixed for free and gave me a small discount for the waste of time. Then he pointed to some cars out behind the shop and asked me to guess which one Mr. Rookie drove. It was not only a Chrysler product, it was a late 60's Dodge Dart, a 4 door version of the Duster. Guess he never had to change a flat on the driver's side.