It looks like the bump passes the dip at the same time the disk goes from 63/64 to 0. So maybe you're supposed to hold it by the dip and notice the bump passing, so you can keep track of how many whole inches have been counted?

@ChrisStaecker

6 жыл бұрын

That's a good idea. I'm not convinced, but it's better than anything I can think of.

@ehrenmurdick

2 жыл бұрын

@@ChrisStaecker No, I think you were on to something with the toothpaste

@adam_sporka

2 жыл бұрын

I think it's there to give you a tactile feedback when the device is reset to zero. This way you don't need to look at the "display" to double-check it's ready to start a new operation.

@ZexMaxwell

2 жыл бұрын

My dad has this device. when I was looking at it. it looks like the bump is an easy way to ReZero the device without looking. the moment its in the middle of the dip, the black sections line up.

@someonespadre

Жыл бұрын

Maybe it’s like a slide rule, it helps with the numbers but you are responsible for magnitude. It’s like when we used to wrap up angles on the transit, there’s no mechanism for when you pass 360, you have to keep track of that yourself.

The dio is there so the bump in the spinning disc hits your finger when you add two fractions equaling more then 1 inch

Awesome! This is such an elegant little device. I'm going to make a few to use in my classroom. I'm a combined math and shop teacher, so I feel like this device was purpose built for me in particular. Also, you can get rulers that divide inches into tenths; they're typically used by machinists. Mitutoyo makes a few nice 6" scales like that

There is actually a standard ruler where the inches aren't divided into diadic fractions or 10ths. A typographic ruler, used for measuring fonts, is divided into 6ths, called picas. Each of these sixths is divided into 12ths, called points. This is why, when you pick a font-size on most computers, the defaults include 12pt (1/6"), 24pt (1/3"), 36pt (1/2"), etc. When counting in picas, you would note 2 picas and 4 points as 2p4. This mixed radix of 6 and 12 is awkward mathematically, but useful when doing visual design, where thirds and quarters are much more aesthetically pleasing than 5ths. Last, the most arcane typographic unit is the agate(US)/ruby(UK), which is 5.5 points. This bizarre and arbitrary-seeming unit represents "the smallest legible text", which was used for large tables of financial data.

@pubcollize

2 жыл бұрын

ah so that's what points and picas mean and the explanation makes sense, i usually use inch rulers or grid for design for the same reason.

@andrewkrahn2629

2 жыл бұрын

@@pubcollize yup! it's a lot easier to make a 3-column grid on a 51p0 grid than an 8.5" one

@pubcollize

2 жыл бұрын

@@andrewkrahn2629 Yeah 8.5" isn't that convenient for a grid of thirds, depending on your tolerances, but 20cm is even worse.

@andrewkrahn2629

2 жыл бұрын

@@pubcollize I haven't worked in it! Are the easy fractions just further from exactly 33.3..% ?

@pubcollize

2 жыл бұрын

@@andrewkrahn2629 That's the exact problem. Percentages are per-cent, centum, they're 100-base. Centimeters are cent-meters, also 100-base. Anything decimal-base only fractions neatly to 1, 2, 5, and 10. Anything 12-base fractions neatly to 1, 2, 3, 4, 6, 12. So basically all the intuitive fractions are messy with decimals. Divide 20cm to 3 parts and you get 6.6666.. cm divide 100 to 3 and you get 33.333..

This probably would say lubricated very well if you use a pencil like it says, the graphite rubbing off inside would make it slick.

FYI you can get machinist rules divided into tenths and hundredths of an inch.

@IONATVS

2 жыл бұрын

Yeah, was gonna say industrial inch-gage rulers frequently have diadic fractions on 1 side, decimal fractions on the other. And inch-based calipers and micrometers almost always are calibrated to thousandths (traditionally called ‘mils’ tho frequently called ‘thous’ today to avoid confusion with millimeters) or ten-thousandths.

@kmill31415

2 жыл бұрын

I've got one of those engineering rulers with a Y cross-section, where it has six different rules (for drawing diagrams at different scales), and they're all in tenths of an inch. It catches me off-guard sometimes when I forget and reach for that one.

Thanks for the Evil Mad Scientist site.

Over in the UK here, we still use imperial Whitworth with steam locomotives and thous. We still travel in mph, still use 24 hour clock (Ha Ha Ha), feet are measured in imperial, still buy pints, tyre pressures come in psi, 100 penny pound coins, and railway tracks are measured in chains for the radius on corners. We're not all Eurocrats.......

The groove on the back plate also makes the whole thing much more rigid. I bet without that it could easily bend in your pocket

Your last answer correct. Beer is always part of the correct answer when dealing with engineers.

Base 12 makes a lot of sense if you're dividing stuff because it has so many divisors. That's why we sell bread or eggs by the dozen. If you have one, two, three, four, six or twelve kids you can give them all an equal number of bread eggs if you buy a dozen. The number twelve even has it's own special name: dozen.

@richardseed8253

2 ай бұрын

It is literally dozen from two ten. Old French etymology.

Purpose of cut out is how the machine is orientated, simply holding in hand with index finger at cut out. Purpose of tab is to manually keep track of whole inches as it rotates past cut out (& index finger). Zeroing the machine is spinning the inner dial by the hole with black to the reading tab, as shown at beginning of video. I can only guess the didn't receive instructions. Machine will also subtract

The bumb and divet are for manufacturing. Without something to lock in the "top" there is no way to align the pieces when applying the markings. Most circular parts have a key like that for alignment during manufacture.

I have two theories on what the point of the bump is, 1 has been mentioned in the comments multiple times now; Tactile feedback for when you should add an inch to your result. This is the more likely one, Granted, But my first thought was, #2: Fine resetting. In both shots of the bump, The 1/4 mark wasn't quite aligned with the hole. Perhaps you are supposed to bring the two black marks together, Which brings the bump and dip together, Allowing you to more accurately align the two discs to avoid misinputs.

Another way cool one Chris!

hahaha i got me a Lufkin Engineer's Scale tape measure that is rocking 1/10 of inches and a standard metric scale. any ways its cool though i have abandoned the colonizer units its still fun to give dad (finish carpenter) measurements in tenths from time to time. hahahaha. been bonging your videos lately keep up the good work!

Maybe it's a British thing, but most rulers I've seen have a section where the inches are divided into tenths.

Despite the name, I think that this was more often used as a "subtracting machine", rather than adding machine. Suppose a machinist at a lathe needs to turn a piece of 1" stock down to 17/32". He needs to take off 15/32, but his machine can only take off a 1/8" depth of cut per pass After the first pass, he measures the work with a digital caliper, and finds that it's at 0.760" (1/8" from both sides of 1 inch should leave 3/4, but the raw stock might be a few hundredths oversize). So, how much more does he need to remove to get from 0.760 to 17/32? Since this calculator is labeled with both fractions and decimals, the subtraction is easy. The fractional result (7/32) can be divided by two by going to the next-larger denominator (7/64) and then to the decimal: 0.109, which is less than 1/8", so he should get close to the final dimension on this pass. It's better to leave a little extra, and make a final clean-up pass, because the machine may deflect a little on the heavy depth of cut. Remember, this calculator was made in Detroit, where manufacturing (especially things with axles) was a big deal in the 40s', 50's, and 60's. Machinists need to do lots of simple math, but quickly (to maintain production) and accurately (to minimize waste).

The rotating wheel, I suspect, has a hole in it which fits smoothly around the indentation seen from the back, so it won't bind no matter how tightly you squeeze between the rivets. You might call it a "ring", rather than a "wheel".

@ChrisStaecker

Жыл бұрын

Yes- I should’ve known, since there are two rivets. It can’t possibly be a full disc.

I have a ruler that's metric on one edge and inches divided into tenths on the other; the only reason I bought it was because of a tabletop game called Harpoon that measured distances in 10ths of an inch. I treasure this ruler because I've never found another...

@someonespadre

Жыл бұрын

Engineers scales have inches divided into tenths.

Thank God (or the entropy fluctuation) for the metric system. :-)

Thanks for the video. Just got one myself. Why the cut out above the 1/4 " mark? Mike's it comfortable to take out and put back into it's holder. Not a big thing but a nice touch. Again thank you for the info, I was wondering how it worked.

how did I find about you just now? Cheers from Slovakia!

The extra semicircular protrusion is a handle for the fingernail to move the disk, in case one does not have a mechanical pen point.

I love this series. I just picked up an R.C. Allen 75 Figuring Machine for $5 from a yard sale, but it sometimes performs calculations incorrectly. I'd love to open it up and fix it but I don't know exactly what the issue is.

@ChrisStaecker

6 жыл бұрын

Hard to say- inside the case you'll probably find an absurd spaghetti of gears and springs. I've never really been able to "fix" one of these machines other than lubricating, which can free up a stuck machine but usually won't fix bad calculations.

@yharna

6 жыл бұрын

Sometimes it just adds a "ghost" number to the sum, even if I add zero it will go up by whatever the ghost number happens to be at that time. It's frustrating to clear the total when I can't get that extra crank in without it adding a number. Not to mention that the machine is from 1921-1945 so all of the screws are stuck.

@ChrisStaecker

6 жыл бұрын

This could be lubrication- maybe the number is stuck in the machine even though the key buttons are popping up. Good luck!

Wow this is super cool, I've tried doing silly stuff like adding 13/64 + 3/8 in my head way too many times.

@someonespadre

Жыл бұрын

I do it on my hp calculator 13 enter 64 divide 3 enter 8 divide plus. Answer is 0.5781 64 times equals 37 (/64)

@someonespadre

Жыл бұрын

If the answer is even then I divide by 64 and multiply by 32 etc.

I do amateur carpentry so there’s some logic to increasing precision by halves instead of tenths. US rough framers work to about an eighth I think. Everyone else just reads millimeters, no subdivisions. British carpenter, now you take your timbah (everything is a timbah no matter how small) and we mark it at 2567 millimeters…

@someonespadre

Жыл бұрын

I was watching a Portuguese lady on KZread build a workbench. Her lumber was 50x100mm, so simple why can’t we have that? Here a 2x4 isn’t even 2” x 4”, 5 quarter board is 1 inch thick, what?

What's interesting is that you could probably relabel the disc, so instead of fractions, you use integers from 0 to 64. And it would still work the same, but it adds integers!

@BLKSG6

2 жыл бұрын

If you are going to do that, you should relabel with two logarithmic scales so you can use it to multiply or divide two numbers (but it’s easier to buy a circular slide rule on eBay)

@Andrew90046zero

2 жыл бұрын

@@BLKSG6 oh wow, didn't think of that

CP is correct, you feel the nib pass to know that you've crossed over an inch.

Almost makes me want to use imperial, almost.

I can’t get my head around the two rivets. How does the middle disk rotate around them? Is there a hidden pivot?

@ChrisStaecker

5 жыл бұрын

I've never taken one apart, but I believe the middle "disk" is actually a ring- there's a big disk cut out of its center. You can see on the back that the circular area in the middle is depressed- that's because the "middle disk" doesn't actually make it all the way to the center of the machine.

@Pfooh

2 жыл бұрын

@@ChrisStaecker Yes, that's also why putting pressure in the middle won't influence the turning

Recently, I learned that there is an old way to finger count that uses the thumb to count the bones in your four fingers; Base 12. By using both hands, you can count up to 144 (a gross). Maybe humanity kept using Base 12 for so long because it made the math easier when dividing by 3? That said, I agree with you: It's weird that fractions of inches don't use the same convention. Thankfully, Sheridan Printers to the rescue!

@stevendebettencourt7651

2 жыл бұрын

12 is evenly divisible by 1, 2, 3, 4, 6, and 12. 10 only has 1, 2, 5, and 10 in comparison. 12 can be considered a lot more useful in that regard.

@IONATVS

2 жыл бұрын

Yeah, the problem with US customary isn’t the “base 12” part, it’s the seeminly arbitrary MIX of bases that arise because each of the units were intended for a specific application, with the conversions only standardized as an afterthought. A mile is 1000 standard paces (=2000 steps for a notional average soldier), feet and inches (thumb-widths) are parts of the body that are useful to compare objects to in everyday life, etc, etc. And most the world has standardized on a numbering system that is decimal by default, which makes anything NON-decimal, more awkward to deal with, even if it is better for many applications.

@IONATVS

2 жыл бұрын

A very fun video on the advantages and disadvantages of various bases: kzread.info/dash/bejne/o314lKRtfa6diZM.html

Ave. True to Caesar.

So I have a civil engineer's scale (that triwing thing) that is divided into 10th of an inch. It's weird.

Also - my guess for the notch: Perhaps there was some sort of larger case/holder that this fit in for a desk so it could be operated one handed - in which case the notch is there to catch the positive notch in the holder to keep the entire unit from spinning.

@ChrisStaecker

5 жыл бұрын

Very good idea- I never thought of that. But I've also never seen evidence of a stationary mount like you describe. Probably wouldn't be too hard to make, if you like useless projects!

That base 12, such as inches and clocks, all comes full circle because of how people used to count on their fingers.

@ChrisStaecker

2 жыл бұрын

People with 12 fingers?

@lourias

2 жыл бұрын

@@ChrisStaecker no..., they counted each of the 3 segments on each finger, but not their thumb. Four fingers, three segments on each leads to a base 12 counting system.

School rulers hace divisions in tenths od an inch.

3:22 OF course you can find rulers with 1/10 inch increments. I have one in my pocket. Where have you been? And have you never heard of base 12 numbering systems? or base 16? base 8? or binary? There are only 10 kinds of people in this world, those that understand binary and those who don't.

so much wrong here.12 is divisible by 1,2,3,4,6, and 12. for many tasks imperial is easier to use. As for a ruler that measure in non-diatic numbers, they are all over in the precision world. Look for '16R' ruler

decimal inch is king

@ChrisStaecker

2 жыл бұрын

Dinch 4eva

The extra thingy is to clean your teeth.

@ChrisStaecker

6 жыл бұрын

I thought of filming that, but decided against it. The people aren't ready for it!

Fraction of and inch would still be the same as a fraction of anything

Stick to base 10 and the metric system.

Cough... calipers ...cough

@devinhiatt9995

2 жыл бұрын

also I think the bump and dip is to help you quickly find zero without having to look at it too hard

There is another video on KZread by (Jaap Scherphuis ) about this same tool that explains exactly what "bump" above the 1/4" is for. His came with the original directions. It can also be used to subtract fractions [starting on the fraction you want to subtract from (instead of zero) and rotating the opposite direction - counterclockwise]. You should edit yours to explain the purpose of the bump. Your video is too long winded and wanders off subject, and doesn't explain the "bump" - keep it short and sweet!

@ChrisStaecker

4 жыл бұрын

"off subject" is kinda my thing. Jaap's videos are excellent though, and very informative.

@retrogiftsuk4812

2 жыл бұрын

I think 7 minutes is 'short and sweet'. I also like the off subject bits. (I think a shopping channel like QVC would have great fun demonstrating the extra functions the calculator has, such as toothpaste holder and doll comb.