What is that? 1

[ajack1]

One of the guys in my office took early retirement a couple of years ago but still does bits of part time work when we are busy. To this day for basic calculations he still uses a slide rule.

One of the junior members of staff came in and asked him what he was doing “playing around” with a rule and when he started to show him he thought he was winding him up, he had never seen or heard of a slide rule. Whilst it has been many years since using a slide rule or log tables, sine tables etc, I guess I just thought people would know what they were.

So am I just getting old (I actually know the answer to that) or what else don’t the up and coming engineers of tomorrow know about? With digital read outs can they still read a vernier, or even a micrometer?

Anyone else been asked what is that?

 

[BJC]

I have an Addiator manual stylus operated calculator that adds and subtract feet and inches (in 16 ths). It's better than any electronic calculator I ahve seen for that. It's very useful for plan drawings with lots of dimensions.
I've ahd it a while and don't know if there still made or not. When I show it to people they covet it. IT travels in my breifcase, never stays in my desk

 

[SomptingGuy]

I was born in 1967; my sister in 1965. She was taught how to multiply using log tables at school; I wasn't.

However, she had no idea how or why the magic log tables worked. Much like my "X" button on my Casio fx180p.

Slide rules, log tables, calculators... All simply tools of the era.

 

[ScottyUK]

ajack1,

Vernier - no problem

Micrometer - no problem

Slide rule - whassat?


I was born '71.




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If we learn from our mistakes,
I'm getting a great education!

 

[SomeYahoo]

Born in '78 but had a Physics prof teach me the way of the slide rule. He even had a circular one he said was "more powerful" but I never got to use that one.

Verniers and Mics are not a problem... use them every day.

 

[Beggar]

I graduated from HS in 1982. I learned to use a slide rule in college and I have my grandfather's but never use it.

Verniers & mics - sure. I sometimes use them in interviews just to see.

A few months back, I was glad I knew how to read a vernier. I was in the Netherlands supporting some equipment and found myself at a machine shop. I wanted to measure something and the calipers they gave me were verniers. I was glad I didn't have to say, "Uh, I don't know how to use these..."

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Bring back the HP-15

http://www.hp15c.org

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[arunmrao]

1954 born in India

Till 1979 i.e upto completion of postgraduation only slide rules and log tables were permitted. Infact knew the full table by memory.(did not need to refer!!) Calculators were not permitted as those who could not afford one would be at a disadvantage.

 

[icelad]

Born in 54

Two good ones:

Interpolating sine tables in the field, sweat dripping on the field book, smearing the calcs and a HVAC final taking the BTU used in a year for a house and dividing by the cost of heating by coal gas elec wood etc Dividing millions into billions long hand. plus/minus calcs were way out of reach money wise so none were allowed ( several hunderd 1972 dollars)

John

 

[BillPSU]

I saw a N/C tape program for a machine which did not have circular or linear interpolation, circa 1972. It could only move point to point hockey stick fashion. The program machined a radiussed slot (kidney slot for a hydraulic pump/motor).

The program was written manually moving point to point using a trig table and movements were about .010 between points.
The programmer calculated about 400 points and then punched a N/C tape manually. Slide rules are too inaccurate for this calculation.

 

[TPNY]

Upon graduation of college (2002), my father presented me with his sliderule, with a brief lesson. He was born in '32 and since I was in grade school, all he did was complain about how "kids these days" don't know math, etc.

One of his favorite jokes is:

An engineer was asked, "what is the square root of 9?" The engineer pulled out his slide rule, fussed around with it a little, then said, "Approximately 3."

 

[BJC]

This has been posted before somewhere in a engtips forum but if you want to play with a sliderule ....

http://www.taswegian.com/SRTP/JavaSlide/JavaSlide.html

 

[ajack1]

Ah more fond memories BillPSU the wonders of programming that were punch tapes, how many can remember them?

Also the joys of drawing on tracing paper that nearly self destructed with humidity change and the constant smell of ammonia from the printer. I can still remember the major leap forward of moving over to CAD, very basic ACAD 2D and the wonderful printer with the little pens that you had to fill with ink that usually lasted about 10 seconds before giving up and needing cleaning again.

 

[BigH]

But the slide rule at least forced the engineers to know how many significant digits there were. Arunmrao - now the Indian engineers report optimum bitumen content to 3 decimals, Atterberg limits to two, etc. (And, I am sure, they aren't the only ones!).

 

[arunmrao]

BigH
You dont need to be a genius to reap the benefits of digital electronics. Research publications show curves drawn with only one data point!!

Today chemical labs while giving lab reports give Carbon content 0.4563%. This has no physical significance beyond stating 0.45%, but the digital computer output is sacrosanct and I have witnessed arguments by stupid inspectors.

 

[ziggi]

Arunmrao,
I feel your pain regarding inspectors, I don't know many times we've had to explain to inspectors that a leakage rate of 0.01 cc over the allowable limit of say 10 cc is not a huge deal. Or that a dimension which is 0.001" off the allowable of say 15.000" is probably attributable to the vernier. Stupid accurate measuring equipment

 

[rb1957]

stupid measurers more like ...

 

[Tobalcane]

Don't you have a tolerance that you have to meet? If you are within the tolerance, then the inspectors can not say anything.

Go Mechanical Engineering
Tobalcane

 

[SlideRuleEra]

Vernier Caliper - Yes, own one.
Micrometer - Yes
Slide Rule - Of Course, including scales for Log-Log, Inverse, Sine, Tangent, Sine-Tangent, Square & Cube Roots, etc.

Favorite however is the 1936 (hand cranked, desktop) Monroe Calculator my father gave me in the mid-1960's. Addition & Subtraction are a breeze, just depends on which way you turn the crank (clockwise or counterclockwise).
Multiplication is more fun, you have watch the registers to keep up with the number of times you turn the crank, and you have to "flip" the carriage to move from column to column.
Division in the real eye-opener, turn the crank "backwards" until a bell rings (literally). Then crank one turn "forward", flip the carriage and repeat the process for the next coulumn.

Also you can use "Newton's Method", and with a good initial guess do a square root very quickly.

Accuracy for this basic model, you can stop the process anytime with less however:
Input: 6 significant digits
Output: 12 significant digits
Decimal Point: Do-it-yourself, but there are little mechanical "markers" that you can move around to serve as either a decimal point or commas.

Maintenance: Spray the insides with WD-40 every 3 or 4 years.

I was born in 1947.

http://www.SlideRuleEra.net

 

[Tobalcane]

Didn’t somebody (way back when) created the “mechanical” computer where it can do calculations but the machine was literally driven by gears, cams, and sprockets?

Go Mechanical Engineering
Tobalcane

 

[ajack1]

Charles Babbage I think, around 1800.