Thread: Slide Rule

Ah yes, mental arithmetic, went the way of the dodo in education and should be on display in the museums next to the slide rules and calculators.

Originally Posted by Mr Brush

BobL - ahhh, the HP-41C calculator !!! I used to lust after one of those, but the budget would only run to a 32S.....

Well you can now afford it, the App costs very litre and the interface is excellent, it even reproduces the little click sound that you get when you press the keys.

And there's even a new advanced version (i41CX+) with symbolic/algebraic capability.

Thanks Bob - I had to go looking for the Android equivalent, but it looks like there are a few available.

Between the PC, smartphone , and my little Nexus 7 tablet, at this rate just about everything in my life will be "virtual". Apart from the tools of course......

I wonder how long it will be before someone comes up with a set of virtual workshop machines, for use with virtual timber?????? Mate this with Sketchup, and you have a complete virtual workflow (complete with realistic machine noises). Wouldn't be long before someone was writing a "Kickback" app for the iPhone though.....

Originally Posted by mr brush

wouldn't be long before someone was writing a "kickback" app for the iphone though.....

During my time as a research supervisor I'd often be training students inside an ultra clean sample preparation facility where we extracted and purified elements from small amounts of sample . To enter the facility was a PITA as it meant washing hands, removing shoes and coats, donning tyvek overalls, bootees, cap and gloves and walking through two or three doors over sticky mats - not too quickly or the bootees would come off. The sample preparation involved use of 4 and 5 decimal place balances so it was not unusual to end up with dozens of 5 - 7 digit numbers which required simple arithmetic to make progress. Even though I would tell the students to bring a calculator (which was used inside a clean ziplock bag) invariably they would forget and as very few could do the arithmetic without one they would have to go and get their calculator. By the time they returned I would have completed the simple arithmetic longhand and moved on, which bewildered the students no end but they never forgot their calculator after that.

Originally Posted by BobL

My favorite mobile phone app is the HP41CV emulator with RPN data entry and that is my standard go-to calculator as I know how to drive these pretty fast. I still have my original HP41CV with the little magnetic card reader - at one stage I had a nuclear reactor model running on it that would take around 16 hours to run - about half of this was because the model itself could not be all held in memory and stuff had to be written temporarily off to magnetic cards.

The HP41CV was a good little calculator. A bloke I worked with had one, while I was working on a HP9845 desktop (if you had a big desk) 64K computer driving 2 plotters, external & internal printer and two 8" 1.1k floppy drives. I wrote a program so that you could type a HP41CV program into the HP9845 and the plotter would write the program in bar code that could be read by the HP41CV's wand.

I was a surveying student just before we were allowed to use electronic calculators, and also just as EDM gear was coming in, so the use of 7 & 13 digit tables and triangulation both become largely redundant with the use of calculators and trilateration. When I think of all those hours spent doing relatively simple spherical trig, which required pages of calculations using 7 digit tables, I think I should have deferred for a couple of years!

In the early days of calculators, I once had to write a tender for a four-function calculator. Finished up getting a 13 digit one with nixie-cube display. Anyone remember them?

Ahhh - mental arithmetic. One thing that ought to be compulsory!!!

i have seen any number of young people who cannot do a simple
estimation using their scone. One reason for this is that we seem
to have scorned the notion that FACTS are actually useful building
blocks. Tables are not given the time and importance they deserve.

Without the knowledge of simple arithmetical tables you can't work
efficiently. It's like asking someone to dig a hole without a shovel.

I still use this one

Originally Posted by Ashore

I still use this one

When do you graduate to counters????

Still got all of my slide rulers. If I get them out of the desk draw now they will still work. (brain hasn't had it yet)

Best one of mine was a 'circular' slide rule.

There's probably stuff here that - like old woodworking techniques - should be preserved and taught.

Also ... it's cool how this all ultimately also relates to woodwork ...

log-table.JPG

A jibe from one of my lecturers in the 1950s:

"An engineer is someone who multiplies 2 by 2 on the slide rule

And gets 3.99"

Originally Posted by Wizened of Oz

"An engineer is someone who multiplies 2 by 2 on the slide rule

And gets 3.99"