[4]

Before There Was Calculators.

  • Thread starter Deleted member 18150
  • Start date
[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!
D

Deleted member 18150

Guest - Please Register!
Guest - Please Register!
#1
Found this round slide rule under the bottom drawer of a Kennedy box. I had a hard enough time learning the basics of a normal slide rule many years ago.
concise 001.jpg concise 002.jpg
*********Just Saying**********G*****************
 

Dinosaur Engineer

Registered
Registered
Joined
Oct 21, 2014
Messages
40
Likes
19
#2
The flat disc slide rule works on the exact similar principal to that of the linear slide rule. If you can use a straight linear slide rule you should be able to use type.
A further more accurate slide rule was the drum slide rule used by a lot of Drawing offices. These had the logarithmic scales on the outside of a drum which could have a scale length of 500 " as opposed to the 10" normal straight linear type. Sure was a lot quicker (though not as accurate) as using log / anti-log tables ( 7 fig. tables in the D.O. !)
Happy days !
 

silence dogood

Active User
H-M Supporter - Gold Member ($25)
Joined
Jul 10, 2013
Messages
376
Likes
224
#3
In hi school, I had one of those. As for being accurate, yes and no. In 1972, I took an electronics theory course. In many cases, there were a series of calculations. The guys who spent about 250 bucks for a scientific calculator many times were farther from the answer than I was with my old slip stick. The calculator took it to too many decimal points where as the slide rule would automatically round it off. Mark
 

kvt

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 21, 2014
Messages
1,999
Likes
988
#4
Ok, are we dating our selves again, Now days I do not think they know how to use a slide rule, (it would take me a little to remember as it has been so long). I had one like that that I used in high school doing engineering and drafting. Of course we had the old T square, Bottled ink with the dropper, and such. None of the fancy stuff.
 

Smithdoor

Active User
Registered
Joined
Dec 23, 2012
Messages
434
Likes
78
#5
I still have one today use it back in the late 60's
Still works today and battier need

Dave
 

Danb

Swarf
Registered
Joined
Jan 23, 2015
Messages
8
Likes
4
#6
Had one in high school, used one for the first two years of college--couldn't afford a calc. Carried one in my shirt pocket as an engr in gas plants--because it was intrinsically safe. Probably still some chicken scratch on the I-beams of those plants where I was trying to keep track of the decimal points. The good old days. Still have a couple and still use them.
 

davidh

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 23, 2012
Messages
1,216
Likes
155
#7
i can certainly relate, remembering the first electric calculator we got. . . i think it was a remington. still have my slide rules in the desk.
 

Cactus Farmer

Active User
Registered
Joined
Sep 24, 2013
Messages
392
Likes
216
#8
Rule #1, Slide rules need no batteries!
My first really good calculator was an HP35. Reverse polish is better in my opinion..........I miss it still.
 

David S

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 18, 2012
Messages
1,261
Likes
1,002
#9
I grew up using the linear slide rule at University. Mine was a K&E, others preferred the Picket, and there was a laminated bamboo Japanese. My first work term was with a British Engineer and he was using a Curta. I never mastered that one.
https://en.wikipedia.org/wiki/Curta

David
 

RJSakowski

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 1, 2015
Messages
3,450
Likes
3,971
#10
I still have my first Picket N902 and the over-the-top Picket N4 Log Log Dual Base Speed Rule along with its holster. I can't remember having used the hyperbolic or log-log scales but I did use the rest of the 29 scales.

One of the problems with linear slide rules was when performing chain multiplications or divisions, you could run off the scale so you had to slide the slide over to the side to continue. The circular slide rule just wrapped around so it eliminated that inconvenience.

I designed and built a custom circular slide rule for my ex, many years ago. It calculated the length of bar stock required to make a horse shoe, based on the dimensions of the horse's hoof. The scales were printed on adhesive backed Mylar and glued to aluminum backing , the product being sold to farriers.

It is amusing to show the slide rule to some of the newer engineers. I like the quizzical looks it generates. Same goes for log and trig tables.
 

Chip Hacket

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 12, 2015
Messages
188
Likes
140
#11
Rule #1, Slide rules need no batteries!
My first really good calculator was an HP35. Reverse polish is better in my opinion..........I miss it still.
Need help! I can’t find the Equal Sign.
 

vocatexas

Registered
Registered
Joined
May 8, 2017
Messages
110
Likes
116
#12
Several years ago I had taken my mother to a doctor out of town and she saw an antique shop she wanted to stop at. I went in too, and saw a strange device like I had never seen before. I think it was marked $25; if that isn't it, it wasn't much more. I didn't have a clue what that thing was and left it on the shelf. About three years ago I ran across something about Curtas somewhere and remembered seeing that one in the antique store. Still kick myself for not buying it. I just had a feeling it was worth something and talked myself out of buying it.
 

homebrewed

Registered
Registered
Joined
Jul 28, 2017
Messages
131
Likes
64
#13
I used a circular slide rule all through college. The HP35 was introduced when I was a Senior EE student but was way too pricey. I still have the circular (somewhere). At work I'd occasionally drag it out to show to my younger colleagues, telling them it was a calculator that worked without batteries.
 

DiscoDan

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Jul 16, 2018
Messages
145
Likes
68
#14
I was at an antique store in Frederick, Maryland yesterday and the guy had a very large slide rule that looked to be maybe a teaching aid and it was about 4 feet long by about 10 inches wide and everything worked. He "only" wanted $495!
 

Bi11Hudson

Artificer00
H-M Supporter - Gold Member ($25)
Joined
Feb 13, 2017
Messages
181
Likes
217
#15
Still have my Deitzgen engineering slide rule. And still like RPN over algebraic calculators. My slide-rule is in a glass front case with a hammer attached. And a sign saying "In case of computer failure, Break Glass". Never went to high school, picked up the EE offshore a few years later. Guess I missed all the fun of high school... ...
 

higgite

General Manger - Proofreading Dept.
H-M Supporter - Gold Member ($25)
Joined
Aug 15, 2013
Messages
798
Likes
841
#16
I still have my Post bamboo slide rule from when I was in college 100 years ago, complete with leather scabbard. If you ask today’s kids, “If Joe and 10 of his friends each had 4 calculators, how many calculators did Joe have?”, they’d reach for their calculator.

Tom
 

tcarrington

Making miscellaneous parts for years now
H-M Platinum Supporter ($50)
Joined
Dec 27, 2013
Messages
53
Likes
45
#17
Took course in engineering curriculum - nomography - we learned how to construct the "on paper" calculators that you laid a ruler across and connected the quantities you had making the ruler cross another line with the quantity(ies) you wished. Miles per gallon calculators are an easy example. Design of pressure vessels is a complicated one. Any equation can be represented with such a chart. It was a very informative course taught by an excellent professor and it explained a whole lot about how the world works and how we approximate it to our best benefit. Now we use spreadsheets and apps to generate these types of short cuts.
 

RJSakowski

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 1, 2015
Messages
3,450
Likes
3,971
#18
Took course in engineering curriculum - nomography - we learned how to construct the "on paper" calculators that you laid a ruler across and connected the quantities you had making the ruler cross another line with the quantity(ies) you wished. Miles per gallon calculators are an easy example. Design of pressure vessels is a complicated one. Any equation can be represented with such a chart. It was a very informative course taught by an excellent professor and it explained a whole lot about how the world works and how we approximate it to our best benefit. Now we use spreadsheets and apps to generate these types of short cuts.
Back in the eighties, I designed a circular slide rule the would calculate the length of bar stock required to make a shoe for a horse, based on two measurements of the horse's hoof. My ex, who was a farrier, made and sold quite a few of these to other farriers.
 

Downunder Bob

H-M Supporter - Sustaining Member
Staff member
H-M Platinum Supporter ($50)
Joined
May 16, 2016
Messages
942
Likes
372
#19
Slide rules, used to love them. As a Marine Engineering student at Sydney Uni (Australia) in the early seventies, calculators were very basic and we weren't allowed to use them anyway. So it was Long hand, Log tables or a slide rule. The slide rule was by far the quickest, you just had to be careful when keeping track of the decimal point. They were in their own when it came to doing calculations involving raising a value to a power that was not a whole number as in 2, 3, 4 etc. calculations on the expansion and compression of gases in particular often involve a power of 1.3 or 1.4 etc.

I still have a couple of good old Japanese bamboo slide rules, they were the best. And a circular one as shown above, they were particularly good at trig calculations,
 
Last edited:

RJSakowski

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 1, 2015
Messages
3,450
Likes
3,971
#20
A further more accurate slide rule was the drum slide rule used by a lot of Drawing offices. These had the logarithmic scales on the outside of a drum which could have a scale length of 500 " as opposed to the 10" normal straight linear type. Sure was a lot quicker (though not as accurate) as using log / anti-log tables ( 7 fig. tables in the D.O. !)
Happy days !
I used five place log tables a lot on college when we needed more precision than the slide rule would provide. One can appreciate the seven place tables when you realize that every additional place multiplies the number of pages of tables by ten. My five place tables in the CRC Math Handbook require 20 pages.
One can also appreciate the power of the modern calculator. The Android calculator on my phone displays 11 decimal places. To replace it with a set of log tables would require 20 million pages.
 
[6]
[5] [7]
Top