Engineers scale 3

[DwattedWabbit]

Some years ago, I acquired a metal engineers scale at a second-hand shop for about $10(US) which is stamped with a patent date of 1879. It has 10, 20, 30, 40, 50, and 60 scales on it. A bit worn, mostly to the outer finish. It looks like it is probably brass with a brittanic silver (I think that's the term) plating. The scales themselves are inscribed, and are perfectly readable.

Has anyone in this forum done any historical research into draftsmen's and engineers' tools and instruments? I have a nice book about drafting instruments from 1580 to 1980, but scales do not feature in it, not that I remember anyway.

 

[gaufridus]

It is likely that scale rules were produced in a variety of scales ddepending on the particular industry that they were used in. When I started work (almost 40 years ago) a long time before CAD was a twinkling in someone's eye we used scale rules. I remember brousing through drawing office equipment brochures and seeing a whole plethora of different scales.
The most appropriate for the industry in which I started working was a scale called 'Armstorng 12ths' - various scales of feet and inches sub-divided down into 1/16th, 1/8 inch etc. Scales shown were 3inch to the foot (1/4 full size), 1 1/2 inch to the foot (1/8th FS) etc. ranging right down to 1/96 (needless to say that at this scale it didn't show 1/16 inch.

We also used inch scale rules with scales 1/2, 1/4 etc in 1/8 inch divisions. I've also seen similar in 1/10 inch divisions.

When we changed to metric (in the UK) we had scale rules with scales of 1/2.5, 1/5, 1/10, 1/25 etc down to 1/100.

My personal favourites were those triangular scales as opposed to a normal flat ruler type scale. The triangular ones thus had three double sided edges and could accomodate more scales.

I still have several of the above scales but rarely use them in these days of CAD.

Also don't forget that pattern makers had their own scale rules suitably calibrated to match the material that was going to be cast to allow for shrinkage as the molten metal solidified. Thus a pattern for an aluminium casting needed to be a slightly different size to one that was going to be used for an iron casting.
Pattern makers' scales looked very similar to an ordinary rule but obviously slightly stretched by a few percent. Never borrow a 'ruler' from a pattern maker!!

 

[pba]

Slightly off subject - I have to work with Microfished reproduction drawings quite often which are of no particular scale.

The beauty of CAD is that I can print off a regular scale at an odd scale and have a near instant rule for measuring dimensions from the drawings. Once done I can throw them away or attach them to the drawings for future use.

 

[BJC]

pba
I too sometimes find myself working with drawings that have no scale, that is they were originally made with a scale but printed by people who think scales are in bathrooms or on fish.
When I have to work with them I sometimes use proportional dividers, which allway gets a least one "What are those things?"

 

[ewh]

I used to use proportional dividers, but have put them aside in favor of doing the math (simple ratios). The dividers are great when working on manual drawings, but with board drawings a thing of the past, I have much more trust in the math results.

 

[DwattedWabbit]

At least when a plan has a graphic scale drawn on it, that can help in enlarging or reducing it on a photocopier. Or if there are some real numbers, like a line marked "7.65 feet." I've sometimes photocopied my engineers scale, reducing or enlarging it to match a drawing's graphic scale, if the drawing has been enlarged or reduced without regard to scale. As long as the level of accuracy that is desired isn't terribly precise, that works in a pinch.

 

[EnglishMuffin]

Off topic, but :

gaufridus "When I started work (almost 40 years ago) a long time before CAD was a twinkling in someone's eye ...."

I started at about that time (first summer job in a machine shop in '66), and certainly by the late 60's I had certainly heard about CAD (in the drafting sense) from university contacts, although it was only in connection with research in universities on mainframes and quite impractical - but a little more than a twinkle wouldn't you say ? And certainly CAD in the non-drafting sense was old hat by then in university circles.

 

[vooter]

http://mbinfo.mbdesign.net/CAD-History.htm

 

[Ashereng]

Many of my drawings now have "NTS". It really makes life difficult because you have to go to another source to get the measurements.

On the other hand, it helps with "photocopies". You don't have to worry about bad reproductions messing up the scaling.

I think engineer's scales will soon disappear. I just tried borrowing one in my office. I got a few "what?" and a whole bunch of "no, don't have one ... here". Oh well.

I like the idea of cadding a scale separately and taping it onto the drawing though. Going to have to try that one of these days.

 

[gaufridus]

Vooter - nice site - I kept thinking "Well how about that!" You learn something everyday.
Having seen Vooter's site, EnglishMuffin, I stand corrected - CAD is much older than I thought but I think that as far as a commercial, everyday draughting tool I am still right. (waiting for howls of contradiction )

 

[IRstuff]

OK, I'll bite:

http://www.cadazz.com/cad-software-history.htm

http://accad.osu.edu/~waynec/history/lesson10.html

The PDF link on the above page also has some interesting history:

http://accad.osu.edu/~waynec/history/PDFs/bezier.pdf

Certainly, in the mid-70s, we were using digitizers to convert hand drawn IC layouts into computer-generated "black&clears" for photoreduction onto photomasks to make ICs. According to the above link, Applicon was started in 1969, which was the system that our supplier used to digitize our color on mylar IC layouts. Beat the heck out of cutting rubylith, which I've only seen, althought I've done tape-ups of PCBs.

And by 1976, Mead and Conway were already touting computer generated layouts for VLSI design. Which reminds me, I'll need to pop home to check out some texts I have on the shelf that might shed some light on CAD for IC design.

TTFN

 

[hydrae]

DwattedWabbit
I would be curious to see how accurate the scale is, from what I have heard that scale would be before the standardized inch was set at 25.4 mm by Henry Ford during production of the model T (or so I have heard)
Got some gage blocks handy? or even a micrometer?
Hydrae

 

[Pseudolus]

Greetings, I found this forum while looking for instructions on how to use a Charvoz #11-1281 10" universal proportional divider. Would anyone be able to assist? The instrument was made in Germany. The scale runs from 10 to 110 and has a vernier. I believe it displays ratios as the distance between the little points divided by the sum of the distance between the little and large points. A German website I found says to refer to the table below the image of the divider for common ratio settings. But...the table is not there. Would anyone have a copy of a table, maybe? Any assistance would be greatly appreciated. I need to rescale dimensions taken from images, photos, drawings or books to garner information about the details I am researching.

I started drafting in 1964 or '65. All my drawings were done in 9H and 5H lead, checked and then finally India inked. The nearest thing we had to a "plotter" was the nasty guy two rows back and three drafting tables over. Never did like him!

Thank you.