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A question about steel rules.

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Machdaddy

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#1
While digging around the dark recesses of my seldom used tool stash, I ran across an unusual Starrett rule. It reads in 10ths 12ths 14ths! and 16ths. None of my colleagues remember seeing one before, and I'm curious as to its purpose. I figure the 12ths may be an architectural standard, but what about the 14ths?
Any insight will be appreciated
Dean
 

mmcmdl

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#2
Could be a shrink scale . I have a few . Modelmakers and moldmakers used to use them .
 
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benmychree

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#3
All my shrink rules have graduations in the regular 4R style, 1/8, 1/16, 1/32, 1/64 they are just longer than a standard rule. Also have a rule with 10ths and 100 ths, and 1/16ths and 1/32nds. what is the catalog number on the scale?
 

Machdaddy

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#6
That's it! Except mine is 12" (or at least 10") and predates the satin chrome finish which seems to be all the rage right now...
 

benmychree

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#7
Satin chrome is all the rage, because it does not rust or stain, has no glare and the grads stand out better than the polished steel finish.
 

Bob Korves

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#8
Satin chrome has been used on scales for at least several decades now, and has been well accepted. It does cost more, but is well worth the cost, especially for tired old eyes.
 

middle.road

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#9
Alright, I have a plethora of scales, from shop scales to drafting machine scales to printing and graphics scales, and I have never seen one with those graduations. 12ths, 24ths, 48ths; 14ths, and 28ths - I am stumped...
 

RJSakowski

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#10
According to Starrett, "#1 pattern has 12 different grads ., many that are not found on usual rules .
This allows the rule to be used for various purposes like laying out and cutting gear teeth (not generally used today)".
 

francist

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#11
This is intriguing. I ran into two references using fourteenth of an inch, both are excerpts from old books.

The first, from 1828 Franklin Journal and American Mechanics Magazine, uses it in the context of "... twelfth or fourteenth of an inch in thickness..."
The second, from somewhat later 1847 A Treatise on the Steam Engine, in the context of scale as in "...Scale three fourteenths inch -- (per) foot..."

Perhaps just an archaic method before more standardized systems? Use whatever you want if it's convenient, type thing. Much like thread pitches before the standards came in to general use?

-frank
 

benmychree

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#12
I looked in Starrett, Lufkin, and B&S catalogs, they all list the #1 graduation, but nothing about what they are for.
 

Bob Korves

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#13
Pre vernier measuring system. Instead of vernier, check multiple scale increments until one lines up nicely. (???)
 

TerryWerm

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#15
Printer's scale does make sense, two of the most common type sizes were 14 and 16 characters per inch.
 

Silverbullet

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#17
I guess it goes with 14-40 14-36 14-28 all old threads we use to use . I have lots of different taps , dies . And I'm sure I have a scale or two with odd sizes on them. Shrink rules ,of no use anymore but there from my past .
 

dlane

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#18
Shrinking scale ?. If it shrinks I wouldn’t trust it
 

benmychree

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#19
Shrinking scale ?. If it shrinks I wouldn’t trust it
Is your post tongue in cheek? Shrink rules are used by patternmakers to make foundry patterns to allow for the shrinkage of the metal after pouring. They are made in many ratios of shrinkage, called out in fractions of an inch per foot of length.
 

hman

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#20
No idea about 14ths ...

but I do have a framing squares that has a couple of scales in 12ths. I assume it's for scaling inches to feet. Roof pitch is usually specified as "X 12ths."
 

uncle harry

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#21
Is your post tongue in cheek? Shrink rules are used by patternmakers to make foundry patterns to allow for the shrinkage of the metal after pouring. They are made in many ratios of shrinkage, called out in fractions of an inch per foot of length.
Shrink rules were also used in making thermo-forming dies for vacuum and pressure forming sheet plastics.
 

Nick spanners

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#22
While digging around the dark recesses of my seldom used tool stash, I ran across an unusual Starrett rule. It reads in 10ths 12ths 14ths! and 16ths. None of my colleagues remember seeing one before, and I'm curious as to its purpose. I figure the 12ths may be an architectural standard, but what about the 14ths?
Any insight will be appreciated
Dean
Hi, I first thought it was a scale ruler,,,,,,,,but no
My best guess is; it just gives the user the option to split an inch into different divisions.
Cheers
 

firestopper

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#23
I have one 12"long with the same graduations. I use it for sheet metal bending alliances. I have to use an eye magnifier.:(
 
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