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Author Topic: A startling tape measure question...  (Read 1567 times)

Offline P-Kasso2

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A startling tape measure question...
« on: 13 October, 2015, 09:25:29 AM »
This will probably surprise you as much as it did me...I was chatting with my friend Tom, the man of a thousand skills who can fix anything from a leaky tap to a seized-up Rolls Royce Merlin engine and he suddenly asked me this staggering question...

"You know on a builder's tape measure, the spring steel kind? Well, why is there a little red or black diamond-shaped tick mark every 19 and three sixteenths of an inch all along the tape measure?"



I'd never even noticed it before.
For decades I've been using these tape measures and I never once noticed these little diamond-shape tick marks.

But I just pulled out my 12 footer and, sure enough, there are all these black diamond marks!

If you take a look at your own spring-steel tape measure you'll see them too. Little black (or in some cases red) diamond shapes right there on 19 and three sixteenths inches.

Then the next diamond mark appears at 38 inches and sixth sixteenths and so on at multiples of every 19 inches and three sixteenths right to the end of the tape measure. Odd or what?

(Actually, to make things even more mysterious, these little black diamond marks actually appear at a tad over the three sixteenths mark and the slight discrepancy grows over the whole length of the tape. But, for the purposes of this question, it's as near as dammit at every 19 inched and three sixteenths.)

Have a look at your own tape measure and see if you can answer me this...

What's it for?

What's it signify?

Is it something new that has suddenly popped up?

Is it worldwide or is it just on tape measures in Britain?

Is it some new EU directive?

Is it only to be found on builders tapes or do these diamond marks appear on sewing tape measures too? And on rulers and yard sticks?

Can anyone explain it?

« Last Edit: 13 October, 2015, 09:28:45 AM by P-Kasso2 »
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Offline antonymous

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Re: A startling tape measure question...
« Reply #1 on: 13 October, 2015, 11:39:40 AM »
Its all to do with roof construction. A standard roof has a  slope, rise over run, ratio( H/W) of 5/8 .

"The so-called diamond mark is actually positioned at exactly 8/5 of a foot (that's exactly 1.6' or 19.2 inches, which is indeed pretty close to 19" 3/16 ).

The diamond marks are also called "black truss" markings, because they correspond to the truss layout which is used with 8-foot sheets of plywood (or other material), namely 5 trusses per sheet.

This is to be contrasted with "red stud" markings which appear every 16 inches by showing the corresponding inch number in red instead of black. The black markings and the red markings coincide at 8-foot intervals (96 inches).
That is to say: 5 black intervals or 6 red ones in an 8-foot width." http://home.att.net/~numericana/answ...ia.htm#diamond

« Last Edit: 13 October, 2015, 11:47:49 AM by antonymous »
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Offline P-Kasso2

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Re: A startling tape measure question...
« Reply #2 on: 13 October, 2015, 11:52:32 AM »
What a revelation your answer was, Ant!  I'll email it on to my mate Tom  straightaway because, although he ought to know this, I am sure he'll be as surprised as I was.

'Black truss marks' sounds more like a boudoir madam's complaint but I can see how useful it would be for sheet rock workers and roofers.

And, also, I'd never even noticed that the figure for the 16 mark was highlighted in red until you pointed it out.

Sometimes it is amazing how much I manage to miss even when it's been in front of my eyes for years!
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Offline Hiheels

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Re: A startling tape measure question...
« Reply #3 on: 13 October, 2015, 01:25:58 PM »
I haven't got any on my 16 footer and feel rather put out  :'(

Offline antonymous

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Re: A startling tape measure question...
« Reply #4 on: 13 October, 2015, 03:20:50 PM »
I haven't got any on my 16 footer and feel rather put out  :'(

Here's a few black diamonds for you to play with to compensate. wve
whisl
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Offline Hiheels

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Re: A startling tape measure question...
« Reply #5 on: 13 October, 2015, 03:32:56 PM »
Ooh, got to love a diamond!

Offline Cosmos

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Re: A startling tape measure question...
« Reply #6 on: 13 October, 2015, 10:08:03 PM »
Mine doesn't have them. Is it because it was made in Korea?
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Offline P-Kasso2

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Re: A startling tape measure question...
« Reply #7 on: 14 October, 2015, 07:46:55 AM »
Mine doesn't have them. Is it because it was made in Korea?

Maybe, maybe your tape doesn't have the diamond marks because it wasn't made for export? Maybe the Koreans don't use our standard roofing widths?

It'd be interesting to see if Aussie roofers have black trusses. Or if tapes sold in your local hardware stores etc have the diamond tick marks. You could start IA's international fact finding survey.

But maybe it's because builders in Australia don't use the standard 8 feet x 4 feet sheets of ply and our standard truss widths?

The plot thickens.

"I live in hope"