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Stuart0742

Chesterman 24" Rule

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I have in my possession a Chesterman 24 inch steel ruler but upon comparing it against a tape measure I find that it is only 23 inches and the metric scale showing 61 cm is actually 59 cms. It appears to be rather old and I cannot understand why there would be a difference between the readings. Could it be that it was made like this for a specific reason and if so can you supply an answer to this puzzle?

Many thanks Rod Allen

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Received this by email

I have in my possession a Chesterman 24 inch steel ruler but upon comparing it against a tape measure I find that it is only 23 inches and the metric scale showing 61 cm is actually 59 cms. It appears to be rather old and I cannot understand why there would be a difference between the readings. Could it be that it was made like this for a specific reason and if so can you supply an answer to this puzzle?

Many thanks Rod Allen

My first thoughts are that the 1st inch was been cut off, but

If you study the photos carefully, the discrepancy gradually moves over the length of the rule, unfortunately the markings at the beginning can not be seen.

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Speaking as a Sheffielder Rod. I think someone has sold you a dodgy tape measure there pal ;-)

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Received this by email

I have in my possession a Chesterman 24 inch steel ruler but upon comparing it against a tape measure I find that it is only 23 inches and the metric scale showing 61 cm is actually 59 cms. It appears to be rather old and I cannot understand why there would be a difference between the readings. Could it be that it was made like this for a specific reason and if so can you supply an answer to this puzzle?

Many thanks Rod Allen

Pattern makers use contraction rules which are bigger than standard rules in order that the wooden pattens are larger to allow for the shrinkage that takes place when molten metal cools. Perhaps this rule is made for making patterns for something that expands when cooling.

Just a thought.

HD

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My first thoughts are that the 1st inch was been cut off, but

If you study the photos carefully, the discrepancy gradually moves over the length of the rule, unfortunately the markings at the beginning can not be seen.

Did someone leave it out in the rain and it shrunk? lol

Is it used by dodgy salesmen selling, for example, cloth off a roll, so that they can short measure you? <_<

Is it used by estate agents to measure up rooms so that they can describe a small box room as a spacious bedroom? :angry:

The possibilities are endless, - but it wouldn't get past the weights and measures people would it?

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Pattern makers use contraction rules which are bigger than standard rules in order that the wooden pattens are larger to allow for the shrinkage that takes place when molten metal cools. Perhaps this rule is made for making patterns for something that expands when cooling.

Just a thought.

HD

This is quite an unusual property as most substances contract as they cool, and those that do expand when they cool only do so when they actually freeze and change state from liquid to solid. Even then, it is not common.

The most notable substance to do this is water which expands as it freezes to ice, as witnessed by many a burst pipe during a cold winter :o

Of the others a handfull of metals, such as Bismuth and Antimony have this property.

These metals were long used in the printing industry to make "type metal" for 2 main reasons, firstly their low melting point made them very easy to melt and cast and secondly their expansion on freezing pushed them out to fill the mould giving a good, solid typeface impression.

With this in mind could the rule have been used by typesetters in the printing industry?

The measurements could indicate the final, printable, size while its shorter length would allow type to be be set up at its true size.

Only an idea, I'm not a printer, - although my brother is.

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Pattern makers use contraction rules which are bigger than standard rules in order that the wooden pattens are larger to allow for the shrinkage that takes place when molten metal cools. Perhaps this rule is made for making patterns for something that expands when cooling.

Just a thought.

HD

Looks like this is what you have Stuart.

There is one important pattern making tool that will make you wince when you purchase, but it is an important tool to have if you want to make accurate patterns where shrinkage rates are concerned.

The tool is the "Pattern Makers Rule", this is a ruler about 500mm (20")long. Made by Rabone Of England. No B5. And the graduations are marked as: 1/30-1/40-1/60-1/80,

The graduations represent the amount of shrinkage allowance for different types of metals. The pattern makers ruler provides a built in shrinkage percentage, which means you don't have to calculate the final measurement or size of your pattern, you simply take your measurement from your shrink rule, and transfer the measurement to the pattern being made.

The system is quite clever in the way it's all been calculated.

For a quick example, the 1/30 scale measurement seems to give

the correct result with patterns used for cast aluminium items.

Article

It must be 30 years ago now so it's a bit hazy but:

I used to have a 3ft rule which had different scales on it, each one slightly longer than the other.

It also had other information on it to do with temperatures.

I assumed that it was a blacksmith's expansion rule for measuring hot metal.

I used it only as a straight edge because the risk of getting the wrong measurement by reading the wrong scale was too great.

Wonder if I've still got it in the cellar somewhere.

I've googled Expansion Rule but no luck.

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Looks like this is what you have Stuart.

There is one important pattern making tool that will make you wince when you purchase, but it is an important tool to have if you want to make accurate patterns where shrinkage rates are concerned.

The tool is the "Pattern Makers Rule", this is a ruler about 500mm (20")long. Made by Rabone Of England. No B5. And the graduations are marked as: 1/30-1/40-1/60-1/80,

The graduations represent the amount of shrinkage allowance for different types of metals. The pattern makers ruler provides a built in shrinkage percentage, which means you don't have to calculate the final measurement or size of your pattern, you simply take your measurement from your shrink rule, and transfer the measurement to the pattern being made.

The system is quite clever in the way it's all been calculated.

For a quick example, the 1/30 scale measurement seems to give

the correct result with patterns used for cast aluminium items.

Article

It must be 30 years ago now so it's a bit hazy but:

I used to have a 3ft rule which had different scales on it, each one slightly longer than the other.

It also had other information on it to do with temperatures.

I assumed that it was a blacksmith's expansion rule for measuring hot metal.

I used it only as a straight edge because the risk of getting the wrong measurement by reading the wrong scale was too great.

Wonder if I've still got it in the cellar somewhere.

I've googled Expansion Rule but no luck.

I think I get this now,

You measure the metal with this ruler while it is hot.

The ruler will give you a measurement which is less than its actual size while hot due to its scaling.

However, when the metal cools and contracts it will shrink to the actual size indicated by the ruler when it was hot.

Sounds about right, - clever!

Except that it would of course only be right at one given very hot temperature and for one particular metal with a given co-efficient of expansion,

hence the need for multiple scales.

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I think 1 in 24 is a MASSIVE contraction rate, i'm fairly sure that for iron it's something like 1 in 120 (one inch in ten feet)

John :)

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I think 1 in 24 is a massive contraction rate, i'm fairly sure that for iron it's something like 1 in 120 (one inch in ten feet)

John :)

What temperature range would that be over johnbaz?

We are talking perhaps a 500 degree change in temperature, but as you say the coefficient of expansion of most metals is small (Mercury being the main exception, - hence its use in thermometers)

Further to this the expansion depends upon the original length of the metal so the scales could be a bit more awkward than I thought.

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Hello Dave

Sorry but i don't know for sure but i think it may be from as soon as the steel solidifies from liquid to fully cooled, i only know the rough contraction rate as i once queried it with our manager, he replied 1 in 120, the contraction rates for the various steels/ iron that we make is used by our planning/technical department..

John :)

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Hello Dave

Sorry but i don't know for sure but i think it may be from as soon as the steel solidifies from liquid to fully cooled, i only know the rough contraction rate as i once queried it with our manager, he replied 1 in 120, the contraction rates for the various steels/ iron that we make is used by our planning/technical department..

John :)

So, we are looking at a much greater range of temperature as iron (steel) melts at around 1370 to 1510 degrees C depending on its exact composition.

My data book gives the linear coefficient of expansion of stainless steel as between 14.4 and 17.3 micrometres per metre per degree C which is pretty small.

Taking a mean value of 16 this means that a 24" length of steel (0.609m) would contract by 9.75mm when cooled by 1000 degrees, or if you prefer between a third and half an inch.

Perhaps we now need to check that 24 inch Chesterman ruler to see if it fits this pattern.

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When my wife worked at Chestermans Pomona St there was a display cabinet showing measuring devices they had made in the past. It used to amuse me seeing the 12 inch steel rules of differing lengths.

Each one was marked with the country it was made for. Apparently before the metric system each country defined their own length for an Inch. I remember the Russian 12 inch rule was considerably longer than any of the others.

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Have you asked the Hawley Collection at Kelham Island? If anyone knows they will.

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