I volunteer for a charity that restores British aeroplanes from the 60s and 70s during my free time and often have to fabricate components alongside older members. It does amuse me when they ask me to drill a hole 3 5/8 inches from the edge etc.

I'm gradually winning them over to the brilliance of a decimal system where all the measurements (in mm!) are nice numbers and not horrible fractions

To be honest, the conversions are not hard to remember, just hard to implement when trying to work out eighths.....and on that point, why when measuring do you say 4/8 and not 1/2?

.mic

Mictheslik wrote on Mar 6^th, 2012 at 7:59pm:

In my experience it's easy to make mistakes when converting between different units of measurement. It's best to work in the units on the drawing or manual you're working from. Imperial measurements were used on the older British aircraft you're working on so it would make sense for you to learn them.

As a general rule of thumb, carpenters worked in units of eighths of an inch & engineers in tenths. The older chippies would say 4/8 instead of half an inch.

I'll give you an example of where this is still done today. My old company is the approved UK distributor for a well-known American flexible hose manufacturer. In the early 1980s I set up a workshop for manufacturing hoses commonly used on aircraft fuel, lubrication & hydraulic systems. (It's quite likely that we manufactured some of the hose assemblies on your flying club aircraft.) The parent company being based in the US all the measurements were in Imperial, as are the fittings & tools used to manufacture the hoses. One anomaly that we soon got used to being that the finished hose assemblies are measured in eighths of an inch (0304 = 30 1/2 inches) while the "cut off" dimensions for the end fittings required to calculate the actual length of the cut hose is in decimal inches (eg. 1.204 in). http://www.sacskyranch.com/h_len.htm

When manufacturing hoses to customer drawings we found that a lot of the drawing offices had adopted the metric system which caused unnecessary complications for us. This involved converting the metric measurements to Imperial before manufacture & converting back to measure the finished article in accordance with the customer requirement. This means that prospective employees for the hose shop have to be fully conversant with all systems. Unfortunately schools don't seem to appreciate this & only teach the metric system. As a result I spent a lot of my valuable time teaching them things that they should already know.

G.K. wrote on Mar 7^th, 2012 at 5:04am:


Which doesn't have to include; "fractions of an Inch" to impress!... ...!

Paul... ... ... ...!

G.K. wrote on Mar 7^th, 2012 at 6:15am:


48/64ths of a tablet of Viagra sometimes helps... ...!

Paul... ... .. ...!

machineman9 wrote on Mar 7^th, 2012 at 9:58am:



Mars Climate Orbiter - 1999. LM engineers, when programming part of the Orbiter's software, calculated thruster performance in Newtons (N), whereas the Ground Telemetry crew used Pounds-force (lbf). This discrepancy caused the spacecraft to enter the atmosphere of Mars too steeply, causing destruction of the spacecraft.

Another Metric vs. Imperial glitch was the "Gimli Glider".

Best thing... learn both systems twice, verify measurements thrice, and cut, trim or formulate ONCE!

Have used both systems regularly; Imperial for Construction & Carpentry, Metric for all the work I did in the Bicycle industry... including all of those old 60's and 70's Raleighs with the British Standard Cycle threading, not to mention French & Italian threading.

Oops... just about forgot; Old Schwinns used a combination of Metric and Imperial!!

Alan