Thread: Metric / Imperial relationship reference

Originally Posted by clear out

I hope I'm not hijacking this thread but could you ...

Well I'll unashamedly commit a Hijack.
While in Calgary did you get out to the SAWS exhibition?
If yes, what were your thoughts.

Originally Posted by Xfigio

@aldav and @nrb, I can assure you that I'm sticking with metric! I have no intention of trying to work in imperial. As I said in my OP, my problem is watching YouTube videos where they talk about leaving a 16th gap etc, and have no internal reference to visualise what they're talking about

I suggest that a chart is a poor substitute for other more familiar measures, especially at small sizes like 1/16th of an inch.
Being in Canada i can't easily access the most common Australian shims -- i.e. coins
For example (from Wikipedia):
a $2 coin is near enough to 1/8" thick
a 5 cent coin is just less than 1/16" thick
a 20 cent coin is about 3/32" thick.

and a credit card is about 1/32" thick.

when setting reveals and gaps, a shim is much easier to use and estimate than any form of ruler measurement

Originally Posted by ian

I suggest that a chart is a poor substitute for other more familiar measures, especially at small sizes like 1/16th of an inch.
Being in Canada i can't easily access the most common Australian shims -- i.e. coins
For example (from Wikipedia):
a $2 coin is near enough to 1/8" thick
a 5 cent coin is just less than 1/16" thick
a 20 cent coin is about 3/32" thick.

and a credit card is about 1/32" thick.

when setting reveals and gaps, a shim is much easier to use and estimate than any form of ruler measurement

That's fantastic! Thanks so much for the simple visual reference. I've written those done to remember.

Lance

other "measures" I commonly use include
the thickness of the rule in a combination square -- these tend to be around 2 mm thick
the width of a rule -- typically 1" or 25 mm if metric, or 3/4" or 20 mm if metric

BUT
the most important measure is a realisation that reveals and gaps are mostly only nominal. Unless you are in a production environment, one part fits another because they fit -- not because one of them is 156.83 mm long.

Originally Posted by clear out

I hope I'm not hijacking this thread but could you explain the printing industry pika measuring system and the type point. I'm particularly interested in the pika as I have a Hammond compositors saw which still has that on the tape. I also visited with a woodie in Calgary yesterday and he had Cost Cutter saw and we got into a discussion about what they were originally used for. We were both stumped as to why they would have a 20" length of cut,was it to do with newspaper sizes? A few pics of his from the Canadian forum.
H

The Pica was not related to any other measurement (that I know of) so in itself the Point and Pica stood alone and had dedicated rules and tools like the setting stick all graduated that way. My memory says that we were never taught any cross relationship between this system and any other but others may have more information. The little sliders like you have were a great saw and with the inbuilt fine adjuster on the fence could be set very accurately. I saw an apprentice lose a finger at tech on one which taught us to be more cautious but I can't remember any specific safety training on using one.

Imperial and Metric work really well together.
Just ask NASA
https://www.wired.com/2010/11/1110ma...server-report/

Attached is my conversion chart, which is an A4 sheet on the shed wall. Metric is the driver (as it should be), and also has thousands of an inch, which is sometimes needed.

I was mid way through my apprenticeship when we went metric and what a head$%#* that was. Had to mark the back of my ruler in mm's by hand

I use a calculator on the rare occasions I need to convert from Imperial.

I'm reliably informed by Google that Liberia, Myanmar and the USA are the only countries left using Imperial. Although the Poms only think they're metric.

mick

I converse with a family group of engine reconditioners. They work in thousandths of an inch - no metric in their workshop

Originally Posted by Lappa

I converse with a family group of engine reconditioners. They work in thousandths of an inch - no metric in their workshop

Yeah, "Pass me the 437½ socket on a 375 ratchet willya?"

Maybe not.

Like others I have a table showing fractions of an inch to millimeter conversions. One in my tool locker, another in the lid of the tool box. Just so I can keep up with the times I now have an app on the mobile phone. (Last used today.)
I measure in metric, but use imperial drill bits although router bits and spade bits are metric.
I work with old machinery where 2' 6" sounds better than 762 mm, and 180 psi is better than 1241 Kpa.
At one site we are instructed to use metric, but 54 inches is not the same as 1.35 metres, or 36 inches is not 900 mm although 27 1/2 inches is darn close to 700 mm (it is actually 698.5 mm).
A lot depends on what you are use to using and if you are working with something preexisting its age and origin.

Originally Posted by FenceFurniture

Yeah, "Pass me the 437½ socket on a 375 ratchet willya?"

Maybe not.

Story I heard so can not verify goes like this.
All of Melbourne trams up to the W class were built using imperial measurements, latter trams from the Z class are metric.
An apprentice who had been trained on the Z class was doing some work on a W class and came up with a measurement of 4 feet, 216 mm!

Originally Posted by Lappa

I converse with a family group of engine reconditioners. They work in thousandths of an inch - no metric in their workshop

I used to have a car like that. Then I resigned from the vintage car club and bought a new one.

mick