Thread: Imperial calculations/conversions especially for T & J plans

Originally Posted by crowie

I too have had difficulty with metric imperial conversations, BUT in saying that, I've found that for me at least,
IF THE PLAN is imperial, make it thus and if it's metric make it thus as with parts that must fit together it's an imperative....
I grew up with imperial, did my engineering in the RAN with imperial then through the 1980's & 1990's worked with a mixture of both with machinery from across the world.
Metric is simpler to work with BUT it's easier to follow the drawings & plans than work out 0.2 of a millimetre.
Just my humble opinion and 2 bob's worth. Cheers, crowie

Originally Posted by ian

converting metric to imperial or vice versa is just recipe for error -- and ditto for decimal feet to anything else.

Gents you are preaching to the converted.

About 10 years ago I gave away all my imperial measuring implements and went totally metric (I even converted my 20-20 vision to 10-10). I purchased a Leigh dovetailer (in metric) and bought the metric conversion kits for my Incra positioner(s). Then eventually when my interest in woodworking surpassed the Australian market's availabilities, I made inroads into the more wider market of USA, with their retrograded imperial measurements. But alas a fully metric tape measure does not have 1/16 markings and I had to do a lot of re-learning, improvising and buying replacement measurers as the recipients of my past imperial gifts refused to part with them.

I still think and measure in metric but find that more often than I desire, I need to get into an imperial mood. To top it all off, those Yanks can't make up their minds, as not only do the stick with imperial they then mix that up with decimal.

Anyway the thing I like about the subject calculator (and as I have recently learnt many phone apps) is that they can display imperial metric measurements as fractions which are the markings used on imperial rulers (not metric).
That's my $29 worth, which is what I paid for my calculator.

PS. Also a lot of quality Yank measurers come either in imperial or metric and not both. I have often been "forced" to buy the two sets for completeness, but that's got nothing to do with this topic other than explain why I often cry poor.
PPS. I've been rather slack with my builds so I had to find something else to write about...

Originally Posted by Dalboy

I found the one I have.

Imperial calculator.

Dalboy, I remember seeing it, however, after about 10 seconds into the video it cheezed me off enough that I thought there was no way I'm going to install that.

From the display it didn't seem to have a metric converter.

I recently built a jig from a plan designed by a German woodworker that was in an American Magazine - instead of 200mm the plan had 7 7/8" etc. etc.
Even though I was brought up on imperial I would have preferred setting out 200mm rather than 7 7/8"

Originally Posted by Alexkara

Gents you are preaching to the converted.

thank the almighty for that

Originally Posted by Alexkara

PS. Also a lot of quality Yank measurers come either in imperial or metric and not both. I have often been "forced" to buy the two sets for completeness, but that's got nothing to do with this topic other than explain why I often cry poor.

I am yet to see a useful metric / imperial rule and I don't believe that one is possible because 12 inches is 304.8 mm and no matter how you mark teh graduations, one end of the rule will be "wrong" when used for the other system.

I got round the problem by buying metric rules for my Starret combo squares.

Originally Posted by Alexkara

Hi artme, I tried with a pencil but the only surface I found was the back of my calculator... When I accidentally flipped it around I realised... what the hell am I doing???

I can add fractions as well... Half a glass of vino and another half a glass of vino gives me same affect as a full glass of vino... and I did that manually, as the cask was hiding my calculator.

Do you become fractious after such activity??

BTW, in case you are interested, that silly little line is called the vinculum. Furthermore the top number is the numerator and the bottom number is the denominator. I learnt all that at school and can still recall it.

[QUOTE=robbygard;1971129

on a separate but related note: when i was in primary school, we used to do all our times tables to twelve, because money and measurements relied on twelve .... do kids still do twelve times or do they now stop at ten?


regards david[/QUOTE]

I was talking about this with my brother the other day. Because there is no need to use the 12x anymore then it is generally not taught.

The imperial system sure makes for mental dexterity. Remember the multiplication and division of money.? Two changes of base to get
things done. I remember many sessions of frustration by many fellow students and many sessions of tears for others. One poor bugger
was so frustrated that he hurled a bottle of ink across the room!

Other elements of the imperial system also required chang of base: 12 inches =1 foot, 3fet- 1 yard, and so on.

One thing that struck me on moving to Qld was the use of percches that persisted until quite recently. It always struck me as an oddity.

Originally Posted by artme

I was talking about this with my brother the other day. Because there is no need to use the 12x anymore then it is generally not taught.



Other elements of the imperial system also required chang of base: 12 inches =1 foot, 3fet- 1 yard, and so on.

One thing that struck me on moving to Qld was the use of percches that persisted until quite recently. It always struck me as an oddity.

thanks for that .. it (the continuing or absence of 12x tables) only occurred to me as a result of this discussion

the land i sold in 1989 was still defined as 27 acres 2 roods ... my current land is in hectares

i never had any trouble doing the imperial measurements and currency at school (or now for that matter) ...

back to the plans though ... as i said i am a bit hybrid about it ... i thickness my timber to mm because that it how the thicknesser is setup ... for cutting out other timber i generally use imperial measures ... because, as crowie said, the plans are written that way ... if they were metric i would turn the rule over and use that scale instead

when thicknessing i don't always look for an exact conversion .... for example 3/8 is 9.525mm sometimes it can be 9.5 and sometimes 10 as far as i am concerned ... depends where it has to fit in and whether a little more can add a robustness

regards david

Originally Posted by artme

Remember the multiplication and division of money.?

So that's why I was always broke at school. At the tuck shop I'd give them a shilling and they'd give me change out of 10 cents.