I'm of an age where I am quite happy working in just about any measurement. From Miles through Barleycorns (1/3") to 'thou's of an inch, and from Kilometres to Millimetres and fractions thereof.
So a simple question. When should we not convert between them?
This question is raised by this months Woodturning magazine article on making a pocket pipe. In it the instructions say drill a hole 3.81mm diameter (Do What!). Now I'm quite lucky in having closed several workshops and 'acquired' many twist drill bits, including several 3.8mm, but what is a 3.81mm?
So I set to working it out, nope, not 16
ths, nope not 32
nds and not 64
ths, I even tried 128
ths, a drill size I've never even heard of (and it wasn't one of them either).
So I worked it backwards 25.4mm / 3.81mm = 6.66667, ah, It's a 1/6 of an inch. Now that is probably a drill bit size but I can't find one. It's bigger than a (Old English) size
'V' at 3.77mm and smaller than the size
'W' at 3.86mm. And I can't see one listed in any Drill Chart either!
http://www.csgnetwork.com/drillsizeconvert.html Anyone seen or got one?
So the instructions are telling us to use a metric equivalent of an unobtainable English size!
Are there times when we should not convert from one measurement system to another, or an I just being grumpy?