A recent thread on using tape measures in the shop got me to thinking about this.
I went on Starrett's website and found that the most that they will write up a Certificate for on a tape is +/- 1/32". They also say on that website that whatever tool you use to measure with should be capable of measuring to 1/10 of what your tolerance is. So, if their best tape is only capable of +/- 1/32", then my tolerances can't be any tighter than 5/16", which seems a tad generous to me for cabinet work.
I have some Starrett and Rabone-Chesterman metal rules that will measure to 1/64", which would allow me to have tolerances of a little heavier than 1/8". I guess I could use these rules for framing houses
- but they still aren't accurate enough for building cabinets.
I have a Starrett dial caliper that will measure to 1/1000" - now that will let me have tolerances of about 1/100", which is heading in the right direction but when I think about it, a piece of newsprint is about 4/1000", or 1/250" and I know that my joints are tight enough, when they are cut properly, that I can't fit a piece of newspaper into them.
And yet, that can't be possible because the best measuring instrument that I have in my shop will only allow me to have tolerances of
1/100".It makes you wonder why framing carpenters and masons even bother to own measuring devices at all and, it has been my suspicion for some time that many of them don't.
It is gratifying to me that I am capable of doing the impossible but it makes me a bit squeamish, if you follow me. A man needs to know where he stands in this world and how can you do that if you can't measure anything proper like?
When I had my first philosophy course in college we studied this old boy named Zeno the Eleatic and his paradoxes. Now, Zeno said that you can never get from one place to another because, first you have to cover half the distance from A to B, then you have to cover half of the remaining distance and then half of that remaining distance, and so on for ever and ever. So, there's no sense in trying to measure anything because it just ain't gonna work out.
Zeno may have been the first framing carpenter, although I am not entirely sure about that - nor anything else, it seems.
Regards, Tom.
Thos. J. Watson - Cabinetmaker