|Forum topic by RogerBean||posted 839 days ago||1071 views||1 time favorited||18 replies|
839 days ago
When I visited Andrew Crawford in England last year, I thought I was a pretty good box maker. In the course of our discussions, he he suggested that I leave a “little extra”. When I asked how much to leave, he replied: two tenths of a mil. Not being too tuned in to the metric system it blew right by me at the moment, but later I realized: “Crying out loud, that’s .007 inch!” Cows have hair that thick! He, and now me, always has a dial caliper handy.
It was something of a revelation. The visit changed the way I think about “close enough”. And my world of woodworking has changed much for the better. It’s just a new way of thinking about how close is close enough. I have learned, sometimes painfully, that on a box, a few thousands gap can look like a chasm. I also work with metal machinery, but I just didn’t connect up the same level of precision to woodworking.
Later, I began to realize that as a bamboo fly rod maker (purely for fun) the level of precision is even less. (I’ve made a few over the past ten years or so.) What Ron Barch (Editor of the Planing Form, the cane rod maker’s newsletter) calls “The most precision form of woodworking.” The planing form for a fly rod tip is typically set to something like .031 inch at the tip. (i.e. that’s a total of .062 or so at the tip for the finished rod once the six pieces are glued up.) It’s set with a dial indicator before the planing of the cane is started. It’s done with a very sharp block plane. So the tolerance here is, what? ...0001????
Obviously, a Queen Anne secretary does not require quite the same precision, but how close is close enough. How close is good enough for your projects? Is precision a mindset? My own opinion is continually shifting.
-- "Everybody makes mistakes. A craftsman always fixes them." (Monty Kennedy, "The Checkering and Carving of Gunstocks", 1952)