Wednesday, August 12, 2009

4 holes, 4 pieces of steel, 4 machinists

I am making a kind of tool which consists of four bars of steel, each with four holes drilled in it. The holes do not need to be precisely located but they do need to be on center and straight. 4 holes, 4 pieces, no problem.

According to the book, the proper way of drilling a hole is to use a spot drill, then to drill a relatively small diameter pilot hole, and then to drill the full diameter hole. There will be a machine screw put in the hole so I also need to drill a countersink so the top of the screw will be flush with the bar of steel. Let's see -- 4 holes, 4 pieces, 4 drill bits - that comes out to 64 separate operations.

I made a pilot piece and discovered it is a pain to change from spot drill, to pilot drill, to full size drill, to countersink. The other way is to do all the spot drilling, change to the pilot and do all of them, then do all the full size drilling, and then all the countersinks. This too is a pain because it takes awhile to keep lining up each operation on center. And there are 64 operations.

Which is faster - or might there be a different and better way? The books, at least the ones I have, are no help for this basic a question. It takes experience - and so I turned to my favorite machining forum on the web. One reason it is my favorite is that if I am polite even the dumbest question is answered.

I asked, and I got four different and better alternatives to the two methods I had inquired about. With one basic question I received insights that will serve me in my future machining. Throughout my adult life I have learned to value experience and here was yet another proof.

This started me musing on book learning vs. experience, and how this particular body of knowledge is vanishing. Manual machining is almost dead due to computer controlled machining. My lathe is sixty years old and works fine now but in another forty years it will either be scrap or be in a museum. As for today's machinery - which are almost all too big to fit in a home shop - there are already 3D computer printers that print solids. It is fairly easy to see that printing metal, nanotechnology, or something else will whisk away today's computerized machining equipment if not within twenty years, certainly within forty years. Manual machining knowledge is destined to become a tiny niche, much the way there are a very few people who preserve the knowledge of making wooden wagon wheels.

Machining is very interesting to me, and I am so appreciative of experts who share their knowledge, it makes me sad to think of the future. Then I realize this is not knowledge of eternal truth, it is knowledge of the real and material world. Its very nature is to change, perhaps to die, perhaps to morph into something else. The proper response is not sadness but gratitude and enjoyment and even as I type this I am back in that place, in those emotions.

This weekend it's back to the shop. One of those new suggestions would reduce the 64 operations to 20. Hmm....

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