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Posted by David Sherman on Monday, February 09, 2009 at 14:02:48 :
In Reply to: Re: rare parts dilemma? Check this out! posted by Kaegi on Monday, February 09, 2009 at 13:52:55 :
Years ago where I worked we almost bought one that made prototypes in plastic by shining a laser into a vat of plastic resin and building up a part layer by layer by congealing the plastic. The thing was insanely expensive, the parts came out with an obvious layered look on the edges, and you couldn't make any part that had any "insides" to it. It looks like they've come a long way. "Printing" a complete working mechanism is just amazing.
On the other hand, I kind of laughed at the example he used -- duplicating a broken slide valve for a steam engine. In the old days, they would have duplicated it by simply using the broken piece (glued-together) as a pattern to press into the green sand directly, or maybe building it up a little with putty where it needed to be thicker, and then casting a new part. I have an old sawmill planer where some long-gone mechanic replaced a broken cast iron part by sand-casting a new one out of brass, using the old one as a pattern, probably because he could cast brass in his shop but couldn't cast iron.