Scientific American Supplement, No. 643, April 28, 1888Various
Science
Scientific American Supplement, No. 643, April 28, 1888
Various
Science -- Periodicals
It may be claimed, in fact, I have seen lathes resting on six and
eight feet, engines on ten, and a planing machine on a dozen. Do they
remain true? Sometimes they do, and many times they do not. Is the
principle right? Not when it can be avoided; and when it cannot be
avoided, the true principle of foundation building should be
employed.... A strange example of depending on the stone foundation
for not simply support, but to resist strain, may be found in the
machines used for beveling the edges of boiler plate. Not so
particularly strange that the first one might have, like Topsy,
"growed," but strange because each builder copies the original. You
will remember it, a complete machine set upon a stone foundation, to
straighten and hold a plate, and another complete machine set down by
the side of it and bolted to the same stone to plane off the edge; a
lot of wasted material and a lot of wasted genius, it always seems to
me. Going around Robin Hood's barn is the old comparison. Why not hook
the tool carriage on the side of the clamping structure, and thus
dispense with one of the frames altogether?
Many of the modern builders of what Chordal calls the hyphen Corliss
engine claim to have made a great advance by putting a post under the
center of the frame, but whether in acknowledgment that the frame
would be likely to go down or the stonework come up I could never make
out. What I should fear would be that the stone would come up and take
the frame with it. Every brick mason knows better than to bed mortar
under the center of a window sill; and this putting a prop under the
center of an engine girder seems a parallel case. They say Mr. Corliss
would have done the same thing if he had thought of it. I do not
believe it. If Mr. Corliss had found his frames too weak, he would
soon have found a way to make them stronger.
John Richards, once a resident of this city, and likely the best
designer of wood-working machinery this country, if not the world,
ever saw, pointed out in some of his letters the true form for
constructing machine framing, and in a way that it had never been
forced on my mind before. As dozens, yes, hundreds, of new designs
have been brought out by machine tool makers and engine builders since
John Richards made a convert of me, without any one else, so far as I
know, having applied the principle in its broadest sense, I hope to
present the case to you in a material form, in the hope that it may be
more thoroughly appreciated.
The usual form of lathe and planer beds or frames is two side plates
and a lot of cross girts; their duty is to guide the carriages or
tables in straight lines and carry loads resisting bending and
torsional strains. If a designer desires to make his lathe frame
stronger than the other fellows, he thinks, if he thinks at all, that
he will put in more iron, rather than, as he ought to think, How shall
I distribute the iron so it will do the most good?
Public-domain text, read in full here on John Shaqi.
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