"Ed Huntress" wrote in message
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"Michael Koblic" wrote in message
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wrote in message
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On Sep 5, 2:13 pm, "Bob La Londe" wrote:
I have been bouncing around an idea for a specialty screw less vise.

The Harbor Freight vises are made of cast iron. Not as rigid as
steel. Look at Youngs modulus.

http://www.engineeringtoolbox.com/yo...lus-d_773.html

Steel is about three times more rigid than aluminum. Cast iron is a
bit more rigid than aluminum, but less than half as rigid as steel.


Puzzled!
Why do they make lathes out of cast iron? When I was in the market for a
wood lathe I was definitely advised to avoid steel construction and look
for cast iron body because of better rigidity.

Cast iron is, or was, a lot cheaper than steel and lends itself to
casting. Steel is a bugger to cast in detailed shapes.

Cast iron damps vibration -- the cheaper and weaker the cast iron, the
better it damps. Steel rings like a bell.

Cast iron is easier to scrape.

Cast iron makes better bearing surfaces with simple lubrication.

It's true that steel is around 20% - 50% more rigid for a given section,
but that's easily overcome with cast iron machine tool construction by the
use of ribs, fillets, varying section thicknesses, etc.

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I learn something every day, thanks.