On Fri, 16 Jan 2009 16:38:02 -0500, "Ed Huntress"
wrote:


"Leon Fisk" wrote in message
.. .
On Fri, 16 Jan 2009 00:25:13 -0500, "Ed Huntress"
wrote:

snip
I would have approached this as a long-term research project years ago,
except that I don't want to spend that much of my spare time, and I see no
money in it.

If a manufacturer could make a lot lighter frame work for
say a lathe, it seems like it would be profitable. The
do-it-your-selfer would buy some decent bags of redi-mix
locally and pour/finish the machine in situ.

First, there's too much labor for it to be commercially viable. That is,
except for the sheet-metal structures with the poured-in concrete. And the
polymer/granite-aggregate machines you see promoted at shows are mostly
viable for special, custom machines.

Second, "pouring" a machine is pretty limited, because it's not that simple
to get the required tensile strength and resistance to cyclic loading. It
can be done, and it doesn't require a lot of skill. But it does take some
time and you have to know what you're trying to achieve.

Unfortunately, concrete is not cast iron. It requires some engineering for
any kind of structure that needs to handle more than compressive loads.


I don't think this is what you had in mind though

I wish it were that simple.

Ahh... but what if you purposely built/added strategically
placed threaded rods and such. I'm sure they would have to
be somehow enclosed in a sleeve, a bit protected from the
cement mixture. After the cement has setup/cured, slap on
plates/washers over them and then add tension to provide for
cyclic operations.

My thinking was more towards building a light weight inner
skeleton and let the assembler build the simple outside
forms from whatever they like. You would simply provide
suggested measurements for them to use for the forms.

With fuel costs/shipping most likely to start marching
upwards again, seems like you could save a lot in the weight
area with some careful thought/engineering.

This is just off the cuff thoughts... needs a lot of
revision

--
Leon Fisk
Grand Rapids MI/Zone 5b
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