chariots used for war were introduced to the Egyptians
during an invasion , but that doesn't mean that the Egyptians
never used the wheel before that invasion.
and a 70 ton block distributed over 10 wheels is only
7 tons per wheel.
the Egyptians did use copper so with a few years of tinkering
with ways to move large blocks it seems to me that they
could have figured out how to copper clad a stone wheel
and axel to make a bearing that could be oiled.
or make solid copper wheels and axels.
cant say they were afraid of building large things ...
and after the pyramids were constructed they would have
melted them down for other uses.
we cant just say that they couldnt have done it unless
we have proof of how they did it , and we don't have that
we can only guess how they could have done it by the things
that they had access to and the precision that is seen in
their work and the types of things that they built.
we used the wheel for thousands of years before we started
building army tanks that are basically self propelled cannons
that have no purpose other than for war.
ie ... the first wheeled vehicles were not war machines.
a timeline for first uses of metals is in the below link.http://www.reshafim.org.il/ad/egypt/trades/metals.htm
Wood was at times covered with thin copper plating held in place by copper nails, like the door of the temple of Amen-Re at Karnak
Its great door was of cedar of the royal domain, wrought with [copper; the great name upon it] was of electrum.
so they did have copper 4000 - 3150 BCE
and even the harder bronze 3150 - 2300 BCE to use
to build with.
so your suggestion than the form was used as a copper form
may be correct.
maybe even a bronze form.
but in either case its shape lends itself to a wheel that
could travel easy on sand as the final product wheel would
have a V shape tread.
the V shape would keep the wheel from bogging down into
the sand better.
you would need to assemble 2 of the wheel halves together
to make 1 wheel.
I don't have the date of the forms construction and a cog
was the first thing that I thought of also ... they could
have even been forms for casting a clay mold to make a cog
if this was used to make a clay mold to use in cog making
ie... to use the clay mold to create a sand mold to cast
then there is a lot more to their advancements in
technology than I had though of myself.
by the way the Egyptians did use molds to cast metal in.
Most copper items in Egypt were produced by casting molten copper in molds. The Egyptians appear to have been one of several groups that independently developed the “lost-wax” method of casting, which is still used today. (Put simply, wax is formed into the shape of the end product, then covered in clay. The wax is melted out leaving a clay mold, which is then filled with molten copper. The mold is broken off when the metal is cool.)
Im thinking that the lost wax method wouldn't work so well
in Egypt because of the temperatures for such a large mold
and that is why they used shaped stones to render a clay
mold to use in making a sand cast.
what else could they be used for if not for making molds?