Re: Steel plate for hexapod bed

> > I bought a 24" x 24" x 0.25" piece of steel plate from Metal
> > Supermarkets, but it's not flat. In fact, it curves away about
>1/8"

I had exactly the same thing happen to me last week, I bought a
30"X30"X1/4" sheet and it was up by about 5mm in the middle with one
corner really bent over. Basically I think it comes from the sheet
being guillotined, that is what gives the poor edge at least. For
mine I managed to straighten most of the bend out using a flypress
and some body weight stuff and the corner that was playing up had a
piece of wood placed on it before I hit it with a sledge hammer.
Not perfect but after I machine about 1.5mm off the top it will be.

you can see my progress here:

http://www.cnczone.com/forums/showthread.php?t=7096

I'll be posting picks again soon as I welded the plate to the frame
on Friday, next is adding the slots and doing the final levelling.
I am lucky to have access to a HUGE milling machine that can do it
all without moving it.

One the hexagon theme, it is possible to by aluminium honeycomb with
aluminium glued on either face. This is super light, stiff and
should be very flat.

Another option is to build a base with the torsion box type
construction like mine but use MDF, glueing does not tend to distort
the structure and MDF is very dimensionally stable if kept dry. It
would rather depend on the machining you intend.

Graham