Stable wood surface?

I'm building a hot-wire foam cutter, and want to use a wooden mount/base board of some type, about 5 feet by 2 feet.
What's the most dimensionally-stable material to use? MDF, OSB, ply,
chipboard, something else?
Thanks,
-- Peter Fairbrother
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Peter Fairbrother wrote:

Use a couple of stiffners along the 5 foot dimension. Seal with varnish.
Bob
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Peter Fairbrother heeft ons zojuist aangekondigd :

I would prefer exterior 18mm plywood. I used what I had, 18mm chipboard as base, MDF for the stand and wood for the arm. Just make sure the wire is, or can easily be set square in 2D. A parallel guide and some holes for cutting circles make it work easy. Dirk
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Peter Fairbrother wrote:

the likes of metal spinning formers. I'm pissed off with maple and other woods changing size with humidity and the Jabroc is supposed to be very stable . I want to find something that is easier to form than metal but is stable, a number of current spinning formers are in steel or aluminium.
UK dist for the stuff is http://www.permalideho.co.uk/hydu.html
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On Sun, 26 Apr 2009 20:17:18 +0100, Peter Fairbrother

I made a simple one for a single job about 3 weeks ago - 22mm MDF about 16 in long with the wire 2in above the surface (to slice some polystyrene packing pieces). It had a pretty average sort of spring tensioner on the wire. I now have a banana shaped baseboard where the MDF has bent.
By the way if you want some resistance wire I've got about half a kilometre of the stuff.
--
Peter Parry
www.remapsherts.org.uk
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Peter Fairbrother wrote:

carton making formes (for cutting cornflake boxes from sheets of cardboard)are made from 18-24mm cabinet grade plyboard (the stuff with 13+ layers which are about 1.5mm thick each) - it is INCREDIBLY stable - formes are usually required to a tolerance of about .2mm - which might not sound much to an engineering group, but it's f*ing close for wood.
It's available in 8x4 sheets - might be about 60! quid+ per sheet.
If you have any carton printing companies in your area, you *might* be able to cadge an offcut big enough.
--
bigegg

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E-mail me Peter. I may be able to help depending on location.
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For ecomomy, can I suggest a visit to your local IKEA. They do 'spares' of doors and shelves, basically bits left over, usually 1 or 2 depending on size.
Various thicknesses and finishes, usually very flat and nicely smooth finish on one side (often holes on the other though).
MH
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