So, what's Hammers up to these days? (Update 2010.09.18)

[Christian]

Bugger

[General Roos]

Nice Peder. Looks great! 

[Alfrik]

Slice / remove backing board and adhere to new board to save work todate?

[Hammers]

Slice / remove backing board and adhere to new board to save work todate?

I am considering slitting the paper mache surface in a criss cross fashion to release the tension and then spackle the cuts...

[Totleben]

I feel with you  I hope you will be able to restore it without too much effort.

Nevertheless quite inspiring and instructive.

[Centaur_Seducer]

I am considering slitting the paper mache surface in a criss cross fashion to release the tension and then spackle the cuts...

You sure that it will help? If the MDF have startet to warp, I don't think that slitting the machier will help the tension to go normal. Or is it like cutting a pack of vaccumed meat?

[Hammers]

You sure that it will help? If the MDF have startet to warp, I don't think that slitting the machier will help the tension to go normal. Or is it like cutting a pack of vaccumed meat?

You are possibly right, but on the other hand you have a 50mm thick sheet of XPS which wants the MDF  to retain its original shape. Anyway, it is not horribly warped, just not perfectly flat, so I may jut let this one be.

I *am* however disappointed since I have done a lot of experiments linky and thought I was well prepared for the shrinkage (If a man ever can). The material is perfect in all other aspects: texture is great, it will hold up to a lot of wear and tear, cheap...  

[Centaur_Seducer]

What I've done earlier is to smash on some filler mixed with a lot of water. That usually makes sure that the styrofoam goes stiff as hell, and will probably avoid shrinkage from your machier We're talking 20 parts water 1 part filler, so its really messy...

[Hammers]

What I've done earlier is to smash on some filler mixed with a lot of water. That usually makes sure that the styrofoam goes stiff as hell, and will probably avoid shrinkage from your machier We're talking 20 parts water 1 part filler, so its really messy...

But you use the expanded stuff, don't you? 'Frigolit'? I use XPS, 'pink foam' which already is much more rigid.

[Centaur_Seducer]

But you use the expanded stuff, don't you? 'Frigolit'? I use XPS, 'pink foam' which already is much more rigid.

I use both, and the expanded stuff does obviously warp more than the XPS, but I've had XPS-boards that've warped beoynd recognition twice. Take the mix and just press it in the board, like baking bread. It'll make sure that at least the top layer is a bit more stiffer and it usually takes away all the warping. But I'm pretty sure that the MDF is the culprit, and that the pressure from the MDF combined with the machier makes the XPS goes 'Plong!'. Have you tried mounting the XPS on the MDF after the machier has set?
I have a friend who's a doctor in those (for real, he did 8 years of research on it), he might have some calcules or answers to this issue if you want to find out more on the issue.
/S

[Remington]

Well, that sucks. Hope you manage to repair it, because it looked very very promising.

[Silent Invader]

Great work hammers, I especially like the main structure. 

A real shame about the warp in the backing board.  Have you tried clamping the mdf to a rigid surface like a workbench while fixing the paper mache?  I haven't tried it myself but maybe cutting shallow lines in the backboard to create some flex with which to flatten it out (much like if you were trying to introduce a curve) could help.  After (if) it's straightened, then some thin superglue run into the cuts might 'set' the shape (or, given that MDF is just wood dust and glue, start a fire!).

Good luck

EDITED for ridiculous typo!

[Hammers]

I have already backed all ten 2x2' boards with 5mm MDF so I am hoping for a solution where I don't have to pry them off the XPS before I do the Celluclay.

I have considered clamping but somehow I doubt it will help. Unless I am a complete idiot in physics the tension will build up regardless of the clamping and as soon as they are gone they board will warp anyway.

[OSHIROmodels]

How about pva-ing some newspaper to the underneath, that might help to counter-act the warping.

cheers

James

[Captain Blood]

Ooooh dear.

I must say, I've never known MDF boards to warp, so not sure how you've managed it Peder... 

The surface looks great though