25mm 'Kingspan type' rigid foam panels

[Chubber]

Hullo Ladies and Gentlemen, can anyone advise me whether or not an 8ft x 2ft piece of the above will be 'self supporting' as  baseboard material if supported at 18" centres across its width but not at the front and back long sides?

 

Additionally, I presume I can peel off the aluminium foil on each side?

 

I know it comes in all sorts of thicknesses, but would like to use 25mm as a SEEP actuator arm will protrude enough to be useful even with a ballast shoulder on top.

 

Doug

 

 

[smokebox]

I doubt if it would be strong enough without full support, especially if you remove the foil which acts as a strengthening member.

[south_tyne]

I too would suspect you will require some bracing. As above, removing the foil will weaken it. I have tried Celotex type stuff for a baseboard in the past but didn't take the project forward. Its definitely useable but I would recommend bracing and potentially also facing in ply too. 

[73c]

Kingspan and Celotex are like a thick foam board. No real strength ( unless greater than 25mm ) and even less with the foil removed, which would be a pain to do!

[ian]

Removing the foil from one side makes it warp.

 

Removing from both sides makes a weak sheet that will crumble if you give it a hard stare.

 

Extruded polystyrene (XPS) comes in various grades - something like Knauff Floormate is required but you will need to face with thin ply to protect the edges.

 

 

Edited February 11, 2019 by ian

[pheaton]

Also bear in mind that you wont be able to pin track down very easily and you won't be able to use solvent anywhere on the board. 

[57xx]

Kingspan/Celotex is pretty rubbish once you peel the foil off. It doesn't crumble but it does warp badly.

[Chubber]

Thank you to all for your considerations, I think I will steer clear of the stuff, at least for the purpose I have considered above.

 

Doug

[south_tyne]

4 minutes ago, Chubber said:

Thank you to all for your considerations, I think I will steer clear of the stuff, at least for the purpose I have considered above.

 

Doug

 

It doesn't have to go to waste though - potential for landscape forming? 

[Chubber]

Thanks, S_T,

I have not yet bought same, but seems ideal for land forms, especially in bits from a local building site skip!

 

Doug

[TheQ]

If you use much thicker say 75mm then with cross bearers and a thin ply surround to protect the edges it will work.  As for fitting point motors,  you just mount the motor on a piece of plywood say 4 inches square,  hollow  out from the bottom of the foam and glue it in place.  I believe that is done on  the Gravett's Pempoul layout. 

The alternative is mount point motors on the backboard and use wire in tube to the points.. 

[Chubber]

33 minutes ago, TheQ said:

you just mount the motor on a piece of plywood say 4 inches square,  hollow  out from the bottom of the foam and glue it in place. 

Thank you, that is worth considering. At that thickness it would sculpt for subtle level changes, and track pinned/glued to stuck down card or thin ply etc..

 

Doug

[37Oban]

On 12/02/2019 at 17:12, TheQ said:

If you use much thicker say 75mm then with cross bearers and a thin ply surround to protect the edges it will work.  As for fitting point motors,  you just mount the motor on a piece of plywood say 4 inches square,  hollow  out from the bottom of the foam and glue it in place.  I believe that is done on  the Gravett's Pempoul layout. 

The alternative is mount point motors on the backboard and use wire in tube to the points.. 

Have a look at Ken Pattersons' 'What' Neat this Week' on Youtube.  It's a monthly programme which has been going for several years, and although American, a lot of techniques are applicable to British modellers. Ken's is a professional model photographer and uses foam board to produce dioramas of various sizes to photograph models and his personal layout has foam baseboards.  Well-worth watching, even if just to see him clean his dioramas with a hosepipe! 

 

Roja