Building Tips and technical articles. > Building techniques
Green Foam
Ken Culbertson:
--- Quote from: Dave Hull on February 08, 2024, 01:17:56 AM ---Looks like Kingspan makes GreenGuard LG insulation board in at least three densities. They list a 25 lb/ft^2 compressive strength, 40 psi, and 60 psi. Their data sheet says the 60 psi material is nominally 2.2 lb/ft^3. The others aren't listed.
The label on Ken's piece doesn't have all the part number info, which may be a local-market kind of thing. So we don't know if Ken's piece is the lightest version. But if it does the job, then it must be the right stuff! Says they make it in 1-1/2", 2, and 3" thickni. And 2' and 4' widths by 8' in longness.
In addition, since your turtledeck will be derived from insulation material, you have a better chance of keeping your pushrod cool!
Material: extruded polystyrene, closed cell,
--- End quote ---
I think the weight can vary some. Also my scale is CHEAP. I ran the dimensions through the balsa density calculator. 1.79 is pretty close to 2.2 so I guess that it what I have. I am going to test it with a 1/32 balsa skin contact cemented and regular covering methods. It is "plastic" so I don't have any idea what will or won't melt it.
Could be a non standard size for Lowes. 24 x 24 x 1.
Ken
Steve Berry:
--- Quote from: Ken Culbertson on February 08, 2024, 08:56:57 AM ---It is "plastic" so I don't have any idea what will or won't melt it.
Ken
--- End quote ---
Well, I would use either epoxy (scraped on very thin), wood glue/titebond, or maybe the original gorilla glue, as we know those 3 are foam safe.
Steve
spare_parts:
Is it different than the blue or pink polystyrene we all know? Some years ago I ran across densities for the various extruded foams available, must have failed to file it in a way I could find it. Density definitely related to compressive strength. The 15lb boards tend to be mushy, but the 25lb sound similar to this. 15 and 25lb 4x8 up to 2" are readily available up here where it snows.
Brent Williams:
--- Quote from: spare_parts on February 08, 2024, 02:34:33 PM ---Is it different than the blue or pink polystyrene we all know? Some years ago I ran across densities for the various extruded foams available, must have failed to file it in a way I could find it. Density definitely related to compressive strength. The 15lb boards tend to be mushy, but the 25lb sound similar to this. 15 and 25lb 4x8 up to 2" are readily available up here where it snows.
--- End quote ---
I saw this xps foam weight info over on RCgroups. Perhaps others have manufacturer derived weight info.
https://www.rcgroups.com/forums/showthread.php?2300174-Weight-of-15-psi-extruded-foam
--- Quote from: T_om;30142639 ---The weight of Dow and Owen-Corning extruded foams vary according to compressive strength.
The 15PSI foams such as Owens-Corning Foamular 150 (pink) and its Dow (blue) counterpart are about 1.3 Lb./Cu.Ft.
The 25PSI foams, Foamular 250 and Dow equivalent are 1.5 Lb./Cu.Ft.
The "white" styrofoams vary from .5 to 1.2 Lb./Cu.Ft. depending on formulation.
--- End quote ---
Ken Culbertson:
--- Quote from: Brent Williams on February 08, 2024, 02:56:49 PM ---I saw this xps foam weight info over on RCgroups. Perhaps others have manufacturer derived weight info.
https://www.rcgroups.com/forums/showthread.php?2300174-Weight-of-15-psi-extruded-foam
--- End quote ---
None of the usual suspects have the crush strength or sandability of this stuff.
Ken
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