Re: Urethane rails?
Posted: Mon Jun 28, 2010 2:42 am
Just ordered some from smooth on. The high density PU plastic and some silicone mold to make up fin molds. Thinking about trying PU twintip fins. Maybe with carbon tow mixed in.
I am not sure is roller skate wheels use the same scale.JMF wrote:With a shore hardness of 90 what could you compare it to in the real world. A roller skate wheel? Can you dig your finger nail into it? Did you de-gas your pots or would they go off to quickly?
I also only used poured rail method couldn't be bothered with gluing ABS to much effort. I used plain old epoxy without fibers for my rails. I was always a bit wary of adding any type of chopped fiber to my pots, theory being that it would make rails to brittle.XSwind wrote:Yup roller skate wheels use the same scale.JMF wrote:With a shore hardness of 90 what could you compare it to in the real world. A roller skate wheel? Can you dig your finger nail into it? Did you de-gas your pots or would they go off to quickly?
Basically if you are going to give the PU system a go, you should be looking at a shore hardness of 90 ish, lesser the number softer the cured results.
FYI, I have never added any micro fibres to my mixes and as yet had no cracking or failures.
Give it a try, its a revolution for speeding up production.
Forgot to say Make sure you scuff the PU with 40 grit before laminating the skins on.
Degassing not really needed and I dont do it myself, my Pu is as thin a condensed milk and flows without any major bubble issues.
My PU starts to go off in 60 seconds so its a bloomin rush getting it poured but not too bad, no failures yet but with such a quick time you need not really mix in small batches.
Forgot to say, no you cant dig your nails into it, its hard but retain a little flexability over length especially in 4mm x 12.5mm thicknesses.