Prepreg
Posted: Sun Dec 29, 2013 8:49 am
My thoughts on prepreg in short.. ( I got a question in a other tread but felt it was better to start a new.)
I don't think prepregs are any good for DIY the main reasons are:
1. The prepregs I've used Needs a temp of 120deg C for 30min and needs to be kept below 123C as that's when the base melts.. To regulate that with a electrical heating blanket will be tough. The press I've used are water heated so the hole ski will hold the same temp as there are quite high flow of that water and massive amount of power, the heater is 40kW for the single stage press and 120kW for the double.
2. Depending on prepreg, but the ones used before needed ca 16bar pressure so you need a BIG press. the beams in the Langzauner are ca 50cm high and made out of 10-100mm thick plate. the newer prepregs have less flow and less glue in them so they need less pressure like 3-6bar but they need a more uniform pressure so you don't press out all glue and create dry spots.
3. they dry out if kept in room temp for a few days to weeks depending on type so you need a big freezer to stor it in.
4. Frozen materials creates condensation and if that water gets in to the pressing cycle you will delaminate your skis at first turn.
I don't think prepregs are any good for DIY the main reasons are:
1. The prepregs I've used Needs a temp of 120deg C for 30min and needs to be kept below 123C as that's when the base melts.. To regulate that with a electrical heating blanket will be tough. The press I've used are water heated so the hole ski will hold the same temp as there are quite high flow of that water and massive amount of power, the heater is 40kW for the single stage press and 120kW for the double.
2. Depending on prepreg, but the ones used before needed ca 16bar pressure so you need a BIG press. the beams in the Langzauner are ca 50cm high and made out of 10-100mm thick plate. the newer prepregs have less flow and less glue in them so they need less pressure like 3-6bar but they need a more uniform pressure so you don't press out all glue and create dry spots.
3. they dry out if kept in room temp for a few days to weeks depending on type so you need a big freezer to stor it in.
4. Frozen materials creates condensation and if that water gets in to the pressing cycle you will delaminate your skis at first turn.