On this week's skedule there's finishing the frame of the hull mold and doing a first test of a flat sandwich plate (with a leftover of glass fiber). I chose to copy the half hull method of the amercans on youtube (see previous link).
The test foam I bought is 5mm Rohacell 51, but it much too stiff, not at all what I expected. I'll try Soteco next, it only comes in 6mm thickness, but that'll do. It's supposed to be more flexible and it's also available partly sliced (pic) for really sharp curves.
Well I'll try and get some pics for next week to make this look a bit better. Thank's for reading !
Hi Michael,
ReplyDeleteCoincidentally, I am just about to start a moth build (http://www.mothflyers.co.uk)
I picked up the molds yesterday and have just started to prepare the workshop.
If you need any advice at all please give me a shout.
Best of luck,
Phil
15 min working time is going to be too short, I think, for hull layups. You may want to look at ways of warming the epoxy before mixing, and of heating the work surfaces if shop temp is a problem.
ReplyDeleteAlso have a google for "thinning west system epoxy" it has some insights on temperature, thinning ( chemical as well as heating) and should nudge you in the direction of thinking about a slower kick with some controlled heated surfaces.
Hallo ,
ReplyDeletefalls noch nicht bekannt:
http://xflr5.sourceforge.net/xflr5.htm
Ist um einiges komfortabler
Gruß Chris
Rohacell is an acrylic based foam and it has next to no elongation. It's strong but too brittle for your application. Your best bet is 5 mm A500 Corecell or H80 Divinicell, although the former has superior shear elongation properties. I would stay away from cross cut foam, especially from Divinicell range as the cuts are huge and you will end up with filling them with very heavy epoxy. The Corecell is knife cut and the resin uptake is minimal. The best bet is to either thermoform the sheet or slice some half depth cuts with a stanley blade. Don't worry about costly and complex ovens, polistyrene boards and a electric fan heater will get you 60 degrees easily.
ReplyDeleteWenn Interesse besteht können wir uns auch austauschen.Habe soeben die 2te Generation an Formen für meine Foils ausgefräst.
ReplyDeleteWelche Re Zahlen verwendest du für deine Berechnungen/ Simulationen?Ncrit geht von 2 bis 3 habe ich aber auch nur irgendwo gelesen.Verwende momentan 2.5
Gruß Chris
hey, i made an oven with a fan, some MDF, alfoil, a blanket with plastic backing and 2 spotlights. its basically 2 airtight layers with alfoil on the inside and insulation between. it gets to 100 degrees if i want it to, admittedly not big enough for a whole boat, but it wouldnt need to be that much bigger. make sure you get epoxy with a long pot life, like an hour or more. araldite 3600 resin has been good. and it loves a bit of heat.
ReplyDeletebest of luck, boat looks great!
nick
Would agree, the cross cut Divinicell will take a lot of resin, go with Corecell. thermoform is easy, just heat the foam with a hot air gun for a bit, and you will get it (especially the thin stuff) into most spots. After the vacuum, check the foam for voids, just tap it, if you get a high pitched sound, cut that bit out with a stanley knife until you get back to a good bond, and stick a bit more foam in by hand.
ReplyDeleteWe easily got our 14ft javelin skiffs up to 60+ degrees with polystyrene "oven", but we used an portable oil column heater, bit safer, and always had problems with the fan heaters tripping out from overheating.
Go for a longer working time resin (less stress if you are new to it), try and get a laminating resin, not just a standard epoxy as less viscous and easier to wet out, especially if it is a bit cooler. try and stay above 16 degrees. Then cook the shit out of it in your new oven (in the mould) as per resin post cure schedule.