so , please tell me …
WHAT do you make your mould out of ?]
is it reuseable ?
how many times , roughly ?
thanks , Plus One …THAT’S the stuff I REALLY want to see photos of and hear about !
, mate !
ben
Sounds like Perspex is an acrylic like Plexiglass; that’s a “no go”. It will fracture.
You want the stuff that some eyeglasses/faceshields are made of: Polycarbonate (trade name Lexan or Markalon here in the states). Furthermore, you don’t need it to be optically perfect (expensive) so you can get it with 20 percent fiber content, which makes it even stronger and a bit stiffer. It will still be clear, though I’ve seen it available in colors.
Earlier I made the comment that you could shape it with a high-speed grinder. Then you could progressively do finer grits until polish-able. I think you could also take a “blow-torch” (I forgot what you guys call 'em…) and carefully use an open flame to get the killer shine. Don’t char it as it will leave a brownish color.
After I read how you were sacrificing boxes to get your moldings; I just hope you don’t “spit the dummy” when I tell you how I do it.
I use wood.
3 pieces: A flat ply board with a strip of 1/2" thick (or the depth of your fin base), about 2" wide and 24" long hard ply screwed tightly to it.
Now the imortant part.
The third piece is identical to the second and is placed parallel so that a 1/4" gap is formed between the two pieces. To get this gap, I use the base of an existing fin (with one layer of tape on it). With the third piece clamped snug, I drive screws into it. Note: all screws are driven from underneath for better access.
Now I take the whole thing apart and put good tape on the flat base and on the side and upper surfaces of the two sticks. Put it all back together. Use plasticine or surf wax to clog the ends of the 1/4" slit to suit your needs.
I set the fins in place and hold them with tape or wax. I mix epoxy with milled fiber, pour, have a beer, and there you have it.
Break down the mold by unscrewing the third member and tug it from the rest of the mold. The tape will stick to the fins but depending upon the tape it should be a breeze to skcuf off. I use the grinder to chop my bases to the right length and profile…
thanks very much … an answer to my question [at last …for a minute I thought it was one of the taboo dark secret areas of the industry]
Any chance, next time you mould some , that you could please take a few pics of what you just described ? [sorry to be a nuisance …I just learn a LOT better from seeing a picture sequence of the process[es] involved .]
thanks !
ben
p.s. - what do you use to stop the resin sticking to the wood ? And do you screw /drill the holes AFTER the resin is all set ?
CF61,
Each piece is coated with good masking tape.
Spray Pam (cooking pan release) on all relavent surfaces.
The pieces are screwed together before pouring.
It should only be a couple of days before I mold some more.
I’ll get pics…
P1
thanks !