The recent threads about fins have me imagining. How to shape a Fins Unlimited type box fin from plexiglass or lexan? From what I recall, a disc sander will heat up the material too much and it will melt/smear. Am I just too impatient, can a disc sander be made to work?
What is the correct glue for sticking plexi to plexi, or lexan to lexan. I THINK for plexi it’s methyl ethyl ketone (MEK), someone confirm?
‘Luke’, where are you ? [sorry to dob ya in mate…but YOUR one got me thinking , too ! ]
…are you still ‘lurking’ here ?
cheers !
ben
how does lexan resin work- who can get it? what r its properties?
You can ask a Tap Plastics store emp, they polish their lexan after cutting and shaping, to a crystal clear sheen.
Main problem with fin is maybe too flexible, but OK for keels, I guess.
The older lexan fins always had that problem, and they were thicker at the fin than the base, to attempt to maintain some amount of stiffness.
I think Tap also sells resin impreg sheets, which are much stiffer.
Yes, they can be shaped and polished, but using different grade cutters, rather than fast speeds.
I had shaped some lexan with no power tools, so no heat, and turned out very clear.
You can cheaply get Lexan in sheet stock from McMaster-Carr.
It may be shaped at low rpms with patience. There are also plastic polishing agents you can use at the end to make it look as shiny as you like. Kinda like an icicle on the bottom of the board.
I’d skip the plexi - too soft. Even Lexan is quite marginal in stiffness, you will need to make a fin quite a bit thicker than a fiberglass fin to get adequate stiffness.
Glue it with epoxy.
If you have access to a machine shop, it’ll machine like butter at low rpms on the mill.
I made a few Lexan fins (and a Lexan finbox, which looks REALLY cool), but I think as a fin material it is inadequate in stiffness to get the thicknesses I think are important in a fin.