This is a follow on to the bonzer side fin/Mike Eaton thread. Lexan seems like a good fin material for a fake bead and as strong finlet material. How do you cut it? What kind of blade? What speed? What tools? What grit to sand edges smooth? Can it be foiled? curved? How to attach to board? Hot glue, then what? Thanks, Rob Olliges
Bandsaw does well. Medium blade for plastics at slow speed. Keep paper on. Sand outline with 80 grit, belt sander does well. Mike Eaton does not foil the lexan per se, he rounds off the leading and trailing edges. Get progressively finer grits down to about 320. Assuming 1/8" thick lexan with a tongue length of about 1", route 1/4" slot, 1" deep, into FINISHED board, the slop allows for the 18-23 degree lean. Hot melt clear flexible sticks are used to fill the hole. With paper pulled, jam the ventral fin into the slot; have an angle gauge. I tape off the fin and board to protect from the excess ooze. It’s good to use a popsicle stick to establish the bead while the stuff is still flowing (caution: H O T ). Excess goes onto tape. Hope this helps. Good Luck.
Lexan is a clear polycarbonate, it cuts and sands easily just like other plastics in the machine shop. Try not to melt it. As an aside, the Turbo Tunnel fin is made of Lexan as well.
Rob, As you probably already know Cheyne Horan’s Starfins are of molded lexan. If you grinding the stuff it wants to heat up and burn easily so slow speed, course grit (24 or 36) and a little touch is the best combination. Foil fine tuning is best done by starting with 80 grit wet dry and going from there. The stuff is hard to polish out well. but a light coat of R.R. epoxy with additive “F” will allow you to get a very nice finish of a 220 sanded surface on the lexan. Mahalo, Rich
With care, flame polishing works well, too.
I’ve done a few executive desk blotters made from Lexan. After routing and sanding, a very fine hand with a propane torch just before the melting point yields a polished edge. Practice first.
I wonder how well a heat gun or strong heat lamp would work? And then there is this cute little gizmo, probably work well enough with an airbrush compressor. http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592
A good high temp heat gun (variable 200 to 1000+ degrees is handy) will work, but not usually as well as pure flame. An object at air temp acts as a heat sink, which is counterproductive. Pre-heat. Use the h-gun to evenly heat the object. That makes final flame polish come out better.
Why does Mike Eaton use lexan bonzer fins instead of fiberglass fins like the Campbell Brothers?
I made a 9" wooden fin with a layer of lexan (about 5mm thick) as a core. It looks good but the thinned out tip of the fin is now covered by plenty of small cracks. It seems that lexan didn’t stand flex too much. Pierre.