I,v been racking my brain for a while now over this little problem.
I need to make (draw) a line on some tack free (but not cured) carbon fibre in witch to trim along, glassed with epoxy.
under the carbon will be a tape line where i wish to trim (not visable), all this happens on the rail so i cant run the blade along a template.
I thought I had the problem solved with a fine white paint marker, this worked great ONCE !. I figure it filled with epoxy… Tried to clean the tip with acetone some time later. No luck. maybe do it straight away???
Two ways to overcome the invisible tape line-under-carbon problem…
Just do super-neatly cut free-laps.
Slide the blade along flat, rather than trying to poke the point through. If you hold the side of the line thats over the tape up a little, you can use the tape line as a guide. It guides itself with practice, but you have to be careful. This is the same way old-school fabric inlays are trimmed.
Either way, with Carbon you have to leave bulky laps, you can’t sand it to feather it in between sides like glass. It is advisable to have
normal glass as the outer layer and reduce sanding, as its speculated that carbon is seriously bad for you.
You have to do this from the beginning of your glassing proceedure. It wont help if what you have is a freehand taped line already, but maybe for next time.
An ancient method, as old as fibreglass boards. You need a gauge. Get a scrap piece of blank about 6in square, cut a right angle “L” out of it and shove a pencil through at the point as far from the inside corner as you want your line on the board. (I’ll bet theres stacks of pictures in the archives)
The pencil is then guided using the rail outline. Make this line on your foam and follow it with tape. Use the same gauge to repeat your line on the lamination later.
Meanwhile, use a white chalk pencil. Its a normal stationary supplier/newsagency thing.
Another thing…
Once you have got your carbon trimmed back to the tape line, run a small hard roller along the cut edge, literally crunching the edge into the foam. This way you can flatten the bulge before doing the deck. This reduces the need to sand carbon, or in the case of pigmented resin, means you dont lose the crisp line by grinding your lap.
Man, you have set youyrself a task. Carbon is a royal bitch to work with. I won’t carry on about it, but I have never seen carbon improve performance OR strength in surfbaords…
chalk pencil. thats also sound right on the money mate.
I used guide as you described also
I must say however I have done only 5 of these EPS Epoxy stringer less carbon rail boards and the amount the board gives you back in performance is truly unbelievable.
I rode this one only two days after it was lamed out on a reef up north 6ft square three days ago for 4 hours (best waves iv ever seen also) and it handeld beautifully. and also today in 2 ft re form slop and it went as good as i could ever hoped for. I’m so sold on the set up.
I’m a shaper for coin and glass for fun at home and im so stoked on this epoxy stuff. not a pretty finnish but %130 in performance. my boards are only 5 11 x 18 and the extra performance is really noticed.
It seams the KISS rule in design really applies with this technology, as i did a staggered rocker with hips in outline and it was a hand full.
re: pics
shot with the guide in it.
there is a seam on the rail from the top and the bottom (seperately glassed) carbon tapes. I plan to use the chalk pencil when trimming the second carbon tape it worked well i thought with the paint pen, but at $5 a pen for one use, not good.
barreling left.
Up north with 4 mates and a boat
Thanks Josh, iv got a feeling you meant a full deck of carbon as not that performance inhancing, I had one and it was shit. stiff as, and it snapped ha ha. I figure cause it had no flex at all? it was a heavy wave that broke it though
You got right, I assumed you were working with full carbon lams!
The stiffness thing is exactly where I was coming from. I’ve seen them crease easily and I got over it. The stuff makes the outer shell so stiff that the foam collapses.
Carbon tape rails however I can’t speak about, what with mine having wood.
I got it from CORE industries in sydney. well i know mine,its a team foam at #28, theres a #34 and ive used a #19 from a different company.
is this a standard measuring system?. I dont really know, but #28 is very relaxing to shape, like hot knife through butter, beady butter… that tends to be magnetic and love your face.
board with double 4 deck and single weighs 1.9kg with glassed on fins. sanded finnish… no pin holes in this one. i used q cell & epoxy to seal blank.
The nose went yellow in the first day…i used add F or could it be q cell or no cure time???
its a team foam at #28, theres a #34 and ive used a #19 from a different company.
is this a standard measuring system?.
I don’t think it’s a standard measuring system with block eps suppliers. They have grade codes: SL M H VH which roughly correspond to different densities measured in kg m3.
I’d say #28 is probably 28 kg m3 which would be a good density for a light weight shortboard, I believe it’d be VH grade if you were buying from a block supplier. 34 kg m3 is closer to PU density but might be a bit hard and stiff. 19 kg m3 is pushing it for a standard lammed board - and probably too dense to be of any use as a sandwich construction core.
Thanks Steve, you know I get all confused by numbers…
Yorky. Its good that you’ve got the harder stuff…They tell me its equivalent to a poly, so perhaps your fin boxes won’t “roll over”.(I went straight from Burfords to Vac bag skins, another ball-game) As Steve says, you want lower density in a sandwich.
Yes they quote ranges sometimes which is a bit confusing. If anyone’s interested here are the grades/densities in AU
L - 11kg m3
SL- 13.5 kg m3
S- 16 kg m3
M- 19 kg m3
H- 24 kg m3
VH - 28kg m3
I use SL for my sandwich boards. VH is actually a bit pricey from block suppliers. You’re probably better off getting a molded eps surfboard blank for the higher densities
Yorky - thought ‘L’ shaped tools work ok, I’ve used them in the past.
I’m sure a soft pensil (2B) would work fine.
But you may not even need to draw and actual line, Try doing a double or even triple layer of tape, you won’t be able to see the actual tape but will see/feel a bump where the tape ends, thats what I do for dark tints and opaques, not sure if it will work with carbon so do a small test with a scrap piece first.
Two ways to overcome the invisible tape line-under-carbon problem…
Slide the blade along flat, rather than trying to poke the point through. If you hold the side of the line thats over the tape up a little, you can use the tape line as a guide. It guides itself with practice, but you have to be careful. This is the same way old-school fabric inlays are trimmed.
SN, could you elaborate on this a little? This was a timely thread for me, as I’m going to do an experiment on a new board, and am thinking of ways to trim through the carbon/kevlar patch I’m glassing on the deck. Are you saying to lift up on the tape and cut from underneath, or lift up the tape and cut from the deck side?
If my memorey surves me right I think thats called a “zip cut” you hold the blade horazontal against the top of the rail pointing towards the stringger, and peal the glass over the tape up and cut from the outside.
in a normal cut the glass is stuck down and you hold the blade vertically and cut downwards, then peaal the tape one the glass has been cut.
I remember reading that some people bend the tip of a blase to a right angle, l shape to make this easier, but I’ve never tried this myself.
You need to cut a starting point on the tape side of the line, lifting the glass off the tape (though not too forcefully, you don’t need to crease the glass.) - til you reach the lammed foam edge where it will no longer lift . The blade is slid along flat using both hands. Slices a tapered cut, half the blade on the lam side, half under the glass between the glass and tape.
(I mean one of those scraper type blades with no handle).
Its still difficult, but you see where you’re heading a bit better. I bet Carbon Kevlar will be a bitch!
I’ll bet you’re absolutely correct!!! The epoxy has to be set just right to get the blade to go through the kevlar. It will be interesting. The test patch I did was tough as nails, we’ll see if it does any good on a surfboard.
