Was watching Parko give an interview yesterday, and noticed the carbon strips running along the stringer were not pulled tight, but were all squiggly and wavy.
I thought this was either glasser error, or perhaps intentional to increase breaking strength but not stiffen the board too much, but thinking along these lines is not without fault either as it would seem the different flexes would cause layer seperation. But throw in the disposable nature of a Pro’s boards and who can say.
Seeing as how they wouldn’t likely have the new laminator working on Parko’s boards, I lean toward the latter hypothesis, but I have never worked with that type of carbon.
Does the carbon tape naturally get all frazzled looking like that? I’m afraid I’d bet a bit miffed and go into Hulk mode if I were glassing and could not get the carbon nice and parallel and taught.
But laminating is not one of my strengths, and I might farm out my next glass job.
Its just really hard if not next to impossible to keep everything perfectly straight, especially in a production setting.
In a custom setting, where you aren’t being rushed, it can be done. A trick is to apply a sealer coat of epoxy, under the stripe, and wait for it to go to “B” stage, or tacky. Then place your carbon down, and when the sealer cures, it will hold it in place. Then glass as usual.
Another help is to put it down with two people. Pull it tight and lay it in the “B” stage. Tight will be straight. But not too tight, or it will creep back and wrinkle. Just something to play with to get right.
I’ve seen some wavyness before but Parko’s board was seriously wavy, like they fit 8 feet of tape on a 6 foot board which made me think it was intentional.
Ha I noticed that too. You know you’re a shaper when… But I’ve done one carbon stringer, and I made sure it was all striaght and stuff, but some of the fibers still get squiggly. I was considering using a tack or something to stretch and pin it at both ends, which would be removed of course as the resin cures. Mine is pretty straight, but it’s not like ruler straight. There’s a gentle wave to it, but the board hasn’t snapped so I like to beleive it’s serving its purpose.
You can read whatever you want to into it. The truth of the matter is that the “Pros” boards are usually done in such a rush that the glass jobs are very often sloppy. When you talk about doing 25 or 30 boards to be done ASAP for the next leg of the world tour tossed into an already busy production glass shop; anything can happen. Everysurfer is absolutely correct on this. His method for applying carbon tape is the best way to do it… Also; poduction laminators in a busy factory who only do clears are not always the best laminators in the “Industry”. Lowel
I just wonder how effective it can be to stiffen and resist breakage when as squiggly and wavy as it was on Parko’s board. Almost like what is the point of using the material and going through the extra effort and expense if it is going to be as wavy as it was on Parko’s board. I’ve not worked with this material used over the stringers, but I just see it is being a complicated extra step, with the goal of increased breaking strength, and I don’t see the carbon, when not pulled relatively tight, increasing strength as intended, or to the degree intended.
How thick is the tape roll? Is there a recess the width of the roll in the foam, to accomodate the thickness, or is the hot coat enough to cover the ‘ridge’? If thick enough to cause a ridge, and it is not obscured by the hot coat, then sand through of the 4 oz over the carbon roll could be an issue, compromising strength, No?
Is is possible the different flexing of carbon and glass layers actually compromise breakage strength?
Thanks for the tips on how to do it properly.
Would having a ‘stretch table’ be an option in a non production setting? Like rolling it out on a clean smooth table of adequate length, pulling it tight, and clamping/ taping the ends, until the memory relaxes?
I had a bunch of pretty heavy unidirectional carbon given to me folded, not rolled, and had some luck hanging strips for a few days with a heavy clamp on the end, but the reflections where the folds were are still obvious. But it was easier to wet out and maneuver into place,( wet out table) but this was not a stringer layup, and I had routed shallow recesses to accomodate the thickness of the carbon, which helped keep it straight too… well mostly straight. Hulk mode was barely averted.
Those stringer strip of carbon are a far better commercial trick than technical LOL. +30 or 40 $ for those strips is a good buisness ! especially if you don’t spend time to do them correctly. Spray lightly some rattel can adhesif (those one sold for fixing fiber in infusion process), glue tape by unroll it directly on glue, it’s stay straight easily this way, cover with glass then laminate, squegge lenghtwise first. Fast and easy to do. Work either for carbon rails. Work your hotcoat to manage the extra thickness, like for laps.
The only way those strips increase breaking strengh is by increase buckling resistance of skin = increase critical Euler force : F=pi²EI / lk². pi² and lk² are constant so you can increase E (stiffness modulus of material) or I (quadratic moment of material) here I=bh^3/12 where b is widht and h is thickness of material. For sure carbon increase stiffness modulus and the thickness of stip increase quadratic moment by thickness^3.
