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Wrapping rails neatly
Posted: Sat Mar 14, 2020 8:58 am
by RichR2
Any tips on how to get a neatly cut edge when wrapping rails. I always get lots of stray strands. Not a problem when hand laminating as I go back with a scalpel blade when the resin is starting to gell and cut a clean line, but not possible to do when using vacuum.
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 10:37 am
by tomtom
dont cut, grind it
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:15 am
by RichR2
No, I dont mean a smooth finish, I mean a clean edge to the carbon weave
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:23 am
by tomtom
i mean that too. Just use hard sanding block. Its just not possible to clean cut carbon if is long after gell
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:33 am
by Herman
Good question sorry I don't have a proven answer. You could try the following tip I heard for cutting dyneema.
Run a 180 grit corse stone over the bevelled edge of your scissors. The idea being to put micro serrations into the blade which grips the fibres resulting in a cleaner cut.
Not tried it myself but it sounds plausible and maybe worth trying! Obviously unlikely to be 100% but may reduce amount of grinding required.
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:40 am
by foam-n-fibre
For some applications I use 3M Super 77 spray adhesive to stick carbon to something with a complex shape before wetting it out. Might sound crazy to some, but google it, its commonly done. Turns out that carbon cuts much more cleanly wen it has one side misted with this spray since the fibers hold together. This would improve it, but might not give the perfect finish you want. You might have to use a paint pinstripe over the edge and under the final resin coat to make the edge look sharper.
Peter
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:45 am
by nixmatters
Herman wrote: ↑Sat Mar 14, 2020 11:33 am
Good question sorry I don't have a proven answer. You could try the following tip I heard for cutting dyneema.
Run a 180 grit corse stone over the bevelled edge of your scissors. The idea being to put micro serrations into the blade which grips the fibres resulting in a cleaner cut.
Not tried it myself but it sounds plausible and maybe worth trying! Obviously unlikely to be 100% but may reduce amount of grinding required.
Just buy a pair of serrated scissors for carbon/kevlar/Dyneema. As low as 20 bucks, but won't last long. Been cutting carbon/Dyneema cloth with such... paper clean cut.
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 11:54 am
by tomtom
Guys - he is talking about fully cured composite - not fabric...
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 1:57 pm
by RichR2
No problems with the cutting, it's the strands that that come away when you do the final wrap of the wet laminate and spoil a clean edge. Not an issue if I'm going to paint over but I'd like to use a clear coat to show off the carbon weave.
My only solution so far has been to wet out the cloth, and then scissors to trim it carefully (the wet cloth tends not to fray in the same way as dry), then put on the peel ply and squeegee round the rails through the peel ply. Not perfect, but better than squeezing the wet cloth directly.
Was just hoping someone had a better method.
Re: Wrapping rails neatly
Posted: Sat Mar 14, 2020 3:48 pm
by Trent hink
I have used a very light coat of spray adhesive to stick very light glass fabric (1.5-2 oz) onto another piece of fabric. This can stabilize the threads if you are cutting the fabric prior to wet-out, but it will make it a bit harder to smoothly wrap it around sharp curves.
The spray adhesive is a neat trick, and it can be very useful, just be careful to only use it on fabric or porous surfaces and use a minimal amount so that the epoxy still has plenty of surface to bond to. If you try to use it to stick fabric onto a smooth non-porous surface it Will fail. For example, it won't work to stick fabric onto a core that has been filled with microballoons and sanded smooth. For that type of application your best bet is to wet the surface with resin and wait until the resin is tacky enough to smooth on the dry fabric, then wet the fabric.