I am making some skimboards and I am having a hard time figuring what is the most effective correct way to wrap this rail which is the bottom 90 deg angle at the bottom of the board where the bottom carbon reaches the upper fabric. Figure 1 shows the way I have been doing it. I have had no problems riding it and getting delaminations, when I drop it however it will. Figure 2 shows one way to fix it, to tie the upper and lower layers together. I think it will be a difficult layup to wrap the inner material up around the 90 with no bridging and then have it stay while the vacuum bag pulls it the other way. Figure 3 shows the way I’m thinking of most, sanding a small radius at the bottom of the core run your material up the core and running a tow strand around the board. It would also be less likely to expose core while trimming. What would you guys do?
are you bagging on a rockertable?
I recently made a matching pair of race wing end plates that I infused both sides including the foam core in one shot.
I shaped the foam blanks profile after forming their silhouette. I wrapped the cores with CF by overlapping the A-side onto the B-side by about 1". Then did the opposing side the same.( think wrapping one hand over your fist.)
The next layer I repeated by an 1.5". I did a total of 3 layers this way and then Infused.Last overlap being 2".
For a skim board which requires the bottom side to be super flat, you may need to cut a slight relief in your core board to maintain a flush overlap . They looked smooth and flat until I sanded to prep for clear coat…then I noticed ever so slightly the overlaps, which could be sanded flush again prior to final coating.
Yes I am infusing it on a rocker table. Worldwealth I agree that would be an awesome joint however it has been difficult to not get bridging because the bag pulls toward the rocker table. Any bridging ruins your joint by separating it while trimming. Maybe I just need more practice or more super 77 which I don’t like using too much of because of the way it impedes resin flowout.
I didn’t bag onto a table surface, I made an envelope bag to cover both sides at once.There was zero gaps. It pulled fully against the 3d shape. I also used very light spray tack.
Using a rocker mould/table you could fold the bottom laminate around the rail and onto the deck then place your deck laminate and just run it off the edge onto your mould surface. Vac bag, push the bag into the corner well and trim just as you did before.
Ive tried envelope bagging it and it does pull it down nice without bridging but I loose my mold surface though.
Any other thoughts guys?
Use a mould as said??
If it’s a flat part then just find some Melamine surface board.
use stainles steel staples to keep your fabric in place, no need for trimming. Exile does it that way… 
(there where rusty spots on some exiles, before they switched to stainless 
)
Excellent idea susho. I’m going to give it a try. Thanks.
May be plastic staples can be used as well.
i used to have the same problem when i made kiteboards years ago… you have a few options… the best option, although more time consuming, is to make a solid edge on the foam core prior to infusing the laminate. After infusion, you can trim the flash and then sand the edge smooth back to your solid edge.
However, i ended up shaping the rail so that it had a chamfer along the bottom edge (where the bridging occurs). I run solid glass tows by pushing them into this chamfered area, with the laminate running over it like your doing now. Get as much of the bridging out as possible so it pulls in tight. When its cured, you can just sand it smooth back to the solid glass edge, the top and bottom laminates are bonded together, via this solid edge… i did it this way as it allowed me to do everything in one shot. Another trick - was to paint the foam edge with black pigmented resin so the carbon laminates looked continuous save a thin black line right on the edge (which was actually transparent e-glass showing the black foam underneath)
You can maybe use a PP/PE sheet as a caul plate (beveled edges), and envelope bag. This way you get your tool surface, and not worry about the tool sides bridging. It’s easy get bridging even when you think your bag is perfectly in that little corner!
Else, build it up, like your tow picture, and trim/sand.
+1 on using staples. Also try a 3M super77 glue but use lightly.
I make similar boards using a rocker table. I use single sided bagging and infuse them from the center outwards with a perforated core. I’m just a beginner, but have been getting good results.
However, the biggest problem I am running into now is resin racetracking along the edges. The shape of the board is more oval as opposed to square, which causes resin to reach the edge/rail faster in some places. Once cured, this leaves a build up of excess resin along the rail/edge, which requires a lot of trimming and sanding in order to get a smooth rail. Anyone have any ideas on how to eliminate this racetracking from happening?
I tried the staples and it works awesome. I just need to drive them in a little further they leave little bumps. I also tried the chamfer on the core and running carbon tow in it and that worked awesome. I trimmed it up and I see no core showing.
Epoxy 45, I also infuse from the center outward and it works great. The resin goes down the rails in the center of the board first but I don’t have any race-tracking. You may have bridging there causing a big void for the resin to run through. Try trimming your top material 1/2 inch after your material runs off the core and tuck it in the corner with a squeegee. That way your bag can pull it in tight.
Stop your flow media 1-2inches shy of the board edge on all edges, this allows the resin front to slow dramatically before it reaches the edge. The rest of the part will fill evenly until all the flow media is saturated first. This allows the front to match the shape of your board before it reaches the critical point along the edges and the inevitable race tracking. The last 1-2inches will fill much more slowly… once the flow media is filled, i clamp off at this point as the excess resin in the job will fill the edges and you will waste bugger all, often can reuse the vac lines as no resin gets in them. Still use a peel ply only resin brake between the vac line and board edge…