rynhardt wrote: ↑Sat Jul 21, 2018 8:16 pm
1. Do you mean the rocker flattened out and bent the other way between the foot pads? 9mm thickness in the centre with 250gr carbon (0 deg, I assume) both sides should be plenty stiff, especially with some concave.
I mean that the board has an almost flat section in the middle, and it has a sharper bend closer to the area where I started thinning the profile, like 5cm off the straps, going to the tip ends. But as I said, it works just fine for a LW board, probably even better than the uniform rocker, or at least that's my impression. Also, I used 300gr biax (oriented corner-to-corner), and 250gr unidirectional, at 0 deg, per side. Actually, bending the cut-offs takes some effort, so I think using 200 uni + 200bi would be plenty for a wood core. Again, I was estimating the materials for a foam core board, and then got distracted... and went with wood. The weight of carbon + epoxy added significant weight to wood core (which was ~2kg), so the naked board is approx 4kg now (0,85m2 area covered by 550gr carbon x 2 + 100 proc epoxy weight...). So the way to reduce that would be to both reduce the core weight (by thinning it) and use thinner carbon. That way I am sure I can lose at least a kilogram of weight, perhaps more, since paulownia is even lighter than WRC. Anyway, I have to give it some more thought. The variables are there, just need to make sure I do the math correctly.
rynhardt wrote: ↑Sat Jul 21, 2018 8:16 pm
3. Depending on how expensive your ABS is, you can either cut strips and bend them, or cut the entire outline (see pic below). I've had good success with just an alcohol wipe,abrade, alcohol wipe regime for bonding the ABS. I haven't flamed it and my boards have held up fine so far.
I'll make some tests, worst case, I found some PU @ 75-80 Shore D here at reasonable prices:
http://easycomposites.co.uk/#!/resin-ge ... resin.html, so I can go the downunder's suggested route and pre-make the rails in a mould. ABS I is less messy though.
rynhardt wrote: ↑Sat Jul 21, 2018 8:16 pm
4. My inserts are mounted inside an ABS rail (pic below). This was for my split board, so there's extra inserts in the middle which you can ignore.
Awesome, I like it. Question though, I see you use two layers of ABS sheet at the middle? This is for the split setup, right?
rynhardt wrote: ↑Sat Jul 21, 2018 8:16 pm
5. Machining with a belt sander takes enormous finesse.. lots of guys use a router instead. In the video below I use a router table with a profile.
Tell me about it
There were a lot of those 'a little... a little more... f***!.. too much' moments, but hey, epoxy covers all the faults!
rynhardt wrote: ↑Sat Jul 21, 2018 8:16 pm
6. Yeah, your carbon layup would be fine with a foam core and is probably over specced for a wood core.
Just a stupid idea - if I were to use a 3mm AIREX C70-90 for the tips, and add extra 3mm layer for the center and pad area on top... Would it be workable? Also, do the
beams, like Brokites do, to strengthen it. I am pretty sure the same amount carbon can take it...