How much carbon needs to wrap around the leading edge of mast?

[jrandy]

Opie,
The stabilizer looks nice. Using a 3D printed mold for a few prototypes is a trend in manufacturing today.  A designer or company can get multiple molded copies for a proof-of-concept without paying for machining or waiting for a metal mold.

What would you think about finishing the wing as a working unit then making a fiberglass mold off of that?

What size hardware? I am at the point of needing to get some for mine, was thinking 1/4-20 UNC in stainless.

[surfcowboy]

Obey guys, let me know what hardware you need. Turns out a buddy of mine runs a bolt/hardware company here in SoCal and I told him about foiling and he's interested in maybe stocking the standard stuff.

Opie, the stab came out nice. I think Jrandy's on to something with the mold off the wing idea. I can't really tell from the pics, where you able to get a smooth surface one the main wing? I'm concerned about that for mine as well when I do one with anhedral.

I made some progress today after a long break. I'll post up what I've been doing.

[opie]

I am using m6 bolts, since that's what my other foils have.

I don't plan on making two wings the same, so no need to make a mold once I have a working wing.  I am just using molds to get around my  lack of epoxy skills.

As far as my big wing being smooth, its not.  One side came out ok but without vacuum my connection indentation caused lots of wrinkles.
I am hoping it still works.

If not, I have mold designs waiting in line for my 3d printer.  I am getting more excited for this method as I just opened a mast mold and it looks good for a first try.

[surfcowboy]

Dude, that's nice! What layup did you drop into that? That's clean man.

[supuk]

If you up the perimeter thickness to 2-3 layers and I think about 10% infill I have found I can use full vacuum.

[opie]

Dude, that's nice! What layup did you drop into that? That's clean man.

I don't really know.  It's 3 quarters of an inch thick solid carbon with maybe 50 percent uni the rest bias.  when I got close to full on each half I put in some microballoon past to help fill it evenly.  I over filled it a bit but next time I'll do better.  The chance of me filling it the right amount the first time was slim.

I got a little impatient at the end and the heat did warp the mold a bit, but the mast seems smooth and straight.

If you up the perimeter thickness to 2-3 layers and I think about 10% infill I have found I can use full vacuum.

I just discovered this ability.  I've been doing all my new molds with 1.2 thickness.  They are way stronger.  I was considering trying 1.6.
Looking back that wing was the first thing I printed and I was experimenting with infills.  I think one section was just 5 percent infill, so that may have been what was collapsing under vacuum.  Thanks.

[surfcowboy]

Wow,  that's like 24 layers of carbon? (Estimating based on the thickness of my 3 ply layups.)  Are you able to keep the resin ratio low enough or is it pretty resin rich?

Are you using a wet out table to saturate your resin? I've been doing that and it's working pretty well, I'm almost 50/50 usually.

[opie]

20 to 25 strips is a good guess.  And its totally resin rich.

  A wet out table is when you wet the carbon in layers with plastic sheets in between stacked up and ready to apply?  I've tried that once with bias cloth and it was hard to deal with.  I could no longer get the strips to lengthen or contract.  I didn't realize it helps with resin to cloth ratio, I thought it was just to speed things up.  I took hours to do the mast because I was trying to avoid heat build up melting the pla mold.

[surfcowboy]

Google the wet out table. I don't stack them up, when I'm putting carbon on, I lay the cut cloth on a table with plastic taped down and wet it out and squeegee all the resin out of it. Then, when you pick up the cloth a lot of excess resin is left on the plastic. Then I lay down the next piece of cloth on the table and it soaks up the leftover resin and then I put a little resin on top, spread it, let it soak and squeegee again, and so on. This and bagging will get you to a pretty nice and lean resin ratio.

A lot of guys do whole board lamps this way. DW did a great video of that. I don't have a good table big enough but I do all my small parts this way.

[opie]

My front wing didn't fit well, so I made a wedge from micro balloon paste.  It's not perfect but good enough, I think.  That'll be my company motto.

I attached it to a sup and tried to kite it for a test.  I had zero lift. 

 The sup was super hard to deal with and I quickly went down a wind hole where I was just too under powered.  I also believe the angle of  attack was too far off.  If it had been a kite board I could of adjusted the angle with my feet, but the sup was just too hard to muscle around.

I am printing a wedge to help the angle and converting a longboard to a plate mount kite board for testing my foils.  I am still optimistic.

[opie]

Did a fuse with PLA mold method.

[opie]

Back to work so this project is in slow motion mode.  I finished a test board so that I can fine tune the foils with a kite.  It will be so much easier to get plenty of flying time.

I also did a pla molded core with pour foam.  I tried to save money by using foam meant for fence posts, but it is coming out brittle toward the wingtips.  the thicker chunks of foam that spilled on my table are solid.  I am guessing it is just not getting hot enough in the thinner wingtips.  Next round I'll try different foam, but this time I'll just use this.

Now I have about 20 days of printing before I can try molding the front wing.  In the future I think regular molds from 3d printed plugs will be the way to go but for this foil I will use this method since it's so easy.

[surfcowboy]

I sanded for about 10 min on mine today. I'm ready to hotcoat the carbon and mount the rear wing but I've been traveling and sick so it's been hard to motivate.

Hang in man and report in on the printing process. I'm curious as to how that goes.

[opie]

I keep putting off sanding anything,  it is not enjoyable.  I plan to wear a full suit and respirator on a cool day and go at it in the side yard.

I laid up the plate today.  It went better than expected, except I had to destroy the mold to get the part out.  No big deal since I have the file.
With the pla mold I am doing better by using 20 minute epoxy, doing a couple layers at a time and waiting for them to gel before the next.  After four rounds the first is solid and I fill the rest of the mold quickly, since I no longer need to worry about melting the pla.

I made a couple discoveries.  The 6.99 scissors from walmart cut carbon fiber as well as the 35 dollar ones I bought from the composites place.
I forget who told me but you guys were right about the rotary cutter.  I wish I had listened,  that thing is awesome.  Instead of a whole session of cutting before even starting to epoxy now I can just zip the strips right up.  And when I discover mid way I want some different shape I can just change gloves and make what I need in seconds.

[opie]

I flew the original "super-ugly-pla-plug-wing" foil on a kite.  It flew super slow and felt smooth, but it was very pitch sensitive.  After trying for about 10 minutes to let my legs adjust, I decided I need to try adjusting the stab.  I think I will try it upside down and bring washers to increase the angle down next time. 
  On the plus side it had a whole lot of lift.  It definitely felt like more lift  than my Takuma but that maybe due to the smaller board.