Help Planning Mold/Part - Sunroof delete panel

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#81

More practice parts.

First a short video of degassing the resin prior to infusion.
http://flic.kr/p/bf8V3v

This time I made a 12x12 square, with a 10x10 foam core. I fed from the middle, and pulled vacuum on the sides. I also put 1/8" diameter perforations in the core every 2" from the center outward. I think I probably over-sized the holes, but it worked. I’ll try smaller holes next time. That test was to ensure resin would wet out the surface underneath the foam, with just small holes to pass through. I discovered that sealing a resin feed hose in the middle of the bag isn’t easy. I ended up with a leak during infusion. I was unable to stop the leak and figured the parts were destroyed. I was wrong. The infusion still went quite well. There is an area where the resin didn’t 100% wet out the fiber where there was a significant amount of air, but its not too bad. Nice lesson to learn on a practice part. Next time I’ll feed the resin tube in under the bag edge seal like I’ve done in the past.
Perfectly transparent fiberglass.

IMG_5573.jpg by Kevin_Doe, on Flickr

Then I also made a 4x12 test panel with a 2x10 foam core, out of carbon. 2x2 3k twill weave. Two layers, core, two layers. This test was to see if carbon infused any different than the glass. It seemed to wet out quicker, but other than that no other issues. The test panel turned out really nice. The carbon panel is super stiff as well. This stuff is awesome.

Mold side

IMG_5593.jpg by Kevin_Doe, on Flickr

Peel ply side.

IMG_5589.jpg by Kevin_Doe, on Flickr

Next test will be a small swatch of carbon epoxied on the mold flange, to make sure that wax alone is adequate to release from the gel coated mold surface. If that goes well, then its on to making an actual sunroof. Well, I may do a test to thermoform some of the core inside the mold, but that should be straightforward.

#82

Wow! just amazing work! keep the updates coming. I am more than impressed!

#83

Does anyone have any comments about the size of perforations in the core material? And also the spacing? I tried 1/8" holes, 2" apart. Worked great, but wanted to know if that is way overkill.

#84

I think it’s ok, since it worked ok

#85

Smaller holes the better, you can get away 1mm holes. less weight and less chance of seeing print through in light laminates. When making your final panel you will want to use a resin with a high tg and post cure it well before releasing it from the mould. Ramp up slow, no more than 10 deg c/hour. If not, it will look great until you put it in the summer sun, then comes the print. Ensure your release system is up to job (temperature wise) ie. some waxes when post cured will not release too well when using neat resin into the tool, meaning no duratec or gelcoat etc. On the real panel you will not need to thermoform your core or even gridscore just drop the core in and place the inner skin over it. The amount of curvature really is negligable in this panel.

#86

Test infusion on flange. Making sure the mold release works on the mold surface.
Test Infusion

#87

Crazy how fast the piece is saturated with resin! Incredible work so far Kevin!

#88

I actually think it may have went too fast. Both the carbon and fiberglass swatch had a little bit of surface pinholes. Its my first piece that had any issues on the surface.

#89

Try using a smaller intake hose. 1/4"-5/16" i.d. One it will help to slow down the infusion and two your intake system wont hold as much excess or “waste” resin. When doing larger infusions it can be surprising how much the intake system holds before the resin reaches the plys. Plus the test piece on your mould had a large piece of flow media on it for the size which could have allowed the resin to flow over the top of the plys before saturating down to the mould surface. With infusions it’s important to have a good vertical flow front to “push” out any remaining air. (If that made any sense) :slight_smile:

#90

Made up a fiberglass sunroof today to test the fit and whatnot. It ended up weighing 3.125 lbs after trimming to fit. I did notice that my flanges for mounting are not nearly stiff enough. I’ll have to add several plys to that area to stiffen the flanges. I also think I may double up the thickness of the foam core in two strips along the edges to increase stiffness. Other than that it was a complete success.

The blue you see is the foam core. The carbon version obviously won’t show this through the fabric.

IMG_5600.jpg by Kevin_Doe, on Flickr

The fit around the edge looks good.

IMG_5602.jpg by Kevin_Doe, on Flickr

The fit with the stock roof line is perfect.

IMG_5607.jpg by Kevin_Doe, on Flickr

#91

great job!!

#92

Exceptional work! cant wait to see the carbon version.

#93

Vearay naice! Look forward to seeing more :).

#94

I would die to see honey comb… Totally feasible with your setup. 1/8 aluminum honey comb carbon skin and glass back ( or vicaversa )! Would be tits! You would have to do two cures with a core bond but it would be super sweet!

#95

Be carefull with carbon and metals though, asking for trouble with those two in contact with each other. Aramid honeycomb is better(and lighter). But foamcores do excell in impact resistance.
Can’t wait to see the endresult!

#96

Aluminum would “probably” corrode if there was moisture, vibration, electrical contamination. Which would be likely in any event but… For show factor, hands down would be tits!

And to clarify you are 100% correct susho about galvanic corrosion and graphite… But my heart skips a beat when core is showed off when it comes to these things… A product that comes to mind is the mid 2000 model burton t6 snowboards that have a see through reveal of the honeycomb core inside the board! Sun roof delete with a transparent reveal of the core… Omg!

#97

Thanks guys! Dallas, did you miss all my text where I mentioned this fiberglass version where you can see the core was a test piece?

#98

About the flange stiffness, I bolted it in the car firmly and the flanges still lack the stiffness required. Granted, there will RTV sealer all around in the gap that will stiffen the mounting and damp out any motion, I’d still like to improve the flange stiffness. I’m still toying with ideas of how to stiffen the flange.

First idea is just a good number more layers of fabric (from 4 to maybe 8) in that local area. The second idea is more complex. I’d use a 1/8" foam core, with small metal inserts to take the bolt clamp load. This would certainly make it more stiff, but the dry layup would be significantly more difficult. I’m leaning toward the more layers of facric due to ease of the solution. Sure it will be heavier, but I’m only talking about maybe 4 oz more fabric. All in all it will still be ~20 lbs savings over the stock sunroof.

#99

Thicken the laminate.

No I didn’t miss it at all Kevin. It just looks great!

#100

I was thinking that I should add the extra layers using unidirectional, since I’m only attempting to stiffen in that one direction. Thoughts? Layup schedule on the flange would look something like:

  1. 5.9 oz twill 0/90 (this layer will span the whole part)
  2. 5.9 oz twill -45/45 (this layer will span the whole part)
  3. 10.5 oz uni (this layer will be local to the flange area)
  4. 10.5 oz uni (this layer will be local to the flange area)
  5. 10.5 oz uni (this layer will be local to the flange area)
  6. 5.9 oz twill -45/45 (this layer will span the whole part)
  7. 5.9 oz twill 0/90 (this layer will span the whole part)

This should result in a flange thickness of 0.102" (up from the 0.048" on the fiberglass one I made). The additional weight from the extra three layers of uni should be approx 4 oz carbon weight, and 4 oz resin weight if I assume a 50/50 weight ratio. 8 oz additional weight to the total weight of the part. I think that’s not too bad for a part with significant additional stiffness.

What does everyone think?