Pic of hood pulled from recent mold posted - Question for U

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#1

I ran into a problem I didn’t think about with this hood. The thing is so damn big that either way is larger than 60". I am trying to figure out how best to run a seam. Any suggestions? I was thinking about trying to do the V pattern in the middle since I have to run a seam anyway. Tack down one side first with super 77, fold it back so that I don’t get the frayed edges on the surface and then lay the opposite side over. Sorry about the overexposed photos, but it was the only way to see the surface of the hood.

#2

did you bag this?

#3

vacuum infused with epoxy resin. It took about 15 minutes to infuse once I got everything set up.

#4

what kinda pump were you using? just out of curiosity?

#5

I used a 6cfm Ritchie Yellowjacket HVAC pump. Its like the Robinair 15600. I actually use a couple different pumps in series. This pump for the first hour or so to hold high vacuum then switch to a smaller, diaphram pump that runs for several hours. I do this because I don’t want to overwork the yellow jacket and the other pump has a vacuum switch wired into it.

#6

I’m confused, the hood is already made. What seem are you talking about?

#7

I am sorry. I will post a better pic. The 60inch fabric stops short of the hood at the rear so there is a seam that you cannot see in these pics that runs from side to side. Looks abrupt.

#8

From the pictures, the surface texture looks great ! And you’ve got about an inch and a half of material as extra over the front of the hood. How far off is the back from covering ?

I’ve just finished 3 molds for large hoods about the same dimensions. Can you tell me what your Epoxy useage ended up being ? And what your reinforcent lay-up consisted of too ?

                         thanks and good job ! 8)
#9

Thanks - Epoxy usage was about 160 oz’s. Does that sound about right? Lay-up was 0, 45, 90, 135, and 180 with the first being 5.6, then 3 10’s and back to a 5.6 3k twill. This was not entirely by design as my fabric on hand was running out. I was thinking about using Uni on the next hood because a guy that runs his own shop out in Livermore, CA (Aerospace Composites) showed me this piece that was only three layers with twill on the two outer and uni on the middle. That thing was extremely stiff. Also, it was a prepreg piece.

On my hood, the fabric is about 5 to 6 inches off from covering the rear edge. I hate to experiment to much with hoods because it is kind of costly to keep wasting a couple hundred dollars a shot. :wink:

#10

very nice :smiley: sweet//

did you use multie resin ports
How about positioning, and what flow media did you use? :smiley:

Iam still havin trouble getting my resin to flow///???I am pritty sure that the temp. is to low in resin and mold.

Just got the temp gauge gun so ill try another infusion.
VER that is aroung 300-400cps viscosity

Any body know what the highest temp that i could heat up the resin to get a better visc. or would that be only from the supplyer…/?
thanks

#11

do you happen to have pics of it all bagged down so I can see where you placed everything?

#12

I am actually building out another hood mold now and taking step-by-step pictures. I will document the process up through pulling the final part. In answer to your question, I did not take any pictures of the part bagged up. I had about 8 3/8inch input ports. I had know from previous experience the approximate radius and placed ports accordingly to get proper coverage. Where I kind of screwed up was that I staged the ports so that the resin was filling from the middle out and since I was the only one working it, I was mixing epoxy and watching the input tubes at the same time. I should have opened the outer ports earlier because one of the outer edges required me to go back and re-infuse to get full coverage. As far as the flow media, I used the red stuff that Evan supplies and it has always worked well for me. To increase flow, I just double it up to create flow channels along the edges. When the vacuum bag compresses against the flange, it essentially blocks the resin from flowing out further since there is nothing there except peel ply, no media and beyond edge of carbon trim.

#13

I have a roll of the red air-tech flow media is that the same thing? I have been using the normal clear bag and I have some strechlon that is Poly resistant. I am getting some VER for my infusion. I have not done anything yet as far as infusion thus far. Does anyone have the infusion video still?