Build Layers you would use for this camper poptop?

General Composites Discussions Composites Talk
#1

I have the female mould. I have sprayed up gelcoat with success half a dozen times, have done about 40 hours of hand lay-up of 450gram CSM. Outside that no experience in anything other than reading alot of info but not able to put it all together confidently.

Here is the product - http://c2n.me/6KxnYs.jpg

I want to put roof bars 1cmx5cm square-tube aluminium in each end.

Hoping some experts in here would suggest the build layers
for A: Hand Layup B: Vacuum Bagging

i.e.
1.Wax
2.Gelcoat
3.?
4.?
.
.
.
…Roof bars
.
.
N.?

thanks in advance.

#2

bumping this up in case nobody saw it :frowning:

#3

This is too broad of a question with too few details for something that is actually a structural part. I think that might be one of the reasons you’re not getting any feedback.

If you’re trying to make this out of carbon for weight saving considerations, you should at least aim for a wet-lay up and then vacuum bagged approach. You’re most likely not going to get a good surface finish though.

If you’re trying to make this out of carbon for aesthetic purposes, I’d suggest making a layed up fiberglass + gelcoat unit, and then just wet laying a layer of carbon over it.

#4

Ok I keep seeing alot of talk about carbon in this forum is that the main focus on the forum?
No I want to lay this up as cheap as possible. I have great surface finish from the gelcoat of course.

Thanks for answering the post but yeh I just want to know what a typical layup would be. I should have specified polyester/glass system. Am not using carbon. I dont think they use carbon for these, always a polyester/glass system. Its the same deal with Ute canopies and I was hoping someone who has built them would see this post. Ute canopies is a massive industry to sell in to .
In case you dont know what I mean by ute canopy - TinyURL.com/pfy8st2
So, basically an auto panel but not one that is going to get beaten around. Its basically what I showing, like all these poptop campers ( http://tinyurl.com/lrhtsoq ), but mine has the 3 hinge points and 2 lever-arm connecting points and I dont even know how I should reinforce those points. http://c2n.me/6OAq4b.jpg
Also I must have 5 cycles in 8 hour shift capacity and both sides of the product need to be Class-A type quality surfaces and that is why I know I am looking at RTM.

The roof bars and PVC tube conduits - I AM NOT PUTTING PVC CONDUITS IN IT ANYMORE, ONLY THE ROOF BARS AT THE ENDS IS TOO COMPLCIATED FOR TOO LITTLE GAIN IN FUNCTIONALITY FOR THE PRODUCT i want to put in will add even more structural rigidity but I want to know first what build-layers would work alone without those additional elements. The original roofs had 1mm sheet-metal plate squares sandwiched inside the laminate in the locations of the connecting hinge/lever-arm points and then around this point shown below had a 9mm diamter steel tube circumventing this spot here sandwiched inside as well (I think that 9mm tubing was excess material from the annex ribs inside they decided just sandwich it in there because they had it, but I dont know what benefit really it gave).
Here is the 9mm tubes I talking about - http://c2n.me/6OAWI5.jpg
And this is where I found one sandwiched inside the roof (I cut up an original)
http://c2n.me/6OB94w.jpg The tubing I found was inside there running around the whole roof.
This version here was made by a different company and in their case they put the sheet metal squares on the outside - http://c2n.me/6OBB4P.jpg

#5

Based on a LRTM mould:

I would probably opt for 1 or 2 layers of Rovicore or similar (Saercore, Polymat, etc, perhaps Lancore, for weight sensitive objects), thickness depending on your findings.

For hinge points, probably would do something smart with Bighead fasteners (www.bighead.co.uk) These could be attached in the mould, in silicone bushes, then glass around it and infused. This way the fastener ends up Always in the same spot.

For 5 shots per 8 hour shift: Either heat your mould, or forget it, Especially with an A class finish. Also work closely with your resin supplier, to get a resin with long open time but rapid final cure.

#6

Hi Herman thanks, there are more insights.
About resin, here in Brasil is basically all Recihhold as far as I keep seeing. They have a big catalog of resins, can you suggest one name of resin that matches your above definition of ‘fast open-time and rapid final cure’? I have seen they have resins with the only difference being those objective times. Which one would you use? I will study its technical data and find a match over here.

  1. Do you think that this mould here which they say has a 30 minute curing time and they do 5-7 cycles per day is heated?
    https://www.youtube.com/watch?v=MWUxhC6-q0c
    Also note I am in Brasil, it is average 20 degrees hear. And i am planning putting this thing in a 22ft container so I can have the same temperature and humidity every time. (I still dont understand how humidity relates to curing time…)
    -Notice their final product on the A side is what I would call Class A finish:
    http://c2n.me/6PzHpp.jpg
    Their B Side is suitable for me too -
    http://c2n.me/6PzLMc.jpg
    I noticed they laid up what looks like a gelcoat at the beginning and the B-side must simply be pigmented resin which is infused into the whole matting? Well that surface quality for the inside of the poptop would be fine then.
    Yep I basically which I had a mould that pumps them out like them.

Also, I showed that video to an RTM expert when I started my project and he told me I would need a heavier counter-mould than they are using, that mine would weigh about 200kg…(after the steel supports). I dont know why he thought my shape wasn’t compatible. I guess it would still have been LRTM but with more rigidity. However i get confused about the naming of these technologies as really underlying it all is same theory and the shape and size of the shape you are wanting to produce, and your budget and sales forecast will justify which one you use. I see there is no strict “way” to do this. Its more about what works, what might work, and what in the end is working.

  1. I am unclear about imagining this point here about how to install/use tyhe bighead fasteners - if you wouldn’t mind explaining further -
    “These could be attached in the mould, in silicone bushes, then glass around it and infused. This way the fastener ends up Always in the same spot.”