Advice from some pro's please!

General Composites Discussions Composites Talk
#1

Hello - I need some advice. I know there are really sophisticated ways to build a camper unit - like making a plug, a mold, vacuum infusion, gel coat, etc. I am looking to build something simple, lightweight but strong enough to withstand the rigors of back road camping. Most good camper companies use a aluminum framework then either fiberglass or aluminum skin. One company makes a gel coat, carbon fiber monocoque (very sophisticated & luxurious) unit, but the price is sky high. I am wanting to build a simple unit out of poly core panels such as Nida-Core and bond the pieces together with carbon fiber in a monocoque unit. Is this feasible?

I would then just finish the interior in a very simple but functional way - and be a happy camper!

#2

You can assemble things from sheet. If you laminate only one side of the sheet, you can even bend it.

Using a “stitch and glue” technique (do a google search on that, it is boat related) you can assemble your camper unit, then laminate a continuous inside laminate.

I would not bother to use carbon. Glass is strong enough in your situation. Saves a few bucks.

#3

You can go simple or complicated or anywhere in between to do what you are talking about. Build a flat table for flat panel construction and assemble as Herman suggested or go all out and build a high quality mold with standard molding techniques. The middle of the road approach (and one I’ve used often) is to build a quicky mold out of melamine to the desired size and then laminate. With melamine you’ll be limited to flat panels but you’ll end up with a structurally sound part with a minimal amount of post molding work.

You can create a fairly nice shape even though the main part of the mold is flat panels. Large radii can be created with fillers (helps to get away from that “homemade” look). A lot of the “how to” depends on “how much” work you want to put into the project.

As Herman suggested, fiberglass is more than adequate for what you want to accomplish. If you have any questions about how to build a quicky mold, fire away.

#4

Thanks for input! Glad to know inside laminate with fiberglass is adequate. That “stitch & glue” concept is interesting.

As far as molds go, I am thinking of possibly building a plug or a prototype then casting a mold in order to duplicate it - but it seems like a major process. Plain honeycomb sandwiched with fiberglass seems much easier. At any rate, it’s all going through the planning stage & thought process! Again thanks much!

#5

I cannot say that I even have a clue what a ‘quickie’ mold is - I know that melamine is a product sold at Lowes or Home Depot - very heavy white panels - are those used as molds? Any ‘how to’ videos you can point me to?

#6

Yes, the melamine at Lowe’s and the Depot are what I was referring to. A quickie mold is just something that you knock together that allows you to build the shape you want without a major concern for the finish of the molded surface. You can do a little post molding finish work (paint or polish) to make the part look good.

You mentioned building something simple and light. Melamine fits the bill for a mold like this because it is relatively cheap and easy to work with. When you build out of a mold, you can create a monocoque structure in the same fashion as the commercial one you mentioned. Your part can be as simple or as fancy as you want. It all depends on how much time you want to put into the mold.

I’m going to assume you can put the basic structure together. I’d build a female mold with the melamine sheets and create radii where panels come together. Not only will a radius make layup easier, but the part will look much better when you are done. You can build a radius through many methods but the easiest is just using drywall mud and/or body filler and an appropriately sized and shaped squeegee.

This method is really for hand layup rather than vacuum processing. I understand many people are enamored with the latest and the greatest but I think sometimes we are using high tech solutions for low tech problems. For a camper shell that is going on the back of a truck, does it really matter if it weighs a few pounds more? You can get a very servicable product with basic techniques. If your goal is to learn the tech, you could do it with a project like this but failure hurts a lot more on big projects than it does on little ones.

I don’t know of any videos but here is a thread from another forum that I posted in. I go by OReely there. http://www.thehulltruth.com/boating-forum/330250-hardtop-material.html It should give you some idea of the method.

#7

I can visualize a mold made mainly out of melamine. I’ve done extensive carpentry work in past, and I totally see it. As for the composite side of it, my experience is limited to some fiberglass patching on my existing camp trailer - which actually came out quite well. besides that, all I know is what I’ve seen on YouTube. Lol - you said ‘fire away’ so here are a few - for starters:

  1. Once the mold is complete with radii, filler & whatever, what material goes first? Wax to aid removal? Then gel coat? Then carbon fiber or ??

  2. How many layers?

  3. Can I sandwich in some insulation foam or something lightweight but has structural integrity such as a honeycomb materiel?

  4. Can the resin be pre colored? (Drab green!)

  5. Can these melamine panels be reused?

Whew!

#8

Trying to estimate cost

Am learning / pricing colored gel coat;
Also estimating 10 sq yards per layer x 10 layers (?) = 100 yards of carbon fiber or mat fiberglass or ??

Amount of resin per yard?

#9

I’ve added some comments above.

#10

Awesome - thanks so much! I think the advantage of knowing zilch about composites is I have no preconceived ideas that need to be shot down. The downside is, I’ll need to ask some pretty stupid questions until I’m able to visualize the project in my mind.

I see that the gel coat is what is colored, not the resin (will have to give serious consideration to drab green)

Also, 1/2" PVC foam - is that the common stuff purchased at Lowes or HD?

Since this will be the only insulation, can I use 1" or two layers of 1/2"?

I’ll go with a white gel coat on the interior. (Sand, sand sand)

So I begin with:

  1. Gel coat (with or without wax?)
  2. 1.5 oz mat (chopped?)
  3. 1708 biax
  4. foam core
  5. another layer of 1708 biax and then 3/4 oz mat - or the 3/4 oz mat right over the foam core?

All the resin vinylester resin?

Any special trick for the edge or just rolled out & cut or grinded?

Again thanks ever so much!

#11

To make your initial mould (the quickie mould or splash mould) you dont need carbon fibre at all and you dont even need to put a woven cloth down. You can use a chopped mat glass and polyester resin. Keep it cheap and basic. You will need to do some finishing work to those moulds to get the actual finish you want and remove imperfections from your plug. Use about 6 layers of a 450gr (not sure what that works out in OZ’s) for that mould and allow 3 times the weight of the glass for resin. You dont need to spend a lot on materials for this mould as you should only ever need to make one part out of it for your master…

Once you have done your splash moulds (quickie mould) you will sand and polish it up to get a perfect surface or as good as you can small indentations are not a problem as when you make your master part from these initial mould you will turn those small indentations into bumps which can be then lightly sanded and polished. Now you can give this master another polish to get a super high gloss surface and now make your production moulds. Now you can use more expensive resins like a good Vinylester or optimould and use woven glass to get a good stong mould that will last many pulls. Take your time and as you progress ask more questions. First you need to create your shape and you can use almost anything to form the shape but you need to try and get a good surface to work from but underneath you can use wood, expanding foam and anything to make your pattern good and strong enough to hold the weight of your initial glass fibre mould.

#12

Not sure I understand - I thought a ‘quickie’ mold, made mostly out of melamine sheets was THE mold - I would start with gel coat directly on the melamine, then my 1.5 oz fiberglass mat, 1/2" or 1" foam core, 1708 glass, a 3/4 oz mat, and finish with a gel coat then disassemble the melamine pieces to break the piece from the mold. Are you suggesting that I make a mold from the first mold?

#13

Welcome to the world of composites, where one persons definition is not the same as anothers. What Morepower is talking about doing is building a composite mold off of a plug (aka pattern). First you would have to build a plug that is representative of the final shape you want your part to be. Second step would be to build the mold with fiberglass laminates. The final step would be to build the actual part out of the mold.

Nothing wrong with the method but certainly not a quickie as I define it. His concept is definitely better if you have a lot of shape and or detail that you want to incorporate or if you wanted to go into production and build multiple units, a composite mold would be the better route. However, for a simple product, especially a one-off project, what I’ve previously described to you is far and away the fastest way to go about doing it that I commonly use.

#14

OK… For a special part the process is usually make the part you want out of anything available… Wood, plastic, glass, melamine or car body filler… The basic shape done you need to get as good a finish as you can but chances are it will not be 100% perfect a surface finish but its shape is 100% done. You then make a “splash mould” just a simple mould off the part you want to make which will only ever make one or two parts… This mould will need to be polished and you can fine tune the surface finish to remove all of the possible high spots too… Low spots will still be there but dont worry… Now you have a base mould you can make an actual part from with all the flanges you will need… You can now make a test part to check it out. You will probably see some imperfections on the surface again which have gone from low spots to high spots again… You can now make a positive part from each section of the splash mould without assembling the mould so now you have masters of each section of the mould… Get these masters and again polish them up as much as you can. NOW you can use good materials to make your mould sections from these masters and when it is done you will have a part with a finish as good as anyones…

A few pictures of my project… You will see the white body kit with the car body filler then you will see a Grey body kit which was actually a master part to make the finish moulds from…






Then this was made from the splash moulds…Which were made from the seat/tank on the bike…

After this the production moulds were made…


Then these now produce my parts…

No one said it will be easy but take short cuts and it will show… do it right and you will have parts as good as anyones…

Sorry I didnt show you the initial splash moulds but I had some other company doing the work and ended up eventually getting involved and doing a lot of the work myself… I had never made a single part before doing this project…

#15

morepower,

Let me see if I am following you correctly. You build a plug, then a splash of the plug, then another plug out of the splash, then a production mold, and finally you can make a part? I’ve built hundreds of plugs and molds to class A and never gone through so many steps. What do you feel are the advantages to all this work verses the standard plug to production mold route taken by everyone else?

#16

If the guy has to make a pattern part which is made of materials like melamine and cannot make the surface perfect then making a splash mould and polishing it back will remove the low spots on the finished part… Then when he makes the master from the splash mould high spots can be polished out at that stage. Also if he damages the original part he has made he will always have a set of master moulds each of which can be replaced if he damages the production mould… Being a beginner there is a chance he may not wax up the mould correctly or damage it removing the part… having a back up master of each section of the mould will just be added security… I have a master of each of my moulds so if I damage or wear out the mould I can quickly lay up a new mould or make a second or third mould so I can produce more parts… Until he is comfortable making plugs which are perfect do you not think doing some extra work will possibly help if he damages anything right up to having a production mould??? he can always go back to the beginning…

#17

That is masterful work, morepower congratulations to you. In the future I dearly hope to do as well in my vein of interest (a camper!).

I see the points you make about making a plug to make a master mold off of. But
I agree with Roger that a quickie mold from melamine is the way for me to start. Very possibly I would get my first knockoff, load up the pile of cut up melamine and add to the local landfill at the county dump and off camping in my half xxxxed camper with my wife telling me ‘I told you so’. But if I decide to reuse the quickie mold again, very possibly I could get serious enough to want to do numerous copies, at which time I’ll know more about what I’m doing to make a plug out of one of my creations & make a master mold from it, and go into production.

#18

Jul 20 2013 notes

I see that I made a gross miscalculation in coverage area - it’s not 10 square yards per application, it’s 560 sq ft or 63 (rounded off) square yards coverage area, top, bottom & sides: PER layer.

So my material list looks closer to:

  1. Gel coat (no wax)
  2. 1.5 oz chopped mat
  3. 1708 biax
  4. foam core
  5. 2nd layer of 1708 biax
  6. 3/4 oz chopped mat (while the 1708 is still wet if possible)
  7. Gel coat finish
  8. Vinyl ester resin

Products:
Gel coat - coverage 1,120 sq ft: (1st application, spray or roll/brush? Second application ?)
1.5 oz mat 560 sq ft
1708 biax 1,120 sq st
Diviney foam core 560 sq ft
3/4" mat 560 sq ft (possibly one more coat?)
Vinyl ester resin; 560 sq ft x 4 (maybe 5?) layers or applications

I’ve seen both spray on & roll on gel coat. Which way should I go?

#19

I see where you are coming from and I can agree to a certain extent, however he’s talking about building a one-off not producing quantity. When I, and the other builders I know go through a tooling exercise, it generally follows the path of perfect the plug - build a production mold - pull a glass master from the production mold. You have an extra step involved but as I’ve said many times there is more than one way to skin a cat. If it works for you, follow that path.

#20

Camper,

I prefer spraying gelcoat rather than rolling or brushing but of course, I already have the equipment to do the job. ES makes a gelcoat gun that works really well for small jobs. Here’s a link: http://www.esmfg.com/g100_cup_gun.html

You can roll and brush the gelcoat if you don’t want to spend the coin on the gun.