Custom Design Project - need advice

Hello

I would like to make my version of the Eames/Herman Millar surfboard coffee table:

http://www.dwr.com/product/eames-elliptical-table.do

But I want to try and put some 3K 2x2 twill on it and still have the plywood edges exposed.

  1. Does the Baltic birch plywood need to be polyurethaned etc first or just a scuff with 60 grit?

  2. Do I do the technique where I put down a layer of epoxy first, wait till tacky then lay the cloth? OR put cloth on dry, then wet it out?

  3. If I have to wet out the cloth - on my first coat, do I have to scape it thin with my spreader so it makes that zipper sound - like they do with surfboards? Then do my next coats?

  4. Any idea for the exposed edges since it will soak it up like a sponge?

  5. Should I lay the whole cloth onto the plywood, do 1 coat of epoxy - THEN use my template and route out the whole shape all at once OR route out the wood/elliptical shape first then lay the fabric, then epoxy?

If there is any potential problems you see - please let me know.

Thanks

How big is it? Can you lay up a carbon sheet on a piece of glass (BIG piece of glass granted) to the thickness you want and bond it to the plywood? Why do you want to use epoxy? Surely it would be easier to put a sheet of carbon on some pre shaped ply wood and trim the carbon with a router.

I would probably do it over some glass if I could… Put 2 layers of carbon down over a cleat polyester gel coat then use glass with black pigment in the resin for the remaining layers behind the carbon. It is just cosmetic and you have no need to make the carbon thick with just carbon as it would be expensive. You only need a perfect cosmetic surface and by using a black pigment in the resin you will not get any difference in colour on the cut edge.

If it is for you why make it hard on yourself?? Do it simply if you can and bond the carbon to the wood.

Its 70" L x 29" W…so 2 yards of cloth.

I don’t understand about the glass. And it would be expensive to buy a big piece of glass.

Would it not be cheaper and easier to put the cloth on the plywood? If you look at the table in the link - the plywood edges are exposed. Thats the look I want. Instead of black laminate on top, mine will have carbon fiber.

And #2 and #3 ??

You could just buy a sheet of carbon, cut it to size then bond it to the wood. This will be more expensive than doing it yourself and it might add more thickness than you want, but it will be quicker.

If you want to have a go at doing it yourself, I would cut the wood then lay the carbon down, if you route it after bonding the carbon, you risk delamination.

Cut your carbon with the same template, but make it slightly bigger, maybe 20-30mm bigger. You might want to base coat the plywood black (not the edges), otherwise you might see the colour of the wood show through the fibres. A better option is to give it a very light coat of epoxy that has been tinted black. The purpose it for it to bite into the wood, not to wet the carbon so wait for it to go tack free, then lay down your cloth very carefully so it doesnt distort, you could apply some spray adhesive or hairspray to the back of the cloth so it stays together better. Make sure there is no trapped air. At this point you could use a roller and lightly go over the cloth so it holds the epoxy under it and doesn’t move when you apply the clear. Now go over it with some clear epoxy. Light coats is better so you don’t build lumps. Try to wet out from the middle out. Using a squeegee like you suggested is fine, but it could distort if you are heavy handed. A roller or even a brush is fine too, whatever you’re comfortable with. When you get to the edge, try to wet out about 10mm from the edge, leaving 10mm dry, but make sure the edge is wet. The idea is to give the bit hanging out a bit of weight so no air can get in, but not too much weight, as this will create a pocket just behind the edge. Make sure its all wet and be careful not to distort the cloth. Keep an eye on it, and wait for it to gel. Now you can easily cut the excess cloth with sharp knife or even a pair of scissors. If you wait too long, it’ll be rock hard, and youll have to use a die grinder to cut it. You dont have to worry too much about distortion, as the resin has set and is holding it in place. Leave about 1-2mm. Once its cured, you can sand down the 1-2mm you left with some 120 then 240. Now you have 2 options. You can hit it with another layer of epoxy if you want more depth, or you can clear coat it to give it UV protection. Or you can get the best of both and give it a coat or 2 of Durepox. Its an epoxy urethane that has good adhesion to carbon, it builds, has UV resistance, and it will seal the plywood edges. Dont go mad as it has a yellow tinge, but even at 2mm, you cant notice it.

I think it will look quite cool!

Thanks CarbonCactus

Yes, carbon sheet would be easier/expensive but I wish to do the wet lay up to gain the experience.

As for the router - if I did a quick coat of epoxy onto the plywood, waited till tacky and then laid the cloth down (will this prevent distortion?)
From there - do a thin wetting from the top - THEN route out the shape (will this prevent delam on the edges?)
From there - finish with 1-2 more coats of epoxy.
Wouldn’t this stop any delamination issues or edge problems? Unless I do 2 coats then route it out? I will have to experiment.

Never thought about the wood showing through the cloth - I could easily paint the plywood black 1st - then do the next steps.

Here is a pic of 1 prototype I made out of Canadian dimes and chrome maple leafs. What you think?

Reason I wanted to do the lay-out onto the whole plywood BEFORE routing out the shape etc - was because the left over carbon fiber would be flat and I can make name plates, and coasters etc from the remnants. Why waste the good stuff eh? :~)

If you want to do it as in your plans:

Saw the plywood 3mm larger than needed.

Roll the top and bottom in black pigmented epoxy. Let cure.

Sand both sides smooth, and add another layer of black pigmented epoxy. Again, sand. The surface should be black by now. Apply carbon to the top. Indeed the zipping sound. After cure, you can roll on extra layers, sand to a smooth surface.

Now attach your template, and route to size. Then apply clear laquer.

The glass option is faster: laminate your carbon on the glass, then glue the (black pigmented) routed to size wood on.

Thanks Herman - makes sense now.

The glass part for the laminating, I’m not quite sure I understand. Get a tempered sheet of glass - then what - put down a coat of epoxy THEN lay the cloth THEN more epoxy? I assume I have to wax the glass first?

Get a sheet of glass the correct size or slightly larger. This is to make your carbon surface… You release the glass with either a good quality wax or semi permanent release agent. For your purposes I would use a polyester resin and gel coat the glass all over then allow it to cure to a very slight tack or allow it to go off over night. Then lay your carbon over the now almost cured gel coat. Put at least one possibly two layers of carbon down and wet out with a polyester resin. The next layers I would use a woven glass and build up layers to get the correct thickness you want. But this time I would wet out the glass fibre with resin but add a black pigment so that when you put it onto the ply wood and create the final shape the edges look black and not show the layers of glass and un-pigmented resin.

Personally I wouldnt use an epoxy as it needs to be lacquered and have UV protection to stop yellowing. A polyester resin can be perfectly clear and not need a lacquer to stop it yellowing.

Ok, thanks morepower.

Wouldn’t polyester resin shrink though? I was assuming that boat builders would be using that too for the non-yellowing properties? I will have to research the differences btw the two.

So I spray or brush on the gel-coat? So, if its brushed on then carbon laid over it - wouldn’t the ridges and imperfections from painting that on show in the outer/top carbon piece once I lift it out and turn it over to inspect?

Instead of adding the black pigment I could get away with just painting the plywood black with a roller and let it dry overnight. Then I don’t have to mess with pigments and finding them etc etc.

There shouldn’t be any problem with painting it do you think?

I would do as morepower suggests, with a slight variation. When it comes time to bond the wood to the laminate, you need either tremendous pressure or you could punch small holes in the plywood (maybe 1/16" on 1-2" centers). If you don’t, you might find yourself with voids due to air trapped between the laminate and the wood. Even vacuum bagging the wood to the lam won’t guarantee no voids if there is not a way for the air to escape.

Laminating the carbon on the glass mold first will give you a smooth, flat surface. If you go the polyester route, you’ll want to order “metalflake clear” gelcoat. Spraying it on would be best but you could probably brush it fairly well. I doubt small brush marks would show in the finished part.

If you laminate the table like a surfboard, you’ll have to keep the part clean and add several hot coats (aka flow coats) to fill the weave. And then you get to do a lot of sanding to get a nice surface.

I would do the whole thing wet in one shot. I would get some glossy .014" thick mylar (polyester film). Wax the Mylar with a release wax. You can also do all your painting, clear-coat, decorative work on the mylar. Roll it with tinted resin, lay on the carbon, roll with more tinted resin, lay your next layer of carbon on, roll with more resin. I would do a second mylar the mirrors the first for the other side of the plywood (prevents warping). Lay the ply wood on top of the first mylar, lay on the second mylar on top of the plywood and stick the whole thing in a vacuum bag. Apply no more than 15"Hg of vacuum until the resin sets. Let the thing fully cure for several days, and then peel the mylars off. All the painting and decorative work that you did on the mylar will get transferred to the layup. You can then route/trim the whole thing with a template, soften the edges, and be done in one shot. The paint/clear should come out as glossy as the mylar. No fussing. I would carefully just brush the edges of the ply with poly and a foam brush. They could probably just be wiped.

Here are two photos of a table that was effectively wrapped over a core…

This took months and months to get right… I didnt do this work but the guy who made my bike kit moulds did and to be honest for a flat surface over the plywood I would do it over a sheet of glass and as for shrinkage it does not matter as it will be made over size ready to be trimmed once bonded onto the plywood… I would peel ply the back and as been pointed out drill a number of very small holes for air to escape when bonding, a 1mm drill would be enough.

I’ve seen this table before… lol.

Yes I bet you have… haha… I saw it for about 6 or 7 months while it was being done from a core to a almost finished table… I learned a lot more new swear words too… Glad I was not working on it… haha

Ok thanks morepower and everyone for the help.

WOW, that is one sweet table. Definitely think-outside-the-box!:nuts:

To clarify: if I only put the carbon on the top of the plywood without air holes - the whole thing will warp/bubble/delam correct? SO THEN: I could also use a neutral colored laminate on the bottom to cover the holes too if I want to really get picky.

I’m just trying to understand why not to go my original way - laying it dry onto plywood then epoxy? Less than perfect surface=more sanding?

PLEASE CLARIFY:

  1. sheet of glass
  2. wax/release agent
  3. gelcoat
  4. carbon cloth/epoxy
  5. take finished carbon and bond to plywood.

Sounds about right… But for I would just use Polyester resin… epoxy gel coats will still need a UV stable clear coat on them and you may find a polyester gel coat is fine but an epoxy resin for your laminated carbon might de-laminate. I try and keep the resin the same all the way through. I wouldnt think putting your large carbon laminated sheet onto the ply would distort it but I would think about the best way to bond it to the plywood… You could coat the ply with a thin layer of gelcoat to seal and create a surface the adhesive can bond to… Paint it on thinly and lay a peel ply over the wet surface and allow to cure. Remove the peel ply material and now you have a textured surface to bond to. Now drill a number of 1mm holes over the surface(any resin pushed through would hardly be seen once you flat and finish off the wood work underneath… Plus it would be out of sight anyway. I would again use the same gel coat as the adhesive and paint both the peel ply textured surface of the plywood and the peel ply textured surface of the carbon laminated sheet… Put this down gently and work it down all over to push both exess resin out and try and work as much air out as possible. If the carbon laminated sheet is a few MM thick I would think it is going to be fine… You just need to take care and not rush…

I have to bond a fuel tank base into a composite monocoque and I use the same resin as the tank sealer to make my own adhesives… I add a few things to improve the properties of the adhesive but that is for a structural part…
But keeping the same resins through out will help you keep it all compatible…

If the laminate cures while it’s on the ply it will probably warp the ply unless the opposite side is also done. This is due to the shrinkage of the resin. Polyester will be more prone to warp the ply than an epoxy.

Now I see - this is why the original Eames/Herman Millar table puts the laminate on the bottom too - to prevent warpage.

Thx Wyo

Ok - makes sense now. I will probable put a neutral colored laminate on the bottom as the final finish once the top is done. This is to hide the holes and to counter the possible warping from the carbon sheet on top.

Thanks for all the help Morepower:)