XPS and Epoxy

[kstills]

Took a while, but I mocked up both weights of fiberglass onto the XPS.

Looks good, just practice on few more small samples and it becomes easier each time.

A couple of tips:

Ive found that prepping the foam to an 80 grit finish produces a better glass to foam bond. I use a cheap random orbital sander to do this.

Get a few plastic bondo spreaders https://tcpglobal.com/products/dynatron-3-pack-spreaders-358?_pos=2&_sid=a8250cbf2&_ss=r and squeegee the cloth down with them. it will produce a nice flat finished product. If you wipe them off with a paper towel when you are done they last forever. You can get these at any auto body supplier for a buck or so each.

a chip brush https://www.harborfreight.com/1-in-chip-brushes-36-pack-58084.html does a great job of wetting out your workpiece. Also used to work air out of the cloth and the resin into the cloth. Use an up and down motion like you are poking the workpiece with the bristles, if you use it like a paintbrush it will distort the cloth, which is to be avoided.

I have used 6oz per sq yard cloth almost exclusively on my build. Give a multi ply layup a test. 2-3 layers will surprise you with its strength.

Welcome to the club!

Thanks for the tips!

I'm hoping that when both sides are laminated the lamination will be strong enough to hold a bolt-nut combo, which would mean I won't have to use any wood for supporting hinges or slides. Have you tried using bolts, and if so what were your results? I figure I can either put moulding or caps over the exposed bolt heads, so I'm not too worried about the aesthetics.

[tony.latham]

I'm hoping that when both sides are laminated the lamination will be strong enough to hold a bolt-nut combo,

I think that would work fine if you used a good-sized washer on the side without the hinge or slide. But you might test it out. You could always bore out the foam with a spade bit at that location and fill the void with epoxy thickened as thick as peanut butter with wood flour.

Tony

[kstills]

I'm hoping that when both sides are laminated the lamination will be strong enough to hold a bolt-nut combo,

I think that would work fine if you used a good-sized washer on the side without the hinge or slide. But you might test it out. You could always bore out the foam with a spade bit at that location and fill the void with epoxy thickened as thick as peanut butter with wood flour.

Tony

Me likey....

[jakejakejake]

I'm hoping that when both sides are laminated the lamination will be strong enough to hold a bolt-nut combo, which would mean I won't have to use any wood for supporting hinges or slides. Have you tried using bolts, and if so what were your results? I figure I can either put moulding or caps over the exposed bolt heads, so I'm not too worried about the aesthetics.

Though bolting as you described would work for very light attachments. I would personally avoid it. If you go this route surface area is your friend! The biggest fender washers you can find or some custom cut 1/4 ply "washers" to spread the load over the biggest area you can.

Tony's method works great, the only change I would make is to use cotton flock instead of wood flour. Cotton flock is a milled cotton available from most composite suppliers. This is where I purchase my epoxy and fillers https://www.uscomposites.com/fillers.html

I've used wood hard points, most with t-nuts for a single sided attachment. I am using screws in a few locations too. This is really only a small amount of additional labor and very little added cost. It produces a really nice system for attachment. I cut the foam and the plywood with the same sized hole saw, and cut the foam to depth with a router. The hard points are bonded in with a loose microballon and epoxy filler to take up any gaps.




Here's some really good reading from the aircraft world
http://www.captoscana.com/captoscana/Do ... uction.pdf

Sorry if Im complicating things, ultimately do what makes you happy and enjoy the process!

[TCJ]

I'm hoping that when both sides are laminated the lamination will be strong enough to hold a bolt-nut combo, which would mean I won't have to use any wood for supporting hinges or slides. Have you tried using bolts, and if so what were your results? I figure I can either put moulding or caps over the exposed bolt heads, so I'm not too worried about the aesthetics.

Though bolting as you described would work for very light attachments. I would personally avoid it. If you go this route surface area is your friend! The biggest fender washers you can find or some custom cut 1/4 ply "washers" to spread the load over the biggest area you can.

Tony's method works great, the only change I would make is to use cotton flock instead of wood flour. Cotton flock is a milled cotton available from most composite suppliers. This is where I purchase my epoxy and fillers https://www.uscomposites.com/fillers.html

I've used wood hard points, most with t-nuts for a single sided attachment. I am using screws in a few locations too. This is really only a small amount of additional labor and very little added cost. It produces a really nice system for attachment. I cut the foam and the plywood with the same sized hole saw, and cut the foam to depth with a router. The hard points are bonded in with a loose microballon and epoxy filler to take up any gaps.




Here's some really good reading from the aircraft world
http://www.captoscana.com/captoscana/Do ... uction.pdf

Sorry if Im complicating things, ultimately do what makes you happy and enjoy the process!

Another option, also used on boats, is to drill the hole to fit the bolt, then remove a halo of foam around the hole by chucking an L-shaped allen wrench in a drill, inserting the end into the hole, and spinning the drill. Then you can fill the gap with thickened epoxy fed through a syringe. Redrill through the epoxy and your bolt won't compress the skins.

[twisted lines]

Someone plugged the threads with ?
Then Epoxied; To save the threads for later!

[jakejakejake]

Someone plugged the threads with ?
Then Epoxied; To save the threads for later!

When I first got started I only used patience to keep the threads epoxy free during the layup, now I've switched to using cheap candle wax. There are probably some other options too.

[mccutheon]

Someone plugged the threads with ?
Then Epoxied; To save the threads for later!

When I first got started I only used patience to keep the threads epoxy free during the layup, now I've switched to using cheap candle wax. There are probably some other options too.

You mean like you 'screw' a candle through the threads, and then remove later, or melted into it? What a great idea.

[jakejakejake]

melted into it

[GPW]

Melt some cheap candles in a pot , drop the screws /bolts /etc. in ... once heated , remove the candles and they will have a Thin coating of wax and are protected , and easier to insert and remove... We do this for many projects ...

[Squigie]

then remove a halo of foam around the hole by chucking an L-shaped allen wrench in a drill, inserting the end into the hole, and spinning the drill.

That is one of the scabbiest Bubba solutions I've heard of in a long time.
Holesaws and fly cutters are not expensive.

[TCJ]

then remove a halo of foam around the hole by chucking an L-shaped allen wrench in a drill, inserting the end into the hole, and spinning the drill.

That is one of the scabbiest Bubba solutions I've heard of in a long time.
Holesaws and fly cutters are not expensive.

LOL but it works, and you don't have to drill an over-sized hole. Sometimes an oversized hole will be visible, and this method conceals the solid fill around the hole.

[fonsan]

Took a while, but I mocked up both weights of fiberglass onto the XPS.

Looks good, just practice on few more small samples and it becomes easier each time.

A couple of tips:

Ive found that prepping the foam to an 80 grit finish produces a better glass to foam bond. I use a cheap random orbital sander to do this.

Get a few plastic bondo spreaders https://tcpglobal.com/products/dynatron-3-pack-spreaders-358?_pos=2&_sid=a8250cbf2&_ss=r and squeegee the cloth down with them. it will produce a nice flat finished product. If you wipe them off with a paper towel when you are done they last forever. You can get these at any auto body supplier for a buck or so each.

a chip brush https://www.harborfreight.com/1-in-chip-brushes-36-pack-58084.html does a great job of wetting out your workpiece. Also used to work air out of the cloth and the resin into the cloth. Use an up and down motion like you are poking the workpiece with the bristles, if you use it like a paintbrush it will distort the cloth, which is to be avoided.

I have used 6oz per sq yard cloth almost exclusively on my build. Give a multi ply layup a test. 2-3 layers will surprise you with its strength.

Welcome to the club!

I have been following yours on youtube and it is very inspiring.

For anyone reading this thread I would also recommend watching https://www.youtube.com/watch?v=p9GTYsNBiaE

My project is an insulated motorcycle trailer 3 * 2.4 * 1.8 yielding 34 sqm surface area.

I am super curious about doing an eco build consisting of only xps foam, fiberglass and epoxy (no wood) and have done some math on the cost per sqm. Epoxy turns out to be the main driver of cost which means that thin plain or twill weave cloth is very attractive due to the high strength yielded by ply weight. As it is more of an utility build I am not worried about scratches, bumps and dents and would rather repair them as they appear.

Would it be feasible with a single layer of 6oz for large flat surfaces? (or even lighter)

Having glassed could you describe your intuition on which weight of cloth is needed for the bare minimum for large surface areas in an ultra light build? My plan is to use large rounder corners and use more plies in the corners to build strength.

If you would redo your camper would you consider using less epoxy and fiberglass?

Can't wait to see your camper fully finished

[tony.latham]

If you would redo your camper would you consider using less epoxy and fiberglass?

I'm a woody guy. The lighter the glass, the better, 2 oz. if you can find the right width. Obviously, heavier cloth means more epoxy. But with wood, you glass to seal the wood. Strength isn't the goal. But I'm sure 2 oz. of fiberglass/epoxy is stronger than PMF over foam. You'll not find someone doing peel tests with glass/epoxy.





Tony

[fonsan]

If you would redo your camper would you consider using less epoxy and fiberglass?

I'm a woody guy. The lighter the glass, the better, 2 oz. if you can find the right width. Obviously, heavier cloth means more epoxy. But with wood, you glass to seal the wood. Strength isn't the goal. But I'm sure 2 oz. of fiberglass/epoxy is stronger than PMF over foam. You'll not find someone doing peel tests with glass/epoxy.





Tony

The thinnest wood i can get a hold of where I am (EU) is 3 mm ply wood for about 9 euro/usd. Presuming having to do both faces of a composite panel it would end up being 2oz cloth with epoxy, 3mm plywood, epoxy, xps foam, epoxy, 3mm plywood, 2oz cloth epoxy

This would more than double the cost and work per sqm and it seems to me that the more elegant solution is just to chose a heavier cloth instead of adding plywood to the mix. I am getting the feeling that 2-4oz cloth might be sufficient in terms of surface resistance as I don't really mind repairing any damage.

I am starting to realise that what I am asking about is the rigidity of the structure and not the surface resistance to damage as it seems that the rigidity will dictate the thickness of the fiberglass cloth