Another Fridge Rebuild

[wholybee]

Originally Posted by RaymondR

Nope, styrofoam, commonly used in refrigerators. It will be epoxy sealed inside a sealed sub assembly so no problems.

If it truly is Styrofoam, you can't epoxy it. It'll melt. Polyurethane foam is cheap and readily available at Homedepot and Lowes. It's the stuff to use, not Styrofoam.

[Bowdrie]

1, Get 2-part foam.
2, Mix and pour in lid, (lid should be like a tray, with bottom and surrounding sides.
3, Board-sand expanded foam flush with top of lid frame.
4, Glass over with epoxy.
5, Add countertop part on top of frame.
6, Install.
Or the reverse, install countertop section on surround/frame, flip over and pour foam in from the bottom, glass bottom.

Now you're ready for more important things like varnish and beer.

[RaymondR]

Polyester resin melts polystyrene but I'm fairly sure epoxy does not however I'll try a test bit to make sure. I have also considered just vacuum sealing it in plastic since they are fairly small pieces.

Unfortunately we don't have Home Depot in Australia the big one being a company called Bunnings and I don't want to buy a large sheet for a small job. I already have plenty of polystyrene on hand left over from the decking over and sink proofing my dingy.

It'll work out fine, trust me.

[GILow]

I’m pretty sure epoxy won’t dissolve the foam too. Unless it’s some kind of super fast cure version maybe, they add some odd stuff to the hardener that might be a problem.

[akopac]

I use this and don’t cut the 2 seals apart. Corners can be crazy glued and I the adhesive goes crazy glue it too. Great stuff

[RaymondR]

All the woodwork on the lids is now completed and the white cardboard pieces are the templates to be used in hot wire cutting of the polystyrene insulation pieces. After sealing and installing these the upper and lower pieces will be epoxied together.

[RaymondR]

The images show the cutting board with aluminium angle pieces clamped on to ensure the cuts are vertical and act as the connection from the hot wire "garrote" to the 12 volt battery.

The second the pieces installed in the lid sections.

The next operation is to seal and glue the polystyrene pieces in place, then trim the excess, then seal the fresh cuts and glue the lids to the bottoms.

[RaymondR]

"Polyester resin melts polystyrene but I'm fairly sure epoxy does not however I'll try a test bit to make sure. I have also considered just vacuum sealing it in plastic since they are fairly small pieces."

The first test did not go well as I tried it using Norseal Epoxy Wood Sealer and it dissolved the styrofoam so I'll just have to bite the bullet and use the more expensive West System epoxy which is supposed to be formulated without the styrofoam eating solvents.

I am beginning to suspect that the 100% solids epoxies would generically be the non styrofoam eating ones.

[akopac]

Originally Posted by RaymondR

"Polyester resin melts polystyrene but I'm fairly sure epoxy does not however I'll try a test bit to make sure. I have also considered just vacuum sealing it in plastic since they are fairly small pieces."

The first test did not go well as I tried it using Norseal Epoxy Wood Sealer and it dissolved the styrofoam so I'll just have to bite the bullet and use the more expensive West System epoxy which is supposed to be formulated without the styrofoam eating solvents.

I am beginning to suspect that the 100% solids epoxies would generically be the non styrofoam eating ones.

You have to be careful when epoxying polyurethane foam as well. Thick fillets and filling gaps with epoxy can melt the insolation not chemically, but thru heat generated by the epoxy curing and the insulation containing that heat.

[GILow]

Originally Posted by RaymondR

"Polyester resin melts polystyrene but I'm fairly sure epoxy does not however I'll try a test bit to make sure. I have also considered just vacuum sealing it in plastic since they are fairly small pieces."

The first test did not go well as I tried it using Norseal Epoxy Wood Sealer and it dissolved the styrofoam so I'll just have to bite the bullet and use the more expensive West System epoxy which is supposed to be formulated without the styrofoam eating solvents.

I am beginning to suspect that the 100% solids epoxies would generically be the non styrofoam eating ones.

I’ve had no problems with epoxy and XPS foam. I buy my resins from Trojan Fibreglass. A small fraction of the cost of West Systrm.

[RaymondR]

Originally Posted by GILow

I’ve had no problems with epoxy and XPS foam. I buy my resins from Trojan Fibreglass. A small fraction of the cost of West Systrm.

Thanks GILow, I've pit their web site into my materials directory for future use.

I took the easy way out and wrapped the styrofoam in film wrap since it will be sealed inside the lids anyway.

[RaymondR]

All the woodwork done, insulation in and all glued together ready for prep and painting.

[rgleason]

Very nice Job, Raymond, in a tough spot to work. Thanks for your documentation anx photos.

[RaymondR]

Now that the lids are made the next task is to build the eutectic tanks.

The tanks are made from steam table trays with stainless steel sheet lids. There were two choices as to how to seal the lids: the first to use an adhesive for sealing and metal screws with nuts for mechanical fastening and the second, nitrile rubber gasket materials for sealing and the same screws for the mechanical aspect.

I decided on the nitrile rubber gaskets bonded to the stainless steel with super glue and the image shows two of the component parts fitted with the gaskets.

[RaymondR]

The first image illustrates the glands through which the copper tubes constituting the condenser coil will enter the wholly DIY manufactured eutectic tank. These are fabricated from large SS washers with a thick rubber gasket, The holes will be opened out to 3/8" and when the gasket is compressed the tubes will be insulated from the SS tank skin.

The second image illustrated an expansion of the eutectic volume of the Ozefridge eutectic tank by way of fastening a second steam table tray to one of it's SS sheet sides. The Ozefridge tank is the largest they manufacture. However my box was designed with side alcoves to allow larger volume tanks without excessively reducing the storage volume.

Whilst it is a manufacturer unauthorized modification and consequently has warranty implications I'm fairly confident, going on the apparent high quality of the Ozefridge equipment, that a warranty claim will not arise.

The tank fillers are also SS washers with a rubber gasket with a 1/4" gas thread turned in the center hole for a brass plug.