Egg Tray Sandwich

Discussion of model railway baseboard design and construction
kebang
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Egg Tray Sandwich

Postby kebang » Sat Dec 15, 2018 4:46 am

Going to build a very small (100cm x 120cm) portable layout. Trying to design the baseboard to be as light and stiff as possible. Has anyone tried to sandwich egg trays between 2 sheets 5mm ply? the egg box dimensions are 292 x 292 x 45mm, so the completed board would be around 2inches thick
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dan8400
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Re: Egg Tray Sandwich

Postby dan8400 » Sat Dec 15, 2018 7:44 am

I haven't tried egg boxes myself, but I have used 40mm insulation (celotex, kingspan etc) with ply both sides. Very light and strong

Thanks
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kebang
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Re: Egg Tray Sandwich

Postby kebang » Sat Dec 15, 2018 9:00 am

Unfortunately they do not sell celotex, kingspan etc here in the Philippines, but I can get egg trays!
I keep looking in the hardware stores but I can't find anything light and stiff that might do the job.

dan8400
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Re: Egg Tray Sandwich

Postby dan8400 » Sat Dec 15, 2018 10:24 am

If they are all the same size then I don't see why it wouldn't work.

Give it a try

Thanks
Dan
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Bufferstop
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Re: Egg Tray Sandwich

Postby Bufferstop » Sat Dec 15, 2018 7:02 pm

I'd give it a try, if t he spacing is uniform, two layers with the trays in the second layer offset by half their width in two directions then trimmed around the edges, would take more trays but be stronger. Glueing on the ply would be stronger if you can put the whole thing between boards and weight it down until the glue has set. What you are building is remarkably similar to a flush faced door, which uses a honeycombs of stiff card between the two surfaces.
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Buelligan
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Re: Egg Tray Sandwich

Postby Buelligan » Tue Jan 22, 2019 7:14 pm

Don't know if you've already done it, but I'd have thought it's work. I know we supply marine companies with cardboard honeycomb, and then a very lightweight but strong paste that they spray in to the honeycomb, this layer sits between the fibreglass layers and is what gives the boat it's strength.

kebang
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Re: Egg Tray Sandwich

Postby kebang » Wed Jan 23, 2019 7:40 am

Not done it yet I'm afraid! 1st. problem was sourcing clean new egg trays. 2nd Problem was that, once I examined egg trays closely, I realised the 'pyramids' that make up the egg trays provided small surface area to glue to the ply. I'm going to try sandwiching a 0.75in piece of styrofoam between 2 thin sheets of ply.
It is only ordinary styrofoam, I can't get the recommended construction grade isulation foam here in the Philippines.

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RAF96
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Re: Egg Tray Sandwich

Postby RAF96 » Sat Feb 09, 2019 9:06 am

Folk have used old interior doors before, the flat panel type which have a cardboard interior ‘structure’, similar to the way Metcalfe card kit platforms are made.
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TimberSurf
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Re: Egg Tray Sandwich

Postby TimberSurf » Sat Feb 09, 2019 10:05 am

A sandwich of wood frame/polystyrene/aluminium has been the basis of Caravan wall construction since day dot! Essentially the same, modern methods use a continuous laminate system. 25mm extruded polystyrene [XPS] with 3mm ply both sides would make an indestructible sheet (they even sell a one sided version in building merchants in the UK). Making the filling thicker will make it stronger, extruded polystyrene [XPS] has much more compresive strength than expanded polystyrene [EPS], so would bend more and going to 50mm may not improve it! The key to composite laminates is the number of layers. I suggest you look at a five layer construction of 3mm ply and two layer of 25mm (or 20mm) EPS, edged with a wooden baton (exactly the same height as the EPS sheet). Use a glue spread over the entire surface. :D
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kebang
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Re: Egg Tray Sandwich

Postby kebang » Sat Feb 09, 2019 10:26 am

I am definitely going to try sandwiching the polystyrene between 2 thin ply sheets. Can't do it yet as my pick up is in the shop for a complete respray. This is scheduled to take a couple of months so I can't fetch my ply until I've got my vehicle back.
This small board (120x100cm) is earmarked for an 009 layout. I would have preferred to try an O 16.5 but I don't think I can squeeze an O gauge layout into such a small space.

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Mountain
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Re: Egg Tray Sandwich

Postby Mountain » Sat Feb 09, 2019 5:26 pm

Take a look at PinkNosedPenguins new layout idea. It is about 60cm x 90cm. My layout is about 60cm x 205cm. You do have to keep to shorter locos and stock to turn in just 60cm, but there is still quite a choice of model kits to buy and build.
009 will easily fit in the size you have available. I used to have H0e and 60cm could run quite large locos and bogie coaches. Both scales and gauges are nice. I prefer 0-16.5 myself as it is easier to handle (Place on the track etc) and chunkier. When I tried H0e the locos were excellent but had such fine detail that they do need careful handling. Either way I hope you can get a nice layout going. You can freely mix H0e and 009 as the slight difference in scale is hardly noticeable. They use the same 9mm track. I have just seen your trackplan. It looks very good.

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Bufferstop
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Re: Egg Tray Sandwich

Postby Bufferstop » Sat Feb 09, 2019 10:47 pm

Do they import single replacement car body panels into the Philippines? I built a 100 * 30 cm working diorama on the packaging for a Citroen wing pressing that my son received when they had to get one sent from France. It's about 10cm thick and absolutely rigid. Worth a look round the back of the body shop. You get similar high density packing around large flat screen TVs, pays to keep your eyes open when the rubbish goes out.
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kebang
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Re: Egg Tray Sandwich

Postby kebang » Fri Feb 15, 2019 2:22 am

Thanks for the idea Bufferstop.

My Isuzu pick up is currently being stripped back to bare metal & then resprayed so I've asked the owner of the shop about your idea. His response was 'It is extremely rare for body panels to be imported to Bohol Island, but more likely in Manila. In Bohol we will remake a panel a lot more cheaply than an import.'

Labour here is very cheap and in metal working the skill level is high.


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