Ok. I'll keep the ply. No big deal, I guess. Although top down drilling of feed holes for droppers will need an exceptionally sharp bit and a steady hand I reckon.

I was just going to use PVA to make the ply/foam sandwich. Aquadhere or something. Surely someone has tested that?

Another thing if I may, is paint. My research suggests that special paint is required. Latex or alkyd. Does anyone have comments on that? Sounds pretty messy. I was hoping that I could use a water based undercoat.

Regards
John
Appreciate your views.

PVA will work but takes a very long time (several days) to dry as there is nowhere for the moisture to go. Liquid nails is much faster but does cost more.

Any water based paint will do fine, just make sure there is a very good base coat to hide the foam or it will stand out like dogs ...ls in photos especially flash photos.

Tony

Tony

Drill the foam by hand, use your power drill to get through the timber if you're worried about the foam deck. The tearing of the foam at the beginning of a hole is not a big deal by the time you ballast etc anyway. You can probably neatly 'punch' a hole in your foam too, just use a suitable size nail and a hammer, test on a off cut and support the underside of the foam so it doesn't tear a chunk off.

Just push any sharp point through by hand, knitting needles, stiff wire, etc.

Tony

...You would be better off making a baseboard with a ply top but using it upside down to normal with the foam inserted into the space that is now the top. This would support the foam completely, and allow you to place things like point motors etc where ever you want without gluing pieces on that might later come adrift to support point motors etc. No glue is really 100% good for holding on especially when heavy things are used under a layout. The upturned layout board would probably be the best idea as it would only require a basic bit of either woodwork or metal work to make a basic frame.

Kind of defeats the main reason for using foam as you are now adding weight not taking it away.
From their website : ClimaFoam XPS Board is highly resistant to compression and withstands both occasional and long term static loads.

Just a basic frame would be fine, it is more stable than the ply and just needs a little support, most of my modules will have just the ends and sides with an occasional cross support if they are long.

Tony

Ok, just to clarify a couple of things from my angle with the XPS foam, because I get the feeling some of you guys are probably using it with a slightly different modelling approach than what I do.  For module bases, yup, certainly would be fine, and be well supported with a fairly basic underframe (in either light timber, or aluminum tube).  Track, or track bed, can be laid directly onto the XPS.  If using something like a Peco point motor, no problems, since could be connected directly to the underside of the track with a hole cut into the XPS to allow for it.  If using something like a tortoise motor, then the thin timber base under the foam (3 ply more than suitable) would be handy to mount the motor against.  In terms of weight and adding extra timber, such as the ply, to this module construction, isn't going to make a significant difference to portability.  If really concerned about that, then remove as much as the ply undersheet as able (ie swiss cheese holes everywhere, leaving mainly supportive sections for point motors or wire looms).   This is really only of concern if the layout is destined to be moved in and about at exhibitions.  If its going to live in your designated hobby room, stop wasting time researching all the super lightweight options that at the end of the day, will mean nothing to a layout that doesn't have to be moved!

My main use for the XPS sheets is for scenery applications.  These are pieces that are going to mount into or onto another form of module or base unit.  The beauty of the XPS foam is its ability to be easily and cleanly carved to shape, easy to mount things into it (such as trees, posts etc), and solid enough to be handled as drop in/out sections.  As an example, see the photo below.  That rock face from my Diggers Bend layout is a stack of XPS shapes hot glued together, and then carved to the rock form.  Easily painted with acrylics, and then also easy to stab my trees into the formation.  This section shown below was modelled on the workbench, as a stand alone section that could then be picked up and mounted into the rest of the layout.  The whole section would have weighed not much over 1kg.  

As I said, that weight is only really a factor when building a portable exhibition layout, but if this was for a home layout in a more permanent setting, the other big advantage of portable scenery blocks is that the often more messier task of doing scenery can be done away from the actual layout.  For how I intend to apply his principle to the home layout I will hopefully be making a start on in the near future, is to use the XPS as scenic sections I can move around between my various work spaces, before eventually mounting them into their final location.  For those of you that may have seen me at exhibitions in the past as part of the Art of the Diorama display, this sort of equates to in the future, what you will likely see me doing on my table is bringing along a XPS foam section of that layout that I am working on.  This might be a rolling hill with a tree line along a ridge, or might be street scene with a few structures on it destined for a township.  Essentially they will be a series of lightweight XPS diorama bases that all go together to complete a big puzzle.



Hopefully that gives a few ideas as to what the XPS is really handy for.

Cheers,
Dan Pickard

I am not looking for what any fool knows, I want to hear of real world experience.
Mark

No, you want someone to agree with your theory that the foam is stable enough to support itself.
That's not going to happen, it needs at least a frame underneath, but it would be better with a light ply top as well.

If it's a shelf layout with widths of 600mm or less, you don't need sheet ply reinforcing...but you might need some light timber stringers (25mm thick by 50mm or so...I used mostly scrap skirting boards left over from a renovation) running underneath. I use 50mm thick foam supported by these thin stringers mounted on shelf arms spaced every 600mm. After five years there's been no deformation....including areas where the foam was thinned down to 20mm for gullies.

No, you want someone to agree with your theory that the foam is stable enough to support itself.
That's not going to happen, it needs at least a frame underneath, but it would be better with a light ply top as well.

I started by mentioning a frame underneath and have never proposed that there be no support, happy to be proven wrong if you can find where I wrote such though.

Mark

While I have not used foam of any type on a layout except for scenery additions. I get both British and American model railway magazines and actually do read some of the articles even if it is not about my favourite topic. So I was just going on what other more experienced modelers have found out the hard way and put it into print. Like Miktrain has said he is going to try a simple frame around the modules to see if it will work.  Good luck to him if it does, others might like to put some supports in places to make sure the foam does not sag, personally I would go with the support method even if it does add a bit of weight to the module, better in this case to be safe than sorry later on. How often do you need to move a layout though if you are not exhibiting it frequently. Like Dan Pickard said if you are building a home layout then weight is not really a factor if it is just going to sit in one place for a number of years.

Any layout should be capable of being moved though just in case you move house but the layout can be a bit heavier in these sections than for an exhibition layout. A light frame in either timber or aluminium and some 3 ply to support the foam still is not very heavy in the long run though.

My home layout has 42X 19 pine timber frames with a chipboard top and built in sections about a metre long and even these are light weight. I can and have carried two sections at once one in each hand. The chipboard was used because I recycled an old bunk bed otherwise I would have used ply or even foam for the baseboard itself! Beggars cannot be chooses too much. Really for a permanent home layout weight is not that much of your problems in a baseboard unless you move house a lot!

...Like Miktrain has said he is going to try a simple frame around the modules to see if it will work. Good luck to him if it does, others might like to put some supports in places to make sure the foam does not sag, personally I would go with the support method even if it does add a bit of weight to the module, better in this case to be safe than sorry later on.

Mine are for display use and will be 40mm x 40mm steel angle on the ends (CNC drilled and pined for alignment) and 10mm x 80mm ply fascias, the overall width will be 600mm and the foam will be glued all round so I don't see any problems.

My design was set for 40mm but I thought i would have a look at the foam at Bunnings, they only had the 30mm in stock, it is flexible but not floppy. I put two layers together and it was quite stiff so the 50mm would be too. I feel the 30mm would still be fine for my use and at $12 it would be a small outlay for a test.

Tony

Bunnings Carseldine for you Brisbane folks has it. At the back of the timber aisle.

Plenty there!

Sounds interesting Miktrain lets us know how it comes out please when you do it! Just interested in hearing the results nothing more.

My first attempt at a portable layout – Granite Rock – used a very conventional pine frame topped with MDF sheet. The backboard was more pine, with a ply backing. It was strong but weighed a tonne. It did the job, but I always risked damaging the thing whenever I moved it because it was so absurdly heavy.

Since then, I've been interested in using extruded foam for lightness, and was especially interested in the uses the Americans make of it. I ended up building a small N gauge “play” layout for my kids about 1600mm by 1200mm that used nothing but foam other than for the track bed. I used the American technique of making a frame about 100mm deep by slicing up one sheet of foam into sufficient lengths to build a frame, and then topping that frame with a second sheet. The result? A baseboard for a layout which was strong, stable, rigid and very, very light. There was absolutely no need for any ply topping or any other form of frame – aluminium or timber or whatever. However, it could probably do with a sheet of thin styrene or aluminium around the edge of the board, simply to protect it from possible punctures.

Points were hand thrown, so I didn't need to worry about a secure base for things like point motors, but had I used them, I’d hardly have covered the whole frame with a sheet of ply just to do that – I would have used small squares just big enough for the job, glued to the underside of the foam.

Ten years later and I’m building a new layout, which at this stage is really a “proof of concept” for a few other techniques I want to try, so this one does have a sheet of extruded styrene on an aluminium frame (Capral’s wonderful Qubelok system). My motivation is twofold: to see if I can avoid timber as far as possible, and to make something as light as possible but is a little more robust than my first styrene baseboard. And the reason for that is that my eventual layout I want to build will be ceiling suspended, to make the most use of my single garage. Hence, something light is important.

Interestingly, I bought the styrene for my original layout from the same place as the one I've just started, but they are not the same product. Ten years ago the stuff I bought was Dow’s “blue foam” whereas the material I’m using now is called Foamular and is pale yellow. I could be wrong but my recollection of the blue foam was thinking it actually did not need a lot of bracing, but that’s certainly not true of Foamular which feels a bit denser than the blue foam, but is also more flexible. So the Foamular definitely does need some bracing, which is what I have done with the aluminium.

How the material at Bunnings compares I don’t know, since the last time I was at the Oxley store it hadn't yet arrived.

I think for many people using foam has a number of advantages: it’s light, it’s strong enough for the purpose, it’s easily worked, it doesn't need power tools to cut, and in a climate like Brisbane’s there is no need to worry about warping over time. Cost wise I’m not sure about the comparison, but I suspect the baseboard I’m building now will not have cost anymore using foam and aluminium than buying good quality timber.

I very much doubt I will use timber in any future baseboards except for very small applications like point motor mounting plates, and even then that could just as easily be aluminium.

Alan

I started by mentioning a frame underneath and have never proposed that there be no support, happy to be proven wrong if you can find where I wrote such though.

Mark

If 50mm foam sagged on an average display layout size module I'd be very surprised. So surprised in fact, I'd probably eat the module. If you are using foam to minimise the module weight, which is surely a logical conclusion, then being sensible about the weight you apply above it will see it sit true.

We use 30mm blue foam as a sacrificial layer on one of our CNC routers, the frame under that, whilst never measured by me, must be 30mm wide 50mm high steel section placed on 500mm centres. That foam is subjected to more force than a layout top surface and does not sag. It gets the crap chewed out of it, but stands up the abusive force with no problem.

I have used EPS for a layout (at least of the type sold in the US) and have seen a bunch of layouts built with it (as can you on any number of US based blogs, online videos, in Railroader etc)

My home layout is an L girder and I use 50mm equivalent foam (2").  When I was first playing around I observed that a brass loco could visible deform (in that it drooped) a 50mm sheet that was only (that is, the ends were not affixed to anything) supported by width-wise cross pieces 1200mm apart.

Accordingly I placed my cross pieces somewhere between the 600mm (2') and 760mm (30") mark and they're all that support the foam.  Which as Aaron says above should mean that the standard exhibition layout shouldn't need any additional cross bracing apart from the exterior frame that supports the foam on all four sides.

I may be misunderstanding some of the posts above but it's somewhat pointless to top the foam in ply or any other wood.  Just use a thicker roadbed if that's what you're looking for as you've just lost the ability to dig into the foam for scenery work.  Note that it is very common to see a plywood subroadbed (especially when spline construction is used) under just the tracks with foam scenery on both sides in the US.  Full foam subroadbeds (especially for upper decks) are also very common.

However, as I noted before, I would recommend a thin skin (2-3mm or thicker) UNDER the foam to let you screw things into the bottom layout for a home layout (probably not worth the weight for a display layout).  Otherwise you're going to be either gluing everything or gluing small sections of ply to screw into.

To prove my above point, said CNC router was in action today when I popped my head through the door. 4'x8'x7/8" sheet of MDF being routed, I asked it they were concerned about the XPS deforming, and got laughed at.

As an aside, later this week we're going to start making a pinball machine, pretty much the entire cabinet will come from a 5/16" sheet of MDF, cabinet sides, ends, floor and dummy ball deck all fit in one sheet. I thought this might have been what was being cut today, instead I find them running some clearly inferior project.

...................Interestingly, I bought the styrene for my original layout from the same place as the one I've just started, but they are not the same product. Ten years ago the stuff I bought was Dow’s “blue foam” whereas the material I’m using now is called Foamular and is pale yellow. I could be wrong but my recollection of the blue foam was thinking it actually did not need a lot of bracing, but that’s certainly not true of Foamular which feels a bit denser than the blue foam, but is also more flexible. So the Foamular definitely does need some bracing, which is what I have done with the aluminium.

How the material at Bunnings compares I don’t know, since the last time I was at the Oxley store it hadn't yet arrived.

......................................Alan

Alan,

Dow's "blue foam" is marketed a polystyrene, the pale yellow "Foamular" is from Corning, essentially the only difference between the Corning, Dow and Knauff products is the dye used to colour it and the size of sheets produced. I would note that Dow and Corning used to be one company Dow-Corning before splitting and I dare say the XPS foam was part of the split.  If you want large sheets (more cheaply) go for Dow or Corning products, I think you will find the per square metre it is far cheaper that the small Knauff sheets being sold at Bunnings.

Cheers,
Hendo

... I also had to remove a switch from the layout recently that was installed around 7 years ago and looked very closely at the feeder droppers - I couldn't observe any deterioration in the jackets.
...

I've had cable lying on a sheet of the bead Styrofoam that had embedded itself into it. However, droppers are normally a single cable from a bus wire to the rail and you wouldn't expect to get a short even if the wire was not insulated.

I've had cable lying on a sheet of the bead Styrofoam that had embedded itself into it. However, droppers are normally a single cable from a bus wire to the rail and you wouldn't expect to get a short even if the wire was not insulated.

Physically, bead (expanded) styrofoam is a different beast altogether. Do both expanded and extruded styrofoam exhibit the same issues with electrical cables?

Physically, bead (expanded) styrofoam is a different beast altogether. Do both expanded and extruded styrofoam exhibit the same issues with electrical cables?

Not "altogether".
Whilst physically different (EPS and XPS) it's the same animal chemically (i.e. polystyrene - PS), ignoring any additives. The wire insulation problem relates to use of PVC which 'reacts' with PS.

FYI http://www.generalcable.co.nz/getattachment/0ebda90b-b4f8-43ae-b622-c9280295116b/PVC-Cables-in-Contact-with-Polystyrene-or-Bitumen.aspx

Not "altogether".
Whilst physically different (EPS and XPS) it's the same animal chemically (i.e. polystyrene - PS), ignoring any additives. The wire insulation problem relates to use of PVC which 'reacts' with PS.

Thanks. I have thus far always laid my track on a ply or MDF roadbed, and only used polystyrene to fill the gaps around the roadbed. THis is something to consider should I choose to use XPS as a layout base, rather than just as a scenic base.

Instead of Bunnings, try you local insulation shop. Here in Warragul, I managed to get 18 sheets of 2.2M x 1.2M x 35mm for $1/M2 less than Bunnings, which is better as the sheets of foam are much bigger

I've been looking for some XPS foam board at Bunnings and have been informed that it's a deleted line. Hence why I had trouble finding it there & at Masters.
I've found a small supply of 1.2m x .6m x (30mm or 50mm) at a local Bunnings and was almost tempted to buy the lot and ebay the surplus, till I saw what people are selling smaller pieces for.

I've been looking for some XPS foam board at Bunnings and have been informed that it's a deleted line. Hence why I had trouble finding it there & at Masters.
I've found a small supply of 1.2m x .6m x (30mm or 50mm) at a local Bunnings and was almost tempted to buy the lot and ebay the surplus, till I saw what people are selling smaller pieces for.

Would also like to get something similar 0 anyone in Sydney know of somewhere in the North/Northwest?

have tried all the Bunnings stores...

Would also like to get something similar 0 anyone in Sydney know of somewhere in the North/Northwest?

have tried all the Bunnings stores...

PM sent

I have been building exhibition modules using 35mm white foam for yrs.

Modules are 1500mm X 500mm.Front & ends are 100mm high X 6mm MDF.  Back board is 400 high X 6mm MDF one piece.

This is constructed into a box & 35mm foam inserted level with top of 100mm front & ends.

3 Light timber stringers are fitted under foam. Foam is glued in with liquid nails.

Track is laid on top of 3mm MDF which is glued to top of foam again with liquid nails.

3mm MDF only laid under track. Does not completely cover top of module.

Modules are strong and light weight.

My modules can be easily lifted and carried by one person. I have actually carried two modules at same time. One under each arm.

BTW, modules are not connected by any nuts,bolts, clamps or hinges but are solidly locked together.

I will have a small layout at this coming weekend Noarlunga club exhibition.

Seaview high school.

Come over to NEVERWOS and say hello and I will explain module construction in more detail.

Cheers

Ian