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Discussion Starter · #1 ·
Hi

Before I make a final decision, if I use 50mm XPS foam as my base board, what is the best way to attach all the wiring underneath?

I've seen people have a 3mm ply and glue the foam to that and others that have just glued to the foam to the supports.

If I go without the 3mm ply, I thought about using cable nail clips and push them straight into the foam, not sure how long that would last, maybe drop some glue on the nail before pushing them in.

Any thoughts.

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Discussion Starter · #7 ·
Hi
Thanks for the replies, I have also looked into the problem of electrical cables interacting with XPS foam, which leads me to use a combination of the two, the baseboard support is going to look like this. So even if I used a combination of 3mply and XPS foam with the supports every 450mm it should be pretty sturdy

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Discussion Starter · #9 ·
Many years ago I was taught that you have two eyes two ears and one mouth, why to look listen and shut up until you know what your talking about.

I'm in the look and listen part of this project. I believe that everyone has something to contribute whether that advise is taken or not depends on a whole lot of factors and I would hope that disrespect was not one of them.

To put some context to my question, my existing layout baseboard started off a scalextric track made from 12mm chipboard over 15yrs ago and not only could I stand on it (85kg) it has not warped. However, it's construction makes it heavy and not very moveable. Converting it over to model rail gave me some experience in wiring up DCC, hornby/peco point motors, a control panel and soldering upside down but it didn't allow for landscaping. Especially since I want to model an iron layout.

The main reason I am considering using XPS foam is from a landscaping point of view, especially for cutting batters. First up I found out some the properties of XPS foam these include:
  • The closed-cell structure and lack of voids in XPS helps the foam to resist moisture penetration.
  • Uniform density distribution, and dimensional stability
  • The closed-cell structure of XPS imparts excellent long-term compressive strength and durability.
  • Because XPS foam is essentially a plastic material, it will not corrode or rot or support the growth of mold or mildew
  • Inert; resistant to low levels of acid, alkaline, and many chemical compositions. However, petroleum-based solvents will attack the foam.
  • Ecologically friendly (no CFCs or HCFCs are used in manufacture).
  • Also is pretty easy to shape especially with a blow torch to create some irregular landscape features
I have spoken to others who have used this material with success.

So compared to plywood, depending on the plywood I would have to seal both products, considering the amount of water based products that are used for landscaping and ballasting.

My new layout will have a number of inclines and I found that 12mm ply just didn't have the flex that I wanted to create transitions from one grade to the next. So I'm considering using 6mm for the inclines. I have worked out a way to cut the batters in the foam that would allow me to place the 6mm ply to create the grades I need, I just have to provide additional support underneath the ply as well, that's when it's cut. In fill I'm not so sure since the track is going on the side of a hill and on a curve.

I can do the same thing in ply going the cookie cut method, it's just getting the interface between the ply (underside of ballast) and the embankment (foam) that I haven't been able to work out.

After a bit of research on migration of plasticisers from PVC Cables into XPS polystyrene there seems to be a solution:
  • you can either use a cable with a migration resistant plasticiser
  • or prevent the cable from contacting the XPS polystyrene
Plasticiser migration from PVC cable in contact with EPS can also be effectively minimised. If the cable temperature can be kept relatively low (50–60°C for a 50% usage situation), the rate of migration will be slow and will not cause a problem over 50 years. Not sure how hot the cable gets for model rail layout and how often would you be running locos 24/7, also in 50 years I won't be around so is it a problem?

I have taken on board everything you have said. I have followed your link and I now have an alternative to putting droppers through the baseboard, rather than the globules of solder I had my old layout.

With the dropper wires only being 22 gauge wire (1.6mm dia) I could always over size the hole the droppers go through and insulate that so the droppers do not touch the XPS foam.

From a glue point of view there are plenty of options that are not harmful to XPS foam

If I glue the 3mm ply to the XPS foam that should provide better rigidity than either product separately, might even change it to 6mm ply depending on the price.

No cables under scenery - check

I would hope that you will still provide advice and if I do not take it and it all goes pear shaped feel free to say "I told you so" and there will be no hard feelings on my part, apart from me not listening.
 
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