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PennsyMan

Posted - 2010 December 04 :  12:00:10 AM  Show Profile
Hey Guys and Gals:

My plywood base is in place, and I was reading about using extruded foam insulation over the plywood. The layout is relatively small (3' x 4') compared to many I've seen while looking at other layouts. If you would all be so kind, I have a couple of questions for those who have used this foam.

1. Nailing track down onto plywood is a pain, given problems manipulating the nails and a tack hammer. With track nails being only approximately a half an inch, will the nails stay in place, going down into the track, cork roadbed, and then the foam?

2. Once the track work is done, can the foam itself be painted, and can plaster or other media be laid onto the foam? My plans are to do a small city layout, and I want to lay down city streets and sidewalks, either using plaster or some type of foam. I'm trying to avoid any unpleasant - and costly - surprises as I go along.

Thanks!
Brian

Country: | Posts: 21

dgwinup

Posted - 2010 December 04 :  03:41:29 AM  Show Profile
I'll take a shot at this, Brian.

Track nails need to go into something that can hold them in place, like wood. Foam will not hold the nails properly. The nails will hold the track onto cork roadbed, but then the whole track/roadbed assembly will come loose from the foam. It won't stay in place very long.

Solution? Don't use track nails. Instead, use an inexpensive acrylic adhesive caulk, the cheaper varieties usually work better. You can find them in any hardware department or store. You can use the caulk for both track AND roadbed. A very thin layer will work; thicker won't hold any better and may cause undesirable humps in the roadbed. Apply a thin bead of caulk and spread it with a putty knife. Lay the roadbed and place weights on it until the caulk holds firmly. Repeat the process for the track. You can use track nails to position the track and the nails can be removed after the caulk cures.

Foam can be painted using latex-based paints. Non-latex paints may cause the foam to melt or distort. Plaster will stick to the foam without any special preparation of the foam, although it can crack and lift off if subject to stress as you might encounter when moving a layout around. Additionally, foam can be carved, cut, shaped and otherwise manipulated to create varying ground contours for more realistic scenery.

Some modelers use plaster-soaked paper (paper towels, brown grocery bags, etc.) to cover the foam. The dried plaster/paper won't crack as easily as plain plaster.

Hope this info helps.

Darrell, quiet...for now



Country: USA | Posts: 239 Go to Top of Page

basementdweller

Posted - 2010 December 04 :  06:42:11 AM  Show Profile
I agree with dgwinup on how to go about using caulk to secure the cork and track to the foam.
Avoid using any solvent based products on the foam.

The benefit to using foam, as opposed to laying track directly onto plywood, is that the foam can be easily carved to create ditches, creeks, or just uneven ground.
There is no need to cover the foam with plaster cloth to create terrain as this can be directly carved into the foam. All of your scenery products will secure to the foam just fine, paint the foam first so no pink shows through.

As for using plaster to build streets and sidewalks you will have no problem with the plaster attaching to the foam.

I would only buy the foam if you planned to carve into it for your scenery. Otherwise for a flat city terrain using plywood may be easier for you.


It's all scenery.

Country: USA | Posts: 2672 Go to Top of Page

flagler

Posted - 2010 December 04 :  08:11:25 AM  Show Profile
Use the foam and KATO-UNITRACK, you can move the track all around your layout and run your trains while planning

PACIFIC INTERCHANGE RR

Country: USA | Posts: 1273 Go to Top of Page

ELNScale

Posted - 2010 December 04 :  09:29:08 AM  Show Profile  Visit ELNScale's Homepage
Pennsyman,

Glue, glue and more glue .

I used contact cement for the foam onto plywood (see here).

I used white glue (or matte medium) to glue the cork roadbed to the foam (see here, towards the bottom of the page).

I used white glue (or matte medium) to glue the track to the cork roadbed.

Then, when I ballasted the track, I used white glue again (in this case I only used matte medium) as shown here.

BTW, one of the photos in the 2nd link shows a side view of an Elmers School Glue container. Although this looks like white glue, my experience with this is DO NOT USE IT. Use the proper stuff, which is called Elmers Glue All. I had to start again (fortunately early in the process).

Certainly there are many ways to do this and it's not to say that glue is or isn't the best way. For me, it has worked great and I have no regrets.

YMMV.


Steve
Michigan

www.scrantonstation.com

Country: USA | Posts: 558 Go to Top of Page

ntrak_newbie

Posted - 2010 December 04 :  6:03:57 PM  Show Profile
I came across a demonstration where the demonstrator was using Red Devil spackle instead of plaster. He claimed it lightened everything up, making it easier to move stuff without damage.

Any comments?


ntrak_newbie

Country: | Posts: 37 Go to Top of Page

peteski

Posted - 2010 December 04 :  7:51:03 PM  Show Profile
Here are my 5 cents.
Do not use foam for subroadbed. Use standard technique of plywood with cork roadbed. The track can be glued or nailed to that (either way works). Use foam only for shaping the areas around the track (hills, etc). Basically use foam in places you would normally use older scenery techniques. Places where you would have used chicken wire or cardboard web and plaster soaked towels or other hardshell scenery can be modeled using foam. I also recommend a hot-wire cutting tool if you are planning on using foam. That allows for quick cutting and shaping of the foam with no messy foam shavings sticking everywhere!

Plaster does not adhere well to foam and will eventually crack. Part of the proble might be different expansion rate and shrinkage of plaster as it dries. Using something like Durham's Wood Putty or Sculptamold works better. Those seem to adhere better and they don't crack as much. You can still have some small cracks but those don't affect the stability of the putty or Sculptamold.

Latex paint seems to adhere pretty well to foam. Once painted earth color you can sprinkle ground foam directly onto the wet paint or after it dries (using white glue over paint for adhesive).

You are probably better off building your town on plywood then use foam only in places where there are elevation changes (like hills).

Liquid Nails construction adhesive works well on foam. But IIRC there are few types of that adhesive. Make sure to get the one which is compatible with foam (won't melt it). I don't recall the specific type now. Ask the hardware store clerk.

Ntrak_newbie,
Spackle is much softer and more fragile than plaster. Ntrak modules take a lot of beating while being dragged between shows. Here I would again use something like wood putty or just paint on top of foam scenery. Using foam for scenery on a module already makes it lighter than the old scenery techniques. There is also vinyl-based spackle. That might actually work if the vinyl additive makes it more flexible. I haven't tried that.


Peteski

Country: USA | Posts: 3324 Go to Top of Page

PennsyMan

Posted - 2010 December 05 :  01:06:30 AM  Show Profile
Awesome! Thanks everyone, for your input.

I don't believe I'll be going the way of using foam. Being I'm going strictly urban (although at an earlier age), the foam isn't needed. I thought it might save me with nailing due to having less dexterity in my hands, but the tips on using adhesive acrylic caulk for the track on roadbed (thanks dgwinup) and white glue for the roadbed to the plywood should be just what I need. Thanks too, ELNScale for the tip on not using Elmer's School Glue. Maybe carpenter's glue would work best.

Seems it may be best to caulk the track piece-by-piece to roadbed, then glue to the plywood once I'm sure it's where I want it.

BTW: Nailing is an exercise in futility. Tried it with a few pieces of track, had cramped hands and bent just about every nail.

Thanks again all!


Brian

Country: | Posts: 21 Go to Top of Page

peteski

Posted - 2010 December 05 :  01:53:30 AM  Show Profile
quote:
Originally posted by PennsyMan

Awesome! Thanks everyone, for your input.

Seems it may be best to caulk the track piece-by-piece to roadbed, then glue to the plywood once I'm sure it's where I want it.




That is a bit unconventional but I suppose it might work. Are you describing sectional track or flex track?

Usually cork roadbed is glued first in long strips to have even and smooth roadbed. That is a base for good smooth trackwork (which is very important in N scale).

If you are using sectional track why not skip the cork/ballast part and instead go with one of many ballasted track sectional track systems? Atlas, Kato, Bachmann and Life Like (or is it Model Power?) offer such track. Atlas is the most realistic of the bunch.


Peteski

Country: USA | Posts: 3324 Go to Top of Page

PennsyMan

Posted - 2010 December 06 :  02:00:06 AM  Show Profile
Petesky,

This is to be done with sectional track. I already have purchased Atlas sectional track. I didn't see it worth going for flex track being the layout is only 3' x 4'. I'd love to go for the Kato track, but I've long since taken the track out of it's packaging, so returning it is out of the question. I had seen some of the type you refer to in the hobby shop, and was not impressed with the way it looked (if I remember, it was Model Power). With very limited resources, I need to work with what I have.

I see your point about laying the roadbed first, but then I'd have to be perfect in making sure it's 100% in place. I could see that working, but I myself am not that precise. Oh, how I wish!



Brian

Country: | Posts: 21 Go to Top of Page

Catt

Posted - 2010 December 06 :  09:40:48 AM  Show Profile  Visit Catt's Homepage
If I may weigh in on this subject.

I would use at least 1" foam to start with,glue it down with a foam safe adhesive (Liquid Nails for projects come to mind).

Lay you track out on the foam according to your track plan of choice.

Using the nail holes in the secional track mark your track centerline for all of the track.

Remove the track ,split the roadbed down the center and glue the cork down following the centerline marks you have put down.do one side at a time,when you glue the other side down being sure there are no gaps between the halves of the roadbed.

Once the cork is dry you can nail your track down on the centerline (the cork will hold the nails very well).Once the track is ballasted you can remove the nails.


Johnathan (Catt) Edwards
CEO,COO &CBP of the
Grande Valley Railway
Enjoy life now - It has an expiration date!


Country: USA | Posts: 835 Go to Top of Page

Roger Perkins

Posted - 2010 December 06 :  1:38:30 PM  Show Profile  Visit Roger Perkins's Homepage
I am a strong advocate for extruded polystyrene over plywood. The two inch thick version which I am now using is sufficiently strong and rigid, that it can be extended at least eight inches beyond the plywood base.
Even if a layout is nominally zero grade, the extruded polystyrene is worth trying.
Straight pins will hold track in place on the 2" foam assuming one selects the product intended for construction.



Country: USA | Posts: 3351 Go to Top of Page

Ed Kapuscinski

Posted - 2010 December 06 :  5:36:09 PM  Show Profile  Visit Ed Kapuscinski's Homepage
I'm currently working on a concept layout that is simply 2" foam over shelf brackets. So far it's been encouraging, despite the fact that my brethren over at the Railwire are giving me the business about it.
http://therailwire.net/forum/index.php/topic,22454.0.html



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Country: Fyro Macedonia | Posts: 1945 Go to Top of Page

peteski

Posted - 2010 December 06 :  6:26:46 PM  Show Profile
Ed, I would also discourage that method. Friend of mine build his layout (about 30' x 15') using similar method. He used wood frames to support the 2" foam base. The layout wasn't quite rigid enough. The layout is now dismantled (he had to move) but when he gets to rebuilding it he will use a plywood base under the foam.

Peteski

Country: USA | Posts: 3324 Go to Top of Page

jdetray

Posted - 2010 December 06 :  6:56:27 PM  Show Profile  Visit jdetray's Homepage
quote:
Originally posted by PennsyMan
My plywood base is in place, and I was reading about using extruded foam insulation over the plywood. The layout is relatively small (3' x 4') compared to many I've seen while looking at other layouts. If you would all be so kind, I have a couple of questions for those who have used this foam.

My N-scale layout is similar in size to yours: 32"x48". I used 1.5 inches of foam on top of 0.25 inch plywood. Then I dropped this assembly into a frame made from 1x3 and 1x4 lumber. For gluing foam to foam and foam to plywood, I used PL300 Foam Board Adhesive which comes in cartridges like caulk.

Here are photos of the foam/plywood "sandwich" and the frame.





I printed a full-size track plan from my track planning software and used it to mark the track centerline for the whole layout. I glued down cork roadbed using the cheapest latex caulk available at Wal*Mart. Then, I glued down the track using the same inexpensive caulk.





As you can see in the photo above, I also used foam blocks as risers to elevate portions of the track.

- Jeff



Country: | Posts: 24 Go to Top of Page

Ed Kapuscinski

Posted - 2010 December 07 :  10:16:50 AM  Show Profile  Visit Ed Kapuscinski's Homepage
quote:
Originally posted by peteski

Ed, I would also discourage that method. Friend of mine build his layout (about 30' x 15') using similar method. He used wood frames to support the 2" foam base. The layout wasn't quite rigid enough. The layout is now dismantled (he had to move) but when he gets to rebuilding it he will use a plywood base under the foam.



Not quite rigid enough? Please explain. Was it moving?



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