Tunnels Portals

[Trainman11]

 Do I need to have portals with the tunnels or not. I am not sure at this point. Can I make the portals on my own, if I make my own, what wood would I use. or do I have to buy them. I am planning on trying to make the mountain out of a shell, and then use paper mache, I hope that is a good choise. I hear good and bad about paper mache.

Thanks to all who answer. I just don't know what to do at this point.

[loathar]

Those dryer softner sheets dipped in plaster O Paris are easier to work with. They don't tear EZ like newspaper or paper towels.

[Dallas Model Works]

I tried papier mache once and then ripped it out.

Smelled awful, at least the formula I was using.

I use plaster cloth and get great results.

I suggest you get Dave Frary's book on Scenery. Kalmbach publishes it.

Sorry, don't have the title handy right now.

 

[selector]

You can create your own out of plaster if you are good at making molds, or don't mind some finicky sanding and scraping to get the portal looking realistic and balanced in dimensions.  Or, if you are going to create scenery with rock cuts, just create a natural portal.  I felt I wanted to try my hand at the latter when I saw a proto photo of a real rock portal, although I had seen several in South America in my youth.  Here is how mine turned out.

 

I used spline roadbed, and what I did to start was cut a longish strip of aluminum window screen and creat most of a loop over the tracks at that site by hot gluing the ends of the strip of screen to either end of a small block of 1X2 screwed transversely to the underside of the spline at that point.  That was the start of the portal.  Then, I mixed several batches of ground goop and hand slathered it in and over that screen loop until it took a hard and rigid shape such as you see.  I had to add the ground foam of various kinds later, and I used cheapo craft acylic paints in heavyish washes to darken the inside.

 

[nbrodar]

For anywhere other then a hardrock bore (like Crandell's), you'll need a portal.

Currently, I use WS cast plaster portals...

 

Concrete portals are easy enough to cut from clear 1x pine or popular.  If you want stone, you'll have to do some carving.

Making the mountains themselves, ask 12 people, you'll get 15 answers.  Personally, I don't like paper mache.  I've always used either paper towels & plaster, or foam.  

Nick

[gandydancer19]

You can use a paper mache ground goop for mountains.  Do a search on "ground goop" and you should come up with several threads and formulas.

If you want to use plaster, you can make your own rock molds using aluminum foil.  Just crumple it up some, then spread it back out leaving some depth to it.  Bend up the sides all around to make a tray so the plaster won't run out.  Then pour your mixed plaster in it.  Let it dry so that when you pick it up it will still be solft and bend, and form some cracks in the back.  Then slap it on the mountain.  When you get good at this, you can use this method to make a rock-work tunnel portal.  Just wrap it around the opening in your mountain.  It will take at least three castings to do it.  One for the top, and one for each side.  It is OK if they overlap, just use a small screwdriver to chip away some of the plaster that overlaps and doesn't "look" right. 

You can also cast your own concrete type tunnel portals using the aluminum foil mold method.  Just don't crumple it up.  You will just have to do some forming, or just shape the outside, then cut the opening for the train while it is still damp but set up and laying flat.  It may not be fancy, but it works.  You can also carve it to simulate blocks if you want to.

[twhite]

I use my tunnel portals according to the geology of the area I'm tunneling through.  Since I model the Sierra Nevada of California, my tunnels go through everything from packed clay to solid granite.  For the granite, I just use a rock bore, for the softer materials, I use everything from wood frame to concrete or stone. 

One thing to remember, when modeling tunnels, it always looks good to model at least 3-4" of the INSIDE of the tunnel for viewing purposes.  If it's timber bracing, you can use styrene to represent this, if it's solid rock, crumpled and painted aluminum foil curved over the tracks on the inside of the portal will represent blasted rock very well.  The trick is to make the tunnel look like it's actually bored THROUGH the mountain, rather than just have a portal and an empty shell behind it. 

Tom

[CSXDixieLine]

Here is an article showing a great looking portal built from cardboard on an n-scale SP Coast Line layout:

Jamie

[wm3798]

You'll also want to consider the history of your railroad.  If it was built between the earliest days of railroading (roughly 1830 - 1875) you're probably looking at cut stone portals.  If it was built after that, especially from about 1895 on, your portals would most likely be concrete.

And obviously, the longer it's been there, the more heavily weathered it would be.

Lee

[Beach Bill]

As mentioned by nbrodar, a tunnel portal would be needed for anything other than a hardrock opening.   Even in such a geographic area, real railroads often use concrete portals just to reduce the chance of things falling in.    If you have a logging line, or model an early period, then a wood tunnel portal could be made fairly easily.   I use purchased tunnel portals that represent stone, but I have always made the tunnel "liner" using relatively cheap bulsawood strips.   "Panels" of liner can be built up fairly quickly, then stained and glued in place.

I suggest you look at your favorite railroad...   find some photos of what type of tunnel portals that railroad uses...  or what is used by other RRs in that same geographic area.  Doing that type of homework ahead will help make your scene more believable and enjoyable for a long time to come.

 I've never tried paper mache, but I've read of a number of folks that have had trouble with that method.  Paper mache tends to absorb moisture from the air during humid times and can thus develop mold and mildew...  getting rather nasty sometimes.  Plaster-based products don't have that sort of problem.

Bill

[MisterBeasley]

I have low hills rather than mountains on my layout.  I use foam for pretty much all of my "terraforming."  It works well for me.  I get plaster cloth from art supply places - much cheaper than the WS stuff.  I use the plaster cloth sparingly, just to bridge gaps or create smooth contours where working with the foam just isn't practical.  I then coat pretty much everything with a thin layer of Gypsolite.  That's a gritty textured plaster which can be painted to resemble either rock or soil.  I prefer rock castings for my stonework, though.

I bought one WS portal, the kind Nick has in his top photo above.  (He's in N-gauge, I'm in HO, so dimension will vary.)  Since I didn't want anything quite that thick or wide, I used latex rubber to make a mold of the face of the portal, and then I poured a couple of Hydrocal castings.  Mine were only about a quarter of an inch thick, vs. the inch or so of the original.

[R. T. POTEET]

Assuming your tunnel is puncturing some kind of hard rock you can construct a natural face tunnel using conventional rockwork scenery techniques.

As far as portals go most of my tunnels on my N-Scale layouts over the years have been box tunnels through fill and I have used commercial structures for this. There have been numerous articles in the hobby press about carving tunnel portals in wood, creating a silicone rubber mold, and then creating tunnel portals from Hydrocal® or some other casting material.

There are a wide variety of tunnel portals available from several manufacturers and unless I needed dozens on my layout I think I would just foot the expense and go the commercially available route. This would have the added effect of giving your layout a uniform civil engineering appearance.