I have a tight space in which to put a couple of tunnel portals. That is, my track enters the tunnel entrance from a very oblique angle from a point 3 inches parallel to the wall and fits between 16" centered studs.
I’m afraid the illusion is rather a stretch being a tunnel in the midst of my flatland desert backdrop, but I had no choice. I think I can get creative enough to make a half decent job, but obviously I will have to carve my own rock portal from plaster or styrofoam. I measured retail double track portals and they don’t give enough clearance on the sides to get my locos through.
So assuming that I can make a rock face/ledge near this area in the tight space next to the wall, and camouflage it enough with vegetation to simulate a tunnel entrance, I am now faced with scenery sculpting as a complete beginner. [*-)]
Any tips or links to videos or threads on carving tunnel entrances/walls abutments would be appreciated. I will look through the forum archives in the meantime.
[EDIT] Ah, I think I see what to do. I looked around a bit and found some threads on carving styrofoam with dremel etc. and/or adding a layer of wallboard mud on to carve. Some examples look great. I think I can do ok with a panel of 1" foam board carved to fit. I think I wlll try for a layer of simple sandstone like this……
(These are old pics…the track is laid, ballasted and trains run fine in and out of my simple cutouts at present.)
I have made portals out of wood, 1/4", 1/2" and 3/4" thicknesses. I covered some in plaster, some I painted and some I brushed on white glue and added ballast to it to give it a rough concrete wall texture. I did this after I fitted the portal in to the scenery to make sure that they would fit properly, then used joint compound to blend it into the surrounding scenery.
I also had an issue with needing tunnel portals to fit in tight spaces. My subway system goes underground going around a couple of tight corners. The tunnels are sized for the subway cars only, so the openings in the portals needed to be somewhat lower than NMRA standards. After all, I’m not running auto-racks down there.
I bought one single-track Woodland Scenics stone portal, and a jar of latex rubber. I made a mold by coating the portal with rubber, and then used Hydrocal to cast new portals. Instead of an inch-thick portal, I ended up with only a quarter-inch, and it was easy to trim the portal vertically as well.
I used the same mold and made a pair of very short castings of only the top of the portal to use as a stone arch highway bridge.
Now, those are very clever ideas, Gentlemen. Thanks.
I was thinking of buying extra portal just to cut out the top lintel and add it in for extra width, but I feared it would make the whole arch look rather odd.
What I have done is cut out my openings a full 14 inches and will be using 1" high density foam and carving some wide sections into simulated natural sandstone portals as in the pic above. The extra wide face of the opening is necessary because of that oblique track angle, and I will have to place power poles actually along on the face going up and over. (This whole portal thing started when I got excited about installing my new Rapido totally-wired power poles and realized every scenic detail pretty well needs to be in place before messing about with all those strings.)
Can you post a picture from a lower angle, looking directly into the tunnel? It looks like there is a piece of wood on the left side of the track going into the tunnel. Because it’s a curve, you may have clearance issues. Better to check now before you get it all scenicked.
No, I am fine. As I put in the original post, the track is all in good working order. I have been running trains for a few months now since this expansion was completed.
The pictures of the construction phase show how I was measuring clearances between the 16" centered studs and pushing big locos along to make sure things fit…and after track installation they did![:D]
Years ago, also needed stone tunnel portal, made to my own dimensions so I cast one, using patching plaster and made it’s form from one of the old type, square, plastic-coated half-gallon cardboard milk cartons. Using this method, was able to get thickness, width, height and. portal opening just right. Used silicone rubber to cement form pieces in place and seal them. Worked fine and I carefully removed form afterward, while plaster was still damp; recommended in a mrr mag article, which claimed that doing so would lessen casting damage and allow much easier stone carving on face [which it did]. Still HAVE the portal in question and will most likely use it on new HO layout I intend to start a bit after the Easter Holiday. TTFN…papasmurf
Have you thought of just building a big honkin mountain in front of the mouse hole that comes right out to the front of the benchwork? It would then look like the Railroad had no choice but to go through it. Instead of veering right through the backdrop the track would go straight into the mountain and veer right inside the mountain and go through the backdrop. The only trouble is, those turnouts would have to be in the mountain as well unless you can move them along a bit.
Yes you do have a tight space there. The inside of the curve of the diverging route doesn’t have sufficient clearance especially when you decide to add the casting thickness of the portal. Whatever you decide on for the portal, foam, wood, styrene or plaster cast, you will have side interference on any longer equipment.
I had a similar problem on a double track pushing almost 3" centers on a 42" radius. My solution here was to use (2) WS cast potals. I cut both portals just past the center of the “keystone” about 3/8" and blended them together glued to a 1/4" piece of ply. When laying out the cut I shifted the exact cut to try to minimize the stone block difference to hide the seam. Doctoring up the splice w/ Hydrocal and recarving all but made it disapear.
MrB mentions making your own molds, if you want to do this , I recommend using RTV over latex, as you can dam and pour RTV over the “master”. The resulting mold will lay perfectly flat, unlike flimsey latex, to obtain flat replica of the original. This method was shown to me by Jeff Adam of Motrack Models when he was a club member. Many other castings were made by him that I used throughout this
No, I don’t have any clearance issues. I guess photos can be deceiving. I carved a couple of portals from styrofoam a couple of days ago and painted them up and glued them on, together with a little tunnel sidewall. Threw a few lichen on just now to take a snap shot. Will have to think a bit more about the scenic details on this portal. But as you can see, I have no clearance issues with long or tall rolling stock of locos. I made sure by running them through before I glued on my portals.
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