Large Scale Central

In-ko-pah Railroad - Another new building

I’ve started a new building for my In-kopah Railroad. This will be the first building in the town of Mineral Ridge. It will also be an experiment in using PVC foam board (aka Sintra) and resin castings to simulate the look of stone construction. In the past I’ve used only real stone for my stone buildings, bridges and retaining walls, but there are limitations to what can be done using real stone. Since this building will be surrounded by real stone cliffs as well as foundations and retaining walls made of real stone, it will be crucial to get the simulated stone to look right!

A while back I did a real “quick and dirty” test on a scrap of PVC to see if it was even possible to texture it to look like a stone wall. Here’s what I came up with:

It’s far from perfect (though the photo doesn’t do it justice), however I know how to improve it. So I’m forging ahead…

The design of my building was inspired by this historic brick-and-sandstone structure:

Mine will be narrower, with different details, and the side wall will be of rubble stone construction rather than brick. Due to its location, only the front and left side of my building will be visible, thus only those two sides will need to be textured. I started by cutting out the front and side walls from 6mm PVC. The left wall will be worked on first. I marked the locations of the quoins with pencil:

Next I roughed up the surface by tapping it firmly with various rocks:

Then I used a carbide-tipped metal scribe to scribe a pattern of random stones into the surface. After scribing the stone pattern, I added more texture by tapping it with rocks again:

Here is the completed wall. The area at lower left will be hidden by a “boulder” so there was no need to detail that section:

Here’s a closer view of the texture:

Next I glued the front and two side walls together, and tested the fit on the concrete foundation:

The foundation was faced with thin stones, glued in place using paintable silicone sealant. I still have to make the sidewalk and stairs:

Here’s a wider shot of the town site and in-progress structure:

The front wall has sections which stand out, so I cut some 3mm PVC and glued it in place:

I also cut a subfloor from 3mm PVC and glued it in place. In this shot of the underside, you can see the strips of PVC and styrene that support the subfloor:

Now, the big question was, How to replicate the rough-hewn faces of the rectangular sandstone blocks? The method I chose is as follows… First I cut some 6mm PVC into strips of two different widths. Then I used a sharp hobby knife to carve the upper surface of each strip, as shown below. (I carved these during a two-hour wait while my wife was getting some medical procedure done.)

These strips were then cut into individual blocks, and the ends carved to shape. I decided the texture needed to be a bit coarser, so I used an old craft paintbrush to stipple a thin, irregular coat of automotive spot putty onto the face of the blocks:

I then glued the blocks to a scrap of rigid plastic sheet, and built up a low wall of styrene strips around the perimeter in order to make a silicone rubber mold:

Here’s the silicone mold:

I poured urethane resin into the mold, covered it with a piece of thick plastic film, and topped that with a flat, heavy plastic sheet. I don’t know what kind of plastic film I used – it came from a large bag that brass screen was shipped in. But it’s a pretty common type, and the resin doesn’t stick to it. After the resin cures, the plastic peels off easily and the castings are popped out of the mold. I added some colorant to the resin to make the castings light gray. They’ll be painted, but this way if the paint ever gets scratched, it won’t show:

That’s as far as I’ve gotten for now. More to come!

That’s as far as I’ve gotten for now. More to come!

Man I hope so…neat build.

I really like that building your modeling!

Excellent work Ray. Those stones look real. Again, I’ll be watching your progress. What are the sizes you settled on for the stones?

Very nicely done. An interesting use of PVC foam board.

Doc Tom

That’s really looking good Ray. I think I’ll go throw my birdhouse conversion in the garbage.

I think you will come to love working with PVC foam board. It plays nice with styrene and is very easy to work with. My only complaint is the sawdust is hard to get rid of due to static.

What glues are you using for the PVC? I’ve had good luck with Weldon-16 and also used PVC Pipe Cement which is cheap.

That is so neat, Ray. I’ve thought about etching brick in the PVC, but thinking is as far as I’ve gone. I love the idea of using a rock to add texture.

I agree with Jon, the PVC has become my first choice for building material. I use my shop vac a lot when ever I cut or sand it; that seems to be the way to handle the sawdust.

I’m sure there was quite a mess in carving those strips, but they sure turned out nice.

Will you have an interior in this one? What sort of business?

Wow Ray I dont how you do it. I could never turn plastic into rock and have it look real. Awsome work.

I was planning on creating a few buildings for my layout this summer…I am throwing in the towel…Amazing stuff!

Amazing work!

My glorified plywood box buildings are starting to look pretty poor next to what I have been seeing on this forum lately.

Keep up the good work. Just don’t let your 3" tall people venture over to my RR they will really think they wandered over to the wrong side of the tracks!

W O W !

Can’t wait to see the finished product

What thickness did you use Ray. I’m thinking about calling my local sign shop to see if they have any.

Thanks guys!

The material for the mold is called OoMoo 30. I like this stuff because you mix it in equal parts by volume, not by weight, so you don’t need a fancy scale. It’s also pretty forgiving of minor inaccuracies, so you don’t have to worry about being super precise. It’s made by Smooth-On, but I get it from this art supplier:

http://www.dickblick.com/products/smooth-on-oomoo-30-silicone/#items

The urethane resin I use is also made by Smooth-on, and is just as easy to use as the silicone rubber. It’s called Smooth-Cast 300:

http://www.dickblick.com/products/smooth-on-smooth-cast-300/

It took me about a week to scribe the stone pattern in the side wall. That was doing a little at a time, an hour here, a half hour there. I did some of it in the waiting room at the doctor’s office!

The small hole in the front of the foundation is drainage. There’s a “pit” in the middle of the foundation for wiring the lights, and I don’t want it to fill up with water when it rains. When I make the sidewalk, I’ll have to include a “drainpipe” so as not to block the drainage.

I use PVC pipe cement to glue the PVC to itself. When I glue styrene to it, I usually use Weldon-16.

The stone block castings are 3/8" x 3/4". The narrower ones are 1/4" x 3/4".

Bruce, I did an experiment with brick texture on PVC and got really good results. I’m planning to do a brick building next.

Great looking building Ray. So where do we place our orders for the cast stones? I’ll take several sheets please. I’ll be watching this one for sure.

Chuck

BTW, here is my source for Sintra PVC foam board:

http://www.foamboardsource.com/sintra-pvc-foam--sintra-pvc-board.html

well, i think it is time to get some popcorn and soda, lean back and watch another special building grow.

I need to find a place to watch this build where my dropling won’t cause any electrical shorts!

That kicksass Ray !

The base material seems to have endless workability options.

(http://www.freethoughtnation.com/components/com_comment/joscomment/emoticons/funny/images/smile.png)…

Editing as I forgot my smiley …

Would you entertain the idea of making another mold of the rocks, and sell it to me, at a price?

Amazing! Just simply amazing. I wouldn’t have near the patience to scribe all those stones.

Dave Taylor said:

Would you entertain the idea of making another mold of the rocks, and sell it to me, at a price?

I might. I’ll have to figure out the cost of the silicone, and then find the time to do it.