In-ko-pah Railroad - Another new building

[Ray Dunakin]

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!

[finescalerr]

That's really terrific so far. Why PVC instead of styrene? Is it softer? I'm unfamiliar with it.

Please document this build. It might be good for publication.

Russ

[Ray Dunakin]

Thanks! The PVC foam board is softer than styrene -- you can cut even a 1/2" thick sheet with an X-acto knife, with a bit of work. The 6mm stuff I'm using here is slightly less than 1/4" thick and cuts with a few strokes. You can also press textures into the surface, as I'm doing here. Yet it's plenty rigid enough for large scale structures. It's also designed to hold up well outdoors.

This is only the second time I've used it. The first was on my Hotel Torgo, which was built almost entirely of PVC foam board, with only some styrene details.

I'm planning to use it to make a brick structure too. The small test piece I did with a brick texture turned out really well.

[darrylhuffman]

Another great work, Ray.

Looking forward to the final product.

[lab-dad]

Really cool Ray!
The step by step is very informative and interesting.
I love all the details you have in your outdoor railroad!
I'm paying attention as i dont think a 1/16 RR will fit inside my house!

(I carved these during a two-hour wait while my wife was getting some medical procedure done.)

Whoever cleans up that waiting room must have asked;
"what the heck?"

-Marty

[Chuck Doan]

Very impressive Ray! Nice carving. Thanks for the description of the process.

[eTraxx]

Great info Ray. I have some Sintra also. Mine is 3mm and it works great for jigs. I really want to get some thicker stuff for that.

Here I have some stacked up for milling jigs. This stuff cuts great.


This is just after a swipe with some fine sandpaper

[Scratchman]

I really like this Ray. You do very nice work. I think I will give it a try. Thanks for the great SBS.

Gordon Birrell

http://www.flickr.com/photos/77318580@N00/

[Ray Dunakin]

Thanks guys! Here's a little more info about the build...

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".

[Design-HSB]

Hello Ray,

Thanks for the interesting post for me.
Show your work but that itself can offer a superior model garden railway.

[Wesleybeks]

Great sbs on the casting process. Thanks Ray.

[Barney]

Some nice ideas there - where do you get this PVC stuff from is it an art shop type of thing ?
Barney

[eTraxx]

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

[artizen]

I have sourced my PVC foamboard from a local sign printer. The material is used for external real estate signs on front lawns. I can only get 3mm thickness but it's free and a scrap from him measures 1200x600mm! Glues easily with superglue and tetra. Carves and cuts really easily. I use it for the base of my buildings, platforms, landscaping and backscenes. Gets heavy as you add more layers though. Wouldn't want to get too close to the fumes if it ever caught fire either. Totally moisture resistant and doesn't change shape with the weather.

[Ray Dunakin]

Progress has been a little slow this week, but here's an update...

I made small sections of wall to be glued to the inner surface of the building's side walls, along the top. This provides texture for the small portion of the side wall which will be visible on both sides, and also makes the wall thicker:




Here you can see one of the pieces glued in place, along with a strip of styrene to support the roof:




And here's the roof glued in place. The roof was cut from 6mm PVC foam board:




When I built up the sublayers for the front wall of the structure, I scribed "board" into the arch area of the PVC foam. Now I've added some trim, made from styrene strips:




The interior rooms of the building will be removable units that can be accessed from the rear of the building. I got the idea from fellow modeler, Bob Santos. I built these from PVC, mainly 3mm thickness but also some 6mm. Here's the lower room. The ceiling is secured by stainless steel, #2 x 3/8" sheet metal screws. Strips of .250" x /375" styrene are glued to the top of the ceiling, to support the upper room at the correct level.:






Here's the upper room. The left wall of the room is recessed about 1/8" inch, to clear the window frame and glass which will be installed in the side wall of the building:




In this view from the rear, you can see how the interior units fit into the structure. The space between the upper and lower rooms can be used to wire the interior lighting. There will also be a gap between the rear wall and the back of the interior units, for wiring:




A closer view of the units in place. Note the slightly recessed wall on the upper unit, designed to clear the window frame and glass which will be installed later:




And here's a look at the lower room, seen through the front opening:




Next up was building the front door and window assembly. On my first attempt I tried doing it a little differently than usual, and was not successful. I started with a sheet of .040" thick styrene, and traced the opening onto it. Then I added the main frame pieces:




Before adding any further detail, I tried to cut out the window openings. The results were too crude -- having the straight edge raised above the surface by the frame pieces allowed the tip of the knife to wander slightly. Also, the knife left ridged that would need to be sanded down. I could have salvaged this, but it would be too much work:




So I scrapped it and started over. I first glued together the main frame pieces, cut from strips of .080" x .125" styrene. Then I used various sized strips of .040" thick styrene to build up what I call the "backplate" on the underside of the frame:




Then the finer details were added, using strips of various size. Here's the finished product:




Here's a closeup showing some of the details. I used .020" styrene rod around the perimeter of the windows and panels:




And here's the door and window assembly temporarily installed in the structure:






That's all for now. Enjoy!