A Gate Valve in O Scale

Often when modeling one thing will lead to another. My need for some gate valves is a good example. I was planning to build a small coke oven bank. While researching I discovered that when the coke was pulled it needed quenching as otherwise it would burn when the oven was opened (coking basically consists of baking coal at high temperatures in an airless oven). Discovering that it required 500 to 800 gallons of water to quench the hot coke, I worked my way back to requiring a pump house and finally a way to control the water. Therefore, the gate valves needed to be created.

A book published in 1907 titled “Surface arrangements at bituminous mines: coal washing, principles of coking, coking in the beehive oven, by-product coking, surface arrangements at anthracite mines, preparation of anthracite” (they loved these long titles back then) is available via Google Books has a very nice illustration of a Gate Valve.

With a front and side view I could bring it into Sketchup. Knowing that it was an illustration of a 6" gate valve it was simple to scale the completed Sketchup model from the valve throat.

I made the decision that I needed three gate valves inside the Pump House. My reasoning was,  it would add to the “mechanical clutter” in the Pump House. Figure that they would have had one gate valve on the line to the storage tank, a second gate valve directly to the coke oven bank and a third gate valve that would by-pass both of those to route the discharge back to the river.

The main water supply will be a water tank placed above the On18 track level. I can easily get 12-in separation between the ovens and where the bottom of a tank could go. This will allow for a scale 36-ft standpipe, which will supply sufficient pressure for the coke ovens.

If for some reason the water tank has to be by-passed, this gate valve would discharge directly to the coke oven bank. I’m not clear (haven’t really looked into it) just what kind of pressure this would be but if the water tank was damaged for example, it would be sensible to provide water to the coke ovens and washery no matter what pressure.

I would think that it would also make sense to by-pass both (1) and (2) working/testing the pump in which case, the discharge will be out the side of the Pump House and back into the river. The best part of this, in addition to more pipe,  is that we get a cool discharge pipe sticking out of the Pump House.

First Drawing

The above Sketchup drawing is an early rendering of the gate valves. 

My plans for the gate valves were created with Sketchup. One of the tools in Sketchup is the Tape Measure Tool. You can measure a known distance on the model and enter the dimension that you know is right and then you can have the program scale the entire model. That’s what I did here, brought the drawing into Sketchup and used it to re-construct the gate valve. Then, knowing that it was a 6-in valve I scaled everything off of the throat opening. As I said, this was early in the process. I wasn’t too concerned about having everything exact to a fraction of an inch as I was making a gate valve that would be similar to the original, not an exact copy.

Assembly

To create the gate valves, the materials I used were:

• Evergreen 5/32″ tubing
• Evergreen 7/32″ tubing
• Evergreen strip in various sizes and thicknesses
• Crimp beads (beading)
• #000-120 screws (at .034″ in dia., they are about 1-5/8″ scale which is close enough for me)
• Tichy NBW (I didn’t use the ones in the above photo. They were too small and so I decided to use the larger ones.)

Here they are assembled. Note that the valve stem is actually made up of two screws. I looked for threaded rod that size and found it but was very expensive. These were so ‘fiddly’ to build that I ended up slightly (more) mad then when I started.

Notice in the above image that the little stems that support that upper plate are not attached. I found that it was easier to add those afterwards.

With the vertical braces added the gate valves are pretty much completed. The final detail, the brakewheel, I purchased from Vector Cut. These were from one of the handwheels that are on the O scale “Steam Age Industrial Gears and Handwheels” which you can find on their O Scale Accessories Page.

Here they are finished, complete with handwheel. Those are toothpicks they are mounted on for painting which gives you a good idea of their size.

Note that the gate valve on the far left in the above image is open while the other two are closed. The open valve will connecting to the piping that runs to the water tank on the On18 railway on my layout. The two closed valves will run directly to the coke ovens and to the line running to the outside and back into the river.

Finally, here are two of the gate valves mounted. The pipes are pieced together using Plastruct elbows. The elbows are fine but I ended up making my own flanges from Evergreen tubing as the Plastruct stuff is simply oversized. I’m pretty much satisfied with how it came out. Looking at this photo there are many places I could improve the mechanisms – if I were totally nuts. Luckily for me all of this is pretty much hard to see with the building installed and what I did is ‘Good Nuff’.

3D Printing

The scratch-built gate valves were, as I said, ‘Good Nuff’ for where they were to be used. I had got into 3d printing a little later on and decided to upload a .stl file from the Sketchup model I created originally just to give me dimensions to build these suckers out of bits and pieces.

The photo above is a screen-grab from the Shapeways website of the original design. Pretty simple – in fact it’s as about as simple as I could make it and still be happy. I ‘did’ add some bolts to the top of the valve body, the packing gland housing and the top support after I had my test parts printed but that was pretty much it.

This thing has undergone so many revisions that I don’t even have a copy of the original design that I could find.

Here are the gate valves printed by Shapeways in what they call ‘Frosted Ultra Detail’ (known to us having things printed in this material as ‘FUD’). There is minor layering that you can see on the upper support bracket on the one laying on the dime but that’s not obvious really, except with a close-up like this.

You can get finer resolution but the cost is quite a bit higher. I’m pretty much happy with how these came out.

This extreme close-up is as good as I can get with my camera and the close-up lenses that I have. This photo has been tweaked a bit to try for more detail so that layering is just a bit magnified since I had to sharpen the photo several times. Still, considering the size of the part, it’s acceptable to me. With some primer that would mostly disappear and after all these are supposed to be cast iron.