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Monday, February 24, 2014

Armature Nite

Building the Skeletal Framework for the Streetlamp that will Act as a Conduit for Wiring and Support the LEDs AND Trolley Overhead! Crazy Project I Know...

Built of brass, this armature performs three functions. 1. Support the LEDs so that the streetlamp will light up. 2. The brass tube is a conduit for the positive wires and the brass itself is the ground. 3. The loop at the top of this assembly is a tie off for the trolley span wires. Then this armature will be placed in a rubber mold and resin will be poured around it creating an ornate streetlamp! That's the plan anyway. Yes sir- that's the plan!

The basis for the armature is a 3/32" brass tube. A brass rod that has been drilled to accept a brass wire loop soldered on, is inserted into the tube just above where the holes for the wires are drilled.

The negative lead of the LED is bent and soldered to the brass. The positive lead is trimmed short and a thin wire is soldered on and then threaded down the tube which will protrude under the layout where the resister and electrical hookups reside. 

Okay! Now this next part turned out to be way too much work and is actually unnecessary! But I'll post it anyway for your edification and entertainment.

The resin will cover the bulbs so I milled lamp globes out of acrylic tube to fill in the space in the rubber mold.

The acrylic tube fits over the LED perfectly. An Acrylic rod is inserted in the top of the tube to fill in above the LED where the fancy curves of the lamp globe will be carved in.

 Using my Dremel Tool as a lathe. I have a chuck the fits snug inside the acrylic tube and the teeth bite in holding the lamp globe firmly.

Then spinning the acrylic a small file shaves it into shape.

Before and after.

Wholly Katz! Its lit! It works! This thing is actually working so far! This project might actually pan out after all.

Alright! Well! This is how the armature fits in the mold. Next week I'll pour the resin and we'll see if we get a respectable looking streetlamp. Yes sir! We'll see if we get a respectable looking streetlamp out of all this!


Monday, February 17, 2014

Bubba Don't Forget Your Rubber

Making a Two Part Rubber Mold for the Streetlamp/Line Pole Project.

Even though this is a rather crazy project, the making of this rubber mold is pretty straight forward. I watched tons of YouTube videos on how to pour rubber molds until I was confident I knew exactly what I needed do. This video in particular comes closest to what I need to do, except that I'll be sandwiching a brass conduit and a couple of LEDs in the mold along with the casting resin (I told you this is a crazy project!).

I'm a beginner when it comes to casting, so I need everything, rubber, sealer, mold release, and casting resin. The guys on the Railroad Line Forums recommended using Oomoo Silicone Rubber from Smooth-On. Smooth-on offers a starter kit that has everything I need to make a mold and castings, so I went with that.

Last week I built this two-part mold box for the two-part mold (bottom part shown). Since the streetlamp master is suspended in the box I was tempted to fill the box with rubber just like that...

...but the rubber crept up the sides of the master and completely covered it in some parts. That's unacceptable for casting. I tried trimming it back when it set, but that didn't turn out too well so...

Take Two!

This time I'm going to do it the right way like all the instructions said to.

That means filling the bottom of the half of the mold box with clay, carefully working it up around all the details of the lamp right up to the half-way line. Packing the clay tightly against the master so there aren't any voids that will be filled with rubber. Some strips of clay protruding up will create a keying effect so that the two halves of the mold will snap together with some precision. 

The top of the mold box is attached and the whole thing is sprayed with sealer. After two coats and drying time, spray on mold release (clean the sprayers afterwards, mine clogged. Now I have to brush it all on!) and let dry. Now were ready for rubber!

To determine exactly how much rubber I need, I had filled the mold box with sand...

... and then poured that sand into the mixing cup. I marked its level with a Sharpie. Remove the sand, pour the liquid silicone Part 1 half way to the mark, and then part 2 the rest of the way. Mix well.

Oomoo is easy. Mix equal parts of A and B and mix it really well. A woman in one of the YouTubes suggested warming up the bottles a little first so that the compound is even thinner.

And then fill up the mold box and let set. So far so good!

Flipped the whole thing over and dug out the clay revealing the master and the first half of the mold. Success! Attached the second half of the mold box and then added the coats of sealer and release. Now were ready for the second pour.

Success! It turned out beautifully. The rubber captured the strata layers inherent from the 3D printing process perfectly!

Next week comes the crazy part: filling the two halves of the mold with resin and then placing the brass armature with LEDs into it and then sandwiching the whole thing together! That's the plan anyway. I told you this was a crazy project. Yes sir! Crazy!


Monday, February 10, 2014

Box of Negative Space

Constructing a Simple Mold Box for a Two Part Rubber Mold.

This box will contain the liquid rubber while its poured around the streetlamp model.

The box is simply constructed with hobby board from a home improvement store.

The hobby board is cut so that the streetlamp model will have at least a 1/2" space around all sides of it.

The lamp is going to be cast with a brass armature inside of it as a conduit for wiring for the lights and to support trolley overhead span wires. The brass tube also extends down through the layout benchwork. So I had to drill a hole in the mold box to accommodate the exposed brass rod.

 This is going to be a two-part mold. Resin will be poured in both halves of the mold,then the brass armature will be placed right into the liquid resin. Then the two halves will be sandwiched together. That's the crazy plan anyway! We'll see if it works.

The two halves of the mold box are screwed tightly together. And there we have it. We're ready for the big silicone rubber pour. Yes sir! We are ready for the big pour!


Monday, February 03, 2014

Boulevard Streetlamp / Line Poles

Attempting To Build A Working Combination Streetlamp / Linepole!

 Well here it is, a fresh 3D print from i.Materialize. But this is only the beginning. This print can't be used on the layout because one: I believe the "Prime Gray" material would be too brittle for the tensions of the overhead, and two: I want these lamps to light up. So this fella will be the "master". A rubber mold will be made from this print that all the other lamps will be cast from. But I digress...

As detailed in a previous post, each of the 6 streets feature distinct line poles. The 1920s era street pictured above is to have Boulevard streetlamps that double as line poles. Right now I have temporary wooden poles that are planted beyond the sidewalks until the streetlamp locations and hole size to be drilled in the sidewalks are determined. But for now, the temp poles are fouling where the building are going to be placed. So these lamps have become the priority project.

 San Diego didn't have these kind of poles but our neighbor to the North was kind of fond of them. The Pacific Electric sported these kind of poles in a few cities. This one was in Long Beach.

The San Diego Electric Railway attached their overhead directly to the adjacent buildings, thus clearing the streets of unsightly linepoles. But I don't want to attempt to deal with attaching the overhead of my layout to model buildings. So I thought I would try modeling these Boulevard Lamp Post / Line Poles (I really wish I knew what these were called!) instead. Besides, they look cool! 

Years ago I fabricated a couple of these lampposts out of brass. But they were very difficult to build and highly time consuming. There are so many small parts that trying to solder one part melts the joints of the other parts. Frustrating. So the project languished until either my soldering skills improved, or I thought of a better way of building these, or some sort of miracle happened.

Well wouldn't you know? A miracle happened! In the form of 3D Printing! Building this lamp with a 3D program is WAY easier than building it with brass. And a lot faster. I modeled this with 3DS Max.

My lamp design is a hybrid of San Diego style Boulevard steetlamps and the Los Angeles linepole streetlamps.

I'm pleased with how the print turned out. The lamp had to be designed with the 1mm minimum thicknesses required for 3D Printing. But I believe the level of detail is just right for HO scale.

Now comes making a silicone mold from this lamp. This will be a new adventure for me. Yes sir! This will be a new adventure!