Oh No! The Rubber Broke!

Apparently, Rubber molds have a shelf life.

Half way through the casting of the street lamps needed for Grand Ave, the rubber mold decides to completely fail.

Now it could be I didn't use enough release agent. But the mold also cracked (Maybe the sun got to it? UV rays are so destructive!). So I'm sure its at the end of its shelf life.

So the next time I make a mold, I have got to make all the casting right away.

Yes sir- Right away!

Dandy

Well Whatdaya Know ~ All Rubber Are Not Alike

Quality Rubber - That's The  Secret Ingredient For A Successful Mold.

      What with the Backesto Bits already to go, its time to make a mold of them all. But when I went to go fetch the left over rubber compound from the Streetlamp Project, I found it has a short shelf life and had hardened.

Anxious to move forward with this project, I stopped by the craft store to pick up some of their casting rubber~ Amazing Mold Rubber. And after some time and effort, well... I found it ain't so amazing. I'm sure its fine for most crafts, but not for precision casting. In a nutshell, it shrinks!

Recycling the box from the streetlamp project, it turned out to be just the right size for this project.

There it is! In all its pink glory. Or so I thought.

The shelf life of the resin is much better. It cast just fine and faithfully with no shrinkage. But when I compared the castings with the originals, there was about 10% shrinkage with the "Amazing" rubber.

So, I'll pay the small extra for the much better quality of the Oomoo rubber compound. Lesson learned.

Yes sir! Lesson learned!

Dandy

Casting Fail

These Lamps Are Way Too Hard To Build To Have Failures Like This!

I can't tell you how disappointing it is to open the mold after 3 days of curing to find it to be a complete fail. It takes a better part of a day to build the armature and to pour the casting resin around it. It's too time consuming and costly to have this happen!

I'm not sure where I went wrong, I didn't do anything different. The only thing I can guess is that the resin ran when sandwiching the two parts of the mold together, creating these bubbles. Surface tension of the resin and no escape routes for the trapped air didn't allow the resin to fill in the voids. This clear resin takes much longer to set than the Smooth-Cast resin does, so its much more liquidy when to two halves of the mold are sandwiched together.

I'm amazed at how delicate some of these structures are. The resin stayed in the corners and edges creating this skeletal look. Unfortunately, I can't think of a way to save this lamp. The resin would have to be pried from the armature, which would damage it. Maybe- I could fill the voids with resin and put it back in the mold? Maybe?

So put it in the past and carry on. Since then I casted this perfect casting. This time I was sure to "paint" the sticky resin onto every surface of the armature before closing the mold so that it would be less likely to run away. And it seems to have worked! So- 3 useable lamps down, 9 to go! Sheesh!
Live and learn? Yes sir! Live and learn!

Dandy

It's De-Bubbly

The second casting utilizing EasyCast resin came out bubble free!

Since EasyCast casting resin takes forever to set, I took the time to remove every bubble before sandwiching the mold together.

And it worked! Not a bubble to be found anywhere.

Some resin dripped onto the end of the brass tube and solidified. I tried snapping it off, but its on there good and strong! I've been wondering how strongly the resin was holding on to the armature inside. Especially since it pops out of the rubber mold so easily. I guess that that mold release works really well because that resin has a hella grip on that brass! So I'm going to have to mill that resin drop off.

Next is trimming the flashing off the castings and then send them to the paint shop for painting. Finally some usable castings. Yes sir! Some usable castings!

Dandy

Easy Cast

Trying Out A Clear Casting Resin For The Boulevard Lamps

After installing the Boulevard Lamps onto the layout, I was struck by how stark white the globes are on the lamp I cast last time (above, far left). While the globes on the first lamp (above, near right) are just the right transparency. But those were carved from clear acrylic tubes and are quite labor intensive. Something I would like to avoid. So I thought I would try a clear resin for the next casting.

After some research on internet I've come to the conclusion that EasyCast might work for what I need to achieve.

EasyCast takes a lot longer to set than Smoothcast, 72 hours! So I cast it and set it aside for a better part of the week. I was toying with the idea of only casting the globes and use the Smoothcast for the rest of the lamp. But that presented some problems, such as mixing such a tiny amount, and attempting to prevent the two resins from mixing (they are almost as thin as water!). So I just cast the entire lamp with the EasyCast.

Success! I can see how the armature fits inside, pretty cool. And the translucency of the globes is perfect! But whats this!?:

The EasyCast resin captured the details perfectly. But bubbles are a problem! I noticed when I was pouring the resin that the bubbles are bigger and harder to pop with this clear resin. Despite my best effort, bubbles persisted. Fortunately, most won't be seen when the lamp is painted. But...

Bubbles in the lamp globes! Geez man. Those can be seen. But since they are so tiny, I might let it slide with this casting. After all, they are about the size of scale bullet holes ;-) So its plausible that the San Diego Police Dept had a shootout on the streets! Right? Yes sir! A shoot out in the streets! 

Dandy

Light Cast

Looking for an easier way to cast these lamps.

Carving the lamp globes beforehand is tedious, time consuming, boring, wasteful, not fun, dull, waste of energy and time, not my favorite thing, noisy, dusty, etc...

And the shape of the globe is cast into the rubber mold, so why not cast it along with the rest of the pole? Seems like a no brainer to me.

I noticed that the last casting was glowing around the bottom of the globes. So I suspect that the Smooth-Cast casting resin is translucent. So I'm gonna do another cast, but this time fill the entire mold with the casting resin and forego the carved globes (after all the trouble I went through to get the correct size clear acrylic tubes!). And see how much light is emitted through the casting resin.

Wow! It glows just as brightly as clear acrylic tubing! Whew! So much easier than carving those globes. Yes sir! So much easier!

Dandy

Moment of Truth

Pouring the Resin Around the Lighting and Overhead Support Armature. And Hopefully End Up With A Reasonable Looking Streetlamp!

Here it is! From a virtual model and crazy idea to something I can actually hold in my hand! The freakin' thing actually turned out right.

Here is how it went:

Last post I had just finished building the support armature.

First the rubber mold needs a couple coats of mold release and allowed to dry. Then the armature is placed into the rubber mold into its precise position. That means bending and wiggling as needed to get it just right. (Note: I took this photo before I added the lamp globes).

Now its ready for the resin pour. I used Smooth-Cast resin from Smooth-on from the kit as described in this post. Just like the silicon rubber used for the mold, its mixing equal parts of resin and catalyst.

The top part of the mold (left) was poured first and allowed to set a bit while the resin was poured carefully around the armature in the bottom half of the mold (right). I'm not too concerned about using too much resin as I want to be sure it gets everywhere.

The resin in the top half has set enough (2 or 3 minutes) where I can flip the mold over. The two mold parts are keyed so that they almost lock together for perfect registration. I clicked the top parts of the molds together and then squished them together from top to bottom so that the excess resin is forced out the bottom (where the puddle is). 

The resin only takes about an hour to set fully. The thicker parts set first and the thinner parts take a little longer (the thicker part has more heat from the catalyst than the thinner sections would and so sets first). I knew it was ready to handle when the thin parts of the puddle had solidified.

The mold release allowed the mold to be pulled apart with no problem. And this is my first look at the lamp. And it looks like it worked!

The lamp peeled out of the mold with no problem. Most of the flash snapped right off. The rest required a little filing to get looking just right. Now the question is: Will it light?

It works! It actually works! I think this project is going to work out as intended! I mean some questions remain. How will it hold up to long term use as a linepole? How will the resin casting hold up with a brass armature inside of it over the long term? How long are those bulbs going to light for (I can't change burnt out ones!)? How is paint going to take to it? What am I going to use for power supply? 

But as it stands now, this crazy project is actually working out. I don't why I'm so surprised. But I am just giddy that this worked out. And its just a streetlamp. Not an Electroliner or something fancy like that. Just a streetlamp. But there it is all the same. A one of a kind model streetlamp.

Well then, one down and 11 to go. Yes sir! 1 down and 11 to go!

Dandy