My first wheel emerges from the primordial ooze

[FJ and G]

They say you make many mistakes before you get the technique down, but my first casting seems to have turned out pretty well (says beaming).

After eating a yogurt, I cleaned out the container and dried it out. Wouldn’t want any moisture in the mix now, would we?!

I happen to have a large brick of non sulfur clay, non hardening, that Smooth On recommends. I used the clay to seat the wheel. In the future I’m using rubber cement. I got my materials from Micro Mark, which markets Smooth On.

I sprayed the wheel with mold release agent so it wouldn’t get bonded to the wheel (not that it necessarily would).



I thoroughly mixed 1:1 mold making material after measuring what I needed (used a 2nd yogurt cup and poured water into it and then into a measuring cup to determine how much mold material I need as the stuff is pricey and didn’t want to use more than I needed). Incidentally, you can reuse these measuring cups as the mold material peels right out nicely (but resin doesn’t).

They advise pouring a thin stream of mold liquid to remove bubbles.



Then, used a heat gun to remove bubbles. A lot of bubbles surfaced. I have no idea how they got in there! Wouldn’t want bubbles in my wheels. Might cause a wreck! The heat gun also works great for other projects like melting those heat tubes you put on wires. It also can unfreeze a turnout that’s coated with ice.

Anyway, I gave the mold 5 hours to cure. Placed it in a sunny area.



Here’s the mold that emerges (I had to cut the yogurt cup as the mold didn’t want to come out).

I then spray painted the mold with Krylon exterior grade rust color paint. Purpose was 2 fold: mold release and to give color to the wheel, which otherwise is white.

Incidentally, I purchased steel, copper coated BBs in the gun section of Wally World. I was gonna use these to add weight to the wheels, but the BBs were too large to fit into the mold.

I used CR600 resin because the CR900 high-strength stuff takes 48 hours to cure fully!!!!!!!!!!!! The 600 stuff takes 1 hour. In the future, however, I’ll use the 900 stuff for the wheels, after I make more mold wheel patterns, as it’s wasteful in effort to do just one wheel at a time.



One of the few mistakes I made was filling the mold too high with resin. In this blured photo you can see there’s a thin coat of resin in the back of the spokes. I used an xacto knife to slice these out. One cautionary note. Wait several hours before handling the wheel, even once it is cured, because it is still flexible and forming up.

Incidentally, the ruler you see here is a 7/8 inch scale ruler I made.



Here’s the cast wheel next to the master.



This was a simple one-part mold. I’ll try the complex molds soon, trying to replicate a tipper car that I’ll build shortly.

While awaiting the mold and resins to dry, I used my half jar of latex mold builder to make this wall casting (fortified with gauze). For the master, I poured plaster in a container and scribbed joint lines with a nail. I purposely agitated the plaster to create bubbles as that’s the effect I want in the rock (aggregate).

I haven’t yet decided what to do with the mold, but I may try a variety of materials to make walls.

[Rene Schweitzer]

thanks for the demo--it's interesting that you posted this, as a new series in working with resin/castings/molds will be starting in the August issue. The author uses Smooth-on and Alumilite products. Intersesting idea to use a heat gun to get out bubbles.

[S&G Rute of the Silver River]

so what are you gona use the wheels for? Verry interesting, I might be able to cast all them small plastic pices that keep breaking.

[FJ and G]

thanks, Rene, I'll be doing many other projects like 2 part molds and special trickey molds and will post results here.

I've seen articles before on this sort of thing and most leave you more bewildered and confused than before; I'm sure the article series will be thorough and easy to understand

[FJ and G]

Sorry S&G,

 

You must've posted when I replied. I'm gonna make a whole load of wheels in various sizes and spoke designs for 7/8n18 and 7/8n2 scratchbuilds.

 

The cost per axle of metal wheels in this scale is $9 so saving $$$ is what I've got in mind.

 

For my next casting project, I'll build a tipper from scratch and cast the whole thing (in several castings) 

[FJ and G]

Incidentally, I wass gonna approach GRR about doing a casting series; but I guess I'll have to can that idea 

[FJ and G]

Cast a bunch of new wheels with the 900 stuff I mentioned earlier. There was a problem with the paint interacting with the 900 and it’s all goey. The 600 stuff works b/c it cures fast (1 hour) but the 900 stuff takes 48 hours to cure so I’m surmising it must have not liked the paint. OTOH, I cast a call (below) with the 900 resin without paint and it cured properly. I added the paint after it cured. Lessons learned.

BTW, I may need to make new wheel molds unless I can get the goo out. Mold material is surprisingly expensive.



Here's the wall that I cast out in the garden. Used the 900 resin for the casting b/c I mixed up too much for the wheels and needed to use it up ASAP. You saw the latex mold in the last photo. I've got to add grey to the joints to represent mortar.



my helper

[dbaker48]

Dave you and BB are being paged at the CTT Toy Train Forum

[Anonymous]

Thanks for keeping the ooze informed for us!