Mold making techniques

[Gary Rowan]

I watch Robert Tolone's channel on u-tube.

He just posted part 1 of 2 on making a mold for an HO scale loco:

https://www.youtube.com/watch?v=JCanxJ_rsgk&list=WLw

Part 2 (next week) will cover the casting process.

Thought the technique(s) might interest someone here.

[Jugtown Modeler]

With a bit of experience in mold making, I would caution using this exact technique.
Tolone certainly offers a lot of practical experience but I believe in this case there are some issues.
There are many ways to do this successfully. I am sure his will work although his part line mistake will be a challenge in the castings.

Many mold makers would argue that you should create a pour opening(s) and vent holes.
With clay, you can control the mold part lines, angle of pour and create more registration keys for mold alignment.

This video, while not perfect, demonstrates the techniques that would improve his mold:


Edit: A mold box would def help in keeping mold rigid when casting. The rubber bands in the video could lead to distorting the mold. A softer silicone would make for easier casting release.

Also, this is done by the distributor of the products.

To each their own. Like many aspects of this hobby, we learn what works for each of us and there is no one rule for all.

[Gary Rowan]

Part two is now up on the 'tube:

https://www.youtube.com/watch?v=12zCDEYNUtg

[Jugtown Modeler]

A bit disappointing in this sequel. I am not sure why that part line caused so much inconsistent casting results. But he knew it would be a challenge.

As I mentioned there is no perfect way to do this as each method can introduce variables with unforeseen consequences. This is definitely a learn by trial and error and $$ aspect of the hobby. But if you get get good, you can get some great results. A large pressure pot is a huge bonus and a whole other episode he does.

I would combine the techniques in his video and the Reynolds video:
A solid wooden 2 part box
mounted on a clay riser, possibly angled so air has a place to rise
Air vents
A pour/vent sprue

very quick sketch for where I would start. I do tend to overcomplicate things but no use in spending all this time and money for a crappy outcome.

mold.jpg

Note: For demo only. the steps would be a very difficult to cast in this example. Assume you'll add your own post casting...