Green Twin Oscillator Cast/Build

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MetalCaster:
And did I mention that if you get too excited and open your petrobond-rammed flask too soon after pouring cast iron, the cloud of smoke that is generated will burst into flames and singe off most of your eyebrows (the excitement was suppose to be over, so no face mask).

Well, it will.
Lesson learned.

MetalCaster:
So far, my gating and risering have been rather crude, and as someone mentioned, you don't need a very sophisticated gate and riser system for models, but I do have some larger castings in mind, as well as some match plate work I want to do, so it is important for me to try and understand how to get a functioning system.

I heard from one casting kit guy who had his match plate sent back to him from the factory because it would not pour right, and he had to rework the runners on his match plate and send it back to the factory a second time.

I have studied the Navy Foundry Manual, the Gates and Risering book, and several other old casting books.

The methods are as varied as species of dogs, but what I am after is a relatively simple gate and risering system that serves the intended purpose, ie: prevent air aspiration in the sprue, reduce turbulence to a minimum using a sprue basin and tapered runners (too much turbulence and pouring too fast can entrain air in the melt), provide a dead end to trap lose sand, tapered gates above the runner to provide a maximum of slag skimming, provide equal pressure at each gate by varying the size of the runner (if necessary for larger castings), provide risers where required for shrinkage control, install gates located at the largest part of the casting, if necessary usee some form of solidification control like a cold shunt, or at least be aware of potential solidification problems which can crack your casting in half, and venting the air and if using water-based sand, steam from the core and mould.

Here is what I have so far for a disk shape such as a flywheel.
Have not tried it yet, but am working in that direction.

MetalCaster:
They have mould-filling computer simulation programs now which allow simulation of various mould, gate and risering configurations.

While I don't need the program, it is important for me to be able to visualize metal flow, temperature gradients etc. so at least I can think in terms of what is happening in the mould.

The video mentions that if you try and fill a mould too fast, the air and or steam may not have time to escape, and also filling the mould too fast can cause too much turbulence, and entrain air.

And this video is amusing, since this is the mistake I made, no weights on top the flask.
And it is hilarious, some guy asks "what kind of sand is that?". The guy answers "petrobond", but it is just a simulation, there isn't any real sand. Its just pixels on a computer screen. :lol:

Jasonb:
Good to see you back on this one Pat, look forward to seing some more progress now we are upto date.

J

MetalCaster:
Thanks Jason-

It is time to do some more castings.

Pat J

Edit: This engine really does not seem to draw much interest here. Maybe its all been seen before, or too long winded, or just no interest in steam, not sure.

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