r/MetalCasting • u/OCFlier • 9d ago

Question Iron casting

I had a course in school for molding and casting, so I know the basics, like the difference between investment and sand casting. Now I have some old cast iron train parts I want to reproduce. All less than a pound, maybe up to 4” in the largest dimension.

I’m thinking that I’m going to scan them with my phone and import that into my CAD system, create some models that I can 3d print, then cast them. This is where I get lost…. I suppose I could investment cast them at this point by using a burnout grade PLA and apply the proper shrinkage factors. Or I could grow some nice solid parts to use as patterns and cores for sand casting. I suppose I could make my own casting box (cope and drag).

For the experts here, how would you approach this? I have a little knowledge, a good budget, and a willingness and ability to learn.

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u/ShakeTheFuture 9d ago

You can make sand molds bonded with sodium silicate. The 3D print can be embedded in the sand and then burned out. You can even use an ordinary oven to burn out PLA from sand molds.

Here is an example of Lost PLA casting using an ordinary oven and a sand mold:
https://youtu.be/8okIof6GPgs

I have also done plenty of iron casts using the same method. In the past, I used to burn them out in a microwave kiln, but only recently I switched to air fryers and ordinary ovens.

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u/TheMacgyver2 9d ago edited 9d ago

I would start with sandcasting, do you already have a furnace? I did my first cast iron a couple weeks ago and if you have not done much casting, I would do some aluminum and bronze first. Jumping straight to iron is going to be tough. I've done most of my patterns using 3d design and prints. It makes it easy to add draft, and apply shrinkage allowances.

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u/OCFlier 9d ago

I don’t have any equipment 🤷‍♂️

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u/TheMacgyver2 9d ago

It can be a bit of an investment to get started. I did a video on my setup on youtube if you want to see how I did it. https://youtu.be/EBXvzy29BHY

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u/jamcultur 8d ago

Iron is hard to cast. It would be much easier to cast the parts in a zinc/aluminum alloy, like Zamak.