Pattern making using 3D printing

[LukerParticipant @luker]

I was inspired by Jason’s thread and pictures of his Thompstone engine, so I took a few pictures for the “Pattern making using 3D printing” article. It morphed into a video, which I’m going to pay dearly for next time my beautiful wife wants to make a rotisserie chicken.

The video shows the 3D printed patterns and the (green sand) cast components. All these components are used in my various live steam locomotives, with all the patterns printed using ABS and cast in my back yard using a home-made waste oil furnace. The materials shown in the video include two different grades of cast iron, brass and alumina bronze, with most of the alloys mixed from scrap or base metals. The methods and techniques for this type of pattern making and casting is explained in the articles as well as methods to use these techniques for investment casting and flexible mouldings for those of us that enjoy restoring vintage bikes and need to make badges.

[LukerParticipant @luker]

[Ady1Participant @ady1]

very nice work

[Neil WyattModerator @neilwyatt]

Hi Luker,

I was impressed by your article in ME. You've had some really good results.

The only thoughts I had were that if you dig around in the settings in Cura (or whatever slicer you use) you should can adjust for any shrinkage to get accurate sized parts. You could even create a profile that prints oversize for patterns automatically.

The other is nozzles I buy them in packs of ten (they are very cheap) and I've only rarely had a duff one – you may have been unlucky. I treat them as consumables as brass ones wear quite fast.

Neil

[LukerParticipant @luker]

Thanks Ady, Neil.

I do actually use Cura, but I personally prefer to scale in the modelling package, with the pattern a linked part so it gets updated if the model is changed. The biggest problem with scaling in Cura is with items with a large hole (like eccentric straps or any part with a cavity in the middle that will be rammed); when scaling, the hole gets bigger but in the mould the metal shrinks away from the sand, again making the hole bigger. So you actually need to scale the part then resize the hole smaller to remove the scaling you’ve just added, minus metal shrinkage and any machining allowance.

Sadly the story in my article of the tips I order being liberated is actually a true story. I agree though if you can get the nozzles rather buy them. Incidentally the brass nozzle I made has lasted 2Kg and is still going strong, I’m not sure how long they should last?

The picture is of some castings from 3D printed patterns (cast iron) but the cavities required the resizing (smaller)…

[Brian HParticipant @brianh50089]

VERY interesting article. Are there any 3D printing materials that can be used in the same way as 'lost wax' ? That is without the need for runners.

I realise that this would destroy the pattern but it would be easy enough to print another.

Brian

[LukerParticipant @luker]

Posted by Brian H on 12/04/2021 17:54:37:

VERY interesting article. Are there any 3D printing materials that can be used in the same way as 'lost wax' ? That is without the need for runners.

I realise that this would destroy the pattern but it would be easy enough to print another.

Brian

Yep, that's in part 2

[Brian HParticipant @brianh50089]

Many thanks Luker, look forward to it.

Brian

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