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3D printing the vintage Russkit rear axle bracket


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#1 tjallen

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Posted 07 March 2018 - 06:23 PM

Scratchbuilders who build replicas of vintage slot car chassis often use the Russkit Bracket as a starting place. In the past, I have cut and bent similar brackets from sheet brass, and I wondered about trying to 3D print them. So was born a project, and here are some lessons learned.

 

First, I designed a Russkit bracket and uploaded it to Shapeways.

 

russkit%20bracket.jpg

 

The software at Shapeways immediately informed me that my design is too thin to be made in many materials, including brass. Shapeways will allow me to "print it anyway" as a test case. But in general, it seems that many things I want to make in brass will be too thin for 3D printing.

 

My next lesson was the expense! Brass is far too expensive at $14 each. Even plastics are $2-$5 each.  That's with no profit!

 

So I lined up 12 brackets -

 

russkit%20brackets.jpg

 

Again, a lesson in cost. Shapeways asks $107 to print my 12 brackets in brass! Paying $9 per bracket just is not worthwhile.

 

Why does brass cost so much to 3D print? Because they do not use modern 3D printing to directly print brass. Rather, a wax model is 3D printed, and the ancient "lost wax" method is used to make the metal object.

 

Shapeways says: "First, the model is printed in wax using a specialized high-resolution 3D Printer. It is then put in a container where liquid plaster is poured in around it. Once the plaster sets, the wax is melted out in a furnace, and the remaining plaster becomes the mold. Molten brass is poured into this mold and set to harden. The plaster is broken away, revealing your new product."

 

I guess I will be cutting and bending brackets by hand for a long while to come!


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Jimmy Allen




#2 Dennis David

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Posted 07 March 2018 - 08:14 PM

Common 3D FDM Printing is a layering process not suitable for these kind of brackets. These brackets should be stamped. 


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#3 Bill from NH

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Posted 07 March 2018 - 09:36 PM

Jim, had you thought of cloning a contemporary forged inline motor bracket, similar to the one Al Penrose sold or the one Professor Motor now sells? Paul Painter on the west coast sells one too. Each is considerably thicker that the popular Russkit.


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#4 Dennis David

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Posted 07 March 2018 - 10:48 PM

That bracket would be perfect to get machined.


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