3D Printing Functional Bronze Propellers

[Patrick Matthews]

In functional boat and ship models, many modelers use brass props made of stamped blades soldered to machined hubs. Nicer props, having a more realistic shape, are made by casting in brass or bronze. The process used for these is lost wax, or investment, casting. Usually, the waxes are made by injecting wax into a rubber mold; the rubber molds can be made from a carved or machined master.

 

Should you need a unique prop design, you’ll need to commission a master and a mold; don’t forget to allow for casting shrink when you specify the master! Need a left and a right? Twice the masters and molds.

 

Another option? 3D print the waxes- no need for masters, no rubber molds, and complete freedom to scale and mirror the design.

BTW: You can also machine the waxes on a 5-axis mill… but that’s another challenge.

 

But if you can create a 3D CAD model of the prop, and don’t mind machining the bore yourself, you can use very convenient 3D printing services like Shapeways to source your own custom props.

 

In this example, I made some props for Monterey Clipper fishing boats, using the Yuba-Hicks “weed cutter” design that many of these boats carried. While it’s possible to draw a convincing prop from scratch with some basic knowledge of prop blade shape, I had the benefit of the original factory drawing to work from:

 

CAD rendering of the design:

 

Raw cast bronze prop from Shapeways-  2.5” diameter:

 

From the same CAD model, a 2.25” opposite hand prop (on left):

 

Machining the bore and threads on my lathe:

 

Prop with a 3D printed Hicks engine model:

 

The 2.25” prop went on this 1:8 scale model Monterey:

[Archi]

Super!

[Matle]

Beautiful Did I understand it right, that you print the wax, make a mould and then cast the final propeller, or am I missing something? What kind of material can you print the wax in?

[wefalck]

The wax is being printed, i.e. extruded hot from the printer's nozzle.

[michael mott]

Very nice.

 

Michael

[CDR_Ret]

I tried to get Shapeways to print a Cold-War submarine 7-bladed screw from an STL file I created in Blender. However, at the scale I intended, the online evaluation tool said the blades were too thin. Anything thicker would have looked wrong, so I gave it up.

Terry