Introduction: Printed Body Shell to Fit Powered Chassis
The body shell fitting a ready to run chassis came about a few years ago, I original scratch built one from plastic and quite a few people who saw what I had built wanted one too but didn't have the skill to build such a model. Four years down the line, I came across 3D printing, and while learning about the technology and what was possible with it, I had the idea of using the technology to replicate what I had built a number of years ago.
Still at a beginners level of making 3D models I used Google Sketchup which I feel is actually a good program for someone like me who isn't fantastic with CAD, but it is reasonably easy to use.
Step 1: CAD's, First Prototype
I originally designed the locomotive body to fit a ready to run Hornby chassis which was from a loco we call a PUG. The body is designed to fit the chassis of this model, which is slightly more complicated than it sounds, as I have to get all the mounting points correct for the motor to mesh with the gear on the driving axle on the chassis so this was quite challenging.
I original designed a first prototype which was designed as a one piece body shell, and printed by a friend on his works ABS / PLA 3D printer. This highlighted some problems with the print, which I noted down, but it was very useful to check the size, and the mounting points on the.
Overall the first test went quite well and lined up as expected.
Step 2: Revisions for Second Print
After the first print I took the decisions to remove some parts due to printing some objects having some pretty bad print layer lines, so I took the decision to remove the front door, the dome, the chimney and the filler caps. This was done to improve these parts quality.
After dividing up the model and modifying the cab slightly where it was too thin, I sent the model off for it's hopefully second and final print.
Step 3: Second and Final Prototype
The second prototype arrived, the body was printed using Hubs,and printed in grey resin using a Form Labs 1 desktop printer, where as the detail or small parts were printed by Shapeways as I had an order to go in for some other parts for other projects.
I was very pleased how the prints came out, and the detail was clearly visible. So being happy (for once) I assembled the body. .
Step 4: Assembly...
The assembly, this was quite straight forward as the previous prototype checked that the general idea and fit was correct so went on the powered chassis with no problem, using the original mounting points from the old body shell.
Most of the smaller parts although not 3D printed were all made by hand using brass, and copper and ay spares I had to complete it.
Step 5: Complete + Testing
The body was fitted the chassis, and taken for a test run, where it worked well after a bit of weight was added which was designed in to the model to add weight if required.
As you can see from the photo's and videos the model as an unpainted prototype is a great tool to show people what 3D printing can do, and the print has done what it was designed to do, which was to allow others to buy and build their own model.
To date I have sold 6 of these 3D prints, I have included the instruction manual as well for those who purchase one, which helps develop new models in the future.
I hope this has been an enjoyable read, although not the most complicated I like to keep things simple.
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