07/16/2024
Len Winn has been hard at work again. Below is his description of his efforts to model:
STEPHENSON’S ROCKET
An experiment in 3D printing
The Model Engineering Website is well worth visiting and features all kinds of models. https://modelengineeringwebsite.com/
While exploring the site I came upon the plans for a stationary model of Robert Stephenson’s ‘Rocket’ modelled and drawn in metric by Julius de Waal of New Zealand. The plans are free to download for non-commercial use. He has also produced a number of other excellent designs which are at the same website.
My initial intention was to attempt to make a half-size version of the model using whatever material worked. Half-size because the model was too large for the space I have available – equivalent of 10” rail gauge and close to 4 ft long including tender.
As a result of numerous conversations and my own curiosity I then decided to try to make the model using primarily 3D printed parts where possible. I acquired an unused but assembled Anycubic Kobra Neo 2 3D printer on Kijiji and started 3d modelling all the parts in Alibre Atom 3D software in order to produce the STL files needed to convert to gcode that the printer could use. I probably used up about a third of a roll of filament making junk parts as I learned what seemed to work best for part support, bed adhesion and part appearance.
After some thought I decided to make the loco chassis out of metal for rigidity as I thought 3D printed parts would be too flexible and I would have to create joints to make pieces which could fit the capacity of the printer bed. This has proved to be a good decision however the loco is more than 90% 3D printed, the tender 98%.
I’ve been impressed by the dimensional accuracy of the 3D printed parts and have had to do very little post-print adjustment other than removing bits of flash. The hard part was figuring out how to show rivet heads particularly on the front and rear plates of the boiler ( the equivalent of front and rear tube sheets ) and the fire box as these show rivet heads on both sides. I was not satisfied with the appearance of 3D printed rivets on test pieces so I settled for the tedious job of cutting small copper and brass rivets to length and gluing them in place using JB Weld Super Weld a cyanocrylic product that cures in 10 seconds. After much time and approx. 800 rivets later the job was done.
Apparently Stephenson painted his original in black and yellow so I did the same. There are museum photos showing the smokestack painted white – I could not persuade myself to paint a smokestack white so mine is black.
Julius de Waal shows his model running on cast-iron fish-belly rails so I have done the same, all 3D printed.
This has been a rewarding and challenging project and I am quite pleased with the results
Len Winn
July 2024
