3D printed parts and Lightwave 3D


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Lightwave 3D and an old Mac

The physical model loco is mainly balsa, but I’ve made a number of 3D printed parts from PLA (polylactic acid) plastic. I usually model the 3D parts myself using a program called Lightwave 3D from Newtek.

Lightwave has been around since 1990, popular at the time on the old Commodore Amiga computer platform, and has been used in many TV and movie productions. As I’m writing this, Lightwave is currently in its 2020 version, but I’m using the 2014 version 11.6.3 on a beefed up 2009 ‘cheese grater’ MacPro (SSD, a pair of 4 core Xeon CPUs, 24 GB RAM and an Nvidia GeForce GTX 980 GPU with 4 Gigs of VRAM). At this time of writing in 2020, an 11 year old computer and 7 year old 3D software are more than holding their own… just a little slower than current offerings!

Lightwave is not a CAD program as such, but is really intended for artistic style 3D modelling and animation for TV and movie production etc. Lightwave provides a 4-view workspace, which I find easier than the single view workspace common on many other 3D modeling programs such as Blender, which I would like to learn. I learned Lightwave when studying at TAFE and University in the early 2000s, taught it at TAFE and have stuck with it ever since.

If you visited the Coupler page of this site, you will see that I got the coupler 3D model file from the net, and then modified it to suit using Lightwave. The loco horns were also ‘off the shelf’ from a 3D model library, again modified in Lightwave to suit my model.

The Handbrake Assembly

Handbrake 3D print installed. Click image for larger view

The vertical slot in the side shown in pic above was cut out of the balsa at the early stages of construction. At the time I didn’t know how I was going to model the handbrake, not having a 3D printer. After buying the 3D printer, I modeled the handbrake assembly in Lightwave at actual size so the 3D printed part would fit into the balsa hole. A real piece of tiny chain was hung from the curved top cover, down into the hole at the bottom of the frame. Below is the hand brake assembly (minus the chain) in Lightwave:

Handbrake 3D model. Click image for larger view

 

Roof Fan Assemblies

Here’s the fan blade 3D model for the three fan assemblies on the roof of the loco. There’s a top view, two side views and a 3D view which can be orbited around to any position in 3D space.

Fan blades, Lightwave 3D model. Click image for larger view

Shown below is the Lightwave model with the fan housing, fan blades and grille. The components are on separate Lightwave layers, so they can be exported easily for printing.

Fan assembly, Lightwave 3D model. Click image for larger view

 

Fans and Horns: From Lightwave to 3D print via Cura

The components are exported from Lightwave as .stl (STereo Lithography) files, and opened in Cura software. Cura is companion software for Ultimaker 3D Printers, but made available by Ultimaker for free (got to love that!) and is not limited to Ultimaker printers. As the 3D part will be printed in ‘slices’ or layers of plastic, Cura’s job is to virtually ‘slice’ the stl geometry and create Gcode (3D printer-specific geometry and instruction code).
In the Cura screengrab below, the cube is a representation of my printer’s build volume – a reasonable maximum print size of 200W, 200D, 185H.

 

Fan blades, loaded into Cura for 3D ‘slicing’. Click image for larger view

The grid represents the printer’s build plate. The model part can be scaled, rotated etc. and other printer-specific adjustments can be made, such as whether the part should be solid or hollow; if it’s hollow, then how thick the wall should be; whether it will need supports (common for any overhanging geometry); the temperature of the build plate (for adhesion during printing); print nozzle temp (depending on the kind of plastic being used) and so on.

There are a number of plastic filament types; PLA and ABS are the most common – I use PLA (Polylactic Acid – much cheaper than ABS). Also available is filament that prints to look like the model is made of wood, metallic filament, filament that glows in the dark, and a range of solid colours. Some printers can print two colours or two types of filament at once, but mine is a single-nozzle printer; if I want to change colours, I have to go through the rather time consuming process of changing the filament.

Gcode

When the model is ‘sliced’, Cura generates the Gcode, which is transferred to the printer via an SD card (I tried using the USB connection, but couldn’t get it to work). The Gcode contains all the geometry as well as all the printing instructions for that particular 3D part.
Printing is a slo-o-o-o-w process; Cura shows a print-time estimate and how many grams of plastic filament will be used. If you set Cura up with filament costs (sold by weight rather than length), it will also show how much the part will cost to print.

The 3D printer

I have a Cocoon brand printer sold at Aldi, but it’s actually a rebranded Wanhao Duplicator i3 from China.  When I bought it, it came with setup profiles, which along with the operating setup instructions, weren’t much help. Fortunately I found some helpful Wanhao Duplicator setup tutorials on YouTube, and just used their settings instead. Used in conjunction with Cura, most of my 3D prints have been fine, although some require a bit of tweaking to get it right. It’s all a learning process!

The Cocoon printer has been reliable and performed well but for a brief problem when a solder joint in the print head heater came adrift. I managed to pull it apart and re-solder it, and so far, it has been working well again.

3D printed parts

To help the printed part stick to the build plate, a skirt of extra plastic is printed. This is broken off and discarded when the print is finished. Click image for larger view

 

3D printed fan assembly components. Click image for larger view

 

The Dynamic Brake fan assembly installed. Click image for larger view

The fan blades can turn, but there’s no motor. The tolerances of the printed components of each assembly were good enough so as to be able to snap the parts together without having to use glue.

 

3D printed parts awaiting installation (door is balsa). The two large circular roof cutouts at the front of the long end are for the radiator fan assemblies. Click image for larger view

 

If parts have to be glued, either Superglue Gel or a hot glue gun does the job. In the case of complex assemblies, such as the horns, it’s easier to 3D print multiple parts and glue them together after.

3D printed horns. Click image for larger view

There are two horn clusters; one on the short end nose and the other on the roof of the long end near the Dynamic Brake fan assembly (close to the cab). There are supposed to be 5 horns in each assembly; 3 large and 2 small, but the printer wasn’t physically capable of printing the small ones (around 9mm in length) without them melting (maybe my Cura settings are wrong), so I just made 3-horn assemblies instead of the 5-horn assemblies they are supposed to have.

Because of the small size of the larger horns (22mm long each and very narrow at the neck), the printer did an average job, so I finished them off with a hot soldering iron (not a great smell!). Maybe I’ll find some small plastic horns in a model railway or toy shop somewhere, or do a bit more experimenting with the settings in Cura.

 

Long end 3D printed radiator grilles were painted and glued into place on the sides with Superglue Gel and clamped until firm. Click image for larger view

 

3D printed horns, and exhaust stacks. Handbrake yet to be fitted. The Dynamic Brake fan assembly is on the roof near the cab; the two radiator fan assemblies are on the roof at the front of the long end. Yellow painted railing is made from sprue left over from a model aeroplane kit. More 3D print and sprue railing along the full length of the long end will be added later. Click image for larger view

Ladder

in its earlier years the X 31 locomotive did not have railing running all the way along both sides of the long end, but the loco’s current owners Seymour Railway Heritage Centre have installed full-length railing and an access ladder.

 

Actual X 31 ladder; Lightwave 3D model; ladder 3D print with adhesion skirt;
skirt removed; ladder painted and attached to balsa model with hot glue gun.
Click image for larger view

Side Railing and End Guard Rails

I tried to print the long end railing entirely in 3D, but the rails proved too difficult to print without distortion. Instead I decided to model the vertical posts in Lightwave, 3D print them and fit rails made form sprue left over from a model plane kit. In Lightwave, I made holes in the post heads just the right diameter to accommodate the sprue rails.

As the model side railing required 18 posts, it was easier to model one post in Lightwave and clone it 7 times to make a row of 9 posts. For ease of 3D printing, the row of 9 posts was cloned and flipped so that the two post gangs were adjacent to each other at the head ends. In Cura, the print was set to have a wide build plate adhesion skirt, which would also act as sprue to hold everything together. After printing, the skirt was removed, freeing the individual posts.

 

Two gangs of posts set up in Lightwave modeler. Click image for larger view

 

Posts 3D printed. Adhesion skirt acting as sprue. Click image for larger view

 

Fitting the posts to the model aeroplane sprue rails. Although the sprue rails had a snug fit into the post head holes, a small blob of Superglue Gel made sure the posts and rails would stay fixed where set so they wouldn’t warp or twist when attached to the balsa model. The original 3D printed rails at the top of the image were not suitable due to a limitation of the 3D printer on such thin objects, causing strings of PLA to peel off when the supporting skirt was removed. Click image for larger view

 

Brake Cylinders and Pipes

Each bogie has a set of three brake air cylinders fitted to each side, along with a brake shoe actuating levers and air supply piping. Another job for Lightwave and the 3D printer!’

3D printed brake cylinders and brake shoe assemblies. The slot in the rectangular brake shoe assemblies allows them to fit around each wheel so that the integrated brake shoes appear to hug the wheels in the correct position… no, they don’t work! Click image for larger view

 

Lightwave model of brake cylinder and brake shoe gear, and below, a complete Lightwave bogie with the clyinders and brake shoe gear fitted.
For the balsa model, only the clyinders, brake shoe gear and air pipes were 3D printed.
The Lightwave bogie is from the other part of this project, the complete X 31 virtual model.
Click image for larger view

 

The side rails and brake assemblies have been fitted. A pair of Lightwave/3D printed hand rails have been fitted along each of the long end sides, above the yellow stripe. Click image for larger view

 

Staff Exchanger

On one side of the cab below floor level, the X 31 has an automatic staff exchanger. To help avoid train collisions on bi-directional railway tracks, a small wooden or metal staff had to be exchanged between the locomotive crew and local station assistants before the train was allowed to proceed to the next section of the line.

Previously, the exchange was performed manually with the aid of an attached hoop at low speeds; if someone dropped the staff and the loco crew didn’t get the replacement staff for the next section of the line, they had to stop the train and go back and get it!

Early developments of mechanical exchangers were fitted to Victorian Railways locomotives from the mid 1920s, along with corresponding station infrastructure which enabled the exchange to occur at higher speeds (up to 40 mph / 64 kmh). The loco exchange arm and hook, such as fitted to the X 31 would be lowered for the exchange and retracted afterwards.

Modelling of the hook in Lightwave was a bit of a challenge, and 3D printing it without breaking it was even more challenging!

 

The automated staff exchange mechanism was modeled as a complete unit in Lightwave, so that the 3D print could be inserted into the hole made for it in the balsa model.
Click image for larger view

 

The 3D printed staff exchanger fitted to the balsa model… not easily, however. I had made the hole for it too small and had to cut into the MDF and balsa (without breaking it!) to make it fit.
Click image for larger view

 

Sand Boxes

To assist with traction on slippery rails, sand can be dropped onto the rails from a set of sand boxes fitted to the underside of the loco build plate. There are 4 sand boxes on each side, each of which have curved pipes terminating with nozzles placed just above the rails near each bogie’s front and rear wheels (i.e the centre wheels in each bogie group of 3 wheels per side do not have sand pipes).

One of 4 sandboxes per side on the X 31; Lightwave version; a pair of 3D printed sandboxes; a sandbox fitted to the balsa model. The yellow reflector is made from paper, glued to the plastic p3D print. In the Lightwave model, the yellow section is created slightly in relief so the corresponding part of the 3D print can serve as a positioning guide for the yellow paper sticker.
Click image for larger view

 

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