Tuesday, February 6, 2018

CN Woodchip Cars - A Follow Up

The CN woodchip car project is still going on. Given it is the only set of cars missing on the layout before calling the rolling stock roster complete, I’ve decided to work again on it as information will be available. I won’t stress enough the help Justin Babcock has already provided and which insure these models to be as accurate as one can be. This is even more important since these cars have not visited Quebec City area since many years.

This is a sketch, not a scale drawing

One of the reason why I started the project again was Julien Boily’s interest in acquiring a few of these woodchip cars. A few years ago, printing one car in Shapeways Frosted Ultra Detail (FUD) material was expensive… really expensive. Well over 160$ (Canadian dollars) per car and mind you, I worked a lot to make sure to trim down any excess material I could to drop down the price. A recent visit on my Shapeways account shown these cars could be printed in FUD for about 72$, which is quite high, but an impressive improvement. Given the price halved over a few years is a testimony to this technology becoming more mainstream.

In the best of worlds, I would print prototypes, make a few silicon molds and recast them happily. The truth behind this is I’m not equipped to do so and know very well it would cost me a sweet amount of money just to get started, experiment and get comfortable enough with the process to handle it with confidence. I’m always happy to learn new things, but I’m no super hero and I still have plenty of stuff on my benchwork (highway overpass, roads and streets, several structures including very large ones). However, I’m open to work with anybody wanting to push it forward.

This is a sketch, not a scale drawing

In the case of Hedley Junction, we need about 10 cars. Given series 878 000 had 300 cars and series 879 000 had 500 cars; the ratio is 3:5.  In our case, having four 878 000 cars and six 879 000 cars would be plenty enough for our needs.

As thing are standing now, series 878 000 (of CN Rail fame) 3D model is complete. I still want to refine a few details, but I would call it almost ready for printing. For series 879 000, nothing has been done yet. However, both cars have similar features, meaning what I’ve learned on the 878 000 can be adapted to 879 000. It is my goal that both models can be available on Shapeways at some point.

Another step will be to create accurate decals for these cars… That could be tricky…


  1. Very nice! What’s your plan for weight?

    1. René, as much as possible, I would like to conceal them as much as possible and keep the interior free of protuberance. NMRA recommends about 5 oz. of weight for this car (I think it is a little bit on the light side though). They are two options which are both compromises. First, sandwich a lead sheet (about 2mm thick) between the frame and underframe. That would probably raise the floor level about 2 or 3 mm above the prototypical height. Under normal viewing it wouldn't be detrimental, however, the cleanout doors would no longer align with the raised floor. The other option is taking advantage of the low side sills to hide weight directly under the car. It wouldn't impact the floor and would be almost unnoticeable on the layout. Brake rigging could be added after. This is the method often used to add weight to flat cars and gondolas. Finally, a third option would be similar to what Rapido did with their mill gondola and use a steel plate to model the floor. A 1/8" thick steel plate would be sufficient though it would raised the floor quite a bit. Also, it would need to be perfectly straight and glued to the delicate underframe. Not a recipe for a great succes.

      Under such circumstances, given the open interior is more important than a well hidden underframe, I feel the best option is stuffing the underframe with lead. With some care, the weight could be easily concealed as much as possible.