A journal following the history, design, construction and operation of Bernard Kempinski's O Scale model railroad depicting the U. S. Military Railroad (USMRR) Aquia-Falmouth line in 1863, and other model railroad projects.
©Bernard Kempinski All text and images, except as noted, on this blog are copyrighted by the author and may not be used without permission.

November 24, 2020

Teaching an old dog new tricks

Many thanks to all of you that expressed sympathy on the passing of my mom.  It's been a rough stretch, but getting back into my modeling projects has been a good tonic. So I'm back in the shop, well actually mostly on the computer, as I restart work on the locomotive.  The locomotive build project and techniques I plan to use on it are evolving as I work on it.

First, last month I purchased a Anycubic Photon 3D resin printer on sale. The price was less than $200. I also got their wash and cure machine, a few bottles of resin, some rubber gloves and alcohol. So I started dabbling in some 3D printing. 

Since I am mostly interested in printing items that I can use on my railroad, I'm pretty much stuck learning how to do 3D drafting as very few fine scale models of civil war era stuff are available. I had a little prior experience with 3D drafting, but I needed to learn a lot more to be proficient. The best way to learn is by doing, so I dove in. 

First useful parts from the 3D printer
The Photon machine is capable of very high quality prints when everything works. So far my success rate has been about 50%. But, I have made some useful parts including a smoke stack for the loco, some civilian figures for the layout that I downloaded from various sites, and a test print of the cylinders for the loco. Learning how to do 3D printing is a skill, or perhaps art, all on to itself.  There are hundreds of YouTube tutorials and websites with help. So I won't cover that here. I will say that 3D printing does change how you look at modeling projects in much the same way that the laser cutter did when I got my first laser about 14 years ago.

As I discussed a few posts ago, I was planning on laser cutting the frame side rails along with some other parts from metal using a outside service. I still plan to do that for the drive rods and some of the valve gear. But, I think I will have the frame and the cylinders 3D printed in metal from Shapeways. Various folks have reported good success in printing locomotive parts in brass. Unfortunately, my frame is too large for their brass 3D printing process. I could cut the frame in parts and solder them together, but I think I will try make the frame in some other 3D printed metal. Shapeways makes their parts in brass using a lost wax process. They also have other techniques for printing steel (actually a steel-bronze matrix) and many other materials. The metal prints tend to be much more expensive than plastic and it looks like their surface texture is not as good, so I need to tread carefully here.

One of the reasons for opting for 3D printing, is I decided to draw the locomotive, or at least most of the critical dimensioned parts in Fusion360.  Since I was creating the 3D file, I thought it might be fun to try printing several of the parts.

The design of the rear of the boiler, the firebox and the back head are tricky and warranted looking at their geometry in 3D. The fact that the boiler is wider than the frame helps complicate the design. Also, the compensating sub-chassis also requires some tricky cutting of parts to make room for it.  So the 3D plan is helping me check all the fits and dimensions. For example, by drawing it in 3D, I detected a problem with my 2D drawing in the area of the back head and cab floor. I still haven't sorted it out yet, but the 3D exercise has proven useful. 

I am also enjoying learning the program, although some things are very confusing to me. I still haven't fully sorted how to align objects. Steps that would take me 10 seconds in Illustrator took me hours to do in Fusion360. One of the factors that made my life more difficult is that I imported DXF files from my 2D drawing to use in the 3D drawing. But, when it comes time to make changes to parts derived from the DXF files, things get tricky. At this point in my Fusion360 skill level, I find it easer to start with a fresh sketch in Fusion360.  Anyway, I'll keep plugging on. 

1 comment:

  1. Be careful with Shapeways printed metals.
    They are not dimensionally reliable and I wouldnt trust them for determining something as important as the driving wheelbase, especially with rods being lasercut. The brass is fairly reliable with a 5% shrinkrate on most shapes but the sintered metals are a little weirder. They are machinable however of what Ive heard, so you could always do the frames with the journal horns raw and machine to finished dimensions for accuracy.
    The CAD views are looking good. Im rather envious of that simple barrel firebox. Figuring out tapered cone dimensions was not a fun exercise.