Changing My Approach

Last week I made some drive rods for the locomotive project and installed them. I cut them on the laser from two layers of  0.025 inch laser board. Then I glued the layers together.  They fit very nicely on the crank pins that come with the Slaters Wheels.  This short video shows the trucks rolling on the track.

This rolling test rig demonstrates the effectiveness of the compensating beams. I will need to add some spacers or make some new bushings for the space between the wheels and the compensating beams to limit some of the sideways play the axles.

As I was working on this project, I've been searching the web for materials and parts. I came across several companies that offer laser cutting of metal. I found a shop in Utah that will do small jobs. They have  4KW and 8KW lasers that can cut up to 1 inch thick steel. That is 1000 to 2000 times more powerful than my laser cutter.

They have some neat software on their website that takes .DXF files and converts them to 3D depending on the material you select. Then their software examines your files for problems and if all is OK, you get an estimated cost (see figure below.) Since this looks so easy to use, I decided to use their service to laser cut my frame parts from 0.075 inch thick stainless steel. I will also submit drawings for the valve gear and some other parts to laser cut in 0.020 inch nickel-silver. The drive rods will be included in that file as well as the parts for the compensating sub-chassis. Since the nickel-silver material is only 0.02 inches, I will double the drive rods and solder them. Nickel-silver solders very nicely. The nice thing about laser cutting metal is that for small jobs the cost is much lower than photo etching. 

The draw back to this approach is that I now need to draw all the parts of the model before I submit them. My earlier  approach of designing as I go will not work. Also, I decided to move ahead with engine Leach. I am using the Talisman drawing to inform the Leach drawings. But Leach was a bigger and heavier locomotive. 

So, now I am in the process of drawing the model in side and front elevations. Those two drawings should be enough for me to create drawings for laser cut parts. I will do test cuts at home with 1/16th MDF and resin-impregnated laser board to make sure the fit and function are OK.

I have spent a good part of the week doing these drawings and ordering materials. It's kind of a iterative process as you must design your parts for size materials that you need. So depending on what is available, you adjust the drawing. For example, brass tubes for the boiler are limited in available diameters. I went with a 1.125 inch diameter boiler on this loco as Leach had a chunkier boiler than other engines. At 1:45 scale, 1.125 scales up to about 50.6 inches. White says in his book on American locomotives that most boilers were under 48 inches in this era. But the photos of Leach show a boiler slightly bigger at somewhere between 50 and 52 inches. I consulted with John Ott on this issue as a sanity check and he agreed. 

The image below shows the work-in-progress of the drawing as of tonight. I have about half the parts I need to draw for laser cutting done. The blue parts at the bottom are the frame parts. The silver parts are some of the valve gear. This drawing also shows how the motor and gearbox fit in the loco. I may not have room for much of a flywheel as it would extending the cab interior. 

Abode Illustrator drawing to plan out the laser cut part.

This image at the left shows one of my frame parts loaded onto Oshcut's website as I tested it for problems. This will be  0.075" stainless steel. Note how I was able to include the spring details on  the chassis. Those would have been very difficult to machine without CNC milling.

Screen capture of a .STL file for 3D printing
 of the smoke stack.

Since I was doing computer drawing, I decided to take a crack at drawing a smokestack for possible 3D printing.  See the image at the right.  I have never drawn a 3D part for printing before, so this is a first for me. I used Tinkercad to draw this smoke stack. I have Fusion360, but I am not familiar with it enough to try this. Tinkercad is very easy to use, though not as powerful as Fusion360 and some of the other 3D software out there. I exported the image as a .STL file and sent it to a friend that is doing some other 3D printing for me for Alkem Scale Models. His resin printer does a better job than Shapeways. I am curious to see how it comes out. 

Also this week I briefly considered getting a milling machine so I could cut the parts as needed from stock materials. But I decided the laser cut parts are probably superior for this project. I may get a small 3D printer though as they are much less expensive these days and the resin printers do a great job. 

So all in all it was a busy week with a lot of computer time both researching information and drawing.