Just leaving this here until I find out which mechanism I have to play with. It belongs to a friend, Andrew Gillette. He TOLD me .. just forgot since.

Some Sketchuping

This is my working model(s) around the SD40-2 mechanism. I have basically copied the inside of the HO body where it fits around the mechanism then added 1/8″ thickness (think frame). The cab shown is an Atlas O scale U23B. The idea is for a narrow gauge road engine.

Minimum Shell

This is where I started. The surface in gold(ish) is the inside of the HO SD40-2 shell which I replicated as best as I could. This includes the coupler pocket location. I then made walls 1/8″ thick. This then was the ‘starting point’ from which I built off of.

Step Test Print

This is a test print for the steps that will go at each corner of the locomotive. I printed the test step on it’s back. This puts the supports on the backside .. hopefully meaning that we end up with a good print (good meaning ‘good nuff’) for the finished model. I printed this on my Prusa MK3 I3 in PLA using a .4mm nozzle and .15mm layers.

This photo shows the print still sitting on the PEI sheet.

Cleaned up (some)

The supports pealed off mostly – cleaned up just a bit with blade and file. Some sandpaper would be good .. primer and sanding even better.

Shell Test #1

At this point I worked the model up to a point I could do a test print. Before I go any further I need to insure that what I have will fit over the mechanism. I will print this and then go from there after seeing what needs to be changed. The body itself is nothing more than a shell.

Test Print #1

I printed this last night and .. it works. The print fits nicely over the mechanism. I haven’t checked the fit of the couplers yet (need more coffee) but that is a minor issue at best.

The small ‘cab clips’ would snap into slots on the Atlas O scale U23B chassis. I have doubts that I can make such slots on this print – probably will just slice them off.

The ‘mechanism frame’ is a bit of the mechanism that will be covered by extending the bottom of the print out to create the frame of the locomotive.

Leave a Reply

Notify of