fr8kar: GE Universal Series/Dash 7 Series Cab

From the U33C and C30-7 models released in the 90s to the U30C, U30B, B23-7 and B30-7 released in the 2000s to the newly released U33B and U36B, Atlas has done more than anyone else to fill holes in the rosters of those modeling GE locomotives of the 70s and 80s. To a large extent Atlas gets these models "right" as far as dimensional fidelity to the prototypes is concerned. Having said that, one area Atlas has fallen down is the cab.

I've read where others have pointed out the issues with the Atlas cab but I couldn't ever find any hard data on what was wrong. The front face of many of the cabs looks wrong - windows too small, windows too big, funny shaped doors, numberboards and headlights that look squeezed or in the wrong place. Nothing about the cabs seems right, but what specifically is wrong? Then there's the Hi-Tech cab, a nice little kit with several options. But I've read people have issues with it, too. So who got it right?

First of all, I set out to find some hard data on the prototype. First choice would be some nice straight-on photos of the cab and some overall measurements. I figured I could proportion out the dimensions of the windows and numberboards with the right photo and a good known measurement. The problem is you're not likely to find a position to photograph a locomotive cab where anything is straight-on since most photos are taken from ground level. Eventually I found Bill Kaufman's locomotive simulator website which features some cool simulators he built using old GE cabs. I asked him if he could measure across his simulator or provide me with a photo taken straight-on. He did one better than that, way better. Bill shared with me some cab drawings from GE that answered all my questions. I was able to create my own CAD file from the scans Bill provided. I also made CAD files of the various Atlas and Hi-Tech cabs.

The early U33C models came with one of two cabs: standard front face window arrangement and SP "L window" arrangement.

The first run C30-7s had cabs with open auxiliary side windows or the later version without the auxiliary windows.

Between the two models all the cabs had windows that were off in size and location. The most obvious issue was the top of the cab door and top of the engineer's front window were even with the top of the center windows. The size of the numberboards and both the size and shape of the headlight housing was also off. The shape of the door differed between the front and rear cab face (Atlas seemed to execute the door better on the back of the cab than the front though the size of the door window was off).

The second run of C30-7s addressed the position of the windows, but they were still undersized. The rounded headlight housing was squeezed too thin and was undersized.

Across all of these versions of the GE cab, the central rounded portion of the roof was too wide and the angled outer portions were flat instead of rounded.

Hi-Tech made several detailed GE cab kits similar in design to Cannon's line of EMD cab kits. The flat kit design incorporating thin walls, separate doors and detail parts made it easy to build a nicely detailed kit.

Hi-Tech also offered a version of the four window cab with plugged auxiliary windows, an effect not convincingly pulled off by Atlas when they simply painted over the glazing in the auxiliary windows. I corrected this on some of my Atlas cabs by cutting in the Hi-Tech cab sides:

In spite of the nicely executed details and well proportioned windows of the Hi-Tech cab, the roof suffered from the same problems as the Atlas cabs from the U33C to the C30-7 to the U30C, only with an even wider central curved section. The narrow numberboards were also a problem with the Hi-Tech kit.

When Atlas released the B23-7 and B30-7, the cab was a new design unlike the models preceding it. The numberboard/headlight housing was a separate part, the cab base on the engineer's side had a noticeable difference in height just as the prototype and the proportions of the windows, cab doors and roofline matched the prototype much closer than previous attempts.

The headlight housing is still too narrow and the headlight assembly is mounted too low between the numberboards, but still not bad.

Before I get too far ahead of myself, let's take a look at these cabs and compare them to the prototype. In light of the errors in the cab windows of the first C30-7 cab, it's not even worth considering. But the later C30-7 cab, the Hi-Tech cab and the B23-7 cab are all worth looking at.

Here is a drawing of the prototype overlaid on a drawing of the Atlas 2nd run C30-7/U30C cab. The prototype is in green, the Atlas cab is in red:

Here is the prototype, again in green, compared to the Hi-Tech cab in blue:

And finally the Atlas B23-7 cab in purple compared to the prototype in green:

So, between the three, the Atlas B23-7 cab is good enough, right?

I'd use it if I could.

Trouble is, like the B23-7/B30-7 fuel tanks, the cabs aren't readily available as spare parts from Atlas. So what to do if the one good cab isn't available and all the others that are readily available have serious issues?

I initially thought I could cut in the good parts of the Hi-Tech cab into the Atlas U30C cab. But there's really no way to get the side walls of the Atlas cab thin enough to allow the front and rear Hi-Tech walls to fit without a ton of work. Then the roof is still wrong. And I'd still need a source for the numberboards since as bad as the Atlas numberboards are the Hi-Tech numberboards are worse. I wanted to avoid 3D printing not because of the quality possible but because of the cost. I figured a detailed printed flat kit like the Hi-Tech kit would cost around twenty bucks, which means I would be spending hundreds getting my fleet up to par. But as long as the Atlas B23-7 cab is so hard to find, it seems like printing is the next best solution.

An advantage printing the cabs offers is the ability to create versions of the cab that were specific to particular locomotives, such as the Santa Fe B23-7s with nose-mounted air conditioners and antenna ground planes or Southern Pacific's "L-window" cabs that were fixed to accept two panes of glazing in place of the single large L-shaped glass. The other advantage is the cab isn't close to the prototype, it is a scaled down version of the prototype. The green outline in the prototype vs. model images is not just the drawing of the prototype, it's the CAD file I used for the model. So aside from the limitations presented by the materials I'm using to print the cabs, these things are as close as I can get to the real thing.

Here are a few shots of the first printed prototype: