My 3D printed kit for a HO Baldwin RT-624 was released in August last year. The kit included the main body shell, 3D printed crew, and details, and also available was an etched brass fret with handrails, grab irons, and details to finish the shell.

The kit was designed to fit onto a Bower HO C-628 or C630 chassis, as shown below, and a 3D printed kit to rotate the trucks was also made available.

The basis for both of the kits was my previous release of my HO Baldwin DT6-6-2000 which, just like the prototype, was the RT-624’s predecessor. The chassis modification kit for both locomotives is the same, but the body kits are quite different once you start looking at the details.

When creating the 3D model for the RT-624, I used my model of the DT6-6-2000 as a starting point and modified it as required. But as is often the case with obscure locomotives which are no longer in existence, finding exact information can be tricky and some of it had to be assumed from photos and film.

However one of my fellow modelers, Gus Foster, has kindly been helping me to fine-tune the model and update some of the finer details for the PPR RT-624 models.

The first and possibly biggest update I’ve made is the difference between the DT6-6-2000 and RT-624 cab windows. The DT6-6-2000 has three window panes and they’re high up on the locomotive, as you can see below. (A Baldwin Locomotive Works builder’s photo https://www.american-rails.com/20001.html)

Whereas the PPR RT-624’s window is lower, narrower, and consists of a pair of panes. You can see this below with PPR 8956 at Zanesville, Ohio, July 23, 1954. (Photographer Paul B. Dunn).

Why I hadn’t noticed that the window was lower was because that would make it very close to the cab floor, but as Gus pointed out, the floor on the RT-624 was lower. There’s a seam you can see running horizontally under the window; this is where the cab floor is fitted in. So in my 3D model, I’ve corrected the windows and lowered the seam marking the cab floor.

Also in the view above, I made several small changes. At the left of the image in the walkway, just before the step, is the cab signal box opening. For my original 3D model I’d scaled this from a photograph, but I’d made it a bit short. Gus was able to give me some more accurate dimensions. But, as you may have read in a previous post (A Baldwin RT-624 in HO – Part 5) the depth of the cab signal box opening had to be reduced to fit the chassis, you can see the first test print not fitting below.

With the cab signal box opening now increased but made shallower it didn’t look right. My solution was to fill the opening in just the same way as the original. Going back to the 3D model below you can see the opening is filled, just like the opening in the photo of PPR 8956 at Zanesville.

Gus also pointed out the fuel fill, which is the circular detail under the bottom left of the cab, which was originally too far to the left, the access hatches under the cab were a little too large and there should have been two more. As you can see above, these have also been updated. The last thing Gus helped point out was the tiny angles on the underside of the plate where it meets the walkway. In the image below this is just to the left and below the brass handrail stanchion. On the original model, this was horizontal.

However, when adding this little detail I spotted something else. A big difference between the DT6-6-2000 and the RT-624 is the walkway with the cab signal box opening, because it’s longer, creating one odd handrail and three which are the same. This I had already modeled. But what I’d assumed was that the handrail on this odd side would be the same just with the crank further along. But that’s not the case. The three regular handrails, just as the four on the DT6-6-2000, have eight stanchions. This is shown on the right in my 3D model below. But the odd one, on the left, above the cab signal box opening, only has seven and they are spaced out further.

Looking back at the photo of PPR 8956 you can see this.

Having changed that in the 3D model it gave me a dilemma because it changed the etched brass details. Not only will it require a new etched brass detail but the layout would no longer work, the previous layout relied on the handrails fitting together to save space, but with one set having an odd number of stanchions at different spaces that couldn’t happen. But after a few attempts at moving everything about I managed to make it work like this.

I also took the opportunity to slightly increase the thickness of the windscreen wipers and add a second pair as the original set was very delicate and prone to bending before they reached the model.

Thanks to Gus, the updated HO Baldwin RT-624s are now available to order. All the parts are available from the links below;

Early PRR HO RT-624 Body Shell

Late PRR HO RT-624 Body Shell

3D Printed Detail Parts (For both versions)

Etched Brass Additions (For both versions)

3D Printed Truck Rotation Kit (DT-6-6-2000 Kit also for all RT-624 versions)

The next version of this locomotive will be the single Minneapolis Northfield & Southern locomotive numbered Twenty-Five which I’ll soon have finished.