A Baldwin RT-624 in HO – Part 5

My apologies for the lack of posts over the last month but this week I have an update to share with you on the Baldwin RT-624 project; the test print has arrived.

The photo above shows the shell and parts after they’ve spent twenty-four hours in white spirit which was used to remove the waxy residue left over from the print process. Some of this residue has turned to powder and can still be seen on the shell. To find out how I remove this see my ‘How To’ post here. I will be doing that next.

The 3D printed parts included with the shell are the crew in the cabs, horns, pilot blocks, Trainphone receiver, and end handrails centers with walkways. As you can see below the receiver and walkways have broken away. This is not an issue but I will update the 3D model to ensure this doesn’t happen again.

The receiver is designed to fit into a ‘n’ shaped slot at the top right of the nose; there’s only one on the loco, the other end doesn’t have one. You can just about see the slot in the loco shell below.

The receiver fits perfectly and once cleaned up can be permanently fixed in place with a touch of superglue.

On the pilot beam in front of the nose you can see four holes; these are for the end handrails centers.

These also fitted perfectly and have the holes to receive the brass handrail section which will complete the nose handrails. But both handrail center posts should have a walkway between them; this is the part that broke away and which I will ensure is 3D printed as one part in future prints.

The reason they came apart was an incorrect joint in the computer model which has been fixed. For this model the parts have simply been glued back together with superglue. Superglue is ideal for this because it’s made from acrylic, as is the 3D printed model. Other glues may have an effect on the 3D printed material and plastic glues may melt it.

The floor tread pattern actually faces towards the nose of the locomotive; this is because when it folds down to allow loco engineers to walk from one loco to another, the walkway pivots at the lower connection so the pattern will then be facing up. The face you will see looking at the nose will be the underside of the walkway. The square holes are for the MU (Multiple Unit) hoses which will be on the brass Additions fret.

With the handrail centre section repaired it again fits nicely into the holes in the pilot beam.

Looking from along side the locomotive you can see the walkway patten. You can also see the radiators in the side of the shell and I’m very pleased with the finish on those. You can also see I’ve added a little material under each handrail location along the side which will ensure each fits in the right spot.

Before I went any further I was keen to test fit the shell onto the chassis and did hit one design flaw. A different feature from the DT6-6-2000 is the RT-624 has a longer walkway on one side for extra batteries and a hollowed-out area. I copied the modelling for this from my N Scale model not thinking about the HO chassis and as you can see below the chassis hits it.

But that’s why I do test prints. The problem is easy to fix in the computer model and I can make a correction to this shell so that it’ll fit the chassis. I think apart from that, the shell is looking good.

I have ordered the first batch of etched brass Additions for this locomotive, and thank you to those who pre-ordered these. Once they arrive I’ll be able to do the final checks on the shell and, if all goes well, the HO Baldwin RT-624 will be made available to buy.

Hopefully next week I will have a cleaned up test print to share with you fitted to the chassis.

A Baldwin RT-624 In HO – Part 4

With the test print of the HO Baldwin RT-624 now in production at Shapeways, I’ve turned my attention to the etched brass parts that will accompany it. As with the HO DT6-6-2000 these will be in 0.5mm (0.0196″) brass and will come on a fret containing the parts for all versions of the locomotive.

The etch contains side handrails, end handrails, sun visors, grab irons, windscreen wipers, trainphone antennas and Multiple Unit hoses.

The sixteen MU hoses across the bottom of the fret fix into the 3D printed end rail section, as shown below, with eight at each end. All the brass parts have locating holes in the 3D printed shell for ease of assembly and strength.

As with the DT6-6-2000 the price for each fret will be £10 GBP and I’ll be looking for some pre-orders to help cover the cost of getting the etch tool made. If you’d like to be one of those pre-orders please drop me an email at jamestrainparts@yahoo.co.uk or get in touch via the contacts page.

I hope the test print will be with me soon so I can share that with you and once the etched brass has been ordered the HO RT-624 will just about be ready to be released.

I’m still looking into 3D printed truck side frames for both the General Steel Castings Delta equalized trucks and the General Steel Castings Commonwealth trucks and hope to have those ready by the time the kit is available.

A Baldwin RT-624 In HO – Part 3

It’s been a few weeks since my last post partly because of work but mostly because I’ve been out enjoying the sunshine! But I’ve also put some time into finishing off the RT-624 HO project and it’s now ready for a test print.

The two versions of the Pennsylvania Railroad’s Baldwin RT-624, as shown below, are very similar but there are little differences that mark the change in the two different batches ordered.

The first depicts the original batch of fourteen units, numbered 8952 to 8965. With the exception of 8952 and 8953, they were fitted with the PRR Trainphone. This has mostly been modeled with etched brass. The item on the front, which I mistook for a bell, is actually the receiver for the Trainphone, with the antenna along the roof working as the transmitter. Thanks to Norman Bell and Gus Foster for the information.

Gus said ‘The device you were questioning on the top of the train-phone-equipped RT-624 is the train-phone receiver. These were disk-shaped devices consisting of a coil of wire that acted as a receiving antenna for the induction radio equipment used in the late 1940’s and 50’s.
As you may be aware, the train-phone system induced electromagnetic signals into the rails and the signal wires that ran parallel to the tracks. The government did not open radio communication frequencies to railroads and others until later in the 1950’s. As a result, the PRR used a radio induction communication system known as “trainphone” for communication between locomotives, cabin cars (cabooses), interlocking towers and railroad stations. The “handrail” shaped equipment on the top of diesel locomotives, cabins and tenders were the sending antennae that induced the signal out to the rails and parallel metallic conductors. The receivers picked up the signal. So to send and receive, both the antenna and receiver had to be near the location of the radio.

The receiver on my RT-624 is 3D printed but I’ve designed it to be a separate part to be fitted later as I can see it easily getting broken off during shipping.

The later batch, numbered 8113 and 8724 to 8731, had no Trainphone equipment and a lowered headlight. They also rode on General Steel Castings Delta equalized trucks as opposed to the General Steel Castings Commonwealth trucks used on the first batch. Currently I’m using Bowsers truck frames for both, along with my truck centers which are required to rotate the trucks 180°, but I’m considering offering a 3D printed set of each truck frame.

The handrail on the end is split by the fold down walkway and MU hoses. I haven’t modelled the MU hoses yet. I have the ones I did for my N scale version but they look huge in HO so I’m re-thinking that and I may make them as brass parts that clip in. The center section will be 3D printed and again it’ll be a separate part to protect it when shipping. The corner handrails will be brass and will fix through holes in the center section to ensure a strong and accurate fit.

And that’s it, the HO RT-624 is ready for a test print. I’m planning on printing the early version with the Trainphone because that one will have more things to check. While the test print is in production I’ll update the etched brass parts sheet for the different parts. Most are the same as the DT6-6-2000 but there are differences; I can’t use the same etch as one of the four main handrails is a different shape. In the image below I’ve circled the walkway which is longer, pushing the crank in the handrail further along.

Once the test print arrives, it should be easy to check it fits as I have the Bowser chassis here that I used with my HO DT6-6-2000. It will also get the powered Kadee couplings so it can be tested doing some switching and I’ll share that with you, well as long as it doesn’t continue to be sunny outside!

A Baldwin RT-624 In HO – Part 2

This week I have some more progress on the HO RT-624 project to share with you, and thanks to Gus Foster who supplied some great information, I also have a clear idea of the two different versions I’ll be making available.

The first model will be as the original batch that were delivered to the Pennsylvania Railroad. These fourteen units, numbered 8952 to 8965, rode on General Steel Castings Commonwealth trucks, similar to those on the Baldwin AS-616 and DT6-6-20000.  With the exception of 8952 and 8953, twelve of them were fitted with the PRR Trainphone and my model will have the antenna on top. I’m also intrigued by what appears to be an electric bell on a bracket at one end. Below you can see PPR 8956 at Zanesville, Ohio, July 23, 1954. (Photographer Paul B. Dunn). The bell and bracket are on the left-hand end to the right of the headlight. Any info on what this is would be greatly appreciated.

The second model will be the later nine PRR RT-624 units, numbered 8113 and 8724 to 8731 which all rode on General Steel Castings Delta equalized trucks. They were never fitted with the PRR Trainphones and had a slightly different car body with a lowered headlight. They were also equipped for MU operation and Gus informs me these generally served in the Philadelphia area. Below you can see PRR 8725 at Overbrook, Pennsylvania, October 26, 1952. (Photographer unknown but from the collection of Craig Garver)

I’ve been making the changes to the 3D printed shells and they’re starting to take shape. The first model is on right; as you can see it has the Trainphone antenna and the higher headlight.

I have yet to sort out the end handrails; these are different from the DT-6-6-2000 and simply scaling up my version from my N scale model looked way too chunky so I’ll need to redraw it.

Once this section is complete the shell will be ready for a test print which hopefully won’t be far away.

A Baldwin RT-624 In HO – Part 1

At the end of 2020 I released my HO model of the Baldwin DT6-6-2000, you can find the post here. But that wasn’t the end of the journey because just as Baldwin updated the DT6-6-2000 to the RT-624, so am I.

The Baldwin RT-624 is the natural development of the Baldwin DT6-6-2000.  Built between 1951 and 1954 the locomotive is classed as a transfer unit, designed for moving strings of freight cars between local yards in big cities.  It was a heavy locomotive, giving it great traction, and it had, for its time, a lot of horsepower.  Baldwin had started changing their naming convention for locomotives by this stage; this locomotive was sometimes called a DT6-6-2400 but Baldwin’s correct name was RT-624.  RT stands for ‘Road Transfer’, 624 stands for 6 wheels per truck and 2400 horsepower.  To achieve the extra 400 horsepower upgrade from the predecessor’s 2000 horsepower, Baldwin replaced the pair of 606SC supercharged diesel engines with their newer 606A supercharged diesel engines.  These each produced 1200 horsepower and were more reliable.

The RT-624 is very similar to the DT6-6-2000 and at first glance, you could be mistaken in thinking they were the same locomotive. Apart from things which you can’t see, such as the larger engine size in the RT-624, there are many differences. Below is my original model in N Scale of the DT6-6-2000.

Next we have the RT-624, again in N Scale.

The first thing that stands out to me is the large section under the cab that covers the fuel tank; on the RT-624 this has been removed. I assume Baldwin did this for ease of maintenance rather than cosmetic looks. Next, at the ends of the locomotive, Baldwin introduced a fold-down walkway to allow crews to pass between locomotives that were coupled together working as MU (multiple units). This split the end handrail as well as adding pipework for the MU equipment.

The trucks on some of the RT-624 locomotives were also upgraded to Outside Equalized trucks from the original Commonwealth trucks. Out of the twenty-four RT-624s made, twenty-three went to the Pennsylvania Railroad, and only the last eight, built-in 1952 and numbered 8724-8731, had the new tucks.

Another difference from the DT6-6-2000 was the walkways on the side. The DT6-6-2000 was almost symmetrical but the RT-624 had one walkway that was a different shape from the rest. This one had a longer raised section allowing for more battery storage under the walkway, which you can see on the left in the image below.

Another visual change that only appeared on some of the Pennsylvania Railroad locomotives was the Trainphone antenna on the roof. I say some of the locomotives because in doing my research I’ve found images of the locomotives with and without the antenna.  The Trainphone system was started in 1945 and was phased out around 1967 so it may be that it’d been removed from some of the locomotives. Below is a good example, PRR 8730 (one of the last batch with the Outside Equalized trucks) is shown with no Trainphone antenna. This photo was taken by Michael Sirotta at Frankford Jct., North Phila. It’s a 35 mm slide photo and dates from 1965 or ’66. (The image came from www.railpictures.net/)

The main body also had many small changes such as different grill positionings, headlight configuration, number board locations, and horn types.

The good news, as with my N Scale version, the donor chassis for both HO DT6-6-2000 and RT-624 kits will be the same. All the differences will be on the 3D Printed or etched brass parts.

I’ll be making shells available for versions with and without the Trainphone antenna for the PPR. I hadn’t planned on making 3D printed replacement trucks as Bowser makes both the Outside Equalized and Commonwealth trucks, but if they become hard to get hold of please let me know.

Out of the twenty four RT-624s made only one didn’t go to the RRP; this went to the Minneapolis Northfield & Southern and was numbered Twenty Five. Researching this locomotive, I noted that a lot of the changes above had not been included. As far as I can see, the only changes between MN&S’s original 5 DT6-6-2000’s and their only RT-624 was a different position to the headlight and a raised grill on the nose side. The large plate under the cab covering the fuel tank was already omitted on their DT6-6-2000’s. So for that model alone, if anybody would like one, I can simply modify the Baldwin DT6-6-2000 HO Type 3 model I already sell, so please get in touch.

I’ve already started working on the HO model and will have some progress images ready to share with you soon as well as a rendering of the model I’ll be sending for a test print.

Bachmann Mainline Replacement Wheel Centers – Part 4

In December of 2020, I first shared my ideas for the 3D printed wheel centers for the Bachmann OO split chassis 4MT. You can find the post here.

After two test prints, the design was finalized and a set was painted, I used a basic acrylic black pray. They were where then ready to be press-fitted into the wheels.

The two with the larger counterweights go on the center set wheelset with the drive gear. No glue was required but I put a pot of superglue near the center of the wheel just to be sure. becare not to put too much otherwise it will squeeze out.

When and once the locomotive was reassembled it looked as good as new.

Now the wheel centers are flat-sided the side rods no longer catch and the locomotive runs nice and smooth. This particular model also needed the axles replacing as they had cracked, the other common falt with split chassis locomotives of this era. The axle set can be found here.

These wheelsets are now ready to be ordered and can be found using the link below or can be ordered through the group order service, send me a message through the contacts page.

Bachmann Mainline Replacement Wheel Centers

But the 4MT is not the only locomotive with this issue. The Bachmann Mainline 2-6-2 tank also this same design and many suffer from the bulging wheel centers. But the 2-6-2 has much smaller wheels, at 19.9mm diameter (equivalent to 10.4′), so a new design is needed.

The crank pin is also closer to the centre of the wheel giving a different shape to the centre casting.

The plastic inset pops out just as easily allowing me to take all the measurements I need to drawn them up ready for a 3D print test.

This wheel centres will be test printed along with my next 3D print order. These locomotive also has cracked axles but luckily those are the same as the 4MT.

Next week I hop to have some more development work to share with you on the HO Baldwin RT-624 project.