A Baldwin RT-624 in HO – Update

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.

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.

Alco C-855 N Scale ESU LokSound Install – Part 3 – Engine Speed Setup

Several weeks ago in July I shared with you my install of ESU Loksound sound decoders into a set of my Alco C-855 locomotives, you can find the post here.  Then in August, I showed you how I improved the running of the locomotives by adding some stay alive capacitors, you can find that post here.  In this week’s post, I’m going to share with you the final step which is setting up the sounds for multiple engines.

Most suppliers of ESU sound decoders give you a choice of sounds when you purchase the chip and they will load the sounds on for you.  But to add your own sounds or load on a downloaded sound scheme you need an ESU Lokprogramer and the accompanying software.  These, along with a computer, will allow you to change all of the settings of the decoder.

However, they can be fairly expensive so if you have your decoders with pre-loaded sound schemes you can use other devices to adjust the settings. For example, although I use a LokProgrammer I also use a Sprog II from sprog-dcc and the DecoderPro software from JMRI.  The Sprog II is relatively cheap and the DecoderPro software is free to download.  Together they will allow you to edit the setting of just about any DCC decoder but please note it will not allow the upload of sound files.

The sound file for the C-855 was downloaded from the ESU website and comes with all the normal functions such as horn, bell, coupling, etc.  The new versions also come with ESU’s Full Throttle settings. These include features such as Drive Hold, Independent Brake, Run 8 and Coast.

These functions can be fairly complex but in short, they work like this:

Drive Hold when pressed keep the model motor running at the same speed and as the throttle is increased or decreased the revs of the engine changes.  Ideal if you are pulling a slow heavy train uphill and you want it to sound like it’s working hard.

Independent Brake when activated slows the train to a stop without adjusting the setting on the throttle, when released it speeds up again to the throttle setting.

Run 8 when activated increases the sounds of the engines to maximum revs irrelevant to the speed of the train.  This is great when simulating a heavy train about to start moving and is my favorite Full Throttle function.

Coast reduces the revs of the engines to tick over irrelevant to the speed of the train.  This is great when running downhill or for light loco movements.

Out of the box, only the Drive Hold & Independent Brake are set up as you can see from the function list below:

F0 Directional Headlights
F1 Bell
F2 Playable Airhorn
F3 Coupler
F4 Dynamic Brake
F5 AUX3 (Rotary Beacon)
F6 AUX1 + AUX2 (Front Ditchlights)
F7 Switching Mode
F8 Sound (On/Off)
F9 Drive Hold
F10 Independent Brake
F11 Radiator (Fan) Sound
F12 Dimmer (Headlights)
F13 AUX4 (Rear Ditchlights)
F14 N/A
F15 Fast Spitter Valve
F16 Spitters on Shutdown
F17 Brake Set / Brake Release
F18 Sanding Valve
F19 Short Air Let-Off
F20 Compressor
F21 Slow Spitter Valve

As standard one of the first things I like to do for my trains is set the Run 8 function to the F5 key, as I don’t put rotary beacons on my models this key is free.  I will show how to do this first using the LokProgrammer and then with JMRI through the Sprog II.  One thing to note, it’s a good idea to save the setup before you alter it, that way if everything goes wrong you have a backup of the original settings.

In the LokProgrammer software, you can see what each function is assigned to in the function mapping tab.  As standard F5 is set to AUX3.

I change this as shown below.  I have also set F6 up as the coast function.

Sometimes, if you’re reading the settings form the locomotive rather than a downloaded file, the name of the sound does not appear, just the slot number.  By default Run 8 is normally sound slot 20 and Coast is sound slot 21.  The changes can then be written to the decoder.

With DecoderPro the process is similar but it takes a little longer as you need to read all the settings from the decoder before you adjust any, otherwise you could overwrite something you didn’t want to. (Please note the Decoder Pro Screenshots are from a different loco).

With the F5 & F6 corrections made the screen looks like this.

Normally that is enough setting up and here is a short video of a single C-855 staring up, then having the engines run with Drive Hold on and lastly the Run 8 function.  Because the C-855 had two diesel engines you here the first fire up then the second.  Also both engines run at slightly different speeds so they are not simply copies of each other, I will explain more about that later.

As the same sound file has been installed in all three locomotives, the two C-855s and the C-855B, all three locomotives are running on the same DCC address so they all respond at the same time, as you can hear below.

The volume is much louder as we now have three speakers pumping out the sound but the problem is although the two engines in each locomotive are running a different speeds, each locomotive sounds exactly the same.  And I don’t think Alco managed to achieve that!  So in order to improve the realism, I will set each of the six engine sounds so they all run at there own speeds.  The change doesn’t want to be much, but a little adjustment can make all the difference.  The great thing about the ESU decoders is you can make adjustments to individual sound files without affecting the overall sound.  After all, we want the bells and horns to be the same across all three locos.

With the LokProgrammer on the function mapping page F8, which turns the sound on and off, controls two sound slots called ‘Dual-ALCO-16cyl-251C-FT-PM#1’ and ‘Dual-ALCO-16cyl-251C-FT-PM#2’.

Clicking on the drop-down menu these are sound slot 1 and sound slot 23.

Switching to the ‘Sound Slot Settings’ tab the setting for all the sound slots can be adjusted.

As you can see below sound slot 1 has a maximum and minimum value of 126, which is 98.44% of the original speed.

But sound slot 23 is set to 130 which is 101.56% of the original speed.  And that’s how the two engines run at slightly different speeds.

So for the three locomotives, I will set the sound slots up as follows.

C-855 60 – Sound slot 1 = 126 (98.44%)
C-855 60 – Sound slot 23 = 130 (101.56%)
C-855B 60B – Sound slot 1 = 124 (96.88%)
C-855B 60B – Sound slot 23 = 128 (100.0%)
C-855 61 – Sound slot 1 = 132 (103.13%)
C-855 61 – Sound slot 23 = 136 (106.25%)

And they sound like this.

Of course, the difference between the locomotives could be increased to give an even more noticeable difference, the difference is a personal preference.

With Decoder Pro these settings are in the ‘Sound Levels’ tab.  Again you will need to read all the settings from the decoder first but you can save them so you don’t have to read all three locomotives.  As with the LokPrograammer software the ‘Function Map’ tab will tell you which sound slots are operated by function F8.

Sound files for the Mallet and articulated steam locomotives, such as the Big Boy, use the same system to archive slightly different chuff sounds for each set of cylinders.

There are lots of settings available with these decoders which allows you to customize your locomotive, or as in this case a set of three.

These C-855s are now finished and ready to rumble their way up the track.

Next week I’ll be looking at the next step in my OO NEM dummy knuckle couplers.

Alco C-855 N Scale ESU LokSound Install – Part 2 – Stay Alives

At the beginning of July I showed you how I install ESU LokSound decoders in my C-855 kits.  You can find the post here.  This week I’ll show you how I added a small stay alive system to improve the performance of the locomotives.

With just the ESU LokSound decoder and speaker installed in the C-855 chassis, as shown below, the loco ran reasonably well but it did hesitate a few times on some point work.

This hesitation was down to dirty contacts in the pickups.  As the power supply was briefly removed from the decoder the locomotive came to a stop and the sounds went off, then it went through its start up cycle again.  As the other two locos in the set are still trying to run, this can be fairly annoying.  As well as cleaning the contacts and wheels I decided to add some stay alive capacitance to each locomotive.  A stay alive system is just what it sounds like; it keeps the decoder alive when the power is briefly lost.  ESU do sell their own stay alive devices, which are very good, but they’re fairly expensive, so I prefer to make my own which also allows me to make them to fit whatever space I have.  The only components I use are capacitors, a resistor and a diode.

The capacitors are 220uF 16Vdc Tantalum capacitors, the resistor is a 100Ω 0.25w and the diode is a 1N4007.  These are all parts which are readily available from most electrical stores or online.

The capacitor is designed to be fitted to a circuit board and is very small, which is ideal for N Scale locomotives. 220uF means the unit has a capacitance of 220 micro farads. You can get similar size capacitors with more capacitance such as 330uF but the price goes up. The 16Vdc refers to the maximum amount of voltage the capacitor can handle; because N scale DCC systems run between 12v and 16v, and the decoder drops the voltage by around a 1.5v, the capacitor will be receiving between 10.5 and 14v, so I find these are fine.

Be careful when buying these Tantalum capacitors; there are a lot of cheap ones out there with a low quality control.  It may say 16Vdc but if they’re cheap that may be an approximation.  If you put too many volts onto a Tantalum capacitor it will blow up, very loudly and dramatically.  The best way I can describe it is like a Roman candle.  And you don’t want that happening inside your locomotive!  The SOO SD50 below just had that happen with some cheap capacitors and the flames went up in the air by about a foot and blew a hole in the shell before I had a chance to cut the power.  So I would recommend a quality supplier.

The Tantalum capacitors have two metal tabs on the rear to solder to and a strip on one side to indicate the positive connection.

For these locomotives I’ll be using a bank of three Tantalum capacitors connected in parallel, which will give 660uF.  That isn’t a lot and won’t keep the motor turning, but it will give a few seconds to the decoder to keep the sound running, which is all I need. With all three locomotives working together the momentum and power of two out of three will jog a stalled loco enough to get it moving again without the decoder losing power and restarting itself.  I’ve glued these three together with superglue.

I’m going to put the capacitors in front of the speaker.  There is room to put in more, and normally the more you have, the better, but I want the space for the other parts.

The resistor and diode perform two important tasks. They are both connected to the positive capacitor terminal and positive (blue wire) connection on the decoder.  The resistor is used when the system is charging.  Power flows from the positive connector on the decoder into the capacitor to charge it.  As it passes through the resistor the current is reduced, which causes the capacitor to charge slower than normal.  Otherwise the DCC command station would detect the inrush of current and think there’s a short circuit when you first put the loco on the track.   The diode is there to bypass the resistor when the stay alive system is in use.  If the track power is lost the power flows from the capacitor back into the positive connector, but we don’t want any resistance.  As the diode wire is thicker than the resistor’s I wrap the smaller wire around the larger, as shown below.

I then solder the connections.

And lastly trim off the excess.

The new ESU Loksound V5 Micro decoders have a Next 18 plug, as described in the earlier post, as well as six solder pads.

The two we’re interested in are shown below.  I have tinned the solder pads with solder.  The one on the right is the positive connection, which is the same as the blue wire.  The left pad is the DC negative or common ground for the decoder.

To join all the parts together I start with the capacitors.  Using the off-cuts from the resistor I join the capacitors together by soldering the wire to each pad.

I then solder the diode and resistor to the positive side ensuring the band on the diode is on the far side from the capacitors.  This is because DC power only flows one way through a diode, towards the band, and we want it to flow out of the capacitors to bypass the resistor when in use.

I then solder a wire to the diode and resistor and another to the negative side.

The assembly is then wrapped in Kapton tape, ensuring there is no connection between the negative and positive terminals, and fix it into the loco.

At the other end I solder the wires to the corresponding solder pads on the decoder, ensuring there is enough wire to allow the decoder to be plugged back into the socket.

The decoder can then be plugged back in and the chassis is ready to go.

All three chassis have now been fitted with stay alive units and the bodies have been fitted, but you’ll need to wait until next week to hear what they sound like when I’ll also show you how to program the decoders so that each of the six Alco 251C prime movers sound slightly different.

EMD DD35 With Body Mount Couplers – Part 2

In last week’s post I shared with you my design and 3D print of an N Scale EMD DD35 with body mounted couplings.  You can find the post here.  In this week’s post I’m going show how well it worked.

The new EMD DD35 shell, as shown below, is sat on a modified Bachmann DDA40X chassis which has been shortened and had its pilots cut off.

The 3D printed pilots have pockets to receive a Micro-Trains body mount coupling.  This can either be a Type 1015 (Short shank) or a 1016 (Medium shank) and there’s a 3D printed hole in the pilot to receive the mounting screw.

I’ve used the 1016 as the extra length will help with the curves.  Because the coupling rotates slightly off of the screw, the longer arm will mean the coupling can swivel closer to the center of the tracks, which is the ideal location.  The further away the coupling gets from the center the greater the risk of it pulling the train off the tracks.

On our layout ‘Solent Summit’ the tightest radius is in the yards at 16″.  Below you can see the new DD35 coupled up to two originals with the truck mounted couplings.  The three run around the 180° bend with ease and there’s still slack in the couplings.

The middle DD35 has the standard McHenry couplings as supplied by Bachmann.

The McHenry sits a little high compared to the micro trains but the connection is good under tension.  Because the couplings naturally spring straight they will not couple up on the bend, they are way too far out of line, but they don’t seem to be affected once coupled.

In order to test the couplings properly I assembled a train powered by a GP35, GP20, GP7, the new DD35, a dummy DD35, a original powered DD35 and another GP20.  All followed by 42 cars and a caboose.

Apart from being lots of fun, the idea behind all the motive power, some 23,000 horsepower with the new DD35 in the middle, was to see how the couplings worked with pulling and pushing forces. The train, comprised of a lot of older rolling stock, had a lot of drag which added to the draw bar pull.  The big train made its way around the layout, through s bends and the 16″ radius yard curves, several times with no problems at all.

But as the other DD35s had truck mounted couplings, the GP locos being short and the box cars in the train also being short, all their couplings were close to the center of the track.  To make this a decent test the new DD35 needed to be connected to other long locomotives and freight cars with body mounted couplings.  And luckily there was one on the layout.  The train in the video below, built by my fellow modeller Chris, has two Kato SD80MAC locomotives pulling a long line of Atlas 85′ trash cars.

Both the SD80MACs and the trash cars have body mounted couplings so they will swing out further on the bends.

The trash car has Atlas Acumate couplings which as you can see work well with the Micro Train couplings.  There’s some swing on the Atlas coupling but it’s rotating about the end of the car, not the truck center point.

The Kato coupling seemed a little low, or the DD35 body may have lifted and I didn’t notice untill I got home and looked at the photos but it didn’t cause an issue.  The Kato coupling rotates about the end of the loco.

Leaving the East yard the train runs through an s bend, around at tight corner and out onto the layout and the DD35 with its body mounted couplings did this with ease.

It’s possible the shorter 1015 coupling will also work and if the tightest curve is 18″ or 20″ radius then it certainly will.  But I think 16″ is about the smallest radius for the new DD35.

I have a few other things to check and then I’ll make the new DD35 shell kit with pilots and body mounted couplings available to buy.

3D Printing The Right Way Up

In last week’s post I spoke about Shapeways’ ‘Orientation Tool’ for their FUD and FXD materials and my intention to make all my locomotive shells available with this option.  You can read the post here.

My plan was to have both the new orientated models available as ‘Deluxe’ versions and the originals as a cheaper option.  And that’s what I’ve done with the Alco C-855 and C-855B.  However, after working through the other models it became apparent that the price didn’t really change.  By moving the position of parts the price of the model dropped and so the increase caused by using the ‘Orientation Tool’ setting was offset.  So all the other models have simply been converted to have the ‘Orientation Tool’ set for the best quality print by making it print the right way up.

Locomotive shells without the orientation set:

Alco C-855

Alco C-855B

Locomotive shells with the orientation set:

Alco C-855 Deluxe

Alco C-855B Deluxe

Alco C855 Shell Only

Alco C855B Shell Only

Baldwin DT6-6-2000

Baldwin DT6-6-2000 Dummy

Baldwin DT6-6-2000 Shell Only

Baldwin RT-624

Baldwin RT-624 Shell Only


EMD DD35 Dummy

The new locomotive shells I’m working on will all be set to the best print quality from the start and the models will be designed to make them less expensive in the printer.  So for now the ‘Deluxe’ versions just apply to the large Alco C-855s but maybe this will come in useful with some of the HO scale locomotives I have planned, allowing me to offer differently priced versions.