A Baldwin DT6-6-2000 in HO – Etched Box Windows Part 14

Now the first three body types for the HO Baldwin DT6-6-2000 have been made available, (see the page here) I need to share with you how some of the details work.  In this post I’ll discuss the etched brass box windows that appear on the Minneapolis, Northfield, and Southern Railway no 21. (Picture from Illinois Railway Museum http://www.railroadmichigan.com/illinoisrailwaymuseum.html)

The 3D printed shell for this particular locomotive is my Baldwin DT6-6-2000 HO Type 3 and can be ordered from Shapeways using the link below.


Several posts ago I shared the design for the box window and you can see the parts which need to made from brass in the image below.

I even designed them so they could be modeled in the open position if required.

To make this design work the shell has a different window configuration, with slots to receive the etched brass on all sides and nothing in the middle.

Because the test print had the standard windows, and I didn’t want to print an entire shell to test the box windows, I simply 3D printed a cropped out section of the window.

You can see the slots around the window opening.

The etched brass sheet has two sets of box window parts at the bottom of the fret.

On the left is the roof, base, and sides, and on the right are the sliding windows.

After I cut out the parts they looked like this.  I confess I rushed this a little and have bent a few parts.  Time should also be taken to file off any burs to ensure a good fit.  But for this test, a quick install is all I needed to do.

The base has two prongs that fit into the slots below the window.  There is a bar on the base that should be facing up.

The roof fits in a similar way with the bar facing down. The roof will fit at an angle because the slots for it are tilted to run at the correct angle.

The sides, when not bent, fit between the roof and base with the two prongs locating in the 3D printed slots.


Both sides are the same so it doesn’t matter which one is used for either side.

The square windows are the parts that slide and fit behind the fixed sections.  They’re designed to rest against the two bars on the roof and base.

Once the square window is positioned the C-shaped window can be fixed resting on top of the square window. Any glazing would ideally be fitted before they are fixed in place.  This can either be cut to fit inside the window frame or fixed to the rear.

With both windows fitted, the assembly is complete.  The left window is closed and the right is slid half-open.  With the parts carefully cut out and any burs removed the box window will be a nice snug fit.

Of course, fitting the glazing before spraying the body may cause an issue, so some careful planning will need to be done.

The windows could be glazed then masked for spaying.  Or the glazing could be fitted last.  Or the body could be sprayed before the brass is fitted and glazed.  I guess it all depends on the modeler’s preference.

A full set of instructions for the whole locomotive will be made available soon for all the parts needed and over the next few weeks’s the other shells will be made available for the different DT6-6-2000 locomotives and RT-624s.

A Baldwin DT6-6-2000 in HO – Project Update

It’s been several weeks since I last posted about the Baldwin DT6-6-2000 HO project but today I had some good news which means we are just about ready for release.

The bulk of the design and 3D printing has been done, as you can see from the photo of the successful test print below, but what was missing was the etched brass parts.

But today I had confirmation that they’ve been shipped from the etchers and I’m expecting them to arrive by tomorrow or Wednesday at the latest.  This means I can do all the test fitting this week, and assuming everything fits okay, I can release the full kit for sale in next Monday’s post.

The Baldwin RT-624 and some of the DT6-6-2000 varients are still being modified, but I should be able to release shells for Baldwin’s demonstrator, number 2000. ()

Elgin, Joliet, and Eastern Railway early DT6-6-2000s. (Uncredited image – If you know where this image originates from please drop me a message).

Santa Fe’s early models. (Picture from http://www.snowcrest.net/photobob/sfl2.html),

The Trona Railway locomotives. (Photo from Vernon Ryder, Jr.- collection of Mark Laundry – http://baldwindiesels.railfan.net/trona/index.html).

The Minneapolis, Northfield, and Southern Railway no 21. (Picture from Illinois Railway Museum http://www.railroadmichigan.com/illinoisrailwaymuseum.html)

And Peabody Coal Railroad’s locomotives. (Picture from Railrpictures.net)

There’ll be more as the variants get done, but if you have a specific DT6-6-2000 which you would like to model, please get in touch via the contacts page and hopefully I can make that shell available too.

I’m really looking forward to seeing the locomotive with all the brass fittings, I’ve just got to decide what color to paint the test print now!

A Cover for an In-Track RFID Reader

Model railways have seen many great technological improvements through the years and Digital Command Control (DCC) is one of the biggest, but sometimes I get asked to work on something that’s totally new.  This week I have a small project to share with you for a customer who’s experimenting with RFID.

RFID stands for Radio Frequency Identification and is used in all sorts of things; there’s a good chance you have an RFID chip in your wallet.  Bank cards that have the contactless payment option have an RFID chip inside the card which reacts to the RFID reader when you hold your card up to pay.  This technology has been in use for a long time in all sorts of industries, from such environments as warehouse management to automatic bridge toll devices.  Now it’s making its way into model railways, at least on one model railway anyway.

To add another level of realism to the customer’s railway, all of his freight wagons have been fitted with an RFID chip.  There are readers either under the track or within it at multiple places around the railway.  This means, when a train enters a freight yard, the computer will know exactly which wagons make up that train.  It’ll then work out where each needs to go, such as a local industry or added to another train, and the operator then has the fun of shunting the train as instructed.

With a newly-constructed part of the layout, adding a readily available RFID reader under the track was fairly easy, but on the already existing section it’s a little bit more of a challenge without ripping up the track.  The answer came in the form of these custom made RFID readers by Eccel.

This are designed to fit between the rails allowing space for the wheel flange to pass.  A hole at one end needs to be driled between the sleepers to allow the cable to pass through. However, they don’t look very realistic for a model railway, so the customer has asked me to design a 3D printed cover to make them look like a timber uncoupling ramp.  The uncoupling ramp below, made by Peco, is designed to clip into the track, but also sits above the railhead so it will engage the UK-style couplings.

The customer uses American-style Kadee couplings so the uncoupling ramp will be purely cosmetic and needs to sit just below the railhead.

As always, I have 3D modeled the original part, and some track, to ensure everything is correct.

The ramp is designed to clip over the RFID board, with space inside to allow for the circuit components.  The RFID reader itself will be fixed using the two holes in the board.

To get the wood grain effect I’ve recessed the patten so it will, hopefully, print and be visible when painted.  I’ll spray these to ensure a thin coat of paint as brushing would probably fill the recessed wood pattern.

Although this a simple project it’s been very interesting to do and I’m eager to see them in use on the layout.  Once they’re all printed and installed I’ll take some video of the trains running, and the computer screen capturing the RFID data.  This may be several weeks away, but I’ll share it with you when I can.

If you have something different like this on your layout that needs a special part, get in touch, I may be able to help.

Replacement Bachmann N Scale Chassis Fasteners & Washers

In February of this year, I shared with you my design for a replacement set of Bachmann OO Chassis Fasteners & Washers; you can find the post here.  Since then I’ve had some requests to do the same thing for the N Scale Bachman US locos. So in this week’s post, I’ll share with you my design for a replacement set.

Unlike the OO set, Bachmann still has the N Scale version listed on their website as spare parts, but they’ve been out of stock for some time. The fasteners in question are used in the older locomotive designs from the 1980s.  A typical example of this is Bachmann’s GP50 as shown below.

The chassis is a split frame design also used in several other locomotives, such as their GP40 and U36B models.  It’s held together by the two chassis fasteners at the bottom corners of the chassis.

Viewed from the other side you can see the screw heads which pull the fasteners tight.

With the screws removed, the chassis separates and the trucks and motor will drop out.  You can see the fasteners and a washer still in the upper chassis section.

The fasteners will push out and the washer will drop off.

Both the fastener and washer are made of plastic to electrically isolate the two chassis halves.  The washer also acts as a spacer to correctly position the chassis halves.

As with the original OO versions, with time the type of plastic used hardens and becomes brittle, so when the screw is removed the cylinder part of the fastening breaks off of the rectangular sections as shown below.

Interestingly the OO and N Scale versions at first glance appear to be the same, but after doing some measuring I discovered the N Scale fastener is shorter and fatter.  This means the N Sale washer also has a larger hole.  Below you can see my OO fasteners and washers in white compared to an N Scale original one in black.

Using one from the GP50, it was easy to modify the existing OO version to create a new fastener for repairing N Scale Bachmann locomotives which have suffered from this part failure.

As with the OO set, the hole in the middle of the tube section will need to be cleaned out to remove the 3D print residue before the screw can be inserted.  For the N Scale fasteners, I use a 0.8mm drill bit in a pin vice.

The inside of the tube has not been threaded for the metal screw so it’ll work as a self-tapping screw, cutting its own thread the first time it’s inserted.  But if the tube is blocked, the excess material will create too much pressure and the tube may crack.

These replacement fasteners and washers can be used on a large variety of Bachmann N Scale locomotives and I’ve made them available in a set of 6 here and a set of 12 here.  I thought it best to make the smaller set start at 6 so you have a few spares just in case something goes wrong.

These little fixes are ideal for 3D printing components, so if you have an idea for a part you’d like to see 3D printed please drop me a message, I’m always interested to hear what fellow modelers are working on. You can get in touch through the contact page.

A Baldwin DT6-6-2000 in HO – Brass Additions Part 13

Over the last two weeks, I’ve been working on the brass Additions to accompany the 3D printed parts of the HO Baldwin DT6-6-2000 and I’ve just finished them, so this week I’ll share with you how they look on their etched fret and where they go on the model.

The fret will be etched from 0.5mm (0.0196″) brass with a lot of the finer details reduced to 0.25mm (0.0098″).  The 0.5mm was selected as it’ll make the handrails roughly 44mm wide at the scale of 1:1, which is ideal.

The main four handrails are in the top left of the fret.  The shell has 3D printed mounting holes and locating marks to ensure these are installed at the right level.  In the top right are the two end handrails which again fit into 3D printed holes in the shell.

Below the end handrails are the sun shades or visors which slide into sloping holes in the shell.  Not all the DT6-6-2000 locomotives had these so I’ll offer both a shell with mounting holes and one without. Further down the etch are all the grab irons and the tiny windscreen wipers.  Again, all of these parts fit into 3D printed holes in the shell.  Some of the grab irons have tiny half-etched marks on the rear, allowing them to be bent at 90° in the right place.

Another part which will only be used on Pennsylvania Railroad versions are the antenna for the Pennsy train phone.  Again, a different shell option will be offered with the slots in the roof for the antenna to drop into.

With all the parts listed so far, the shell will look like this with the exception of the grills, which I’ll come to later.

At the bottom of the etch fret are 16 parts that form the window boxes which were found on several locomotives, such as the Minneapolis, Northfield, and Southern Railway’s No 21, and later Elgin, Joliet, and Eastern Railway models.

The etched parts form the sill, roof, and sides and I’ve allowed space for glazing to be fitted, just like the other windows in the loco.  Because the brass parts slide together, I’ve designed them so the inner two windows can be opened, just like the real loco.

The fixing for the brass window box is different, and the original window is removed, so this will be a fourth option that I’ll make available.

The last etch part I’d been planning was the grill mesh on the front of the nose. To get such a tight mesh it would’ve needed to be etched on a thinner sheet of brass.

A 0.2mm (0.0078″) sheet with half etching would’ve given this effect shown below.

Up til now I thought I’d solved the problem of the mesh design. However, upon doing some more research I found this really high-quality image of MN&S No 21 taken by Mike Roth on Flicker.  You can see the original here.

Zooming in on the picture, which I haven’t been able to do this closely on all the old photos I have, I can now see it’s not a grill mesh at all but an actual radiator.

With my original N scale version, even though I thought it was a grill, I modeled it as a flat surface recessed into the shell.  Once painted, it looked great.  So I think the same thing will happen here and the etched mesh will be removed.  My test print has the hole for the mesh but that can easily be filled with plastic card.

These etched frets are much bigger than my previous ones, not just because they are HO, but there’s more on them so they’ll be more expensive. The tools are the expensive part, and can’t be changed, that’s why I put the parts for different versions on one fret as it would cost too much to make several different ones. The price 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.

Once I get the first set I can test fit all the parts, make any adjustments to the 3D model, and then make all the different versions available.  The brass etches for the Baldwin RT-624 will be different because the handrails and end rails are a different shape.  But I’ll come to that later when I convert the DT6-6-2000 3D model into the RT-624.

A Baldwin DT6-6-2000 in HO – Powered Couplings Part 12

As the HO Baldwin DT6-6-2000 project moves to the end of the testing phase, one of the key features I designed into the locomotive still needed testing: the powered Kadee couplings. I think these will be a great addition as this locomotive spent most of its life moving freight around yards, so this week I’ll share with you how it went.

For those of you who’ve been following the design and build of this locomotive from the start, you may remember I decided to use Preci Models DCC auto uncoupler system to automate the Kadee couplings.  You can read about that in my earlier post here.

Because I’m designing this locomotive shell from scratch I had the option to mount the Preci Models motor in a more convenient place rather than simply fixing it to the back of the coupler as shown below.

The tiny motor fitted perfectly into the shell, with the brass spindle protruding out just behind the Kadee coupler.  It’s very close to the shell mounting hole, but that’s the great thing about designing the shell as a 3D computer model; I knew it would fit.

The couplings I’m using are Kadee #148.  These are medium metal couplers with the Whisker®.  The Whisker® is the tiny wire you can see either side of the actual coupling arm which keeps the coupling centered in its box.

To make these work with the Preci Models motor, I needed to cut a slot in the rear of the box.  As the plastic is fairly soft this was easily done with a new blade in a craft knife.

The string, which is supplied with the Preci Models motor kit, can be laid through the coupling box.  The string needs to be parallel with the coupling arm otherwise it will put more effort into pulling the coupling to the side rather than opening the coupling knuckle.  The string also needs to run free from any obstruction inside the box; it will be above the Whisker® as shown below.

With the box lid fitted you can see how the string passes through.

There are different ways to connect the string to the knuckle but I like to use a drop of superglue. To do this I put a drop of superglue on a piece of card, use a small toothpick to place it on the right spot, then lay the string in the glue.  I also use a spray actuator to instantly set the superglue. It’s important to note the spring on the side of the coupling; you must not get any glue in this or the coupling won’t work.

The coupling can now be tested.  By simply holding the coupling box between my fingers I can pull the string down and the knuckle should open.

There should be no resistance, other than the small spring on the side, which should cause the knuckle to close with a little snap when the string is released.

The coupling can now be screwed to the shell.  Of course, I would recommend painting the shell before fixing the couplings as you don’t want to get paint on any of the moving coupling parts.

The string is pulled by the rotating motion of the motor and it’s important to keep the string as straight as possible, so in the picture below you can see I’ve wrapped the string around the motor spindle in an anti-clockwise direction.  This way the string will come off the spindle at the top and be in the right place.  To keep the string in place it’s actually tied onto the spindle, adjusted to the right tension, then fixed in place with another drop of superglue.  Again, I do this with a small toothpick to avoid getting any between the spindle and the motor.

Next, we need to power the motor.  It’s worth pointing out here that this system works on the principle that the motor spins as much as it can, which may only be half a turn, then stalls until the power is turned off and the spring in the coupling pulls it back.  If the motor is left powered on for more than 5 to 10 seconds it will overheat.  Also, if the motor is powered directly from the decoder or track, it will again overheat and probably burn out.  So the Preci Models motor kit has two 68 Ohm 0.5w resistors, one for each motor, which needs to be included in the wiring to limit the power running into the motor.

The motor needs a minimum of 150mA of current to work and not all decoders can provide this from their function cables.  It should say on the decoder documentation.  There are options for this in the Preci Models motor kit instructions but this locomotive will eventually be fitted with an ESU LokSound decoder that can handle this.  For this test, I have a basic ESU LokPilot which also has the required power output.  First I connected the red motor wire to the Blue DCC chip common and the black to the purple DCC chip function wire.

As the motor is a DC motor and the DCC decoder outputs +DC from the blue wire and -DC from the function wires, the motor spun clockwise when wired like this, and that’s not what I wanted.  So I swapped the red and black wires over and the motor now spins in an anti-clockwise direction.

With the chassis sat on my programming track and the DCC decoder plugged in I was able to test the coupler, and it worked well.  With the function wire activated, the motor span and the knuckle opened all the way as shown below.

And when the function was turned off it sprang back.

Here’s a very quick video of it working.

Once I was happy it was working properly I trimmed the excess string off the motor.

The last test was to fit the shell to the chassis and try it in situ.  The string on the knuckle is hardly noticeable, and I think once the shell is painted you won’t be able to see it at all.

I don’t have a long enough length of HO track on my modeling bench to do a full action test but I was able to simulate it using another loco in this video below.  The SP&S Geep looks high on the right because there was no track under the rear truck and I was holding it up!  But as you can see the powered coupling on the DT6-6-2000 works perfectly.

I won’t install the coupling at the other end yet, as I want to paint the shell first, but I’m very happy with how the automatic Kadee uncoupler works and I think it’ll be very valuable on shunting operations.

The very last test for this shell is fitting the etched brass parts and I’m very close to having them all drawn; it’s taken a little longer than expected, but I want to get it right and the better the design of the etch sheet the more parts I can get on to it, which in turn brings the cost down.  Hopefully next week I can share that with you as well.