New Gears For A Bachmann N Scale Street Car & Brill Trolley

This is a project that I started at the beginning of 2020 so it’s about time I shared it with you. The Bachmann PCC Interurban Streamlined Car has been around since 1983 and was released in a large variety of paint schemes and liveries. However, all the models released up until about 2000, when Bachmann upgraded the chassis, suffer from the same problem; the white plastic gears on the axles crack. In this post I’ll share with you my 3D printed replacements to fix this.

The PCC Interurban Streamlined Car, and similar Brill Trolley released the year before, share a similar chassis with the same trucks. The body is all plastic and clips over the metal chassis, which fills the body.

The underside is fairly basic and you can see all four axles are driven via gears. These are the gears that crack under the pressure of the metal axles press fitted into them.

With the body removed you can see the chassis, which is made of two halves and separated by Bachmann standard fastener and washer system. Should these brake I’ve made replacements available here.

With the two screws removed the chassis haves come apart and the trucks fall out, although the repair can be done without separating the chassis or removing the trucks if you wish.

The large drive gear in the centre of the truck doesn’t have any issues.

The wheels have a short axle which press fits into the gear, when fully inserted the two axles do not touch each other so the gear also forms the electrical isolation. The wheels should just pull out. If the gears are cracked they’ll come out very easily.

The original gears, as shown on the right of the photo below, are made from a material that’s prone to cracking and you can see the light change as it hits the crack in the gear. With the metal wheel inserted the crack opens up. This causes two issues; firstly the spacing between two of the teeth is larger than the rest and causes a bump as the gear turns or jams the other gear. The second issue is there is little friction between the gear and the axles so the gear may turn, but the wheel won’t.

3D printing a set of four to replace all the gears is the answer and given the small size of these gears, roughly 5mm (0.196″) diameter, the best material is Shapeways Smooth Fine Detail because of its accuracy and hard-wearing properties. All four have been printed on a sprue so they don’t get lost in the printer.

Unlike injection moulding the sprue doesn’t actually touch the gears, it just passes through the hole in the middle. This can easily be cut with side cutters and the gears are ready to use, although I would recommend cleaning out the hole in the axles of any 3D print residue before you use them.

Refitting the gears and wheels is fairly simple. Position the new axle gear inside the truck and lightly push the wheel axle through the hole in the truck and into the gear. With both wheels lightly fitted, press the wheels together to press fit them firmly into the gear, just don’t push them in too far. The inside distance between the back of the wheels, commonly known as the Back-To-Back dimension, should be 7.65mm (0.301″).

Even if only one of your gears is cracked I would recommend changing all four as it’s probable the others will crack once you start using it again.

And that’s it, the street car is ready to use. The set of four gear axles can be found here.

I have several new gears for different loco types and scales to share with you over the next few months, but if you have something that needs a gear, get in touch. Just like this project I started last year, I may have all ready done it!

A Baldwin RT-624 in HO – Now Available

This week, as promised, I’ve made the HO Baldwin RT-624 kits available to purchase. They’ve now passed all of my checks and had all the little improvements made.

There are two kits available, and both look very smilier but there are differences. Below is the first version.

This kit is for the early Pennsylvania Railroad RT-624 locomotives with the Trainphone. The kit has three parts; the main 3D printed shell, 3D printed detail parts, and etched brass Additions. The 3D printed detail parts and etched brass are the same for both versions.

The second version is for the later Pennsylvania Railroad RT-624 locomotives without the Trainphone. It also has some body differences such as a different headlight position.

The donor chassis used for this model is a Bowser C-628 or C-630, the kit does not come with this.

Please also note that these locomotives have the correct asymmetric trucks but they’re facing the wrong way round. It will work but in order to make it look right you will need to rotate the trucks. As with my DT-6-6-2000 kit I developed a 3D printed kit for rotating the bowser trucks and re-using their side frames. (Bowser sell the correct side frames as spare parts if your donor chassis has the wrong ones).

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)

Commonwealth truck side frames are available from Bowser with their kit 96-603; it can also be used to upgrade an older Stewart Chassis to better pick up if that’s the one you have.  It can be found at the bottom right of the Bowser page using the link below. (If these become hard to get let me know, I can make a 3D printed set of side frames available.)

The couplings for this locomotive has been designed as Kadee #148 HO Scale 140-Series Whisker® Metal Couplers with Gearboxes – Universal – Medium (9/32″) Centerset Shank.

These locomotives have also been designed to receive powered Kadee couplings using Precimodels motors. To make the couplings powered you’ll need the Precimodels kit.

The last shell in the HO RT-624 range will be the single Minneapolis Northfield & Southern locomotive numbered Twenty-Five which I’ll soon have finished.

If you have any issue ordering or any questions please let me know. Ready-To-Run versions can be made on request if you prefer, please contact me via the contact page for a quote.

Now the kits are finished I’m going to paint up the two test prints. I have an ATSF DT6-6-2000 and an early PRR RT-624 which I think will look great, and I’ll share them with you once done.

Bachmann Mainline Replacement Wheel Centers – Part 3

A few weeks ago I received my first test print for my Bachmann Mainline replacement wheel centers, you can read the post here.  Although the first test prints looked good, one of the dimensions was incorrect, and consequently they didn’t fit.

This week I’ve received the second test print.  Again these have been printed in Shapeways Smooth Fine Detail Plastic.

Compared to the originals you can see there are four wheel centers with small counterweights and two with large ones.

This time the wheel centers fitted perfectly.  There was a little 3D print residue inside the crank peg hole which I cleaned out before test fitting.  The wheel centers are a snug fit and it’s worth bearing that in mind when painting; if the paint’s too thick it’ll prevent them from fitting correctly.

These can now be prepped for painting.  I do this by soaking the parts in Goo Gone for 24 hours, rinsing under a warm tap, and then leaving to dry for a few days.  Any 3D print residue left behind will turn to powder and can be brushed off.  I’ll then spray them black and re-assemble the locomotive.

As the wheel centers are a snug fit it’s unlikely they’ll fall out but as a precaution, I’ll put a few drops of superglue on the center of the wheel.  I wouldn’t recommend putting any around the outer rim or under the spokes as it’ll certainly spill out.

These are now ready to be ordered and can be found using the link below.

Bachmann Mainline Replacement Wheel Centers

These will fit the Bachman (Mainline) Split Chassis Standard 4MT, as well as any other locomotive that has a wheel diameter of 24.5mm (flange to flange) and an inside diameter of 20.6mm.

If you need a wheel center for a different locomotive, please let me know and I can make that available as well.

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

In my post, two weeks ago, I said that the HO D6-6-2000 project was just about ready and I was just waiting for the etched brass to arrive so I could do a test fit.  Then it would be released last week.  Well as you may have gathered from the last week’s absent post there was a little more work required before I could release the models.  But they’re now ready.

The etched brass arrived and looks very nice. It’s much thicker than my normal N Scale etches, and this gives it a sturdy feel.

However, because it’s thicker there was an added complication I didn’t foresee. To etch the metal, it’s done in two halves.  The front is half etched, then the back.  Any areas which are etched from both sides will form a hole.  All etching will have a rounding to the etched side, and the thicker the metal, the larger the rounding.  Normally for my thinner N Scale etches this has been insignificant, but for HO this means all the handrail and grab iron posts that fit into the 3D printed holes, didn’t fit as smoothly as designed, causing the etched parts to bend if forced in.

This is easily overcome by increasing the square hole size in the 3D printed model.  The larger hole won’t be visible once the brass is fitted, but it will make the fitting much easier.  For my test print, I’ll need to drill the holes to fit the brass parts and I haven’t gotten to that yet.

As I was making these modifications to the 3D model I also took the chance to make some other improvements.  The side handrails, as shown below, fit into a hole next to the cab door and two holes in the raised deck.  But alongside the lower deck, they were originally located by a small vertical block that represented the handrail fixing, but this didn’t set any height. So I have made the block an ‘L’ shape so the brass can be set in the correct position and ensure the handrail is level.  This will greatly improve the installation of the handrails.

Also in the image above you may have noticed I added the detail for the structural section which sits directly over the truck bolster.  This was missing on my N scale version.

Under the coupling in the pilot, there should also be a triangular-shaped section.  Looking through the photos I have of the originals it wasn’t always present.  I guess it was removable and not always replaced.  I’ve made this a separate part that can be attached to the Kadee coupling box if required.

So now I know all the parts work it’s time to let you know what you need.

To start you’re going to need a Bowser (Stewart) chassis from an Alco C628 or C-630.

The chassis looks like this:

Other chassis can be used if the mounting points and truck spacing are the same.  As shown below the chassis has a mounting point at each end.  The distance between the hole centers is 217.2mm (8.551″).

The chassis comes with different trucks depending on the loco model.

The C-628 should come with ALCo Trimout trucks which are what you need as a starting point.  The C-630 comes with ALCo Trimout trucks or High-Adhesion trucks; both have the gears required, but the base plate from the High-Adhesion trucks is shorter and won’t fit the DT6-6-2000 trucks.  But with a bit of modification, it can be made to fit.  (I’ll cover that in a later post).

Although the Baldwin RT-624 and possibly some later DT-6-6-2000 had trucks very similar to the Trimout trucks, the bulk of the DT6-6-2000s had Commonwealth trucks, so you’ll also need to get a set of the Bowser side frames.  I recommend the Bowser kit 96-603; it can also be used to upgrade an older Stewart Chassis to better pickup if that’s the one you have.  It can be found at the bottom right of Bowser page using the link below

If these become hard to get let me know, I can make a 3D printed set of side frames available.

To convert the Bowser Trimout or High-Adhesion trucks to Commonwealth, you’ll need my conversion kit which contains four truck center halves and 8 gears and can be ordered from Shapeways using the link below.

Next, I’ve made the small parts as a separate model; this was the only solution to getting them to 3D print properly.  This model contains the crew and cabs, horns, and triangular pilot blocks I spoke about earlier.  This can be ordered from Shapeways using the link below.

All the brass is on one fret and is ordered directly from me at a cost of £10 GBP each plus postage.  Please contact me directly for these.  I’ll add a page to the website soon.

The couplings for this locomotive has been designed as Kadee #148 HO Scale 140-Series Whisker® Metal Couplers with Gearboxes – Universal – Medium (9/32″) Centerset Shank.

To make the couplings powered you’ll need the Precimodels kit.

Lastly, you’ll need the shell.  So far I have three different versions available.

Baldwin DT6-6-2000 HO Type 1 has no window shades or frames and the horns are further forward in the roof.  This is to model the Baldwin demonstrator, No, 2000. ()

ATSF 2600 before any rework. (Uncredited image – it was in a magazine but I have no idea which one, so if you know where this image originates from please drop me a message).

Elgin, Joliet, and Eastern Railway early DT6-6-2000s such as no, 104 shown below. (Uncredited image – If you know where this image originates from please drop me a message).

My Baldwin DT6-6-2000 HO Type 1 can be ordered from Shapeways using the link below.

The Baldwin DT6-6-2000 HO Type 2 has slots above the windows for the brass sunshades and the horns have been moved back closer to the cab.  This is to model the early ATSF locos such as 2601 & 2602.  I think it’ll also work for some of the EJ&ER locos.

My Baldwin DT6-6-2000 HO Type 2 can be ordered from Shapeways using the link below.

The Baldwin DT6-6-2000 HO Type 3 has slots around the windows for the brass window box and the horns have been moved back closer to the cab.  The side plates under the cab have also been removed.

This is to model The Minneapolis, Northfield, and Southern Railway no 21. (Picture from Illinois Railway Museum

The window box looks like this, I’ll do a post later to show how it fixes together.

Because the side plates have been cut back you will be able to see the model chassis.  I’ll  look at making a fuel tank section to cover this at a later date, this will also be used for the RT-624.

My Baldwin DT6-6-2000 HO Type 3 can be ordered from Shapeways using the link below.

There’ll be more shells coming over the next few weeks to cover:

The Trona Railway locomotives.

The Peabody Coal Railroad’s locomotives.

The Soo Line Railroad locomotives.

If you have a need for a DT6-6-2000 shell that I haven’t covered please get in touch via the contacts page.

A New Drive Gear For an OO Airfix Class 14xx

This week I have another replacement part to share with you.  As with most of my replacement parts, this was a request from a customer who has one of these locomotives with a damaged part.

The Airfix class 14xx 0-4-2 model has been around since the 1970s, and was a mainstay on many UK model railways as they were the only maker of the model.  It’s had several upgrades over the years as the model moved to Dapol and then to Hornby but the original can still be seen running today.

However, constant use over time will always cause parts to wear out and with the 14xx it’s the main drive gear that starts to go.   The original chassis had a thicker gear which can be seen at the top in the image below.  The thinner gear is for one of the newer chassis introduced under the Dapol line.  Interestingly Daopol also moved the traction tire to the other wheelset.

The metal worm gear on the end of the drive shaft drives sits directly over the main axel drive gear and the metal eventually wears down the plastic gear, especially if the wheels get jammed up or start to bind, due to lack of lubrication.

The gear in the image below is still in good condition, but you can see the teeth are intentionally not square to the axle.  This makes the mesh between the two gears smoother and improves the running of the loco.

Using the original I was able to 3D model a replacement.  Because the gear is thick, 3.18mm, it should be strong and hard when printed in Shapeways Smooth Fine Detail material.

The test prints came out very well and were immediately ready to use.  The hole in the center has been printed slightly smaller than the axel size to ensure a good tight fit.  If it’s too loose the gear will spin on the axel. If it’s too tight the new gear may crack. To allow for any 3D print shrinkage or oversize on the axel, I’ve 3D printed two gears; one has an even smaller hole to allow for any differences mentioned above.  It’s always easier to remove material if it’s too tight than it is to add some!

To identify the two different gears I’ve marked the side of the gear with the smaller axel hole with a hole in the sidewall as you can see on the gear on the right.

The replacement pair of gears for the Airfix OO 14xx are available using the link here.

As long as I can find an original gear, even if it’s cracked or damaged, I can replicate it using 3D printing, so contact me if you’re in need of a new gear that you can’t get hold of.

Next week I hope to have some more to share with you on the HO DT6-6-2000 project, the brass etches are in production, and the different variants of body shells are being drawn.

Replacement Atlas N Scale Motor Universal Connectors

Atlas make lots of railroad locomotives and rolling stock in a variety of scales, and I have several of them because of their quality and they enable me to use the chassis for other builds.  In particular, I use their C-628 and C-630 N Scale models as the donor chassis for my N Scale DT6-6-2000 and RT624 kits.  The chassis has been revised over the years to make improvements, but one version has an issue with the driveshaft coupling to the motor failing.  In this post I’ll share with you my fix.

Below are a pair of Monon C-628s; the rear one is actually a dummy using my 3D printed chassis kit.

The powered chassis is a standard design, used on many of Atlas’s N scale locos, with a central motor and flywheels.

The chassis is held together by the two screws near each end, and the fuel tank, which clips over both chassis halves.

Inside at each end is a driveshaft linking the flywheel and the worm gear, which drives the truck towers. These simply pull out.

The motor is clipped in a cradle which in turn is clipped into the chassis.

With the motor removed you can see inside the flywheel; there’s a plastic universal joint, and it’s cracked.

The universal joint is press-fitted over the axel and uses the friction to spin it with the flywheel.  Even when cracked it’ll spin so the loco will probably run okay on its own.  But as the load is increased, such as adding a train, the amount of force on the split universal is stronger than the friction, and the axel just spins.  So if your loco seems to run okay, but won’t pull very much, this is most likely why.

The universal joint is a plastic tube with two pegs which fit into the driveshaft.  The hole in the tube will be smaller than the axel to create the required tight fit but the constant pressure on this particular material causes it to crack.

Replacement universal joints are available from Atlas, but these have been known to fail as well.  So I’ve 3D modeled the part and printed it in Shapeways Smooth Fine Detail plastic because it’s both accurate and also hard-wearing

The new part is a direct replacement for the original.

If the old universal is cracked it should simply pull off leaving a clear axel inside the flywheel.

I fitted the new universal by placing it with a pair of tweezers but not pushing it on fully, just enough to hold it in place.  If it’s pushed at an angle it too may crack.

I then used a flat screwdriver, as to give even pressure, to push it on fully so the universal is all the way to the back of the flywheel.

And that’s it.  The loco is ready to be reassembled.

These are now available in packs of two and four using the links below:

2x Replacement Atlas N Scale Motor Universal Connectors

4x Replacement Atlas N Scale Motor Universal Connectors

This universal is used in many of Atlas’ diesel locomotives and will fit all.

I’m juggling an HO project as well as testing recent 3D printed replacement parts, but my focus is on returning to work on customer’s layouts where possible, so who knows what I’ll be sharing next week!