Minitrix 9F Replacment Drive Gear

This week I have another new replacement part to share with you for the N Gauge Minitrix 9F.  I’ve already made replacement parts for this locomotive such as the eccentric rod crank pin which you can read about here and the cross head, which you can read about here.

The Minitrix 9F has always been a good runner but, apart from the eccentric crank pin and cross head, it suffers from wear in the plastic gear after lots of running.

The worm gear on the motor shaft is metal and drives a plastic gear, this in turn drives two metal gears which drive the metal gears between and on the axles.  The first gear is made from plastic, I believe, because it’s a double gear and it’s cheaper to make it in plastic than metal.  A double gear means it has a large and small diameter gear moulded into one piece as illustrated below.

Because the original gear is plastic and is driven by and drives metal gears, over time it wears down and looks like this.

Sometimes a slight wear can be overcome by slipping a pack under the rear of the motor, tilting it forwards, causing the worm gear to push down onto the plastic gear but eventually it will wear out.

You can see the larger gear, which is driven by the worm gear, has lost its points and the bottom left side has worn more than the rest.  This may be because the side rods jammed, stopping the gear, but the worm gear carried on turning, chewing the plastic.

The new 3D printed part, as shown below, is printed in Shapeways Fine Detail Plastic.  This is a hard material and long-lasting which has been proven with the O Scale gears I made a few years ago.  You can read more about those here.

The plastic gear spins on a metal axle which fits into the new gear without enlarging the hole.

Fitted back into the chassis before the motor is re-fitted, the new gear can be seen in the top of the tower.  At this stage the gear can easily be tested because the worm gear is not stopping all the gears from turning.  Running the wheels along the work bench turns all the gears, including the new one.

With the motor re-fitted, along with the weights and shell, the locomotive can be tested on power and it runs nice and smoothly.

The gear is available here.

Next week I’ll have another new replacement part to share with you.

Bridging the Gap Between Kits and Production Models

As you may have read on my blog before I often do commission work for companies allowing then to mass produce models using 3D printed parts.  And in this week’s post I have the latest release to share with you.

Three good examples of other projects which have been created this way are:

The Pennsylvania Railroad (PRR) F22 flatcars & naval gun load.

The 4 vat open pickle car.

And the enclosed tank pickle car.

All three of these were drawn for the N Scale Architect who sells them as kits.  However, sometimes the projects are only sold as ready-to-run models and this new project is one of these.

My brief for the project was this photo of Pennsylvania Railroad gondola G26 #440375 taken around 1951. (Andrew J. Hart collection from “Pennsylvania Railroad Gondolas,” PRRT&HS).

The concept is to have a bridge girder load carried on or in a gondola car with the ends removed.  The overhang spans over flat cars, or idlers, at each end. I found it particularly interesting that the girder is not symmetrical;  I have seen this type of load modelled before in HO scale but never as an asymmetric girder.  This makes it unusual as the center of gravity will not be in the center of the car.

As well as making the girder I also had to work out how it was supported and strapped down in transit, taking into account the offset center of gravity.  And, as with all my projects, this work is all done in a 3D model.

The red parts are separate, allowing easy painting, and represent wooden blocks which brace the girder.  The black bars are just that, bars which clamp the girder between the blocks.

All five bottom wood sections will be fixed to the gondola car deck.  The two sets of vertical timbers prevent the girder from rolling over.  Two of the timbers clamps are positioned either side of the largest part of the girder, each one pulling towards the other, preventing the girder from sliding up and down the gondola.  The third clamp simply holds that end down.

And just to make sure it all fits I also modeled in the cars with just enough detail.

The next step was to order a test print to see how well it all worked, and I think you’ll agree from the pictures below that the actual girder looks good.

The supporting wood blocks are hard to see without any color, so the girder and the wood blocks took a trip to the paint shop and now they looks like this.

And here is a video of the train crossing the road, just as if you had stopped in your truck!

So where can you get one from?  These are on sale as a special run in limited numbers from the N Scale Enthusiast.  They have been painted and assembled by The N Scale Architect as a Union Pacific load from Kaiser Steel as shown below.

All three cars are made by Micro trains and include the shipping crates on the flat cars.

This was a great project to work on and really shows how 3D printed parts can help ‘bridge the gap’ between kits and production models.


Pennsylvania Railroad (PRR) F22 Flatcars & Naval Gun Load

Several weeks ago I posted about the N Scale Architect’s new kit for a set of Pennsylvania Railroad F22 Flatcars & Naval Gun Load.  This kit, which was still in development, was announced at the Amherst Railway Society Show 2018, in West Springfield, Massachusetts.

And I spoke about it again two weeks ago as the sample came to the Bournemouth N Trak convention here in England.

Well, this kit is now complete and it looks amazing.

Here is what the N Scale Architect has to say about them:

“The Naval Gun Load kit is based on the Mark VII Naval Gun designed in 1939 and first used aboard Iowa-Class Battleships during World War II.  Measuring 16” in diameter, these guns could fire a 2,400 lbs projectile up to 24 miles. Each of these 68 foot guns weigh nearly 270,000 lbs and were shipped (breech first) across two(2) heavy weight flatcars with a third flatcar used as an idler. Many of these guns were manufactured by Bethlehem Steel in Pennsylvania and transported via the Pennsylvania Railroad across three(3) F22 flatcars. This kit comes complete with Frosted Ultra Detail (FUD) 3-D printed parts, full-color illustrated instructions, sixteen(16) inches of phosphor bronze rod and a ‘DO NOT HUMP’ placard sheet.

The Pennsylvania Railroad (PRR) F22 Flatcar 3-Pak Kit builds three(3) of these wood-decked 30 foot heavy-duty flatcars which had a loading capacity of nearly 200,000 lbs when upgraded to the Crown 2F-F1 cast steel trucks modeled in this kit. These flatcars were originally designed in 1913 and, at their peak in the 1940’s, there were over 100 in use on the Pennsylvania Railroad (PRR) roster with some of them surviving into the 1960’s. This kit comes complete with Frosted Ultra Detail (FUD) 3-D printed parts, full-color illustrated instructions, photo-etched stirrups & cut-levers, brass car weights, Micro-Trains brake wheels & body-mounted couplers, Fox Valley metal wheel sets and a PRR F22 decal sheet that features nine(9) verified road numbers, pertinent car data and prototypical reporting marks.

The ‘Naval Gun Load’ kit (#20100) retails for $39.95, the ‘Pennsylvania Railroad (PRR) F22 Flatcar 3-Pak’ kit (#20101) retails for $69.95 and the ‘Box Set’ (#20102) retails for $89.95… a $20.00 Savings !!!  These kits are available exclusively at the THENARCH.COM.  Additional 3-D printing material options are available at our Shapeways Shop:”

This was a project I really enjoyed working on as it’s such unique load. It was great to get everything correct from the trucks to the length of the gun barrel. The lack of restrictions, which are often caused by donor chassis and other parts that I have to use when designing a locomotive, are what made this easier to do. Only the wheels and couplings are bought in items.

As The N Scale Architect says the kits are available direct from their website or via their Shapeways shop if you want to order them in Frosted Extreme Detail (FXD).  If you do purchase a kit from Shapeways don’t forget to contact the N Scale Architect via their website (THENARCH.COM) or e-mail ( to obtain the additional pieces and instructions needed to finish the kit.  Be sure to include your name, mailing address and Shapeways order number in this message. These items will be mailed to you at no additional charge (including international orders). Please allow 7 to 10 business days for delivery (international orders may take longer).

For me it’s back to the virtual drawing board and on with my current projects, and I hope next week to have some more progress to share with you.

New Axles for a Bachmann HO 4-8-4 Northern – Part 2

Last week I shared with you my designs for a set of replacement Bachmann HO 4-8-4 axles as shown below.

The locomotive was tested and ran smoothly with new axles fitted: the set of four axles are available in my Shapeways shop here.

One thing which I wasn’t sure of last week was one of the original axles has a square center section rather than circular as the other two.  I have since been informed by a fellow modeller that the orignal version of this locomotive also had smoke but the smoke unit had a section which was driven from this square axle to create the puff effect.  As the model was improved this feature was removed but the square axle was never updated.

This coming weekend, 9th to 11th March 2018, is the N Trak convention in Bournemouth, England and again it’s at The Trouville Hotel.  You can read a bit more about last year’s convention here and the 2014 convention here.  I’ll be there over the weekend if you are in the area and want to come by and say hello.

3D Printed Minitrix Cross Heads Part 2

Two weeks ago I shared with you my designs for a 3D printed replacement N Scale Minitrix cross head; you can read the post here.  This week I have the actual 3D printed cross head to show you.

The design, as pictured below, followed the original closely with the exception of the weaker areas which were strengthened by adding a bit more material.

The actual parts look like this, next to a broken original.

The parts have been cleaned by submerging in Goo Gone for 24 hours, rinsed in warm water and left for a further 24 hours in open air; this is my normal cleaning process for all parts 3D printed in Shapeways’ FUD and FXD materials.

In the image below you can see a new and an old cross head on the slide bar, the slots in the sides are just right to allow the crosshead to slide without being too tight or too loose.

The upper hole on the cross head is for the piston and connecting rod joint and as you can see below this fits together well.  The piston is actually a bar with a ninety degree bend in.  The bar passes through the cross head then the connecting rod.  When it comes to getting the bend through the two parts it needs a bit of a push.  This also stops the bar from falling out.

One thing I did learn at this point is the piston bar needs to be fitted after the lower hole is connected otherwise it’s very hard to assemble!  So it came out again.

Also, to connect the lower hole, make sure the crosshead is on the slider bar first. Don’t ask me how I know that!

The lower hole connects to part of the valve gear. This time it uses a metal pin.  The pin is actually a tube and the end is flared over to prevent it falling out.  I carefully un-flared the pin by squeezing it together with a pair of tweezers.  Then the remaining part of the old crosshead fell away and I was able to push the pin through the new one.  This is probably the stage when the new cross head is most at risk of breaking, so try to make the end of the pin as close to the diameter of the pin as you can.  Once it has passed through the pin can be re-flared by pushing in a needle file or something similar.  It doesn’t need to be flared much, just enough to stop the pin from passing back through the hole.

The piston bar can now be inserted, completing this part of the assembly.

The wheels and motion can now be inserted into the chassis; this is a really tricky job!

And here we have a repaired Minitrix cross head.  The chassis rolls up and down freely and is ready to have the motor and other parts refitted.

The cross head is available on my Shapeways shop in sets of two and four here via the links.

I will also try to keep a few in stock, although not until after Christmas, so you can also contact me directly for a set.  I will also offer the cross heads in a set, along with my replacement Minitrix Eccentric Rod Crank Pins.

Next week I’ll have another how-to to share with you about coal loads.

Getting in a Bit of a Pickle

Over the last few months it might have seemed that I haven’t really been doing much in the way of 3D printing design.  Well in fact I have; I just couldn’t tell you about it, until now!

The N Scale Architect has commissioned two new N Scale freight cars to accompany their new turn-of-the-century pickling plant kit, pictured below.

This lovely kit has everything you need to build a pickling plant, but how do you move the produce around the layout? The answer comes in two forms.

The 4 Vat Open Car.

And the Enclosed Tank Pickle Car.

Both car kits come complete with a full-color illustrated instruction sheet, photo-etched ladders & stirrups, bronze tie-rods, four 1/4oz car weights, a decal set of your choice and Micro-Trains brake wheel, trucks & body mounted couplers.  Each decal set is inspired by vintage pickling company markings and includes four different road numbers.

The 46′ open 4 vat pickle car follows prototypes made by Thrall, GATC, ACF and other manufacturers from the early 1900s up until the 1950s has four printed sections forming the chassis, vats, roof supports and the roof.

The roof supports are separated before they clip into the chassis.

The 42′ enclosed tank pickle car follows prototypes made by Thrall, GATC, ACF and other manufacturers from the early 1900’s up until the 1950’s and has three printed sections forming the chassis, sides and roof.  All are printed with the best side facing up to get the finest detail.

The etched ladders on both and the sign on the enclosed car are stainless steel.

Both of these new cars are available from the N Scale Architect’s Shapeways shop or through the website.

And that’s not all, there are more cars on the way from myself and the N Scale Architect but you’ll have to wait to see what they are!