Replacement Bachmann OO Chassis Fasteners & Washers

This week I have another new replacement part to share with you. A locomotive was brought in to get DCC sound fitted and I know from experience there’s a good chance certain parts will break when the locomotive is taken apart, and in this instance I was not mistaken.  The Locomotive in question is a Gresly V2  made by Bachmann under their Branch Line range.

These locomotives are very good, although now an older model, and are normally very reliable.  The primary problem these, and other locos in the range, suffer from is split axels and I’ve already 3D printed parts to repair them, which you can read about here.

However, the axels on this locomotive are fine; the issue is with the split chassis fasteners.  A lot, if not all, of the Bachmann locomotives of this generation, have a split chassis.  This means the chassis is in two halves with each side conducting power from the wheels to the motor, eliminating the need for wires.  For DC operation this is perfect.  But for DCC I need to separate the chassis halves to electrically isolate the motor.  The chassis halves need to be screwed together but electrically separated.  This is achieved by using a plastic chassis fastener, plastic washer and metal screw.  The fastener has a square head that fits into a square recess in the left chassis half to stop it rotating.  The washer fits between the chassis halves, over the fastener to separate them, and the screw pulls the parts together as it bites into the fastener.

The problem comes, as with this V2, when the locomotive has never been taken apart and the plastic fastener has either deteriorated or maybe shrunk.  I’m not sure what actually happens.  But the screws are very tight and the force needed to get it to move is often more than the fastener can take and the tube section twists off the square head; as you can see below.

Or the tube section simply breaks at the end of the screw, which also happened on this locomotive.

It is possible, if you’re both careful and lucky, to glue the parts back together, but more times than not it doesn’t work and I often come across these locos with several missing fasteners.

So my solution, as is my way, is to 3D print replacement parts.  I designed the fastener to be a direct replacement and included a washer as sometimes the originals can get lost.  They are 3D printed in Shapeways Fine Detail Plastic as it’s the most accurate.

Before these can be used it’s very important to clean out the tube section.  This is because it will be full of 3D print residue which, if left inside, will add pressure to the tube wall as the screw is driven in, cracking the tube.  To clean out the tube I use a 1.26mm (0.049″) drill in a pin vice.  This won’t actually remove any of the tube material, just ream out the hole, as you can see below.

There’s usually a lot of residue in the hole because it’s small and Shapeways post-cleaning processes can’t get in there.

With the fasteners ready the chassis can be reassembled.  The V2 uses five, as you can see below by the holes in the right side chassis half.

With both sides fitted you can see the square heads in the left side chassis half.  It was only when I put this photo up I realized I had the front one in the wrong way round.  Fortunately with that one it works from either side.

The square recess in the left chassis half has a bit of tolerance so the head will rotate a little.

These replacement fasteners and washers can be used on a large variety of Bachmann split chassis locomotives and I’ve made them available in a set of 6 here and a set of 12 here.

This particular V2 is now back up and running and has an ESU sound DCC decoder, working lamps, and a realistic firebox flicker whenever the fireman opens the firebox door, which reflects nicely around the cab.

If you have another part, such as this fastener, which has broken and you can’t find a replacement I’d be happy to see if I can draw it up for 3D printing.  You can get in touch via the contact page.

Replacement Bell Cranks for an MRC/Rowa N Scale 2-8-4 and 2-8-8-2

Back in May of 2015 I needed a replacement eccentric rod for an N Scale Rowa/MRC 2-8-4 Berkshire to replace a missing one on a second-hand locomotive, and designed and 3D printed the part.  The post can be found here.

Since then I’ve had a request to provide a replacement bell crank for the Rowa/MRC 2-8-8-2 Y6B.  This mighty steam locomotive was one of the original N scale greats dating back to 1969 when MRC first released it.

It went through a few changes and was re-released in 1977 by Con-Cor/Rivarossi.

One of the main differences in the two versions is the side rods and valve gear.  The original MRC, and later Rowa version had plastic parts, whereas the later Concor/Rivarossi ones had metal.  The part I’m replacing is on the earlier MRC/Rowa version, which coincidently is exactly the same on their 2-8-4 Berkshire.

The original Berkshire bell crank and eccentric rod are shown below.  They simply clip together and the bell crank rotates about the round lug, which is at the other end from the C section.

The new 3D printed bell cranks are printed on a sprue, simply because they’re so small.

Up close you can see the new 3D printed part is slightly chunkier than the original injection molded part to give some extra strength to it.  Once fitted it’s very hard to see the difference.

On the Berkshire, with the bell crank removed, you can see the circular hole at the back of the bell housing to receive the round lug.

The new part clipped right in and rocked back and forward with ease.  The part will ideally be painted silver before the final install.

The original eccentric rod clips into the new bell crank and the main drive wheel, fixing with ease, and that’s it.  This particular Berkshire has no motor in it so I can’t show it running, but it ran freely along the track by hand with no issues from the new bell crank.

The Y6B, as I said before, has the exact same bell cranks, just more of them.

The only difference is the eccentric rod is shorter, which is caused by the altered geometry of smaller driving wheels compared to the Berkshire.

A pack of 6 bell cranks for MRC/Rowa 2-8-4s and 2-8-8-2s are available here.

I’ve had some time to get around to finishing some other long overdue 3D printing projects and over the next few weeks, I look forward to sharing these with you and making them available to buy.

New Gears For A Bachmann N Scale Doodlebug

The first post of this year showed you the problems with split axels on a Bachmann N Scale Doodlebug, which can be found here. In this post, I’ll show you the result of the 3D print.

The four 3D parts, as pictured below in the top of the image, are the two drive gear axels and two free axels.  The Doodlebug does have other gears between the motor and the wheels but it’s only these parts that break as they have metal axles forced into them, causing them to crack over time.

The two parts in the middle are an original cracked gear and axel, and at the bottom are an original gear and axel with the wheels fitted.

Before I fit the wheels to the new parts I pass a 1.5mm (0.058″) drill through each part. The drill is ever-so-slightly smaller than the hole in the part, so no actual material is removed, but it cleans out the 3D print residue and ensures a good fit.  If there’s residue the fit can be too tight and cause the new part to crack.

One thing to note; two of the wheels have traction tires and both fit onto one of the axels.  If, like me, you accidentally fit a regular wheel to this axel it can be very difficult to remove and there’s a good chance you’ll break a tooth on the new gear, which is what I did.  That’s why in the new set below I still have one original gear that wasn’t cracked.

The drive gear set clips into the truck tower, with the new gears meshing with the originals.

The plain axels for the trailing truck simply rest in the cutouts.  Both trucks have a plastic clip that holds everything in place.

With the trucks refitted, power pickups replaced, and truck sides attached, the chassis is ready for a test.

And it ran very well, smooth and free, so I refitted the shell.

At some point, I’ll fit a DCC decoder to the Doodlebug, but first I want to tone down the paint job.  Although it’s in the UP colors or Armour Yellow and Harbour Mist Gray, I do find it a bit bright.  But with some weathering, I think it’ll look just fine.

The 3D printed replacement axles for the Doodlebug are now available through my Shapeways shop and can be found here.

I’m slowly working my way through the older Bachmann locomotives which I’ve found tend to have split gears.  I’ve got the first two versions of the N Scale DD40AX and the N Scale PCC Interurban Streamlined Car next on the workbench and will be drawing designs for those for replacement 3D printed gears too.

An N Gauge Dapol Britannia Driveshaft

This week I have a new product to share with you.  The N Gauge Dapol 4-6-2 Britannia is a great model.  But in a similar way to the N Scale Roundhouse, now Athearn’s, 2-6-0 and 2-8-0 steam engines, and the Atlas N Scale 4-4-0, this particular model also needed a new driveshaft and yoke.

The motor, and DCC decoder, is packed into the tender and a drive shaft runs through the cab to power the main driving wheels.  The motor axle has a yoke fitted to the end, as does the spindle in the cab.  A driveshaft connects the two yokes and allows the tender and locomotive to twist without breaking the transmission of power, just like a drive shaft does on a car without being affected by the car’s suspension or steering.

I modeled the three parts after taking measurements from the originals.  I made the driveshaft slightly longer as I’ve often had originals come apart when handling the locomotive. The set on the left are loose, but in order to avoid an individual part print charge, I’ve combined them into the set on the right.  None of the parts actually touch the sprew which can simply be cut away.

The parts were printed in Shapeways Smooth Fine Detail Plastic, as it’s the most accurate for small parts, and they came out very well.

On the model, it was the yoke on the motor axle which was missing.  This is normally due to the original splitting.  If the valve gear on the locomotive jams and the motor carries on trying to spin, the force can cause this to happen.

The new yoke, with a little bit of pressure, fitted onto the axle.  I’ve designed the hole in the yoke to be very slightly smaller than the axle so the pressure fit will prevent it from spinning on the axle.  Whenever fitting anything like this it’s important to make sure the inside of the yoke is clean and free from any 3D print residue, as this may cause an even tighter fit and could lead to the new yoke cracking as well.

As the old yoke on the locomotive spindle was intact I didn’t change it, but as you can see the new driveshaft fits well.

With the locomotive reassembled I also tried it with the original driveshaft; you can just make out the black spokes in the new tender yoke.

But I did find, as with the original setup, the driveshaft came out too easily.  The new 3D printed one is almost 0.8mm longer than the original and this helped keep it in place as you can see below.  Another alternative would be to slide the tender yoke slightly closer to the locomotive.

The last step was to test the new driveshaft and as you can see below I’ve lifted the locomotive driving wheels off the track for the first test.  I wanted to run the loco at speed for a while, and as the rear set of drivers have traction tires which are susceptible to coming off, I didn’t want to give them the chance.

The next test was to do several successful trips around the layout with twelve coaches behind, which it did with ease.

The Dapol N Britannia Driveshaft Repair Kit is available here.

This coming weekend is the NMRA(BR) Benson winter meet and I’ll be there with my fellow club members and parts of our ‘Solent Summit’ layout.  As this is only a one-day event we won’t be putting on a 5 Mile show like we did at Warley!

The event is at the Benson Village Hall, Sunnyside, Benson, Oxfordshire OX10 6LZ from 10am till 4pm. I hope to see you there if you can make it, if not I hope to get some photos to share with you next week.

Adding Power Pickups by DCC Concepts

As well as the drawing I do for 3D printing I do a lot of train repairs and DCC installs, particularly sound installs.  These can sometimes be a bit tricky and I often have to use other products to make it work.  Normally I don’t do reviews of products but recently I found something that worked so well I wanted to share it with you.  In this post, I’ll show you what I did to add additional power pickups to a Hornby OO B17 with plastic wheels in the tender.

The B17 has been around for many years and every now and again it gets a facelift as parts are re-tooled and improved.  The most recent version is quite fantastic, but the previous one had, in my opinion, one major problem.  The tender was the same design from many years before, and still had plastic wheels.  The two pictured below are of this version; you can tell by the basic molded coal load in the tender.

This means although the locomotive had been re-tooled to include power pickups on all the drives, it still only had the pickup footprint of an 0-6-0.   For DC operation this is often just fine, but DCC, and in particular DCC sound, the decoder required an unbroken power supply and when you factor in dirty track, dirty wheels, and dirty pickups, the 0-6-0 footprint on this loco simply wasn’t working.

Looking under the tender you can see the plastic wheels and even the hole above the third one which allowed a strip of card with a rough surface to hang down.  A cam on the last wheel used to rub against the surface and make a kind of chuff effect; this dated back to the 80’s and Hornby called it their ‘Realistic Chuff’ effect.

The red you can see through the hole is a stay alive unit.  This locomotive is fitted with a Zimo Sound decoder, but even with the stay alive, if the loco stopped in the wrong place it wouldn’t start again without a push.

The axle for the wheels is simply a bar and the plastic wheels are in two parts.  This design has been repeated on many locomotives of early design.

The first problem is to find metal wheels to use.  The reason why it’s a problem is just about all the current metal wheels come with much shorter axles with pointed ends.  But the old Mainline or Replica Railways (which is now Bachmann) locomotives had metal wheels in their tenders which were the exact same size on long axles.  Of course, this does mean sacrificing another loco but six axles from two tenders is enough to do three Hornby locos as I’ve only replaced two wheelsets in each tender.  An afterthought would be to see if the plastic wheels fit in the Mainline or Replica Railways tenders?

I found two types of wheelsets in the Mainline/Replica Railways tenders.  Some, as with the set on the left, have metal wheels but a plastic axle which doesn’t end in a point.  The center and right side wheelset both have metal wheels and a metal axle, electrically isolated, with pointed ends.

As the original Hornby axle measured  26.35mm I wanted to get as close as I could.  Any longer will cause binding and make it harder to fit the new wheels.

The set with the plastic axle came in just under and worked perfectly without modification.

The set with the metal axle was ever-so-slightly longer, but this was easily remedied by filing off the points on each end of the axles.

As you can see below both types of wheelsets fitted into the tender and they all rotated  very well.

The second issue was how to collect the power from the metal wheels.  Over the years I’ve built many homemade pickup systems, normally from strips of brass that rub on the wheels at some point, but it doesn’t always work well and the pressure of a flat strip rubbing on the wheel creates a lot of drag.

Then I discovered DCC concepts’ gold plated bronze wheel wiper sets.

The pack contains 12 sets of wheel pickups, each picking up from both wheels and a pack of screws for mounting.

The actual pickup is a strip of PC board with two folded brass contacts, both gold plated.  The contacts have a rounded section to provide a pinpoint contact on the wheel which will reduce drag.  Next to the mounting hole are two solder pads, one for each side.

The rear simply has the connection between the pickups and the solder pads.

As you can see below the pickups fit perfectly between the wheels and provide just the right amount of pressure to ensure a great contact with the wheel.

Now it’s time to fit them.  With the tender shell removed you can see the metal weight.  It will be important to keep this as it’ll ensure the wheels keep good contact with the rails, but it’ll need to come off for now.

The weight was held in place with a few spots of glue.

With the new wheels fitted the pickups can be moved around until the ideal location is found.  You need to make sure the rounded part of the pickup is in contact with the middle of the metal wheel flange and not the plastic inner.

Then using a pin vice I drilled a hole, smaller than the screw, in the tender chassis using the hole in the pickup as a guide.  The screw will cut into the soft plastic of the chassis.

The pickups can now be fitted in place.  I also fitted the wheels again at this point to test everthing worked properly.

The screws were longer than the thickness of the plastic chassis and protruded out of the top. That’s why I removed the weight, and they need to be cut and filed down to refit it.

I refitted the weight using some Black Tack, it’s very sticky and malleable, which is ideal for this job.

The solder pad can now be linked with wire.  If you have a large soldering iron you may want to solder the wires on before the pickups are fitted to prevent caching the chassis with the iron as it will melt very quickly.

Lastly, I solder on two wires to connect back to the main locomotive pickup points.  It’s important to ensure you match the tender wheels from the correct side with the loco wheels or it will simply short out.

With the tender reassembled and all the wires connected it was time to test the loco, and it ran very well.  The best test was to raise the loco off the rails, so it isn’t picking up any power and see if the tender pickups worked on their own, which they did, as you can see in the short video below.

I could’ve fitted three sets to the tender, but after testing two proved to be plenty, and both the B17 locomotives from the first picture are now running equally as well as the latest version of this locomotive, which comes with factory fitted tender pickups.

These pickups from DCC Concepts are very good and, I think, very well priced because you get 12 in a pack.  I’ll certainly be using them again. I just hope they bring this product out for N Scale.  You can get the pickups direct from DCC concepts or at a stockist such as Model Railway Solutions in Poole.

Next week I’ll share with you some of the 3D printed parts which arrived last week.

A Quick Post of New Parts

This week’s post will be short as I just want to give you a look at what arrived in the mail today from Shapeways.

The large spikes at the top are exactly that; spikes to repair a track system for a wooden toy train. The assembly below contains lots of gears, axels, a drive shaft and a set of drive shaft couplings.  These are to repair several locomotives such as the N scale Doodlebug from last week’s post, an N scale Minitrix diesel, an N Gauge Dapol Britannia and a HO scale Samhongsa brass locomotive.

After the parts are tested I’ll share the outcomes with you, but for tonight it’s back to the workbench, as some unexpected jobs have come up.  Next week I’ll have a review of a new product I found that was a tremendous help in upgrading some older steam engines to DCC sound.