A Dummy Knuckle Coupler for OO Gauge – Part 2

Today I had a delivery from Shapeways containing some parts I’ve been waiting a while for and I thought I’d share them with you before I get a chance to really test them out fully.

As well as several other bits the package contained the two parts below.

The white jumble of parts contains many bits, from gears to couplings all on one sprew, which have been 3D printed in Shapeways Fine Detail Plastic.  The parts I’m interested in for this post are the couplings; there is a new sample set of my 3 Link and Instanter fixed couplings without the flexible section and a set of dummy Kadee couplings.

The new 3 Link and Instanter fixed couplings will be covered in a later post as they need to be tested on a OO layout and as I’m an N scaler that is a little difficult tonight but the dummy Kadees can be test fitted now.  Below you can see one next to an actual Kadee with the NEM fitting.

The dummy’s fit together well and there’s a bit of movement to allow for rotation.

They also fit well into the real Kadee.  However, they rotate well in one direction, as shown below, but in the other direction the left hand side of the dummy catches the lug designed  to hold the Kadee spring to the knuckle jaw.  This can easily be rectified by reducing the length of the left hand side.

I do have one OO Gauge loco to hand with NEM pockets and it’s a Bachmann Class 66.  The new dummy coupling clipped right into place and looks good.

As I only have the one item with NEM sockets to hand tonight I can’t do much more testing than holding the original Kadee up so you can see how well they fit.

But what about the black mesh cylinder?

This is how I 3D print my N Gauge Short Rapido Replacements in Shapeways Black Versatile Plastic; you can read about those here.  I added a few dummy Kadee couplings into the cylinder as well to see how they printed in this material.

And I must say they came out even better than expected.  They fit perfect with the Fine Detail Plastic set and the original Kadee.

Plus they also fit perfectly into the NEM socket as you can see on the class 66 below.

As the Black Versatile Plastic ones come pre coloured, are more flexible, strong and don’t need to be cleaned before painting I think these will be the ones to use.  But as with the new 3 Link and Instanter fixed couplings it’s now off to the actual OO railway for some proper testing before I’ll know if they really work.  I’ll let you know more when the testing is done.

A Review of My OO Gauge Fixed Link Wagon Coupling’s

This week I had hoped to bring you the next post about fitting ESU Loksound decoders to three Alco C-855s but time has been rather short this week and they’re not ready yet.  You can find the first post here.

So this week I’ll simply leave you with a review of my 3D printed ‘OO Gauge Fixed Link Wagon Coupling’s’ by Charlie at Chadwick Model Railway.

Thanks to Charlie for the review, for me it’s back to the work bench, until next week.

Alco C-855 N Scale ESU LokSound Install – Part 1

As well as being an iconic-looking locomotive the huge Alco C-855 also had an individual sound being powered by two Alco 16cyl 251C prime movers.  Together they developed 5,500 horse power and would’ve really rumbled as they passed by.  ESU have captured the right sounds and made them available for their V4.0 and new V5 LokSound decoders so in this post I’ll show you how I install sound into these locomotives.

Although the chassis has a step down section at the rear of the locomotive I wanted to add a good size speaker to ensure the sound has some bass to it.  The easiest solution is to cut a section out of the top chassis as you can see below.

Cutting the chassis just behind the inner screws leaves enough room for the speaker and provides a plastic shelf for it to sit on above the worm gear. The worm gear is below the top of the plastic so it won’t catch the speaker.  The chassis has already had parts cut out of the chassis making it lighter.  But given the sheer size of the locomotive, the fact that it pulls like a tractor anyway, and it will be running in a set of three, a little more removed will not be a problem.

The new Lokssound V5 micro sound decoder is a neat package and comes with a good 4 ohm speaker already attached and parts to assemble a speaker enclosure.  This chip came with an 8 pin plug, but as it will be hardwired in, the plug will be cut off.

Unlike the V4.0 Micro decoders which had different plugs soldered to the decoder all the V5 decoders are actually the same.  Below you can see copper pads on top of the chip.  This is actually a removable part with a Next18 socket underneath.  Next18 means it has 18 wire connections.

The chip looks like this.  The six copper solder pads next to the plug are for auxillary functions 5, 6 & 7 as well as stay alive connections.

The underside of the socket has no connections.

The flexible cable can be cut off leaving the socket section and copper solder pads.  The pads include track power positive & negative, motor positive & negative, speaker positive & negative, front & rear headlights, auxillary 1 & 2 and the common positive.

I will be mounting the decoder at the front of the locomotive behind the cab.  There are two ideal power fixing points to connect to.  Bridge wires will also need to be run to the corresponding screws at the rear of the chassis because the glue used to extend the chassis isolates the parts.  See the previous post about fitting a decoder to read more about this, which can be found here.

The original chassis came with a light bulb for the headlight which was attached to the screws via a contact plate.  But as this will need four connections, and I’ve lost the original plates, it’s easy to make some more.  For this I tend to use the excess solid core wire from a resistor, as shown below.

I wrap the wire around the screw.

Solder the ends together.

Cut off the rest of the wire and it’s ready to go.

The one screw which is sunken into the chassis, behind the one with the new contact, can’t be modified in the same way.  For this one I simply strip off enough insulation from the wire and wrap it around the screw twice.  Then as the screw is tightened down it grips the wire.  Make sure you wrap the wire clockwise so as the screw is tightened it doesn’t undo the wire.

With all the connections soldered to the pads the socket can be seated into the area behind the front screw.  But as the chassis is metal it will short out on all the solder pads, so cover the area with Kapton tape first.

The socket can then be put in place and the wires taped down.  Remember to set the wires in the middle of the chassis otherwise the shell will not seat properly.

One thing to note is the decoder will be sat directly above the screws which are delivering track power so the decoder should also be wrapped in Kapton tape, except for the Next18 plug.

The ESU speaker enclosure comes in four parts.  A base, two thin sections and one thick allowing different heights to be made.  Even with the chassis cut down one of the thin sections will need to be left out.  I use superglue to fix the enclosure together and to the speaker frame, ensuring not to get any on the actual speaker.

The assembled speaker can then be placed at the rear of the chassis with the wire connections at the top facing forwards.

The top of the speaker is just about in line with the top of the decoder which sits just under the roof line of the shell.

You may have also noticed the brown wires from the decoder socket were not quite long enough.  I could’ve replaced them but it was just as easy to extend them, covering the joint with heat shrink. If you’ve never worked with heat shrink before I did a ‘how-to’ on it which can be found here.

With the decoder plugged in the chassis is now ready for its trucks and then testing.  This particular chassis is for a C-855 B unit so I haven’t added any headlights, but both the C-855 A units will have lights, so I added wires from the socket and included a resistor which is tucked under the front of the decoder.  Below you can see all three chassis ready to be fitted to their respective shells.

The chassis have been tested and sound very good but installing the shells will add an extra level of resonance, increasing the volume. Once they are totally finished and fitted I’ll share a video with you so you can hear all six Alco 251C prime movers running.

A Dummy Knuckle Coupler for OO Gauge

It’s been a busy time over the last few weeks, which you may have noticed by my absence last week.  But I’ve not been idle and I have lots of new things on the way, but for now they are still on the drawing board or being tested.

One thing I can share with you is a new design for a fellow UK OO gauge modeller who is fitting Kadee couplers to his rolling-stock.  He wanted to have a non-functioning Kadee coupler to make sure that rolling-stock in fixed rakes would not come uncoupled but maintain the look of the Kadee coupler.  As most of the new OO gauge rolling stock now has NEM standard sockets it seemed that this would be fairly simple.

A working Kadee coupler with a NEM fitting, as shown below, rotates about a central pin and the knuckle opens and is held closed by the spring on the side.

I designed the dummy so that it’s fixed in the closed position.  I also omitted the rotating pin and made the whole coupling one piece.  Hopefully there’ll be enough play in the knuckle to allow for some rotation.  My first design looks like this.

This is now being test printed and as usual I will share the results with you once they arrive and I’ve had a chance to test them.

But for now it’s back to the drawing board.

OO Gauge Fixed Link Wagon Couplings Revisit – Part 1

In March of 2017 I first introduced my OO gauge fixed link couplings for UK wagons, you can find the post here, and they developed into a range of couplings to suit both 3 Link and Instanter couplings.  They’ve been doing well but there have been a few issues so a revisit to the design is required.  In this post I’ll be showing you the first steps.

The couplings, as shown below, are designed to fit into NEM standard pockets and form a permanent link between two wagons whilst retaining the look of a 3 Link and Instanter coupling.

And I think they do this very well.

At the time, an important design feature was the ability to add some flexibility onto the coupling to allow it to navigate corners.  I considered the main part of the coupling too stiff and was worried it would pull trucks off the rails on corners.  A solution was achieved through a flexible section; this was covered in the second post which can be found here.  But it’s this flexible section which has caused the issues.  The material used for the couplings is Shapeways’ Smooth Fine Detail but, as you may have read in other posts, it is brittle and the couplings tend to break at the flexible section, especially when handling several wagons joined together off the rails.  They tend to break here as it’s the part of the coupling with the least material.  One thing I also noticed is that the direction of the print also had an effect on the strength.  The original couplings were printed loose and often standing up on end.  This meant each layer of 3D printed material had a small surface area to bond with the last.  Printing the couplings laid down significantly increased this area and therefore the strength.  Since I made the alteration to print the couplings as a group, see the third post here, they’ve all been printed laid down, but they could still benefit from more strength.

As it turns out the couplings do have some flexibility and the required amount of movement is not great so I’m going to try some 3D printed couplings without the flexible section to see how they do.  Below you can see the revised couplings on the right.

The taller couplings had a much larger flexible section and coincidently it was much stronger; it was the flat coupling which broke more than any others.  But I’m going to try them all.

I’m also going to do some experiments with some of the other materials.  Once I have samples in hand I’ll share the results with you.

A Different Material for Gears

For a few weeks I’ve been experimenting with different materials for small gears and in this week’s post I wanted to share with you one of the materials which doesn’t work.

For a while now I’ve been 3D printing replacement gears for a variety of locomotives in Shapeways’ Smooth Fine Detail material (formally known as FUD).  This material has the advantage of being very accurate to the 3D model size; the detail is crisp, which is ideal for small teeth, it’s hard so it wears well, and several gears can be 3D printed in close proximity to each other without actually touching.

The disadvantage of this material is it hardens, which also makes it brittle.  For larger gears this isn’t a problem as the big surface area also adds strength, but with small and tiny gears the teeth tend to break under shock loads such as a locomotive suddenly stopping.  The tiny teeth have no flexibility and crack when overloaded.  The Smooth Fine Detail material is acrylic, or very close to it, and the properties don’t allow for flexibility.

Recently Shapeways’ introduced a new materiel, Multi Jet Fusion Plastic or PA12.  This is a product which comes from Hewlett-Packard and is a nylon plastic.  This sounds ideal for gears as it’s hard, but with a touch of flexibility, meaning the teeth can take a shock impact.  And it comes in dark grey which is nearly black.  Reading the design specifications for this material the level of detail attainable is not as high as the Smooth Fine Detail but I wanted to see how close it was.  So with a set of gears I’ve recently produced for the 009 Society I 3D printed them in both the Smooth Fine Detail and the PA12.

As you can see the PA12 simply doesn’t have the precision of the Smooth Fine Detail. The teeth have rounded as the material has flowed into itself and the gears are all fused to the spindle.  With the Smooth Fine Detail set the teeth are crisp, the same size as the 3D model, and all spin freely on the spindle.  To be fair these gears are particularly small at only 4.3mm in diameter for the larger and 3.4mm for the smaller.  The PA12 may work with some of my larger gears and I’ll give it a go with a later order.

But for now my primary material for gears is still the Smooth Fine Detail.