In last week’s post I shared with you my designs for a stackable enclosure that allows you to build any height sound box for your DCC speaker.  You can find the post here.

This week the parts have arrived from Shapeways and I thought I would show you how they came out.  Right out of the box the parts are transparent and look like this.

The hollow parts are the wall sections and the closed off parts are the bases  As with all parts printed in the Shapeways Frosted Ultra Detail material they need to be cleaned up to remove the waxy residue left behind from the printing process.  This is done by soaking the parts in Goo Gone overnight.

Once the parts have had a good soak they are rinsed off with water and left to dry.  As they dry they will turn opaque and can now be painted if required.  If you dont clean off the waxy residue it will prevent paint and glue from adhering to the surface of the part.

With all the parts clean and dry it was time to do some test fitting.  As designed, they all fit together perfectly, and with a spot of glue will be come a solid enclosure.  The Zimo speaker is also a perfect fit; it actually fits better into the 3D printed part than it does into the injection molded enclosure it came with.

The depth of the enclosure can now be easily adjusted by 1.5mm by adding or subtracting a wall section.

These means you can create any size enclosure that you need.

It even fits into the base on its own should you be very tight on space.

The next stage is to do some testing to see how it sounds compared to the stock enclosure.  As a comparison here is a video of the stock speaker that comes with the decoder.  You can hear the engine running and me sounding the horn.

Next we have a video with the Zimo speaker fitted on its own.  A word of warning; the speaker is designed so that you can solder wires to it, but remember a speaker has a powerful magnet inside and if you are not careful it will attach itself to the soldering iron and get very hot, causing damage to the speaker.

The speaker on its own is very quiet as there is nothing behind it for the sound to bounce off.

Then we have a video showing the Zimo speaker with and without the stock enclosure.  When the speaker is lowered onto the enclosure the volume gets much louder.

And finally we have the Zimo speaker and the 3D printed enclosure made from three wall sections.  The volume increase using the 3D printed parts is roughly the same as the stock enclosure.

The parts that made up this enclosure were not glued together for the test so the sound should get even better once they are all sealed up.

I will shortly be making these speaker enclosures available via Shapeways and through my blog where you will be able to get them in different quantities.

There are now many options for adding sound to DCC locomotives but, with the limited space often found inside N Scale locomotives, fitting in all the parts can be a problem.  Apart from the actual DCC decoder the speaker is one of the larger problems and in this post I will share with you my design for a customizable speaker enclosure.

When you buy a DCC sound decoder it normally looks something like this.

This sound decoder, model SDN136, is made by Digitrax and is designed to fit into N Scale locomotives.  The standard 8 pin plug is attached to the wires coming out of the left hand side.  The right side has wires attached to the speaker and a capacitor which is used to keep continuos power to the decoder when crossing dirty track.  This prevents the sound from stuttering.

The speaker has a sticky area with white peel-off paper. This can be stuck to the inside of a locomotive shell, preferably in an area which has some holes to allow the sound to come out.  Although this works it can be very quiet as the speaker is small and not capable of making lots of sound.  Or it may simply sound tinny.

To improve the sound volume the speaker can be placed inside an enclosure.  This works in the same way as speakers used for home stereo systems. The speaker is fixed to the front of the enclosure facing outwards. The air inside the enclosure acts like a spring returning the speaker cone to the ‘zero’ position more efficiently than if it was surrounded by open space.  Not only does this reduce noise from the back of the speaker but it amplifies the sound from the front.

Several companies sell speakers already mounted on enclosures and these can easily be used to replace stock speakers.  However the speaker is now getting bigger and finding space for it can be an issue.

A speaker which has been regularly used by members of my local club is the Zimo LS8X12.  This speaker comes with an enclosure as you can see in the images below.

The speaker simply fits into the recessed top of the enclosure.

Because the enclosure is fairly deep by N Scale standards, it doesn’t fit into some of the locomotives. To get around this the modeller tends to file or cut down the enclosure.  Because it is tapered this then creates the problem that the speaker no longer fits properly and may leave gaps around the edge preventing the enclosure from working effectively.

To solve this I have designed an enclosure that is built up in layers allowing the modeller to make it as deep as they want in 1.5mm steps.

The enclosure is made from two different types of part.  The first is the base and the second is a wall.  They are both shown below from top and bottom. The recesses in the tops of both allow the speaker to be fitted, even in the base.

The walls push together creating a 1.5mm extension to the enclosure.  Once it’s at the required size the speaker will simply fit into the top wall section.

There is a tolerance gap between the flange that fits them together to allow a small amount of glue.  This will hold the parts together and ensure a good airtight fit.

I have now ordered a test set of these enclosure parts in Shapeways ‘Frosted Ultra Detail’ material and I should have an actual working enclosure to share with you soon.

Earlier this year I shared with you my plans for my new N Scale Alco C-855. You can read parts one and two here and here.  I have recently started to do more work on the project  and have test printed the 3D printed parts which will extend the chassis for the new locomotive.  In this post I will share with you how they came out.

As discussed in my previous posts the chosen chassis, as modeled below, for the C-855 is going to be Con-Cor’s 4500 Gas Turbine/GE U50 chassis.

This chassis needs to be extended, as shown below, because although the C-855 uses the same trucks they are spaced further apart.

The chassis needs to be extended by 10mm and ideally in the middle over the motor.  To do this I have designed a complete replacement section that will extend the chassis and clamp the motor keeping it in the correct place.  Below is a rendering of the new parts.

These have been designed to be printed in stainless steel.  Although this metal is more expensive to get printed than plastics I didn’t want to reduce the weight of the chassis as this would have a negative effect on the locomotive’s tractive effort.  As the C-855 chassis will be longer it should now be heavier which will hopefully add to the tractive effort.  The C-855 did have 1000 more horsepower than the 4500 Gas Turbine and 500 more than the U50 after all.

The new extenders were printed by Shapeways and arrived ready to use as you can see below.

In close up shots like this you can see the layering effect caused by the 3D print process; this is more pronounced than on some other materials as the layer thickness is greater with stainless steel.  Shapeways also offer this material polished which removes these lines but as the parts will not be visible once the locomotive is complete this did not seem necessary.

A small change to the parts from the rendered view above is the introduction of wire routes.  This allows the bottom motor wire to run up between the shell and the chassis. For DC this is not necessary but for DCC the motor feed needs to be isolated from the chassis and a wire used to connect the motor to the DCC decoder.

Just to show that these really are metal, below is a photo of a basic volt meter set to measure continuity.  One of the parts has been laid across the pins.  As you can see the meter is reading 100%.

The parts will also be available in the cheaper plastics.

I did not allow any fitting gap between the motor and the new chassis parts.  Because they have been printed to such a high level of accuracy the hole for the motor is the exact same size as the motor and consequently it won’t fit.  This is easily remedied by grinding some of the inside of the chassis away. Alternatively I could have shaved down the motor casing.  I ground the inside of the parts with a flat stone in an electric modeling drill. Simply grinding the surface flat and removing the layering effect was enough for the motor to fit.

The motor now fits and I have also updated the 3D model to make the fit a bit easier.

As well as extending the chassis both drive shafts needed to be extended by 5mm as the ends will no longer reach the gears on the motor.  To do this I designed a 3D printed gear extender that will fit into the existing drive shaft gear as you can see in the rendering below.

The new part has been designed to be printed in Shapeways Frosted Detail plastics.  This is the best material to ensure the accuracy of the gear teeth.  My set was printed in Frosted Extreme Detail and below you can see how they came out.

Test fitting them into the original gears was a perfect push fit.  Below you can see one fitted into a drive shaft.  When it is time to fully assembly the locomotive I will put a small dab of super glue between the parts just to ensure they stay together although friction will do the job.

The next task is to finish the 3D model for the main body shell and set-out all the brass Additions.  My other locomotive kits have brass Additions for handrails and parts as well as 3D printed handrails but for this locomotive the only handrails will be brass.  I decided to do this because there will be lots of finally detailed handrail parts and if they are printed in plastic they are still a bit oversized and are very fragile.  With brass etching I can get decently sized handrails as well as lots of other details such as grab irons and roof top walkways.  Once I get the drawings done I will be sharing them with you.