3D Printing The Right Way Up

In last week’s post I spoke about Shapeways’ ‘Orientation Tool’ for their FUD and FXD materials and my intention to make all my locomotive shells available with this option.  You can read the post here.

My plan was to have both the new orientated models available as ‘Deluxe’ versions and the originals as a cheaper option.  And that’s what I’ve done with the Alco C-855 and C-855B.  However, after working through the other models it became apparent that the price didn’t really change.  By moving the position of parts the price of the model dropped and so the increase caused by using the ‘Orientation Tool’ setting was offset.  So all the other models have simply been converted to have the ‘Orientation Tool’ set for the best quality print by making it print the right way up.

Locomotive shells without the orientation set:

Alco C-855

Alco C-855B

Locomotive shells with the orientation set:

Alco C-855 Deluxe

Alco C-855B Deluxe

Alco C855 Shell Only

Alco C855B Shell Only

Baldwin DT6-6-2000

Baldwin DT6-6-2000 Dummy

Baldwin DT6-6-2000 Shell Only

Baldwin RT-624

Baldwin RT-624 Shell Only

EMD DD35

EMD DD35 Dummy

The new locomotive shells I’m working on will all be set to the best print quality from the start and the models will be designed to make them less expensive in the printer.  So for now the ‘Deluxe’ versions just apply to the large Alco C-855s but maybe this will come in useful with some of the HO scale locomotives I have planned, allowing me to offer differently priced versions.

Getting Things The Right Way Round

3D printing locomotive shells with Shapeways has always been a gamble as regards to the orientation of the shell on the print bed.  Understandably, in order keep the cost of the print sensible, the print ended up on its side or totally upside-down as this is the cheapest way for them to print.  The disadvantage is often the best surface finish would be on the underside of the model.

However back in the beginning of October this year Shapeways added their ‘Orientation Tool’ for the FUD and FXD materials allowing the 3D print orientation to be fixed by the designer; me!  You can read more about the tool on my post here.

My original intention was to immediately set all my locomotive shells to print orientated in such a way as to give the best finish possible.  But this does come at a cost,  especially with large locomotives like my Alco C-855 which has a huge volume of space under the shell.  This space needs to be totally filled with support material in order to print the roof.

After experimenting with different compromises and ideas I came to the conclusion that I didn’t want to cut corners; the best has to be available for those who want it but it was unfair to simply push all the prices up to achieve this.  So I have decided to offer both:  prints as they have always been as well as the shells with the orientation which will be set at the higher price.

My new models on Shapeways will be called ‘Deluxe’ and will include the Alco C-855 & C-855B, the EMD DD35 and the Baldwin DT6-6-2000 & RT-624.

Both models will be offered in FUD and FXD materials.  The FXD ‘Deluxe’ will be the ultimate 3D print available.  Hopefully all the models will be available on Shapeways by next week’s post.

As for new locomotive shells designs, well, I may design them differently.  Doing things such as making the roof a separate part would bring the cost down dramatically by reducing the amount of support material needed, but this does raise some stability issues as well as creating a joint which would need to be concealed. However that’s the challenge, and I do have something on the drawing board, but that will have to wait for another post.

3D Print Orientation Tool

My apologies for missing a post last week; I was travelling around Northern France on my motorbike, and I had a spectacular time, so hopefully you’ll understand!

Getting back to trains; this week I have some images to share with you from a 3D print which just arrived from Shapeways.  This model has been printed many times in the materials Frosted Ultra Detail and Frosted Extreme Detail, but what makes this different from the previous prints is using one of Shapeways’ new tools: I was able to specify the orientation of the print.

Why is orientation important?  With FUD and FXD 3D printing, the print material sits on a support material, which is a form of corn oil.  This support material, despite being very fine, leaves a slight imprint on the surfaces it touches, whereas the top of the 3D print is normally smooth.  Therefore we ideally want the surface with all the detail to be at the top.  However, the support material is fairly expensive, not as much as the print material, but lots of it can soon add up.  So Shapeways have previously positioned 3D printed models to minimize the amount of support material needed.  This means models like locomotive shells, which are basically bath tub shape, would get printed upside down to avoid the whole inside being filled with support material.  The models, as many of you know, still come out very well, as you can see in the images below.  This particular DT6-6-2000 shell was printed upside down in FUD.

The detail’s good but there’s still a level of fuzziness on the surface.

The inside of the shell is nice and smooth.

As you may have read in some of my previous posts Shapeways have reduced the cost of the FUD and FXD materials almost by half and added a charge for the support material used; so I can keep the orientation as it was and have a slightly cheaper model. But here’s where the choice of orientation is really good news. Now that they’ve added a tool which allows me to specify which way I want the model to be printed  I can guarantee all the crisp detail is on top and pay a bit more for the extra support material.

And that’s what I’ve done.

This DT6-6-2000 shell has also been 3D printed in the FUD material, which is not such a fine material as the FXD, but I think this is the best DT6-6-2000 shell I’ve received so far.  All the details are crisp and the top surfaces are smooth.  The images above were taken the day the shell was delivered before cleaning it.

The shell still had a waxy feel, which is normal as the corn oil leaves a residue.  To remove this I always soak my models in Goo Gone for 24 hours.  Many others use Bestine in the US but I’ve found Goo Gone works well for me.  The images below show the model after it’s come out of the Goo Gone, been rinsed under the tap and left to dry overnight.  Before I put any paint on it will need a bit longer to dry and I’ll give it a dust-off with a soft brush in a Dremel tool.  This is because any remaining corn oil residue will turn to powder as the model dries.  But as you can see the detail is very crisp.

And all the main surfaces are smooth.

So from now on I’ll be setting all my new models with the ‘Orientation Tool’ so the best detail gets the best print.  I’ll also be working through my existing models and making the change, but if the price difference is large I may offer the model with and without this option.  If you are about to order a 3D print and would like to know if the tool has been used, or what the price would be if it has not, please send me an email or get in touch via the contact page.

The quality of the 3D printed models we’ve been ordering from Shapeways has always been good, but this new tool takes the standard up and as modelers, we all like to get the best out of our hobby, so I hope you’re as excited as I am about this great new development!

Drawing an Alco C-855 for N Scale Part 5

If you have been following my blog for a while you will know that I have been working on an N Scale Alco C-855.  You can read the first part here.  In this week”s post I will share with you what I have done to finish the A unit and get it ready to order a test print.

In my last post about the C-855 I showed you the first print of the metal chassis extenders and how I fitted them into the Con-Cor Turbine/U50 chassis.

C-855 Chassis Build 15

This chassis runs well, and pulls even more than in its original counterpart; probably due to the increased weight.  However there were a few issues with the print so I have improved the 3D model to rectify them.  In the image below you can see both parts from the top and bottom.

Alco C-855 Chassis Extenders mk2 (render)

The space for the motor has been widened by a fraction as the motor was a tight fit in the first print.  The wire channel has also been increased in size so the motor wire is a better fit.  I have also made some changes to the bottom of the lower section.  The arrows point forward on both parts to help with orientation when assembling the chassis.  There is now a rectangular nub that sticks out to locate the fuel tank on the bottom of the locomotive.  Also a square hole has been added which has been designed to take a 3D printed screw fixing which is used to hold on the fuel tank.  The exploded view below shows how these fit together.

Alco C-855 Fuel Tank Fitting 1 (render)

I have designed this assembly so the original Con-Cor turbine/U50 screw can be used athough any similar size screw will work.

Alco C-855 Fuel Tank Fitting 2 (render)

This section of the fuel tank is only the bottom as the sides are part of the main body.  Looking at the image above you can see a square hole in the side of the fuel tank, this is designed to receive a nub sticking out from the shell. You can see the nub in the image below which shows half of the shell.  As the bottom of the fuel tank is fixed with the screw it becomes a solid fixing for the shell.

Alco C-855 In Side Shell (Render)

As with a lot of ready-to-run locomotives, to remove the shell it can simply be spread in the middle and lifted off.

To make painting and adding decals to this model easier the four large sand boxes on the sides have been made as separate parts.  The rear six are the same but the front pair are longer as they have to step over parts of the chassis.  The shell has slotted fixings in the side of the running board to receive the sand boxes so they can be securely fitted.  The holes on the tops are handrail fixings.

Alco C-855 Sandboxes (render)

As with my DT6-6-2000 and RT-624 locomotives my C-855 will come with crew for the cab, Bert and Ernie.  The controls on the console are very basic but this is N scale so once they are inside the cab it will be hard to see anyway.

Alco C-855 Crew (Render)

Because of the shape of the chassis, there is a large chunk of metal sticking up into the cab, the crew had to be pushed to the sides.  There are locator pockets in the shell walls to receive the crew once they have been painted.  As the C-855s ran in an A-B-A configuration you may not want crew in the rear A unit so they can simply be left out.

Below you can see the crew in their place with half the shell removed.

Alco C-855 Inside cab (Render)

This view also shows you the headlight fitting in the roof of the cab.  The shell has been shaped to receive a standard 3v 2mm LED.  A nice warm white LED can be fitted directly into the roof of the cab and a pair of headlights will shine from the front.  This area will need to be painted black on the inside to prevent the light from shining through the shell.

Even the horn is a separate 3D printed part; this is both to make it easer to paint and to protect it from being knocked off in shipping.  Below you can see all the 3D printed plastic parts for one C-855.  The large gears are the drive shaft extenders which are needed when the chassis is extended.

Alco C-855 3D printed parts (render)

In the cab you can see lots of holes; this is because all the grab irons and handrails plus many other details are brass parts that will be supplied in a brass Additions set. The set will also include some of the metal walkways, windscreen wipers, side ladders, MU hoses and sun visors for the cab.

So putting this all together, this is how the N Scale C-855 will look.  Please note the trucks under the 3D model are not yet correct.

The end will have brass grab irons up the center and walkways over the air intakes.

Alco C-855 end (render)

The cab with all of its brass parts will be well detailed

Alco C-855 666.Front (render)

Overall this monster of a locomotive has an imposing presence.

Alco C-855 (Render)

The next step is to finish the drawings for the B unit and design a dummy chassis so an A-B-A set can be made without powering all the units, if required.

The new 3D printed metal parts as well as the 3D printed plastic parts for the C-855 have new been sent for test printing so I should have the first N Scale C-855 within the next few weeks.  Once it arrives and I have cleaned up all the parts I will share some images with you.

Converting An N Scale Bachmann F7 to DCC

The N Scale Bachmann F7 has had three revisions to date and the most recent one, made available in 2013, is supplied with DCC.  But what about the first two?  In this post I will show you how I add DCC to the locomotives in a cost-effective way.

The Bachamm F7 over all is not a bad locomotive; it has great polling power and the body work, although not as good as the Intermountain model, is nice.  They do tend to run a bit noisily so installing a sound decoder for me was not an option. As I have several of these, installing a basic decoder in each starts to add up, so again I am going to use one decoder to power two locomotives.  When doing this it is important that the locomotives run at similar speeds when used together on DC power.  Luckily these do, but if yours don’t I have already covered a topic like this and you can read about it here.

Bacmann F7 DCC Install 34

The F7 A & B set I am converting to DCC, as shown above, is the second version but both first ‘Plus’ version and the second ‘Spectrum’ version are very similar in chassis shape and design so this method will work for both.  You can read about the difference in Spookshows N Scale encyclopedia here.

With the shells removed, as you can see below, both the A and B units are exactly the same with the exception of the A unit having a light bulb pushed into the hole at the front.  To remove the shells simply spread them at the fuel tank and they will un clip then lift off.  You will also see that the chassis totally fills the A unit shell leaving no room for a DCC decoder to be installed.  But because the B unit has the same chassis there is space in the B unit where the cab would have been so I will be putting my decoder there.

Bacmann F7 DCC Install 1

There are no wires inside the chassis, which is split into two, and the light bulb simply picks up power by touching the chassis halves.  A down side to this when running on DC is the light comes on in reverse as well.  And for DCC,  the motor picks up its power in the same way so we will need to isolate it.

To take the chassis apart is fairly simple.  First remove the fuel tank by undoing the screw in the middle.

Bacmann F7 DCC Install 2

Then undo the two chassis screws in the left half and it will lift off.

Bacmann F7 DCC Install 3

Turning the left half over you will see a spring projecting out of the chassis.  This is the bottom motor contact that connects the left half to the motor.  This spring needs to be removed simply by pulling it out.

Bacmann F7 DCC Install 4

With the two halves separated the whole assembly will come apart.  The motor simply lifts out and the truck assemblies will already be free.

Bacmann F7 DCC Install 5

The right half of the chassis has a stub that sticks out and connects to the top motor contact.

Bacmann F7 DCC Install 37

This stub needs to be removed.  This can done with a good pair of large side snips and a file.  The chassis is made from a fairly soft metal so it files down quickly.  In the photo above you will also see the inside of the black tape that has been put across the holes in the chassis. I believe Bachamnn added this to the second version to prevent particles getting into the motor winding.  Also as it is sticky on the inside it will catch any particles thrown off the motor brushes.  You can see some of those just below the stub. Filling the stub will create metal fillings which you also don’t want to get in your motor so once the stub has gone remove the black tape and clean the chassis half to remove all the filings.  A stiff brush will normaly do this.

With the chassis half clean, you can do a test fit with the motor to make sure the motor contacts to not touch the chassis.

Bacmann F7 DCC Install 6

To do a proper test the chassis can be resembled with just the motor in it and you can do a continuity test with a volt meter.  Dont forget to put the little plastic spacers back in, there is one for each screw and one in the fuel tank.

Bacmann F7 DCC Install 7

Next we need to create a path for the bottom motor wire.  As there is no room inside, the wire will have to come up the outside of the chassis but as the shell is a snug fit around the motor, there is still no room.

Bacmann F7 DCC Install 8

So in order to make room I have filled a V grove up the side of the right chassis half.

Bacmann F7 DCC Install 9

The grove also continues round under the fuel tank.  The grove needs to be just big enough to take the wire you are using so the face of the chassis and wire will be flush.

Bacmann F7 DCC Install 10

Once any metal fillings have been removed the chassis is now ready and we can turn our attention to the motor.  The motor body is already isolated from the contacts so all we need to do is add our wires to the contacts.  Although we can change this later it is useful to add the right wires onto the motor now so we know which is the positive side.  Normally orange is the positive motor wire and gray is the negative.  But there is no indication on the motor as to which is which.  On my work bench I have a DC controller with a test track and a pair of wires.  When a train is running forwards and to the left the right rail is my positive, colored red, and the left is my negative, colored back.  Touching the red and black wires onto the contacts will make the motor spin and in the configuration shown below you want the motor to spin anticlockwise.  That would be the same as forwards to the left.

Bacmann F7 DCC Install 11

To add the wires I quickly heat the contacts with the soldering iron, for one to two seconds, then add a little bit of solder just to tin the contact. You don’t want to over heat the contact is it is a perfect conductor of heat and there are plastic parts inside. Next I tin the end of my wire, hold it to the contact and quickly touch it with the iron.  The two tinned areas fuse and you have a good connection.  Note the wires need to be long enough to run up inside the locomotive and across to the B unit.

Bacmann F7 DCC Install 12

Before re-assembling the chassis I also change the couplings on the loco.   When these where being run under DC I used Unimate couplings from Red Caboose.  These provide a nice close couple that will not come undone on the track however as I will now have wires running between my locos I don’t want them to come uncoupled at all.  To do this I will replace the Unimates between the A and B unit with one of my fixed link couplings.

In the image below you can see the underside of the Bachamnn power truck.  Just to the right of the tuck and before the coupling box are a pair of pins that can be squeezed together with a pair of needle nose tweezers.  This will cause the coupler box to pop off.

Bacmann F7 DCC Install 13

Inside the coupler box is a spring that fixes over the peg on the back of the coupler.

Bacmann F7 DCC Install 14

My 3D printed fixed coupler is a direct replacement for the old Rapido style couplers so drops right into the Bachmann coupler box.

Bacmann F7 DCC Install 15

For now I only fixed one truck to the fixed link but you could do two, one from the A unit and one from the B unit, at this point.

Bacmann F7 DCC Install 16

Now the chassis can be reassembled.  Note the wire form the bottom motor contact is coming out the bottom of the chassis in front of the plastic spacer. (I know the wire is brown and not gray but I have run out of gray!).  Also when you refit the tracks make sure the metal contact for power pickup is rubbing against the underside of the chassis not the inside as this will prevent the trucks from rotating.

Bacmann F7 DCC Install 17

The brown wire (bottom motor connection) can now be placed in V grove that was filed earlier and the fuel tank can be replaced.  Also I have put some Kapton Tape over the holes in the chassis to replace the black tape I removed, this also holds the wire in place.

Bacmann F7 DCC Install 18

Now the motor is isolated and wired up the next two wires are the power supply.  On top of the chassis are four nubs that the shell sits onto.  Interstingly these are slightly narrower on the bottom than they are on the top so all I do is wrap the end if my wire around the base of the nub a full 180° and solder it in place.  I have yet to have one of these fail.  And as long as there is nothing sticking up above the top of the nub the shell will still fit.  The red wire goes to the right side and the black, or purple in my case, goes to the left.  I must order some more different colored wire!

Bacmann F7 DCC Install 23

The last wires, for the A unit, are for the light.  The standard light is a light bulb and these can be power-hungry and get hot.  So I replace mine with warm white LEDs. Below is a comparison with standard 3mm LED on the right and a 1.8mm LED on the left which I will be using.

Bacmann F7 DCC Install 19

As all LEDs need a resistor in line I make the resistor a part of the headlight by folding one of the resistor legs back onto its self and soldering it to the LED.

Bacmann F7 DCC Install 20

Then I wrap it all in Kapton Tape to prevent it shorting.

Bacmann F7 DCC Install 21

Finally I trim back the legs ready to solder on the wires.

Bacmann F7 DCC Install 22

The LED will sit in the same place as the light bulb.  To protect against shorts I put a strip of Kapton Tape over the nose then cut out the hole with a sharp knife.

Bacmann F7 DCC Install 24

The LED light assembly then pushes into the hole and the legs, sitting on top of the Kapton Tape, can be soldered too.  As LEDs only work in one direction it is important to know which is the positive and negative.  The blue wire, matching the decoder, is the positive.

Bacmann F7 DCC Install 25

With all the wires in place they can now be taped down with Kapton Tape so they are tidy and clear of the shell.  Check to make sure the trucks rotate freely.

Bacmann F7 DCC Install 26

To fit the shell I you could simply run the wires through the window in the connecting door at the back but this can be really tricky so using a sharp knife I simply remove the plastic under the window.

Bacmann F7 DCC Install 27

This allows the shell to be lowered onto the chassis without pulling or pushing on the wires.

Bacmann F7 DCC Install 28

When it comes to the B unit I do exactly the same, except the wires run to the front and there is no light.

Bacmann F7 DCC Install 29

To join all the wires up I like to uses little bits of cooper strip board.

Bacmann F7 DCC Install 30

These are then superglued to the nose of the B unit.  You could use one piece and glue it to both sides of the chassis but this would mean the unit could not be taken apart for repair if needed.  You also need to make sure the DCC decoder will fit behind the cooper strip boards and they do not protrude out side of the chassis so the shell will still fit.

Bacmann F7 DCC Install 31

Once you are happy with the placement of the cooper strip board, solder the wires together, orange to orange etc. The red and purple (black) can go directly onto the B unit chassis.  At this stage there are a few checks that you should make.  First, using a volt meter set to a continuity check, check that the left B unit chassis is connected to the left A Unit chassis, and repeat for the right.  Secondly check that the left and right chassis are not connected to each other.  Thirdly check that none of the chassis are connected to any of the cooper strip board terminals.  Then using 12v DC wires from a controller test that both motors are running the same direction when you connect them to the orange and brown (gray) wires and finally test the headlight works when you connect the 12v DC wires to the blue and white wires.

Bacmann F7 DCC Install 32

I also connected the fixed link coupler to the front truck of the B unit at this stage.

The last stage is to solder the six decoder wires to the copper strip board terminals and chassis points.  I have used a Digitrax DN163, it was a bit of a tight fit because this decoder has a plug on it making it thicker than normal but most N or Z scale decoders will fit.

Bacmann F7 DCC Install 33

I cut the front door of the B unit shell to fit over the wires the same as I did with the A unit and fitted it onto the chassis.  And there you go; two powered locomotives connected with a draw bar, which is prototypical, and one decoder.

Bacmann F7 DCC Install 35

But there is one more thing that you can do to make this even better and that is to have four locomotives with two decoders.

Bacmann F7 DCC Install 36 Normally the locomotives would all have different numbers but to make things easy I have configured the two DCC decoders to be both the same address and switched the rear pair to run in reverse as their forward direction.  This means you don’t have to consist the locomotives, and they won’t take up two slots in your DCC command station. This can all be done by changing the configuration variables or CV values; which can be fairly in-depth subject so it is something I will cover in a later post.

Re-powering A Dapol Semaphore Signal

Recently I have been working on a British outline OO layout which had some working semaphore signals.  Sadly some of these signals had suffered some electrical damage which rendered their control circuit boards inoperative. In this post I will be sharing with you a few simple methods of repairing Dapol semaphore signals.

The Dapol semaphores, as shown below, are nice looking signals and have a fairly basic drive system which is self contained in the tube below the signal.  Above ground there is a nicely detailed rectangular post with the rotating arm on top.  The arm is connected via a crank to a push-rod that runs down behind the post.  You will be able to see this in some later photos.  The glass lenses in the end of the arm are transparent and a small LED shines through creating the correct color.

Dapol Signals 1

Below ground is where all the clever parts are.  Interestingly the drive system on these OO signals is also used for their N Scale signals; Dapol have simply changed the size of the signal on top.  In the large threaded tube at the bottom of the signal is a circuit board, electric motor, gear rack and worm gear.  After the large nut has been removed there is a tiny screw at the base of the signal which holds the two halves of the tube together.  Once that has been removed the tube can be separated.

Dapol Signals 2

The motor is in the left half and the circuit board is in the right.  You can also see the push-rod that runs up behind the signal pole in front of the ladder.  And if we zoom in you can see below the push-rod is a spring.  This spring is attached to the push-rod and when it’s moved up and down the signal arm moves up and down.

Dapol Signals 14

The two pairs of metal contacts are part of the circuit board; as the motor spins the worm gear it drives the rack either up or down pushing the rod.  A spigot sticking out of the rack touches one of the pairs of contacts creating a circuit and telling the circuit board that the rack is at the end of its travel.  However as the circuit board is damaged these are of no concern to us.

As new, the signals work by providing 16v AC power to the red and black wires.  This powers the circuit board and the LED at the top of the signal pole.  Then by simply touching the two yellow wires together, using a momentary Push-To-Make switch, the signal will change. Even when you let go of the switch the motor will keep going untill the rack gets to the end of its travel.

On the first of the two damaged signals only the motor drive function was inoperable, the light still worked when 16v AC power was applied, so the circuit board was still producing low voltage DC which is also needed to drive the motor.  In the picture below you can see the wire connections.  The red and blue are the DC feed to the motor.  The tiny red and, hard to see just above the yellow, tiny black are the LED feed that run up inside the signal pole.  The big red and black are the 16v AC power in and the yellows are the activators.

Dapol Signals 4

So to fix this signal I removed the motor wires from the circuit board and extended them by soldering on some more wire and heat shrinking the joint.

Dapol Signals 5

Then I removed the yellow activator wires from the circuit board and added a pair of wires to the LED feed connection points.

Dapol Signals 6

The signal was then reassembled with the new wires coming out of the bottom.

The next step was to take the low voltage DC power, coming from the new blue and green wires, out to the layout control panel. Then, using a momentary double pole double throw (DPDT) switch, return the power to the motor wires, in positive or negative, to make the motor go one way or the other. The DPDT switches I use are toggle switches as shown below.

Dapol Signals 16

These have six connections on the bottom.  When it is thrown one way it joins the middle pair to the top pair and the other way joins the middle pair to the bottom pair.

So, if the incoming low voltage DC power is connected to the bottom pair, then reversed and connected to the top pair, throwing the switch one way or the other will reverse the DC power.

Dapol Signals 15

The motor is then connected to the middle pair of terminals, not shown above, and the signal can be manually controlled. My apologies as I got a bit carried away with the work and so didn’t take any more photos of this particular signal.  As the switch is a momentary, when you let go it springs back to the middle and stops the motor.  There’s no danger of pushing the motor too far as when the rack gets to the end of its travel it simply stops, although the motor keeps spinning.  The spring on the end of the push-rod, and there is another one on the bottom of the rack, supply just enough pressure to make the rack re-engage with the worm gear when you want it to run the other way.

This fix, although functional, is not ideal as you are still relying on a damaged circuit board and all the small parts inside the tube.  Plus you have to hold the switch untill the signal has reached its position.

The second fix I have for these signals is a bit moire drastic but I think in the long run is a more durable solution.

The second signal’s motor and circuit board had failed so I removed all of the parts from inside the tube.  Sadly the LED had also blown on this particular signal so the wires for that will go as well.

Dapol Signals 7

As all the points on this layout are powered with Seep point motors it made sense to power the signal in the same way.  Seep make a special point motor with a latching spring which is designed to work with hand-built points that don’t have a latching spring of their own.  The latching spring means the motor will stay in the required position even though the spring on the push-rod will be pushing back.  This latching point motor was mounted to a ‘Tee’ shaped mount as shown below.

Dapol Signals 8

There is a slot for the motor throw bar to pass through and the large hole above the throw bar is for the signal tube.

Dapol Signals 9

You can see the latching spring under the motor cross-bar.

Dapol Signals 11

As the tube on the bottom of the signal was now empty it could be reduced in length; this was also necessary so it didn’t hit the throw bar.  The last thing to do was to connect the throw bar to the signal push-rod.  However there is a problem in that the point motor movement is more than the signal needs, and as the point motors are powered by Capacitor Discharge Units the motor bangs over very hard which will damage the signal.

To counteract this I made a very basic omega ring out of thin nickel rod.  One end was superglued into the spring on the bottom of the push-rod, the other was looped around the motor throw bar.

Dapol Signals 13

Although basic, this omega ring absorbs the sudden shock from the point motor as well as any extra movement while still supplying enough force to move the push-rod.  The two shorter tube halves were glued together and the ‘Tee’ mount was screwed to the underside of the layout.  The signal was then put though the hole in the layout and mount.  Before the large nut was tightened up the signal could be tilted to one side to alow the omega ring end to be slid over the point motor throw bar. Once tightened up the omega ring could not slide off the throw bar, but as an extra measure I glued a small washer onto the end of the rod.

This second fix was a lot better because the signal changed quickly with a single touch of the switch and any wiring is the same as a standard point motor.

These signals have also been modified in a similar way with servo motors which gave a very nice smooth action and this might be something I will try next time.  If I do I will share it with you.