Laying Track to Foam

I chose to use foam as the baseboard of my layout. I started experimenting with this in 2008 (Photo). This actual track on the test rig was only pinned in place as it was never permanent.

  • Foam base is great to lay my Peco code 75 HO flextrack. I can easily pin it in place using ordinary dressmaking pins. But you can’t nail it down.
  • Instead, I use an adhesive, LATEX CEMENT and I buy it from carpet suppliers or carpet layers. I take a 1 or 2 litre plastic container and get it filled for say $10 or so.
  • It needs to be thinned with water to a consistency of milk. I originally thought it would need to be thicker, but the thinner it is the better it penetrated under sleepers etc.
  • What happens if you change your mind and want to move something? It is actually reasonably easy just by dissolving the dried latex – see the last photo.
For the track base I use a product from DCCconcepts (in Western Australia) called Trackbed OO/HO Scale 3mm
The company describes the product as:
“A box of 100 feet (31metres) of high quality, OO/HO Scale trackbed (3mm thick / scale 9~10” approx high).
Made from very long life EVA, closed cell foam trackbed with precut ballast shoulders and a pre-scored track centreline underneath to allow it to be easily split for laying along track centre-lines if wanted.
Based on tests and feedback each piece is 605mm / 2 feet long for easy handling. Cuts perfectly with a snap off knife.”
STEP 1 – track pieces were pinned into position according to the layout sketches. The layout plan was derived in a slightly odd way. Firstly I laid out old code 100 track, some points, paper copies of points until things were as I wanted them to be. I then took a whole series of overlapping “aerial photos” as shown above and below.
And subsequently “stitched” all the photos together on a PC so that I had a somewhat bizarre mosaic diagram of the layout:

STEP 2 – the Code 75 Peco flextrack was adjusted into position with dressmakers pins (easy in foam)
Curves were laid out with Masonite (hardboard) templates. In this case 1m radius.
Note the use of plywood alignment pieces to keep the track joins in line.
STEP 3 – once I was convinced I had the track in the right place, guidelines  were needed to allow the underlay to be glued in the correct position.
To do this I made a little mobile jig from an old loco pony truck with a ply guide screwed up from the bottom so it just cleared the rails.
  • This foam roadbed is lightly cut down the centre to make it easier to lay curves.
  • The other advantage of gluing the track to foam is that it provides an improved noise barrier.
  • That is lessened of course when the track is ballasted but I am experimenting with very dilute latex as a ballast adhesive.
STEP 4 – I ran this mobile jig along the pinned track to get a guideline for the edges of the underlay.
STEP 5 – I took no photos of this process, but the diluted latex cement was brushed along between the guidelines onto the foam (none was brushed onto the bottom of the underlay). The underlay was butted up to the end of the previous piece with a little cement brushed onto the end. No weights or clamps were necessary although some pins were used around curves.
The photo above shows the container of diluted latex glued to a block of wood to help prevent spills. The photo actually shows a point being glued to the underlay and weights ARE needed for this process.
STEP 6 – The track is held in position by long dressmaking “T” Pins.
This aligns the track but allows it to be lifted to coat the underlay lightly with latex cement.
STEP 7 – for long runs, I held the track up with paddle pop sticks which allowed me to brush on the cement.
I used a chisel shaped brush about 10mm wide and applied it sparingly down both sides.
As above but a little more latex cement was needed under the PCB sleepers which were later cut across the join. A better solution would have been to use a more powerful adhesive under the PCB sleepers eg. Liquid Nails, as this track needs to be cut and remain strongly fixed.
STEP 8 – Once the glue is in place, remove the paddle pop sticks and place weights on the track until the glue sets.
The long brown strip is paxolin – about 3mm thick and cut to fit precisely between the rails. It serves to align long straight section and can be left in place until the glue sets. It can be made from any similar rigid maerial.
I have many of these 2mm (0.080″) plywood pieces cut to be a neat fit inside the tracks.
They guarantee alignment of track especially with crossovers.
Small pieces are great for keeping curves aligned where flex track joins. In this photo Carr’s Flux has been used to get a good soldered join between rail and sleeper (tie).
Using a long straight edge on the edge of the rail and the paxolin stip between the rails to align trackwork past the future station site.

WHEN THERE IS A DISASTER:

If everything goes pear shaped, then Latex bonded track or points can be lifted. Realising an extra crossover was needed, I had to lift a section of track. Brush some water onto that section and leave it for an hour or so and a thin spatula can be worked under the sleepers to free the track/point. The old latex can be removed with a wet sponge.

Yes, yes … I know if I am flooded out, the trackwork may be in trouble. But the bloke in the house across the road will really be in strife. The peak of his roof is lower than my floor!

Servos for Points

Points /turnouts on my layout were initially operated manually using a wire-in-tube mechanism. There are currently 44 points on the layout and I started converting to servo control about half-way through.

The wire-in-tube (WIT) method I used worked very well and is shown to the right.
The mechanism is relatively easily fabricated and the cover is removable with one screw to allow easy adjustment of the point blades at the fascia.

It will handle a second wire to allow push/pull operation of 2 points in a crossover.
If there is any interest, contact me and I will add a section on the design and fabrication of the WIT method and the fascia mounted lever frames..

I changed to servo operation for the following reasons:

  • with this type of mechanical operation, control panels would not be able to operate the points (there are 4 mini panels on the layout).
  • the system selected allows precision adjustment of each point blade; variable speed of movement; position indication
  • servos can be installed from the top of a 50mm (+) foam layout
  • points can be controlled from a central position; a local panel; by a computer; as a route by changing many points at once and other options.
  • the system I use is based on the UK MERG model. Circuits vary from simple to complex.
  • Plus – I like working with electronics.
The photo shows the basic setup. The servo is located to the side of the point/ turnout and connected to it with a short “L” shaped wire. I use 1.2mm steel wire running through a short guide tube. This connects to the servo arm via a “Quick Connector”. The servo cable exits under the layout. SEE PHOTO
The mounting slot in the foam is formed by drilling 12mm holes through 50mm foam to fit a micro servo … SEE DRILLING HOLES IN FOAM
The guide tube I use is a short piece of bicycle bowden cable outer – used for gear selection from memory. I just bought a metre or so length from the local bike shop.
The servos I use are Tower Pro SG90 style or my preference Micro 9g Metal Gear Servo.
Shown above is a “Micro 9g Metal Gear Servo For Futaba Hitec HS-55 GWS walkera RC HELICOPTER GA” as described on eBay.
Here is a LINK to the eBay site I used but check other sources for a possible better deal. The current cost is $4.87 (16 July 2016) with free postage to Australia. There are cheaper plastic gear models but I have found these ones to work more smoothly and to be much quieter. As you can see, they come with a variety of servo arms (aka servo horns) and any will work in this application.
To connect the servo to the point/ turnout a “Servo Quick Connect” (shown above) is very good. I bought a set of 20 for $4.12 !! ($3.83 in June 2017)
That’s a little over 20c each. They were sold as “Durable 2mm Aircraft Stopper Servo Connectors Connector with Screws – Set of 20” and one eBay supplier I used was at this LINK . These things are TINY. The Allen Key grubscrew is 3mm.
This what you get for about 20c (Aust). A beautiful piece of micro engineering.
I use any of the servo arms supplied. Select the second hole from the pivot point of the servo arm and drill a 2mm hole in there to take the servo quick-connect. The point needs to move less than 3mm (HO) and initially I went for maximum torque by using the first hole and that is what is shown in the very top photo of this post. That hole is too close to the hub of the servo arm and some fiddly trimming was needed. I discovered that there is no need to use it as there is plenty of torque when using the second hole as shown above.
Assembly order is shown for the quick-connect. It needs to be free to rotate in the servo arm and the nut is best secured using a tiny bit of thread locker. The grub screw allows positioning adjustment but the travel and end points need to be set by some electronics.
This servo is being retrofitted to a turnout on EPS foam. As the control wire to operate the point was already in place, an additionally longer access slot was needed to allow the servo to slide in under the actuating (control) wire to the throwbar. The brass foam “drill” can be seen on the right.
Shown above – 2 MERG boards in use on my layout. The left hand one controls the servos (8 of them) and the right hand one handles the switches controlling the servos operating the points. This system was devised by the MERG group in the UK – see their Website MERG.  The operating system uses a CAN bus (2 wires) to distribute control events around the layout in a manner similar to that used in modern motor vehicles. You still need a distribution bus for DCC (plus, in my case, sub buses for the yards etc) and a bus for 12V DC to operate points and the power the CBUS boards.
This is a MERG design for TESTING SERVOS with the left hand one designed only to test servos – in this case I use it to test new servos and to set them to their midpoint.
The right hand one is, in effect, a stand alone method of controlling one servo & its point with a switch. The 3 blue components are variable resistors used to control the speed of the servo and distance it moves Left & Right. I also use it for testing the servos.

MERG sells kits for the above 2 projects and they cost just £1.55ea  +postage from the UK for MERG members. Almost all of the more sophisticated CBUS kits are based on professionally manufactured Printed Circuit Board (PCBs) and usually kits of the necessary parts are available or you can buy the parts locally.

There are other alternatives:

The device shown to the right is a ” MegaPoints Controller” by a UK company and could be very good for those people not confident in building PCBs themselves. I have not used it or seen it in operation but it comes ready to connect to 12 servos and has 12 corresponding switch inputs. Here is their Website and here is a YouTube Demo There are 2 videos in sequence. Cost is said to be £50 in the UK.

I also notice that DCC Concepts have an “above board” system that looks interesting for someone not interested in a DIY approach – Cobalt SS.

Drilling Holes in Foam

Since my layout uses foam sheets as a trackbed, there is a need to drill holes, often many of them, through the foam.
The drill used is made from a piece of metal tube. I use brass tube which does the job and is available in in a variety of appropriate diameters (eg. K&S). I use two main sizes:

  • 6mm for track feeders and points (turnout) wiring.
  • 12mm for mounting Servos in foam
  • + 10mm for other odds and ends

You could use aluminium tube but it doesn’t hold its edge well. Steel tube would work well if you could get the size.

This is why I needed to drill lots of holes in foam: Track feeders; Points wiring; Servo Mounting plus other odds and ends.
Prepare the cutting edge by bevelling the end of the tube on the INSIDE.
I carry out that operation on a lathe using a scraping tool but it could be done in a drill for short tube drills.
It may even be possible to use a tapered reamer to form the bevel. There may be a need to touch-up the edge from time to time.
Use a battery drill on a fast speed. This 12mm hole is through 50mm foam to fit a micro servo
(eg Tower Pro SG90 or my preference Micro 9g Metal Gear Servo). The marks on the “drill” indicate just how deep I need to go for the servos.
The result is a very clean hole
For 12mm brass tube it is necessary to reinforce the end held in the drill to prevent crushing.
I machined a small piece of aluminium in the lathe (about 20mm long) and epoxied it into the top end. But anthing will do eg. a piece of dowel or plastic can be hand filed while spinning in a power drill and have a (say) 6mm 1/4″ hole drilled through.  Or fill the end with epoxy and drill a hole.
A hole is necessary through the middle so you can use something to push the waste foam out.
Pushing the waste out… and below:

Here 4 holes have been quickly drilled to accept a servo with minor trimming.
MORE DETAILS ON MOUNTING SERVOS IN 50mm XPS FOAM – COMING SOON
In this photo a hole was drilled under a point to carry the wiring from the micro switch under the layout.
Note the use of a length of paper drinking straw to line the hole so that the chemicals in the foam don’t attack the wire insulation.
The straw is held in place with a dab of PVA woodworking glue or similar.

This is the underside of the layout showing five 6mm holes, lined with a drinking straw, to carry track feed droppers.
The centre 6mm hole carries 3 wires from the microswitch fitted to the point.
The 4 x 12mm overlapping holes have accommodated the micro servo and its connecting wire.
Working Expanded Styrofoam (EPS) can produce a SNOW STORM!!
I use a suitcase type vacuum cleaner with the nozzle directed at the work area whenever shaping EPS
The drilling process is fairly mess free but care needs to be taken when pushing the waste out of the drill.
The attachment shown above holds itself on by suction and has a hole to accept a drill to capture waste before it escapes!
Brilliant for working up under a layout. My suitcase type vacuum came from a local chain store (BigW in Australia).

Drilling Acrylic Panels

Drilling holes in acrylic sheet is easy with a small modification to the cutting edge of the drill. You should then have clean holes with no cracking in the acrylic.

Shown above is a small drill with the cutting edge suitably modified such that it has a “scraping” action, rather than digging into the plastic. The diagram below shows the effect required. Some sources indicate that the included angle of a drill for acrylics should be around 60° rather than the normal 120°
I don’t subscribe to this view as it is already difficult enough to grind the cutting edge of very small drills without having to alter the included angle as well. I use standard drills and just “blunt” the cutting edge as shown later.
Drill angles
Here is a set of modified drills I keep on the workbench with a piece of drilled acrylic so that I can test the fit of things like switches, bolts and screws etc.
This is one way to produce the “scraping” effect on the cutting edge. Use a Dremel tool mounted in a holder or in a vice with rubber jaws.
Make sure you wear eye protection and a face shield in this operation.
It is also possible to “touch” the cutting edge on a fine bench grinding wheel provided it has sharp corners but the Dremel is best for tiny drills. This photo shows a diamond impregnated disk but a normal brown abrasive disk will work (with a face shield). Do both cutting edges on the drill.
I always use a magnifier to carry out this operation.

Here is an interesting link from an Aussie Plastic Fabricator on how a pro sharpens his drills and other tools for plastic.

Strain Relief

Not actually how to fix a hernia! but more about how to ease the problem of working under a fixed layout.

With advancing age it becomes increasingly difficult to work under the layout. There are some alternatives such as tilting or fold-up layouts but they have disadvantages. I didn’t want a portable layout so my layout is screwed to the walls and supports. The layout height is 1020mm (3’4″) with a floor to head clearance of 840mm (2’9″) under the layout. Having the seat close to the floor was mandatory.

So I had to figure out a way to work with at least some comfort under the layout. I tried a very low stool on rollers but on my lino floor it was just too prone to sliding around (rocketing around might be a better explanation) and had no back support. The back support is what I need along with a stable base.

 

This is the prototype (and final product) to allow me to drag it around the floor. Made from workshop offcuts (pineboard and MDF) and some old fabric padding.
The other bit of padding on the floor looks like an offcut and it is – but I use it to kneel on while I roll (collapse) into the seat.
I just experimented with the back angle, hence the hinges plus they were also laying around the workshop. The other gadget visible in this photo is a locking clamp to which I have attached a roll of solder.
This is clamped up under the layout on some appropriate part of the frame and provides solder at a level close to the work.
When soldering under a layout DON’T have any part of your body UNDER THE SOLDERING AREA for obvious reasons.

Lifting Entry Flap/ Section

Easy Access without Crawling Under

A light weight lifting flap (entry panel) to make getting into and out of the Layout Room  easier than ducking under. Especially for an around-the-wall layout and useful for geriatrics!
The panel has an electrical interlock which cuts all power some distance
either side of the panel when it is raised a few millimetres. That still doesn’t cater for person who attempts an “underpass” but rises a little early, distributing locos etc. onto the floor.  I think a mechanical interlock is the next project!

This is a view of the completed lifting section before scenery. The hinges will be covered by a scenic “feature” (!)
The non opened clearance under is 950mm (3′ 1.5″) for tiny people and flexible adults. This has been in use for 4 years with no problems but normally opened to enter. My mechanical wire-in-tube manual point control is visible. Works well but I have been seduced by the magic of MERG (worth looking at even if you only download the EXCELLENT free “Electronics for Model Railways” book) and using electronics, DCC and computers is my thing, so all are in the process of conversion to servo control, the fitting of which is the subject of this post.
Preparation of the bench work either side is critical, as is assuring that the whole thing is level fore and aft.
This shows the basic construction using quality light timber (in this case hoop pine – Araucaria cunninghamii). The joints are all epoxied together and reinforced by using biscuit joiners.
The CRITICAL consideration is that timber shrinks and swells ACROSS THE GRAIN and there is very, very little shrinkage along the grain.
So as much longitudinal timber as possible must be used across the opening so that damp/dry weather changes have minimal effect. The next photos show other additions to further reinforce that in the other direction.
The underside showing additional cross bracing, both to support the 1″ (25mm) foam and to restrict any shrinkage or expansion at right angles to the track so that the latter remains aligned where it crosses the joins. There has been no problem with track alignment or binding of the lifting panel since July 2014 even through flooding rain periods and temperatures in the room between less than 10°C and over 32°C.
The section alongside the lift up section has been prepared to accept the 2″ foam. This photo shows a hinge rebated into the support.
The hinged side. Quality heavy duty brass hinges (3″ 75mm) were rebated into the frame and panel and the foam is being bonded to the top of the layout with PVA & weights (no, this is not a Valvoline advert!)
The “landing” side carefully fitted so the top surface aligns when shut.
A later photo showing the H/Duty micro switch interrupting the DCC feed to the section behind.  The inset shows the one on the under side.
Underneath with the wiring necessary for the track on the lifting panel.
The track feed to the lifting panel has two terminal blocks near the hinge line and a short section of flexible cable which can be replaced if necessary.

 

The joins across the lifting hatch require a little bit of care and attention.
Track is laid straight across the join substituting PCB sleepers at the join. Doing 5 sleepers would be better than 3 for more surface contact. The conductive copper is removed between the rails. I used a paper sanding disc in the Dremel before soldering them in place. Clean the copper and the bottom of the rail with a flux. “Tin” the surface of the copper PCB and you will need little if any additional solder to sweat the rail in place.
I always attach the track to the substrata with diluted Carpet Glue (latex adhesive). It is quite thin, very cheap, and only needs application to the foam / wood etc followed by weights to hold it in place until dry. The great advantage of this method is that there is no mechanical connection to the substrata AND … it can be lifted if you have a stuff-up. Just brush some water over the track or point (turnout) you want to lift, leave if for half an hour or so, then carefully slide a thin spatula under it.
After the latex adhesive has set, cut the track with a very fine blade. I had to cut a sleeper as the track was diagonal at this section.

Also see the section on “Laying Track Across the Join” Yet to be added.

 

Reinforcing Foam Sheet

This section explains the important step of reinforcing (or stressed skinning) the 1″ (25mm) foam sheet to give it tensile strength on the bottom surface. The top is not such a problem as the extruded foam seems to have reasonable compressive strength.
This technique borrows from bridge building and surf board building techniques – remembering that our loading is occurring primarily from the top. You can also use it on 2″ foam to allow increased distance between the supporting battens.

I am assuming that you are not going to be walking around on the top of the layout! Having said that, I have stood on the layout by placing strategic wide pieces of plywood on distributed spacers between the tracks and close to the edges.

The technique is extremely simple – coat the bottom side with a layer of cloth glued to the the surface with PVA. You could use exotics like fibreglass or carbon fibre cloth – but we are not building a spacecraft! Just some cheap muslin cloth is what I use from a fabric shop. A tea towel may do the job. Cut it a bit oversize; coat it with a generous layer of PVA glue and squeegee it into the surface … as below.
foam-reinforcement
Reinforcing using muslin cloth and PVA glue.
Squeegee / roll/ brush the PVA so that it fully impregnates the cloth.

No hi-tech tools here! You may need to thin the PVA with water just a little to help spread it. Re-coat if doubtful.

When it is completely dry, cut around the edges with a sharp knife. The reinforced surface will be the bottom!

Then glue the sheet in place with PVA. (No, this is not an advert for Valvoline!)

The underside showing additional cross bracing, both to support the 1″ (25mm) foam and to restrict any shrinkage or expansion at right angles to the track so that the latter remains aligned where it crosses the joins. There has been no problem with track alignment or binding of the lifting panel since July 2014 even through flooding rain periods and temperatures in the room between less than 10°C and over 32°C.

The reinforced side is down (up in the photo) and and the assembly rests on a flat surface to keep the top true. I then glued the battens and all the support timbers to the bottom of the foam and to the supporting structure so no screws were needed.

Shown below is a  test run I did in 2008 when I lived at Bensville (I tend to live in places with strange names). It was a test track for both DC and DCC which fitted on the bar in our lounge room. It vaguely reflects the track layout (considerably condensed) used at Oberon in the Central West of NSW when I lived nearby at Hazelgrove. The latter was a station on the now closed/ suspended railway from Tarana to Oberon. A model of the mighty Hazelgrove station will feature on Kalrail layout (later to be re-named “Brolgan Road”).

I couldn’t resist adding this photo of Hazelgrove Station posed on a temporary diorama. Yet to be finished and weathered.

The underside of the test track shows that 1″ foam has been coated with muslin and fitted with a light weight frame. The ugly blocks on the right were added to help it fit on the bar which was a bit narrow. It is 2m long, 58cm wide and weighs 4kg. Could be made much lighter with thinner timber and no ugly blocks.

Could be a neat way to take a 2m x 1/2m layout to a display. Carry it in one hand.