Yet Another Point Tie-Bar Mechanism - 2

Here is how the mechanism described in my previous post is fitted below the baseboard and the point. Remember, the point blades are fitted with operating wires, formed using the Easitrack bending jig, so the point has two vertical operating wires dropping down near the ends of the point blades. Two small slots are drilled and carved in the baseboard surface before gluing the point down. The slots are wide enough to allow the brass tubes from the operating mechanism to pass up through them, with enough sideways throw to allow operation of the point. This photo shows the point in position. When it is ballasted, there should be very little of the mechanism visible, I hope:



The mechanism is glued underneath the point. As it is put into position, the two operating wires dropping down from the point must be threaded into the two tubes of the mechanism. The ends of the tubes will be just below the top surface of the baseboard when located properly. Some rigid brass wire with an omega loop formed in it is hooked into the hole drilled at the end of the PCB in the mechanism. I am using servo mechanisms to operate the points. These are very cheap on Ebay. I have some MERG Servo4 electronic kits to drive them (each board will drive up to 4 servos) and the first of the MERG CBUS kits will be used to control them. More on the electronics will be in a later blog posting. I had hoped to glue the wooden blocks that the servo is mounted on to the baseboards, but the glued joint was not strong enough, so small countersunk screws have had to be added which will have to be covered by the scenery.

Yet Another Point Tie-Bar Mechanism

I purchased an Easitrack point operator and put it together, and I was impressed by the engineering, and how nicely it operated. The problem with it was, though, that my baseboard (being a hollow door) has a very thin surface and only an inch or so overall depth. I could not see how I could fix the mechanism in place, and much of the operating mechanism would be hanging below the baseboard, where it would be easily damaged in transit.

Up to now, I have used moving tiebars (copper clad glass fibre board) operated by relays from below. Although I had found them to be simple to produce, and reasonably reliable, they are a bit disappointing to look at. For Fresherwater, I wanted to try something better. The Easitrack blade wire bending jig provides an answer to my main worry over many solutions in that the wire bends and passes below the stock rails, so the blade tips cannot rise up and get caught while track cleaning. I am still worried that if the solder joint between the wire and the point blade fails, I will not be able to repair it with the track laid, but we will see if that worry is justified.

In designing a new mechanism, I had to take my notable lack of engineering skills into consideration. The mechanism had to operate with large tolerances in almost all measurements. Where I work, tea and coffee comes in pouches which hang from plastic channel 'rails'. Consequently, large numbers of these pieces of plastic end up in the bin each day, so I took it on myself to try to recycle at least some of them.

I started by cutting a length (about 2 inches) and removed some of the side pieces at the ends. It is soft flexible plastic, easily cut with a scalpal. Then I cut two rectangular slots that small brass tubes will pass through, and move lengthwise to operate the point blades. In the photo below, the channel as it comes is on the right, and the cut up piece is on the left:



I then took the L- profile pieces I had cut from the sides and glued them with epoxy resin so that they restricted the size of the channel. These are just visible in the photo. I also glued a small micro-switch in place on a piece of paxolin board:



Next I cut a strip of single sided glass fibre PCB, wide enough to pass smoothly along the inside of the channel. I cut this strip into lengths of about an inch and a half, and made some insulating gaps. I drilled the end for an operating wire, and around the centre for one of the small brass tubes. I left drilling the hole for the second tube, as that is the only critical measurement, and will depend on the point it will be attached to (the way I make them):



To the opposite end from the operating wire hole, I soldered a bent piece of rail with a 12BA nut on the end. The bolt through this nut will operate the microswitch, allowing some final adjustment once in place:





Now I needed a jig to help solder the small brass tubes in place, and here it is - a few pieces of old plywood, and a stiff wire pushed into a drilled hole. The tube sits over the wire and stands vertically while the PCB sits on the top of the ply ends, leaving the right amount of tube protruding below:





So there we are. Having created the first one, I easily made 6 more almost matching ones for the rest of the layout in one evening. How they fit, and work will be revealed in the next installment.

Ian M.

First piece of track laid

There has been a bit of a pause in progress while constructing the track required. As I only have one evening a week to allocate to modelling at the moment, it has taken longer than I would have liked. I also found a new way of slowing up progress by deciding to try filling the insulation cuts in the copper-clad sleepers with milliput (after checking the gaps were actually insulated). With a spray of primer (after washing with Cif and a finger nail brush) they really do look better for being filled.

I also built some MERG servo control boards and a tester/programmer box, as I will be using servos to operate the points and uncoupling magnets. More on these subjects will come later, I hope.

Anyway, the first length of track to be laid is across the board join to the fiddle yard. I am trying out the easytrack brass sleepers for this. Six of these sleepers were soldered in with concrete sleeper profiled copperclad, and the whole lot primed. I had to smooth out my poor carpentry by planing the surface slightly, and digging out a little to cater for the brass sleepers being fractionally thicker than the copperclad ones. The whole length was fixed down with Araldite and weighted down overnight. This morning I have sawn the rails across the gap, and sawn the brass speepers in half to restore insulation between the rails. A little more Milliput filling is required before painting the sleepers, and ballasting.



The photo also shows some foamboard being used as a basis for the river banks. The river is still tidal here, so it will have steep, deep banks.

The first point will be situated just beyond the bridge, so I now have to decide on, and build the operating mechanism, more on that next time.

Changing my Mind

Not a lot of visible progress for a while, but I have been beavering away building track. Having built a couple of points using the jig I have (equivalent to about 3 foot radius) I scanned them, and printed paper copies which were cut out and used for trying to mark out the track layout on the baseboard. Try as I might, I just could not get the track to match the original layout, with the outside slip. So, I decided to revise my plans, and follow the later track layout without the slip. This also means losing the locomotive facilities, but does reduce he number of points that need to be built. The revised layout plan is shown below:



I also used the scanned images to put together a template for the crossover at the buffers end of the platform road. With some care and attention, I managed to build most of it in the point jig, re-inserting the construction into the jig in different orientations a few times.



If I had realised that the jig is exactly the right width, I could have used it as a sawing jig for the full length sleepers. Note, I have not used chairplates for this layout in a bid to save time. Previously, when I have used chairplates, the daylight gap beneath the rail disapeared during ballasting anyway.

Here is the track built so far. Three more points and plenty of plain track needed for the layout board. More needed for the fiddle yard.



Having tried traversers, sector plates, turntable points and cassettes on previous layouts, proper points have proved to be the most reliable solution, albeit they take up a long length of the fiddle yard. I will be attempting a 4-way point for this fiddle yard. Wish me luck.

More Fresherwater Progress

After some consideration, I decided to change my mind about moving the road. Instead, I added a couple of pieces of wood below the baseboard ends to reinforce the cutouts for the river bed, and added the second cutout on the front edge. I also added four small squares of wood to make locating the trestles better defined. Both these additions can be seen in the following photo:



The photo also shows a brick holding down the river bed while the glue dries. Three layers of 5mm foam board were used to form the river bed, and the stream bed that runs along behind the platform. The ends of the river that pass over the board edges had the foam and the lower face removed, and will be glued to the woodwork separately (hopefully leaving the river surface smooth). The banks will be formed from more foam board later.

Baseboard progress

Another Saturday morning, and some more progress. The trestles I purchased cheap on the Internet turned up, and I have assembled them. They are just what I had hoped for, and make a steady, sturdy support for the layout, and adjust from really low (for a layout) to a bit too high.



The cabinet makers dowels and catches also turned up in the post, and so the fiddle yard board now connects to the layout. My poor carpentry skills let me down a bit, and I have ended up with a little step to be dealt with when track laying, but it should end up OK.





I scratched my head a bit over supporting the far end of the fiddle yard. The catches and dowels would not survive the stresses for very long, but the weight to be supported at the end of the fiddle yard is not very heavy. I did not want to resort to a leg, as it would not be adjustable in height like the rest of the layout. There was not really anywhere to mount a diagonal brace to, easily. I had an idea about cantilevering somehow. I found a suitable piece of timber about 5 feet long, and attached small pieces of timber at each end (see photo above). The centre of the timber rests on top of the trestle, and the attached pieces of wood hook under the layout and fiddle yard at each end (see photo below). It seems to work, but I might add some catches to hold it in place.



So, that is it for this week. The layout needs a backscene board, and I will put a safety fence around the fiddle yard. I also want to build boxes to protect the layout for transport and storage. All this heavy woodworking needs to be complete before track laying starts. I had better start building some track to lay.

More hacking at the baseboard

After last weekend's work on resizing the door, and making a cut-out area underneath the layout for the point mechanisms, etc, to go, this weekend's activity was a little less to do. The glue having set, all the edges were sanded down. Two cross members were screwed and glued across the underside. These will be used to locate the board on the leg trestles, but were also intended to strengthen the layout before the cut-outs for the stream and river Yar were made in the layout's top surface:

The rounded ends of the new cross members can be seen below the layout, about 4 inches in from each end. They also mean that the layout does not lie flat on the floor when off its legs, and can be picked up more easily.

The 6 inch grid has been drawn on the topside of the layout, and the trackplan sketched out on it. The locations of the strengthening timbers around the underside cutout have also be marked, to help me avoid them. The areas for the stream and river were then cut out with the jig saw and the cardboard lattice removed. The level of the river bed will not be the full depth of the door thickness. It will be as deep as the cutout in the edge timber.

I shied away from making a similar cutout in the timber at what will be the front of the layout. I decided, instead, to move the road bridge downstream a little so it covers the timber. I may change my mind again later, once I have completed the fiddle yard connection. Now, I can just await delivery of the leg trestles, and brass baseboard joining dowels. I intend to complete all the woodwork construction, including backscenes and transportation/storage boxes before starting any track laying.