simplest TOU/tiebar suggestions

[jon price]

Most instructions for turnout construction seem quite shy when iut comes to TOU and tiebar construction options. What suggestions do people have for simplest, most straightfoirward solutions requiring the minimum of construction and engineering skills?

[Philip Hall]

I use the system described some years ago by Norman Solomon in MRJ 151. It is simply a thin strip of fibreglass with two brass pins upside down with the tails bent over. The blades are soldered to the tails. Operation is by steel or brass wire in tube or rodding on top of the baseboard connected either to a lever frame or a ground throw/hand lever, or the occasional solenoid motor in awkward places.

It's not prototypical but unobtrusive and very robust. I'll take a picture later today.

Philip

[John Donnelly]

I've made mine from two small pieces of double sided copper clad 1mm thick, connected by a 0,5mm phosphor bronze wire underneath. The copper clad provides both the insulation and the means for keeping the switch rail from rising, and the wire is finished in a pigtail loop that takes the wire from the servo off to the side.

John

[davebradwell]

Masokits.

It's very important that the drive to any tiebar has both excess travel and some form of sprnginess - the omega loop or equivalent - in order to hold the blade against the stockrail. If you just park it adjacent to the rail, in time something will move and your stock won't. Most likely at hot clammy exhibitions.

DaveB

[steamraiser]

I make my stretcher bars from a thin piece of copper clad turned onto its edge and gapped. Each blade is connected to the stretcher bar by a piece of guitar string with a 90 degree bend.

[Tim V]

I separate the two, the TOU is from Peter Cross ideas in MRJ 20. The stretchers are dummys, just strips of brass inserted into the roadbed. Where I got the idea I can't remember.

The mating surfaces I found between stretcher and rail were so small to be unreliable - and prone to breaking/failing. Using the enhanced area from Peter Cross resulted in a much more reliable interface.

[David Knight]

I use the one described by Dave Booth in MRJ 139 p 297. It is made up of Plastruct sections although Evergreen will also work, with brass droppers into tubing to connect to the rails. It can be controlled by a point motor/servo or wire in tube. Note, some of the sizes given in the article were incorrect but can be deduced by logic.

IMG_0222.jpeg

The unit is attached under the baseboard with screws through the dark L shaped section that sits behind the moving parts.

Cheers,

David

[Philip Hall]

Here are a few pictures. The first shows the actual tie-bar as per Solomon. Simple and very robust, OK not so prototypical, but looks fine from a foot or two away and easy to make and maintain.

IMG_6725.jpg

The second shows an arrangement with rodding made from old Model Railway Constructor steel binding rods (I knew it would be useful one day!) and as it is yard trackage, is connected to a Caboose Industries sprung N scale ground throw. No need for an omega loop or similar since the throw is itself sprung. Common crossing wiring is from a Stores microswitch and high quality thin cable as used for alarm systems. No soldering underneath rails or to rivets for me, all wires are soldered into the web of the rail where I can see it and maintain if required. All can be later concealed.

IMG_6723.jpg

The third picture shows an overall arrangement, again in the goods yard, but this time connected to the ground throw via copper 'wire in tube' (remember 'Mercontrol'?) and here there is an unsprung ground throw. On this occasion there is an omega loop beneath the cork underlay adjacent to the tie-bar.

IMG_6729.jpg

Pointwork that would normally be connected to a lever frame will eventually be connected to old Hambling's 'Addalever' frames, sometimes with solenoid motors in awkward situations. The Caboose ground throws are decently made, very reliable and can be recommended. Quite satisfying to operate as you wander around the yard too.

Hope this helps!

Philip

[Tim V]

A couple of pictures, first a facing point on the main line with flat (dummy) stretchers (a C10), on the left a siding point (B7) with round, dummy, stretchers

2010 Progress (17).JPG

and a close up of a failed TOU but showing the dummy stretchers and dummy point rodding.

2010-2 Progress (36).JPG

[DougN]

Could just be me I have never seen written down the centres for the holes through a tie bar for the blades. Or does every one make them to suit each location?

[Philip Hall]

Doug, I think Norman gave dimensions but we just drilled holes in what looked like the right places. In hidden areas the blade gaps were bigger as appearance was less important.

Philip

[Terry Bendall]

Most instructions for turnout construction seem quite shy when iut comes to TOU and tiebar construction options.

Probably becuase there are all sorts of methods of doing the job as the responses so far show.

I use the Masokit stretcher bars made up as per the instructions operated by a function crank on the end of a 3mm diameter rod comung through the baseboard. That method needs a lathe to reduce the diameter of the rod to fit into the hole in the crank.

Terry Bendall

[Jol Wilkinson]

I also use Masokits tie bars, with a loop formed in a piece of .5mm wire fitted between the linkage "ears" on the tiebar. A steel wire from either a Cobalt/Tortoise or servo passes up into this from below the baseboard to drive the tie bar and switch blades.

I used to add a second "cosmetic" tiebar/stretcher but since Ambis no longer produce their earlier etch for simple fold up stretcher to switch connection (with thin pcb stretcher bar) I haven't been able to master folding up the later version.

[Enigma]

On Braynerts Sidings I've used a copper clad sleeper on edge with 2 small sections of brass tube soldered on. Several were done at once using a simple jig to hold the sleepers so that a complete length of tubing could be attached rather than very short lengths. Close fitting brass wire was bent at 90' and the bent end flattened (big hammer on a solid surface) and cut to fit the length required. A slot was cut in the cork underlay in the tiebar area for the tiebar to 'run' in. The tiebar was then soldered to the operating wire attached to a slide switch. The switch was held in mid position, the blades held at an equal distance from each stock rail and the blades soldered to the 'L' section of the wires. I have a 'spring-thing' built into the operating wire to maintain contact of the blades and stock rails.

Point Op.6.A.jpg

[DougN]

Enigma, your solution above matches one I experimented with but never got very far. (OK, I got distracted by something else and never came back to it!)
I think it is exactly what a lot of us could use! Extending out to the sides results in the use of Tortoises or other mechanical movements!

Once I get over my current modelling itch I think I will come back to this one!

[nigelcliffe]

A friend of mine has done this:

Walnut sleeper timber, on edge. The walnut comes in strips from one of the model boat suppliers.
The sleeper (on edge) has two 0.5mm holes drilled right through (requires a decent drill, a Proxxon in a drill stand was used). A jig to get the two holes in the right place is useful.

Fine pins are pushed through the hole, and then bent over at 90 degrees, then cut down to a few mm. The pins ends solder along the lower inside edge of the blades. The pin is free to rotate in the sleeper, so no strain on things after fixing.

This worked fine at 4mm scale. Its being tried at 2mm scale with 1mm x 3.5mm timber. Early experiments say its works in 2mm scale as well....

[davebradwell]

What stops the blades lifting, Nigel? Having the timber rub on bottom of stock rail to preform this function would surely be liable to rapid wear. I think a weak point of the design by Enigma is the small area of the soldered joint but using the bent wires from the otherwise complicated scheme in MRJ 151 would help here.

DaveB

[nigelcliffe]

What stops the blades lifting, Nigel? Having the timber rub on bottom of stock rail to preform this function would surely be liable to rapid wear. ...

Yes, the timber goes directly below the stock rails. The amount of wear will depend how much "upwards pull" there is from the blade rails; unless the blades have a lot of upwards pull, the applied force and thus the friction wear will be low.

It worked on a 4mm scale layout which lasted for several years before it was dismantled. Once installed, no adjustments.
Those seeking mechanical perfection will need something more complicated.


- Nigel

[davebradwell]

It's not about mechanical perfection, more awareness and properly made and fitted blades shouldn't need serious holding down anyway. I'm sure hardwood is a perfectly sound material although Tufnol might be an alternative - it's usually about what you have to hand. It can be abrasive, though so might it try to saw its way through the stock rail? Suspect it's probably safe enough!

Most of my own track is now over 30 years old so I do tend to think about robustness, probably more so than when originally laying it but it gives very little trouble. Droppers are the biggest source of troubles.

DaveB

[Highpeak]

Scalefour News issue 181 contains two articles on the subject, one describing a robust but prototypical design by Howard Bolton, the other a more pragmatic approach taken by Mike Norris.

[Enigma]

[quote="davebradwell" I think a weak point of the design by Enigma is the small area of the soldered joint but using the bent wires from the otherwise complicated scheme in MRJ 151 would help here.[/quote]

This and similar designs have been used on several layouts since the late 70's with very few failures. Some of them intensely operated exhibition layouts with point motors. I tend to allow a fair amount of surface for soldering to and have a good fillet of it on the joint. A bit overscale for some maybe but, like Dave, I prefer to have strength and durability in an important working element of a layout.

Wiring.3.A.jpg

This example is, I admit, a bit large but it's on the inside of the rail and can't be seen. The shot also shows how I attach feed wires (0.5mm brass) to the non-viewed side of the rails and how the L-wire end projects under the stock rail to prevent lifting.

[davebradwell]

Well that certainly looks well stuck-on Paul and I'd do the same - reliability is more important than having a delicate scale item. I do replacement droppers just like yours and they've been fine.

A general comment about under baseboard types - you don't need a slide here as the blades do all the guiding required. In the finer engineering circles it is wrong to have 2 slides that can fight each other so ok if there's plenty of clearance. I have a flat Perspex plate glued under the switch timbers and a Delrin block with the 2 holes slides on this, guided by the blades. Washers soldered on the bottom of the wires hold the blades down and the block up. Plenty of Masokits, too and I really ought to add more of these to form the 2nd tiebar.

.....and don't forget the blade opens far more than the checkrail clearance.

DaveB

[Chris Pendlenton]

Wholly empathetic to the drift here that reliability is more important than appearance. However while I have occasional nerves about the robustness of Masokits tiebars they have stood up well, with a good soldering surface. All my points are mechanically worked which is gentler on tiebars than older emphatic point motors that slam the blades across. I also like the hole for soldering the operating rod, affording easy adjustment.

The fit and shape of point blades is one of the big factors in reliable running through point work and I think it worth spending a lot of time here getting a perfect fit. The acid test is to run your finger over the toes blind and not know whe you pass over the toes. Recent experience in going back over all this while extending North Shields may bear mentioning:
Nigel mentions "upward pull" and of course blades whose tip is higher than the stock rail invite derailment in the trailing direction and a bump in the other. Equally and often overlooked is a blade that is lower than the stock and again in the trailing direction this can lead to derailment as the outer face of a wheel tread can become nipped by the stock rail and lifts its oppo up and off, particularly if the wheel tread edge is sharp and not bevelled as it should be. You would think it impossible to have a blade lower than the stock but all it needs is a fraction and how many of you have found as I have that different batches of rail can be of different heights. It is a good start to check this and also to ensure you have a good flat slide chair flush alongside the track rivet.

Finally, Dave is right to remind folk to set blade toes in relation to each other at something safely less than wheel back to back. I go for 17.5mm max. Quite wrong to set blades against stock rails rather than to each other. Think of gauge widening.

Just as a slight digression, underside of sleeper to rail height can be a very variable feast nowadays with variable rail section heights compounded by rivets that do not always have a head of uniform depth- current Stores brass ones are deeper than old plated brass stock. How heavily you rivet them in to ply sleepers also bears and then plastic based track comes in different depths as can depth of glue films and this can all add up to quite a challenge to those depending on absolutely flat bump free track to run their rigid stock!

Re dropper unreliability I'd reiterate that the most reliable solution is to drill the rail and clamp the dropper wire through the hole and solder. Never fails. On new construction I always drill 0.8 in the web at random points hoping that one will suit dropper positions. For retro fitting I have managed to drill in situ rail with a mini drill and a long piece of 0.9 mm piano wire with a spade bit filed on its end and hardened.I steady the wire with a pair of serrated tweezers dug into the ballast with the wire shank running in the serrations. Hairy but it works.
Chris

[Chris Pendlenton]

As a postscript to mine above another couple of points about blade fits. First you must get rid of any inward lean in the rail carried through from the 1 in 20 of running line rails, and second, it is wise to file small bevels in the inside foot of both the blades and the stock rail to cope with any microscopic detritus between the two. Full size do it too. And the third of my two points is to keep the blades lightly fixed at their other end in no more than a couple of chairs so as not to inhibit easy traversing. You want no inbuilt desire of the blades to return to a centre position.
Chris

[Barry Davis]

Hi, I’ve been hand making wire in tube surface mounted turnout operating units for many years for the simple reasons : I have limited access to the underside of my baseboards, they are 100% reliable, they are cheap to make, and on the real railways, turnout operating units are not buried 4 to 6 feet underground.

Each TOU is operated by a DPDT slide switch which while operating the tie bar, also changes the electrical polarity of the turnout crossing vee.

On later TOU’s, I have reduced the length of the unit by 6 mm to 34 mm, the length of a standard sleeper.

I have attached three photos to give an idea to their simplicity.

Regards
Barry.