Mystery tiebars

[Armchair Modeller]

Many thanks for that tip - I am now the proud owner of my first copy of MRJ for several years

[martin goodall]

One significant advantage that Roger Eaton's units had over later copies by Alan Gibson and C&L was that they used teflon tube (which the others did not), which was not damaged by the heat when soldering to the switch blades.

I still have some in use on my layout, but found it desirable to double up on these stretcher rods, in the same way as on the prototype. However, on balance, I now prefer the type of stretcher used by Normon Solomon, for the reasons explained below.

Roger's design, also adopted by Alan Gibson and C&L, relies on a soldered joint between a twist in the wire and the switch blade. This joint is not all that easy to make and is liable to stress fracture, due to the flexure of the switch blade as the points are changed. I found that these soldered joints were all too prone to failure (although easy to repair). It was this that led me to double up the stretchers, i.e. fitting two to each turnout, which seems to reduce the incidence of breakages.

I did not find the teflon tube as rigid as Roger seems to indicate in his recent note. There was a tendency for the tube to bow. Just occasionally, I have also experienced movement of the wire inside the tube, which can affect the setting of the switch blades. However, this is easily remedied with a touch of super-glue.

As indicated, any problems encountered with these stretcher rods in service can be easily and quickly remedied, but I really wanted to avoid them occurring in the first place. It was this that led me to replace these stretcher rods on the most heavily used turnouts (the ones that exhibited the greatest propensity to suffer from the problems mentioned above), substituting the units designed by Norman Solomon, as described in MRJ 151. This relies on a strip (or bar) of paxolin or similar material, admittedly not prototypical in its size or shape but not unduly conspicuous when in situ, through which pins are inserted from below, which are free to pivot in the bar. The pins are then bent over and soldered along the insides of the switch blades, low enough to avoid fouling the wheel flanges. This design has the advantage of relieving the soldered joint on the switch blade of any stress as the switch blades move, because the pins are free to pivot in the stretcher bar.

I have not tried the etched components mentiond in this thread and described in MRJ 216, but they seem a bit more fiddly to assemble than the Normon Solomn design, albeit perhaps rather more prototypical in appearance. "You pays yer money and takes yer choice."

[Armchair Modeller]

As indicated, any problems encountered with these stretcher rods in service can be easily and quickly remedied, but I really wanted to avoid them occurring in the first place. It was this that led me to replace these stretcher rods on the most heavily used turnouts (the ones that exhibited the greatest propensity to suffer from the problems mentioned above), substituting the units designed by Norman Solomon, as described in MRJ 151. This relies on a strip (or bar) of paxolin or similar material, admittedly not prototypical in its size or shape but not unduly conspicuous when in situ, through which pins are inserted from below, which are free to pivot in the bar. The pins are then bent over and soldered along the insides of the switch blades, low enough to avoid fouling the wheel flanges. This design has the advantage of relieving the soldered joint on the switch blade of any stress as the switch blades move, because the pins are free to pivot in the stretcher bar.

Any chance of a photo/sketch please? I am building some turnouts at the moment and would be very interested in your idea.

[martin goodall]

It so happens that Philip Hall took some photos of the stretcher rods on my Burford layout for a possible future article in MRJ on track construction for the layout. I am breaking my rule of not publishing here photos that might be used for future articles in MRJ, but this shot does illustrate the stretcher rod rather well, together with the soldered connection to the switch blade (on the far side), plus the ground connection.

The whole assembly will be a lot less conspicuous when the track is ballasted and painted.

8102 Photo © Philip Hall (by courtesy of WSP Ltd.).jpg

[grovenor-2685]

I am building some turnouts at the moment and would be very interested in your idea.

I don't think that Martin or even Norman Solomon can lay claim to that idea
It was common practice in the '60s. I'm pretty sure we used it on the MRC 00 layout and I fitted a lot of them before moving to P4 and the Studiolith TOUs. I don't have an illustration to hand but Martin's description should be adequate, (and now his photo, added as I typed) it really is just a strip of paxolin, or whatever, PCB sleeper strip will do suitably gapped, and two bent pins.
Regards,
Keith

[martin goodall]

I omitted to point out that Philip's photo also shows one of the Roger Eaton stretcher bars. This was the second of two fitted to this turnout, as mentioned earlier. (Note that it has bowed.) It was no longer needed following the fitting of the Norman Solomon stretcher bar (actually obtained from Norman Solomon in this instance, although similar bars are available from C&L), but was left in place for purely cosmetic reasons.

Keith is no doubt correct in pointing out that there is nothing new under the sun, and I am not at all surprised to learn that something very simialr was in use up to 50 years ago, but Norman's description is the most recent I have come across - and is succinctly sumarised in MRJ 151.

[Armchair Modeller]

I am breaking my rule of not publishing here photos that might be used for future articles in MRJ

Wow! I feel very honoured that you should consider my trivial request worthy of such a huge sacrifice.

Many thanks for the photo and the additional information.

[Tim V]

I never put functional stretcher into my points. They are usually fitted with modified Studiolith TOUs, and cosmetic stretchers are fitted - got the idea from I think it was a Martin Goodall article on Bodmin in the old MRC (I do listen to Martin sometimes....):!:

Why?

Because in my experience, the more one can "beef up" that critical joint, the less likely it is to break. Look at the area of solder using the functional stretchers - it's very small.

[Russ Elliott]

Being of the North London Skool, I too am wary of flexing small solder joints.

Martin's picture reminded me I couldn't fault Andrew Jukes' suggestion to me that doubles (regardless of their method of blade attachment) would work best if the place where they were pushed and pulled equalised the axial forces of the two stretchers, which will optimise the fit of planing angle to stock rail on both blades:

twin-stretchers.png

[Jol Wilkinson]

I've used the Masokits tie bars on the turnouts and single slip for the extension to London Road . Like Russ, I am wary of "flexing" soldered joints, but I decided to take the risk due to the ease of installation of these with Cobalt point motors.

By chance, I decided on the same approach described by Bob How in the latest (216) edition of MRJ. Bob states that he has used this approach on some 80 sets of point blades and has had only two failures in over ten years, so perhaps my optimism is justified.

Unlike Bob however, I've used the Ambis "simple" tiebars as the second bar or stretcher. These have more flexibility than Masokits version and hopefully put less stress on the various soldered joints. For several turnouts I have now also followed Don Gilliland of the N&SAG's advice and soldered the Ambis unit to one blade only leaving the other end just pushing against the opposite blade.

London Road's original turnouts use the NLG operating unit (as I think of it), together with the "flexible tube" stretchers. I didn't wan#t to use these again as I don't like the look of them and found that the wire can move in the tube. The worst problem we had was a short circuit at one show, where heat expansion pushed the wire ends together. Mind you that was only once in twenty plus years, but something to be aware of.

Jol

[steve howe]

Wow this is an old thread!
Reading Steve Hall's letter in S4 News 231 Mailbag about functional tiebars, he mentions "SPMR as sold by Scalefour Stores" from the description this sounds like the Masokits tiebar?

I've been using these for a while and as Steve says, they are a fiddle to assemble, although I find it easier to do as much work as possible before releasing the etched parts from the fret. But they do make up into robust units. I'd be interested to know if these are one and the same.

Steve