• The Plug Track functions are experimental and still being developed. Some of the earlier pages of this topic are now out-of-date.

    Some pages of this topic include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files.

Help with tie-bars / stretchers

Location
Sydney
Does anyone have a good picture of whatever the linkage might be for the switch blades? At the moment I have been building a small sliding sleeper style of thing, but I imagine even if I were to cut a thin PCB board tie bar, and then add a piece of some cosmetic thing on top of that to make it resemble more like something I might find between the switch blades on east coast area (LNER style). I wanted to use the idea of two double sided clad pads with rod soldered underneath but I think just a cosmetic thing on top to improve the look if it might also work. Just inspired by the picture Martin added. But I have a feeling that might be a GWR style of thing.
 
_______________
message ref: 3036

Murryb

Member
Location
New Zealand
From LNWR Details of Permanent way as of 1916. By Brian Nicholls for the LNWR Society. These are just a few from this comprehensive publication which are taken from official Crewe Drawings.
 

Attachments

  • 20211018_172905.jpg
    20211018_172905.jpg
    1.8 MB · Views: 99
  • 20211018_173024.jpg
    20211018_173024.jpg
    1.8 MB · Views: 95
_______________
message ref: 3037

Martin Wynne

Admin
Location
West of the Severn UK
Info
.
Enjoy using Templot?
Thanks.

Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add
helpful replies.
@Captain_Mumbles

Hi Ben,

The prototype object is called a stretcher bar or stretcher rod.

You can find more drawings in this download file:

http://www.lmssociety.org.uk/assets/pdfs/permanentWay1928.pdf

which contains the standard REA bullhead track info. Stretcher bars start on page 20.

Here is a photo you wanted:


sretcher_bars_drive.jpg


You can see that prototype stretcher bars (2.1/2" x 1/2" spring steel strip) are much more flexible than the switch rails, which makes them very tricky to model in the smaller scales and remain functional and electrically insulating. Many modellers opt for a purely functional model "tie-bar" device instead. Numerous designs have been posted over the years, including from me. :) If you ask about "tie-bars" in your RMweb topic you will likely get many ideas and suggestions.

This is my preferred functional model tie-bar, which I supplied with my turnout kits back in the 1970s (you need a small lathe to make it). The pin is free to rotate in the tie-bar -- preferable in any tie-bar design because it removes most of the stress from the fixing, and allows the open switch rail to take up a prototypical curve -- replicating the flexible nature of the prototype stretcher bar.
pf_tie_bar.png

The great advantage of the grooved pin is that it locates directly onto the rail foot, so can be assembled dry before soldering, with some packing between the blade and stock rail. Easy to solder neatly because the solder flashes into the groove.

The tie-bar material is unclad 0.8mm fibreglass or SRBP. If you don't have a source, it can be made by etching all the copper from copper-clad laminate. It can be disguised by gluing some ballast on top of it, after which cosmetic models of proper stretcher bars can be added between the switch blades.

An important function of any stretcher bar design is that it holds the switch blade down on the slide chair and level with the stock rail, by running directly under (or sometimes through) the stock rail. Several model designs have been published over the years which fail to do that, sometimes called "Turnout Operating Units" or TOU. If the switch tip is not held down, it can lift up as wheels run along it, possibly derailing the following wheel.

cheers,

Martin.
 
_______________
message ref: 3039

Lancastrian

Member
Location
Milton Keynes
Hi,

I don't know what scale you model in, but C&L Finescale produce an etched tie-bar kit for 7mm modellers:
https://www.clfinescale.co.uk/onlin...Gauge-Tie-Bar-etch-copper-clad-x-3-p128257156
Another option similar to Martins example, is to use lace pins. These are pushed through holes drilled into the srbp/fibreglass "tie bar", bent though 90 degrees and soldered to the rail.

A third option (or fourth) is to solder a length of brass rod to the switch blade, which passes through the baseboard and locates into a length of brass tube soldered to a piece of SRBP/copper clad strip. You can then use cosmetic tie-bars/stretcher bars on the point.
Something like this:
https://www.clfinescale.co.uk/online-store/POINT-UNIVERSAL-OPERATING-SWITCH-BLADE-BAR-p128941015
Ian
 
_______________
message ref: 3042

Captain_Mumbles

Member
Thread starter
Location
Sydney
@Martin Wynne , common sense tells me the tie bars should eventually break off when the solder reaches a threshold, or do we ignore this because it just works??? This idea of pivot is especially important if I were to connect two tie bars together somehow in a double slip. I have a few of those to make later. I stocked up on lots of little brass rivets, so hopefully this lets me make something. I dont have access to a lathe at the moment unfortunately :-(
I think the turnouts that are far away from the operator the plain 'tie-bar' is fine. I did incorporate the mechanism of keeping blades from lifting in that the brass pads I soldered all my rail to slide underneath the stock rails like a reverse slide chair and it seems to operate very smoothly like that.
What I was getting at, even though it isnt prototypical in the slightest, now I have seen your close up picture is I could make the tie bar small enough and simply add some small detail on top of the tie bar that will 'pop' when painted, games workshop warhammer/model aeroplane style. I think that will not be unlike RTR turn outs except I can aim to have it look a little bit more like your picture.
@Lancastrian I like the under base board idea but in my plan it does get a little busy and some of these may interfere with each other to the point where it is possible I could have a very small amount of working point rodding as I also dont see me being able to put turnout motors that close to each other either. This has given me the idea that I could make a sliding T or L shaped wire thing in some bushes to link to the motor somewhere else under the base board.
 
_______________
message ref: 3044

Nigel Brown

Member
Location
Wales
Hi,

I don't know what scale you model in, but C&L Finescale produce an etched tie-bar kit for 7mm modellers:
https://www.clfinescale.co.uk/onlin...Gauge-Tie-Bar-etch-copper-clad-x-3-p128257156
Another option similar to Martins example, is to use lace pins. These are pushed through holes drilled into the srbp/fibreglass "tie bar", bent though 90 degrees and soldered to the rail.

A third option (or fourth) is to solder a length of brass rod to the switch blade, which passes through the baseboard and locates into a length of brass tube soldered to a piece of SRBP/copper clad strip. You can then use cosmetic tie-bars/stretcher bars on the point.
Something like this:
https://www.clfinescale.co.uk/online-store/POINT-UNIVERSAL-OPERATING-SWITCH-BLADE-BAR-p128941015
Ian
I use the lace pins approach, actually small brass nails. Works OK. As the pins/nails can rotate in the tiebar hole, the geometry can alter so avoiding stresses building up. I believe Pendon uses something similar.

I once tried an approach involving tie bars of nickel silver rod soldered to both switch blades. It meant one could use multiple tiebars as per the prototype. Both blades were of the same polarity, so it was essential that wheel backs didn't rub on the switch blades. It worked, but the hassle of making sure all BtBs were spot on and making sure the switch gap was wide enough meant that eventually I ditched it.
 
_______________
message ref: 3046

Nigel Brown

Member
Location
Wales
@Nigel Brown , sounds like next level insanity, or is it tranquility???
Seemed like worth trying, and it gave an easy option for shoving in multiple tie bars. The thin n/s rod was flexible enough to allow the geometry to alter. But, once the track was used in earnest... :(

I like the look of the British Finescale tiebar approach. When the 3mm/ft turnouts are available I'll give them a try.
 
_______________
message ref: 3053
Top