=== Switch drive - 3D slider ribs ===

<color #ed1c24>Draft text and diagrams</color>

(Description and diagrams produced by Martin Wynne)

The idea is that a resin-printed (or home-made) slider runs between the ribs and the timber webs and flanges, having sideways slots for a 1mm dia. brass pin:

{{:playground:pasted:20241109-092450.png}} \\
<color silver><sup>© Martin Wynne</sup></color> \\

The pin is retained in the slider with a soldered collar (not strictly necessary, but it makes assembly easier) which might be a small washer or a wrap of copper wire.

The top of the pin is bent over and soldered to the foot of the switch blade in the usual way.

If suitable pins are hard to find, the pin could be replaced with 1mm brass wire, bent over at 90 degrees below the slider.

The ribs are angled at 45 degrees to enable the rib to be FDM printed more accurately. The short slot in the slider (rather than a plain hole) allows for the curving of the open switch blade.

(On a curved turnout the two timbers are not exactly parallel, although this is barely noticeable at any normal model radius.)

The whole gubbins is hidden below a thin card or thick paper cover which can have some ballast sprinkled on it and/or be covered in the usual track gunge, having a couple of openings for the pins. If made from paper, the openings can be simple knife slits, which would close round the pin very effectively.

Dummy model stretcher bars can then be added, which can be resin-printed and fully detailed. This drive design also maintains full daylight below the rails between the timbers, not relying on the underside of the rail to hold the switch blades down on the slide chairs -- the slider does that. On the prototype the stretcher bars do that, and can be modelled with dummy extensions. (And full dummy rodding added, if wanted.)

The actual sequence of assembly is still to be determined. If built on the bench it can be fitted from below quite easily. If built in-situ, it might be necessary to insert the slider and pins before adding the rails.

Obviously none of this works for plywood timbers, but folks building plywood track probably already have their own preferred means of driving the switches.

{{:playground:pasted:20241109-092403.png}} \\
<color silver><sup>© Martin Wynne</sup></color> \\

And the result is slider ribs between switch timbers S1 and S2, and between S3 and S4: \\
{{:playground:pasted:20241109-194518.png}} \\
<color silver><sup>© Martin Wynne</sup></color> \\

You can have up to 5 sets of switch slider ribs, for long switches which need more than one drive (tie-bars and/or prototype stretcher bars/rods).

Enter the first timber number in the boxes, and the ribs will appear between that timber and the next one. Leave blank if not wanted.

You could add the ribs to any timbers, not only switch timbers -- but I can't see any likely need for that.

Switch timbers count S1, S2, ... from the toe timber (the one with the blade tips and soleplate). To see all the timber numbers, start the shove timbers function.



<color #ed1c24>this is a playground version as an example - more description etc to be added here</color>