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TEMPLOT 3D PLUG TRACK - To get up to speed with this experimental project click here.   To watch an introductory video click here.   See the User Guide at Bexhill West.

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 Some of the earlier pages of this topic are now out-of-date.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics 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. All files derived from Templot are © Martin Wynne.
  • The Plug Track functions are experimental and still being developed.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics 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. All files derived from Templot are © Martin Wynne.
Martin Wynne

REA chair dimensions -- screws and fixings

Copied from: https://85a.uk/templot/club/index.php?threads/messin-with-resin-3d-printed-track.103/post-957

Chair base is 1/4" thick at edge.

Seat for rail is 1.3/4" thick.

Chair screw:

chair_screw_400x742.png


The ferrule provides a precise location on the timber without needing a close tolerance hole in the chair casting. The ferrule stands proud of the casting to be effective. If frequent tightening causes the screw head to contact the casting, the ferrule must be replaced. Ferrules were originally oak, but modern ferrules are a tough plastic polymer.

Screw top height above timber:

Before tightening: about 3". After fully tightening: 2.3/4" min, say 2.7/8" in new track.

The standard REA chair drawings are available here:

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

Unfortunately the scan quality is rather poor and some dimensions are difficult to read. Chair screws and ferrules are on page 1. The ordinary S1 chair is on page 4.

Extracting some dimensions from more readable scans:

Screw head top. 1.1/16" sq.

Screw head at flange: 1.1/8" sq.

Screw head height above flange: 7/8" at side, 15/16" at corner.

Flange thickness: 3/8" at side of head.

Overall height of screw head and flange: 1.1/4"

Flange diameter 1.7/8"

Ferrule diameter at top (before compression): 1.35/64"

Boss on casting: overall height: 1.1/2"

Boss on casting: top diameter: 2"

Pictures of some chairs. Notice how prominent the screws can be. The screws are galvanised, the chair castings are raw, which is why the screws stand out in photos, especially when new:

bullhead_crossing_detail1.jpg


long_check3.jpg


pw_heap.png


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