Permanent Way GWR 1S and 2S - official drawings?

Dog Star

Western Thunderer
I am looking for Swindon drawings of the 1S and 2S chairs which were used with loose heel switches circa 1900 onwards - so drawings dated late 1890s to early 1930s. The need is to help with producing 7mm scale 3D printed chairs - rail section is probably not important for the task in hand given that the printed chairs have to work with 7mm bullhead rail.

Anyone got anything or know where to look?

thank you, Graham
 

Phil O

Western Thunderer
A further thought, the switch rail jaws of the S1 chair do not grip the rail, they are 1/4 to 3/8 inch wider than the rail web, to allow the rail to move in the jaws.
 

simonr

Member
Is this of any use Graham? I have never uploaded a photo before and with no broadband in these parts here's to hoping it works
cheers Simon
 

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Dog Star

Western Thunderer
Is this of any use Graham?
Yes, an improvement upon the comparable drawing in GWSG "S&C Practice", good to see the table of "variations" in the RF-RF distance for different switch lengths. What is missing from this drawing (and from the quoted reference book) is the angle of divergence between the switch and stock rails at the 1S and at the 2S chairs..

The reason for asking for GWR drawings is that 3D printed chairs have a disadvantage when compared to the ABS mouldings that are supplied by the S7 Group... the 3D chairs are rigid and inflexible whereas a 1S chair made by cutting ABS chairs is both flexible (to an extent) and can be "adjusted" to fit the model turnout. If a 1S chair made as a 3D print derived from the drawings in the S&C Practice book, or the illustration above, then there is a good chance that either the chair is going to fracture when used or the Switch rail is not going to lie close to the Stock rail along the planed section (and yes, both of those statements reflect recent
occurences in using 3D 1S and 2S chairs).

Looks like a trip to Didcot to hunt for suitable research material, preferably in a stack/pile of fittings rather than incorporated into a turnout along the main ladder.

regards, Graham
 
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simonr

Member
Yes, an improvement upon the comparable drawing in GWSG "S&C Practice", good to see the table of "variations" in the RF-RF distance for different switch lengths. What is missing from this drawing (and from the quoted reference book) is the angle of divergence between the switch and stock rails.

The reason for asking for GWR drawings is that 3D printed chairs have a disadvantage when compared to the ABS mouldings that are supplied by the S7 Group... the 3D chairs are rigid and inflexible whereas a 1S chair made by cutting ABS chairs is both flexible (to an extent) and can be "adjusted" to fit the model turnout. If a 1S chair made as a 3D print derived from the drawings in the S&C Practice book, or the illustration above, then there is a good chance that either the chair is going to fracture when used or the Switch rail is not going to lie close to the Stock rail along the planed section (and yes, both of those statements reflect recent
occurences in using 3D 1S and 2S chairs).

Looks like a trip to Didcot to hunt for suitable research material, preferably in a stack/pile of fittings rather than incorporated into a turnout along the main ladder.

regards, Graham
Ah, do you mean "Table of leads" by any chance Graham? From studying the drawings angle of diversion is not included as a criteria as the diverging track is curved.I do have the table of leads from the GWR civil engineers office dated Jan 1962 which covers switch radii from 5 chains (203' ) to 3822'.

I have some true scale bullhead track underway in 7 1/4" gauge. After researching the subject I am full of admiration for those Victoria civil engineers.

A fascinating subject.

Simon
 

martin_wynne

Western Thunderer
I was referring to the angle between the rails at the individual 1S and 2S chairs.

Hi Graham,

You can find that easily from Templot:

rail_angle.png

1. set the required size of GWR loose-heel switch.

2. switch on the timber centre-lines.

3. use the mouse action to slide the peg along rail 2 to the centre of the required timber.

4. read off the peg angle from the info panel.

If you need more details about how to do this, please ask on Templot Club: Templot Club

The GWR loose-heel switches have been available as pre-sets in Templot for about 25 years now, originally taken from the data in the Paddington Track Notes.

cheers,

Martin.
 
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