How to use blade filing jig?

Discuss the prototype and how to model it.
Terry Bendall
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Re: How to use blade filing jig?

Postby Terry Bendall » Wed Sep 09, 2015 8:06 am

Will L wrote:For preference you need both a Fine cut and medium cut.


Will has quoted the types as listed on the Eileen's web site. However, in the interests of Getting It All Right, the correct designation of types of cur are dead smooth, smooth, second cut and the most common coarsest one which is called a bastard cut. Don't ask me why, but when I was teaching that always raised a smirk from some pupils. :) Then of course the nasty teacher asked them to explain what was so funny. :D

A flat file tapers in width and thickness and has teeth on all four sides. A hand file is parallel in width and thickness and has one edge with no teeth as shown in Will's drawing. This is called the safe edge and allow filing up to a step or shoulder.

My personal preference is for a 6 inch second cut file to start filing the blade and then finish with a 4 inch smooth cut file. A fine finish can be obtained by draw filing. This is where the file is held at right angles to the work and is drawn up and down rather than being pushed across the work. For a really smooth finish wrap emery cloth around the file and move up and down. Putting emery cloth (or wet and dry paper) round the file helps to maintain the flat surface.

BTW always fit a handle to your files. This saves the tang being pushed into the palm of the hand. I have seen it happen. :(

Here ends the metalwork lesson.

Terry Bendall

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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Sep 09, 2015 9:56 am

Derek wrote:Have you looked close up at a turnout on a real railway? A lot of what these chaps say made much more sense after going and looking at our local heritage siding that masquerades as a steam railway, and seeing a real turnout and how it is constructed.

+1
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Derek
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Re: How to use blade filing jig?

Postby Derek » Wed Sep 09, 2015 10:14 am

Martin Wynne wrote:
Derek wrote:Have you looked close up at a turnout on a real railway? A lot of what these chaps say made much more sense after going and looking at our local heritage siding that masquerades as a steam railway, and seeing a real turnout and how it is constructed.

+1


Hello Martin
I think it fair to say that I personally have learned more about turnout design and construction from a) using Templot and b) asking you and/or reading your rather extensive catalogue of comments that you have made over the years.

But it is very useful to have a look at the real thing and see "ahhh... that's what Martin meant/Keith/Terry/whoever meant." In fact in view of the comments made here about blades, I'm going to have to go back to the aforementioned siding...


PS a 'friend' gave me some close up photos of turnouts from the Esk Valley line (I believe from a small town named Whitby or something similar). They were taken on Christmas day with no trains running and due to an error in the signs from NR and a missing gate, my 'friend' managed to walk down the track on the wrong side of the fence. Tut. They aren't the best photos as my 'friend' had a new camera, but if they're any good I can upload them.

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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Sep 09, 2015 10:30 am

Derek wrote:They were taken on Christmas day with no trains running

Hi Derek,

If you want to get "out and about" to look at railway infrastructure, you can't beat Christmas Day. Image

Martin.
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Derek
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Re: How to use blade filing jig?

Postby Derek » Wed Sep 09, 2015 10:42 am

Martin Wynne wrote:
Derek wrote:They were taken on Christmas day with no trains running

Hi Derek,

If you want to get "out and about" to look at railway infrastructure, you can't beat Christmas Day. Image

Martin.


I will tell my 'friend' that.

As you so rightly noted before- it is about the only time you can take photos of track without someone going and parking a train in the way.

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jon price
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Observing trackwork for modelling purposes

Postby jon price » Wed Sep 09, 2015 11:37 am

I agree that looking at the real thing is obviously useful, though from the platform you don't often see much, and what you do see is often non-standard and modern, compared to 1906 practice. But yes it is the best way to understand track. As a result I now know that todays railway uses 30ft rail lengths, diagonal sleepers and a random selection of chairs on a strategic line. According to these photos I took this August anyway..
P8010264.JPG
P8010265.JPG
P8010266.JPG
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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Sep 09, 2015 1:03 pm

Hi Derek,

If you are having trouble filing blades, here's a Templot idea for a filing aid which might help.

For "B" blades, print a straight template for a strange-size turnout having a 12ft straight switch and 1:32 crossing angle. The turnout road will then be straight. You need to print only this part of it. Make it up on some scrap copper-clad with the stock rails only (blue rails). Make sure the set bend is accurate and correctly positioned by measuring the stock gauge at 2 in the diagram. There are no curved sections:

Image

The yellow rail is the blade being worked on. Mark it all over with waterproof felt-tip marker, so that you can see where you are filing. Make sure you have it the right way up (thick edge at the top). File the back of it, just going down to the web at the tip, and running out in a length of 29mm (29.33mm to be precise) at the end of the planing. Don't go far into the web, otherwise the blade will be too flexible at the tip, and it will be difficult to get a clear flangeway all along behind the open blade.

Clip it to the stock rail all along the planing (bent-up paper-clips are ideal), at 1 in the diagram. Adjust the filing until it sits nicely flush against the stock rail all along the planing, and the rails diverge at the end of the planing, at 2 in the diagram. At this stage the rail at 3 will be wrong (too close to the stock rail).

Remove it and make a small bend at the end of the planing (2 in the diagram), so that when clipped back in place, the rail at 3 is correctly aligned. You can check this using track gauges from the opposite stock rail. Repeat trial and error as necessary.

When you are happy with the fit, you can start filing the front of the bade. Getting this right is not as important as the back of it. Remove the bulk of the metal first, then for the final filing you could perhaps do it in place on the filing aid if you clamp the rail down at 3. To that end it would be good to make the filing aid on a piece of board which can be held vertically in the vice.

Use the file at an angle, with the safe edge at the bottom to leave the rail foot intact, and file until the the blade tip is a knife edge at the top, with the running edge dead straight all through the filing aid. The filed length is the same as for the back of the blade, running out to nothing at 2. Some more ink on the rail may help to see it.

Finally fettle it with abrasive paper to make a smooth top edge against the stock rail for the wheel flanges. This will cause the knife edge at the end to be reduced a little below the top of the stock rail in the prototype manner.

Image

That makes a left-hand point blade. Now print a right-hand version and repeat the whole process to make a right-hand blade. Image

For "A" blades make the template a 9ft straight switch and 1:24 crossing angle. The planing length is 22mm.

If you are careful these filing aids should be good for several blades. But cost next to nothing if you need to replace them.

More about planing lengths and the stock gauge here: http://www.templot.com/martweb/gs_realt ... lit_switch

regards,

Martin.
Last edited by Martin Wynne on Wed Dec 09, 2015 11:12 am, edited 2 times in total.
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Winander
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Re: How to use blade filing jig?

Postby Winander » Wed Sep 09, 2015 2:07 pm

Will L wrote: A 4 inch Vallorbe engineers file from Eileen's is ideal ....Same thing available from elsewhere (e.g. Shesto)


Having talked to Howard Bolton (JFS) at successive S4Norths, his engineers advice was always to use the biggest tool that will do the job. I think he uses a 14inch file. With a longer file you get better control; there is less inclination to introduce a see-saw motion.

Axminster have a better range of lengths (4, 6, 8, 10 inches) and the prices look good http://www.axminster.co.uk/vallorbe-swiss-hand-files.
Richard

Derek
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Re: How to use blade filing jig?

Postby Derek » Wed Sep 09, 2015 2:38 pm

Hello Martin, thanks for that. I have read a couple of tutorials that you have written in "the other place" and Templot forum. This is an even better idea and I shall try it at the weekend.

The match between blade and stock rail is already not too bad and it works, but I know I can get it looking better. It's going to be an interesting weekend...


Jon,
Re: your photos- is that one for the "prototype for everything" box?

I agree that you can't see too much from the platform, but if your local preserved siding has a non-running day, it's usually possible to get down on the track and have a look. If you have one of the larger heritage railways nearby there's often viewing areas where you can get up close.

Terry Bendall
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Re: How to use blade filing jig?

Postby Terry Bendall » Thu Sep 10, 2015 7:22 am

jon price wrote:As a result I now know that todays railway uses 30ft rail lengths, diagonal sleepers and a random selection of chairs on a strategic line.


This is often the case. For those who want to know more about track, especially flat bottom track a conversation with Colin Craig is useful as are his three articles about flat bottom track track that can be found on the web site of the Manchester Model Railway Society.

Jon's second picture of different types of rail fixing on adjacent sleepers is nothing new. When repairs have to be doe the track gang will use whatever they have with them. In this picture the track furthest from the camera has BR1 type rail fixings which can be replicated in 4mm scale using the components that Colin sells.

Terry Bendasll

Derek
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Re: How to use blade filing jig?

Postby Derek » Fri Sep 11, 2015 6:50 pm

Martin,

Thanks again for your tutorial. I have now made several blades that are straight and fit against the stock rail perfectly.

I did still use the Scalefour jig still, but I used your 9ft/1:24 Templot idea to make the stock rail with a far more accurate set than using the main template as a guide. Also, some better files did help.

Now that I have managed to make good, accurate crossings and now good, accurate blades, after Expo tomorrow (and a visit to relieve Eileens Emporium of some of its .5mm brass strip for soldering the crossing) I will see if I can stick both bits together.


Jon, I feel that I have hijacked the thread you started, but I hope you are gaining as much knowledge from these chaps as I am. Now to plot Clapham Junction in Templot...

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jon price
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Re: How to use blade filing jig?

Postby jon price » Fri Sep 11, 2015 10:27 pm

Derek
this has been a good discussion which has taken my understanding forwards. Exactly why I joined Scalefour in the first place so really this is excellent stuff. Thanks.
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Andy W
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Re: How to use blade filing jig?

Postby Andy W » Sun Sep 13, 2015 10:46 am

I've built locos, coaches, wagons etc in P4 for decades - but I only started building track recently. It was only then that I appreciated what the wheel and track standards were REALLY about. I'd always used P4 back-2-backs etc - but I hadn't fully appreciated (for example) that having less slop in the track work meant better running. The model track work then does what the prototype does - guide the wheel sets.

It sounds obvious I know, but a number of large pennies could be heard dropping into my empty cranium. As Homer Simpson would say - "DOH"!
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Re: How to use blade filing jig?

Postby Derek » Sun Sep 13, 2015 3:25 pm

Andy,

That happens to me every time I come on here, Templot forum, or the track building sub-forum of the 'other place'.

If I saved every penny that dropped I'd be able to pay someone to build this for me.

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Re: How to use blade filing jig?

Postby Julian Roberts » Wed Nov 04, 2015 12:12 am

I am new to this, though in a previous 00 existence have made three points. I am embarking on a B8, and seek advice on making undercut pattern switch blades. I have failed to find anywhere more information on the undercut bit of the planing. I refer to Martin Wynne's post above on Sept 9: how long is the undercut? - and how low does the undercut go below the head of the rail? Ideally a side view sketch of the desired shape is what I need... and, referring to photo he has put on the Templot Club (1/1/2011) of the actual points on the Severn Valley Railway (one staightcut and one undercut planing) - does the very end of the undercut planing pattern blade correspond to the very end on the diagram here? As he observes, it is some distance till the rail shows wear from bearing the weight of the wheel.

Jumping ahead, even if I get the gauge right at the switch I am anticipating derailment problems on the diverging road unless I get the filing as good as possible - or resort to a joggle. However speed is going to be low - this point will be in some sidings. I don't know if this is correct to say, but are not the undercut pattern switches with a set rather than a joggle more common than staighcut with joggle?

Maybe anyone could refer me to where this is covered if I have missed it? Thanks if anyone can help...

BTW this is for a layout depicting a location in Scotland.

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Re: How to use blade filing jig?

Postby Derek » Wed Nov 04, 2015 3:52 am

Hello Julian

You are in the same position I was until fairly recently. I would firstly recommend reading Scalefour News 194

http://www.scalefour.org/members/newsar ... ews194.pdf

In it you will find a good explanation from Howard Bolton (who goes by the forum name 'JFS') on how to make switch blades. He uses a home made jig, although you can buy jigs from the society's stores.

As well as getting the blade right, you will need to learn about the set; Martin Wynne has a couple of very useful comments earlier in this thread on how to design a guide/jig for gauging the set. Also he has a useful idea for quickly and easily putting the set into the stock rail.

http://85a.co.uk/forum/view_postx.php?post_id=8209

From a side profile (and this is for pre 1925 NER switch blades, the top of the rail is shaved down by 3/4 of an inch over 3ft (so .25mm over 12mm length.) It does have a second taper on it, but that is such a small amount you would never see it in model form.

My understanding is that you are correct that joggled turnouts are in the minority, primarily found on GWR areas, though I understand these did also turn up elsewhere, but not in great numbers (that's my understanding- you'd be better waiting until someone more knowledgeable appears to be certain).

There's more about it here http://www.templot.com/martweb/gs_realtrack.htm

I hope that helps.
Derek

Julian Roberts
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Re: How to use blade filing jig?

Postby Julian Roberts » Wed Nov 04, 2015 10:58 am

Thanks very much Derek. Somehow I had been unable to find Howard's very good article though I remembered it having been recently in the Snooze, so thanks for that link. Yes I had seen these things by Martin Wynne and was referring to the first of them (I just have not yet got the hang of how to put the link in here) - thanks. I have done an extensive trawl through a lot of material these last few days (I have some leisure time while working away from home so have opportunity for internet researching - i.e. hotel and railway journey armchair modelling). So I understand about the set in the stock rail and related issues.

You have answered my query however: the .25mm over 12mm information was exactly what I was seeking. (But how did you get that information?!) So I assume that over the 12mm the rail head gradually tapers down so that at the end it is .25mm lower? Obviously miniscule but if so that tells me what I should aim to be doing with the fine wet and dry paper in the finishing off stage.

So am I right to suppose that over this 12mm the knife edge is gradually wedging or knifing its way up the top half of the flange of a wheel travelling over it (supposing for argument's sake the (0.4mm deep) flange is already hard against the rail) at the same time as redirecting its travel...so it needs to be quite finely finished off...? Howard talks about restoring the gauge corner radius, polishing the head of the rail so that it follows the gauge corner radius of the stock rail (Step 3) though he is not mentioning about this undercut business.

I foresee no problem with the straight ahead road, but the diverging road has got to persuade the wheel to take the diverging direction. 12mm in to the switch before the rail is at full height...hummh - is that going to work? Just wondering if people like you and Howard actually do this undercut, whether it actually helps the running of the model, particularly as it is pretty much invisible so possibly not worth it from the visual fidelity point of view...?

Obviously I will find out for myself, hopefully when back at home this weekend. I have already spent two hours making one switch blade without a jig just filing by eye last weekend (just to prove I don't only do armchair modelling!) I am only charged with making one turnout though obviously will buy or borrow or make a jig for further efforts.

Many thanks for your quick reply!
Julian

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Re: How to use blade filing jig?

Postby grovenor-2685 » Wed Nov 04, 2015 11:30 am

I'm pretty sure, without looking up my references that undercut switches are only used on FB rail. Either way it would be very difficult to do them in a 4mm model. Firstly the web on the model rail is proportionally much thicker than the prototype leaving little room for the switch to fit and secondly undercut switches need the stockrail head to be planed on the underside which would be a difficult task. I suggest you forget undercut switches and stick to the simple designs. There is no need of a joggle for them to work reliably.
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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Nov 04, 2015 11:49 am

grovenor-2685 wrote:I'm pretty sure, without looking up my references that undercut switches are only used on FB rail. Either way it would be very difficult to do them in a 4mm model. Firstly the web on the model rail is proportionally much thicker than the prototype leaving little room for the switch to fit and secondly undercut switches need the stockrail head to be planed on the underside which would be a difficult task.

Hi Keith,

Undercut switches were quite common on bullhead, here's one:

Image

undercut_closed.jpg
undercut_closed.jpg (23.63 KiB) Viewed 5282 times

They don't require any machining of the stock rail -- you are thinking of chamfered switches, which do, but are only on flat-bottom as far as I know.

I agree that attempting to model such designs would be tricky, and impossible to do to scale because of the overscale web thickness in model rail. A simple planing to a knife edge at the tip works just fine and is not difficult to do:

Image

regards,

Martin.
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grovenor-2685
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Re: How to use blade filing jig?

Postby grovenor-2685 » Wed Nov 04, 2015 4:28 pm

They don't require any machining of the stock rail -- you are thinking of chamfered switches, which do, but are only on flat-bottom as far as I know.

I agree that attempting to model such designs would be tricky, and impossible to do to scale because of the overscale web thickness in model rail. A simple planing to a knife edge at the tip works just fine and is not difficult to do:

Yes I was thinking of chamfered switches, not sure why as I had seen the diagram of overiding FB versions in Andrew Dow's tome just the other day.
Anyway here' a more comprehensive diagram from the Grant Lyon Eagre catalogue.
gle-1.gif

Andrew Dow had just used the top row from it.
The diagram of the bullhead undercut switch shows rather more planed off the head than your photo but I suspect that is a drawing issue, the photo is how I remember them.
And your diagram showing how to file a straight cut switch tip is exactly how I do them, and they work fine without needing a joggle.
Regards

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Re: How to use blade filing jig?

Postby Derek » Wed Nov 04, 2015 4:40 pm

Hello Julian

Glad to help. As a beginner, I found the biggest problem is that there is a huge amount of information available and often unless you partly know the answer you can't easily ask the question- certainly in search engines.

I have found another document this morning which contradicts the one yesterday (both NER but presumably from a different era) and this suggests that the vertical taper is variable dependant upon switch length and it appears that the vertical taper finishes just shy of the lateral taper.

The information comes from the NER Association's book on 1926 track standards- these are photocopies of the original engineering drawings used (link below). This particular booklet was about £4, so well worth it (I have their main selection of 'standards' booklets now and they are very informative)

https://sites.google.com/site/northeasternrailwayassoc/

There is an equivelant book for those interested in GWR track. Martin Wynne gave me the link for its title and where I could buy it, but I'm damned if I can find it right now. I believe there are also other titles for the main railways, but these seem to be less well publicised (there certainly is for the LNWR and LSWR).

I may well be wrong on this, so don't take it as gospel, but dependant upon the era, Scottish railways were very closely related to NER designs pre-grouping and post grouping of course much of it came under the control of the LNER anyway.

I can definitely recommend the NERA titles; when you have the actual engineering drawings in front of you, the comments from esteemed chaps such as Martin and Keith do make more sense.

Hope that helps.
Derek

EDIT: Also can I recommend looking at the "00sf" or "4sf" threads on RMW. Although if you are here presumably you are working to P4, there is a lot of talk about rail/wheel interaction, coning angles and so on. It is WELL worth reading, although you will have to filter out a lot of rubbish and nonsense in the process. By following advice from people such as Martin, Hayfield, AndyID etc I went from turnouts that would knock on the crossing to turnouts where I couldn't feel the crossing vee whatsoever.

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Re: How to use blade filing jig?

Postby Derek » Wed Nov 04, 2015 4:50 pm

Martin/ Keithh

RE: Undercut switches

I have seen this confusion between chamfered and undercut switch blades being repeated many times on the internet.

Can I clarify this is correct:
UNDERCUT blades have a vertical, as well as lateral planing in order to bring the blade tip below the height of the stock rail in order that they do not take any axle load until they are sufficiently thick to do so.

STRAIGHT CUT blades have NO vertical planing at all as they are thicker at the end and thus able to take some axle load.

I have seen all sorts of curious explanations of the difference, but the above is the only one that matches with photos and comments that you have both made.

I am going to guess that there's some mathematical formula for the length of the vertical planing and the way it will guide the coned wheel treads when the wheel is reaching the end of the vertical chamfer. I think I will leave that bit alone.

Derek

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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Nov 04, 2015 4:51 pm

Derek wrote:There is an equivalent book for those interested in GWR track. Martin Wynne gave me the link for its title and where I could buy it, but I'm damned if I can find it right now.

Image

From: http://gwsg.org.uk/GWSG_Publications.html

Essential reading for anyone interested in modelling bullhead track, even if not GWR or not 4mm scale.
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Derek
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Re: How to use blade filing jig?

Postby Derek » Wed Nov 04, 2015 5:02 pm

Thanks Martin

I shall order this now before I lose the link again.

I have seen a few extracts from it and its detailed notation, together with the pretty NER pictures with "compressed" notation should be an interesting weekend's reading.

Derek

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Martin Wynne
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Re: How to use blade filing jig?

Postby Martin Wynne » Wed Nov 04, 2015 5:21 pm

Derek wrote:Can I clarify this is correct:
UNDERCUT blades have a vertical, as well as lateral planing in order to bring the blade tip below the height of the stock rail in order that they do not take any axle load until they are sufficiently thick to do so.
STRAIGHT CUT blades have NO vertical planing at all as they are thicker at the end and thus able to take some axle load.

Hi Derek,

Everything varies with different companies and periods. That is one reason why the REA designs were created immediately after grouping to bring some sort of standardisation to the party. It didn't entirely work, the GWR ignored the whole thing, and other companies at first picked and chose which bits to adopt.

Rather than type it all out, here is a scan from BRT3 of 1964. It's copyright to the Permanent Way Institution but I'm sure they won't mind for our educational purposes. Image

Image

Martin.
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