Graphite Treatment to Rails.

[kevinlms]

5 hours ago, polybear said:

 

C&L have already done this - it's their "HiNi" range of NS rail, that looks a lot more like steel than ordinary NS does.

Yes I knew someone did it, but it's not exactly mainstream.The reality is not everyone is concerned about the 'vivid yellow' colour, as described. Just the same way that OO or even EM is extinct, or Set Track too for that matter.

[Nicktoix]

Quote from a popular science website

 

"Graphite is an interesting material, an allotrope of carbon (as is diamond). It displays properties of both metals, and nonmetals. However, like a metal, graphite is a very good conductor of electricity due to the mobility of the electrons in its outer valence shells."

 

Pencils very rarely contain much graphite these days except for the more expensive artists types.

Nick

[Pacific231G]

I'm afraid that all this is reminding me of the (probably fictional) French official who was heard to say "Yes monsieur, that's may be all very well in practice but it could never work in theory". It also reminds me of some of the advanced maths in 1950s  Model Railway Constructors relating to everything from laying out transition curves to avoiding buffer locking- both important but taken to an absurd level of theoretical mathematical perfection.   

[The Johnster]

On 08/09/2020 at 19:40, Pacific231G said:

taken to an absurd level of theoretical mathematical perfection.   

Like P4 you mean?

 

Coat?

[Pacific231G]

15 hours ago, The Johnster said:

On 08/09/2020 at 19:40, Pacific231G said:

taken to an absurd level of theoretical mathematical perfection.   

Like P4 you mean?

 

Coat?

I couldn't possibly comment but to be fair I don't think even the most avid P4 modellers use interferometers to check their track gauge and 18.83mm is simply what you get (to two decimal places) when you divide 1435mm by 76.2. If they'd been satisfied with defining it as 18.8mm they'd have been accurate to within about a thousandth of an inch- perhaps some people really do model to finer tolerances than that!   

it's always amused me when 16.5mm gauge is described as "close to scale" in H0 (1:87). If you multiply 16.5 x 87 you get 1435.5mm. Since SG (without gauge widening) is 1435mm and UK gauge tolerances for lines with trains running at 100MPH plus is I believe 6mm (The PW experts here probably know the exact tolerances) then trying to be more accurate than the prototype would be absurd.

 

Edited September 10, 2020 by Pacific231G
phraseology

[The Johnster]

It's a similar story with driving wheel diameters; the nominal value (Black 5, 6 feet for example) is correct for the loco in ex-works condition with new tyres shrunk on to the wheel.  The loco may run 100k miles or more before it's next overhaul, and the wheel diameter when it returns to works might be over 2 inches less than the nominal, around 5'9".  This makes a difference, increasing T.E. but knocking perhaps 10mph off the loco's top speed, increasing water consumption over a given distance,

 

At Canton, the Britannias were arranged in a pecking order according to mileage since last works visit.  The higher mileage locos were kept for 'down line' work to Swansea or beyond, where their worn tyres were an advantage on the banks and where there are more stops, so water was less of an issue.  You'd also see them on North to West route expresses for the same reason; locos fresh out of works were kept for the Paddingtons, better for Mr Brunel's billiard table which was much of the route, and the part where you let the speed rise to regain time lost on the climb from Severn Tunnel bottom to Badminton.

 

There is therefore little point in worrying too much about driving wheel diameter on models, and 'close enough for jazz' is fine so long as it is under, not over, the nominal value.  I would be more concerned about the correct number and form of spokes than losing any sleep over spot on correct diameters, and if building a loco with splashers and having trouble with the wheels fouling or shorting out on them would have no hesitation in going down a mm in size and weathering the loco to look as though it's done a few miles since the last works visit!  Since the track gauge is too small, smaller driving wheels will help the loco look more proportionally correct as well, though this will be a very minor effect.

[Barry O]

2 hours ago, The Johnster said:

It's a similar story with driving wheel diameters; the nominal value (Black 5, 6 feet for example) is correct for the loco in ex-works condition with new tyres shrunk on to the wheel.  The loco may run 100k miles or more before it's next overhaul, and the wheel diameter when it returns to works might be over 2 inches less than the nominal, around 5'9".  This makes a difference, increasing T.E. but knocking perhaps 10mph off the loco's top speed, increasing water consumption over a given distance,

 

At Canton, the Britannias were arranged in a pecking order according to mileage since last works visit.  The higher mileage locos were kept for 'down line' work to Swansea or beyond, where their worn tyres were an advantage on the banks and where there are more stops, so water was less of an issue.  You'd also see them on North to West route expresses for the same reason; locos fresh out of works were kept for the Paddingtons, better for Mr Brunel's billiard table which was much of the route, and the part where you let the speed rise to regain time lost on the climb from Severn Tunnel bottom to Badminton.

 

There is therefore little point in worrying too much about driving wheel diameter on models, and 'close enough for jazz' is fine so long as it is under, not over, the nominal value.  I would be more concerned about the correct number and form of spokes than losing any sleep over spot on correct diameters, and if building a loco with splashers and having trouble with the wheels fouling or shorting out on them would have no hesitation in going down a mm in size and weathering the loco to look as though it's done a few miles since the last works visit!  Since the track gauge is too small, smaller driving wheels will help the loco look more proportionally correct as well, though this will be a very minor effect.

 

did they use Graphite on the trak as well then?

 

Baz

[Oldddudders]

31 minutes ago, Barry O said:

did they use Graphite on the trak as well then?

Oddly enough, yes. Very early in my career I was told a story of a chap out with a PW gang, and he watched incredulously as the Inspector wrote in pencil on the conductor rail. Plenty of graphite in pencil lead in them thar days! The story said that he asked if he could do that, and then pulled out a little stump of a pencil (think old Argos pencils but shorter) and was a bit nonplussed when he got bitten, having had part of his hand touching the 'lead'!

[Pacific231G]

15 hours ago, Barry O said:

 

did they use Graphite on the trak as well then?

 

Baz

I imagine the carbon content of steel rails and wheels may supply that automatically . Actually it's a not uninteresting question. Railways seem to have had endless problems with lightweight railcars not making sufficiently good contact* with the rail to operate track circuits safely so I guess it's not a problem confined to us. I don't know whether that's ever been a problem with lightweight electric railcars or trams that rely on the rails for their electrical return path but presumably the far higher voltage used for traction has fewer problems finding its way back through the rails than 50V track circuits.

ISTR a case in France not that long ago where some new diesel units that could operate singly or in MU were supposed to be economical enough when run singly to provide services on lightly used lines. Unforutnately they had a bad habit of "disappearing" from track circuiting so had to be MUd in pairs. The catch was that they were then no longer so economic and the services ended up being bustituted.  

 

*Would tiny amounts of rust on steel or just general crud not being broken up by lighter wheel loadings be the factor here?

 

Edited September 11, 2020 by Pacific231G
to add the footnoted question

[Oldddudders]

4 minutes ago, Pacific231G said:

Unfortunately they had a bad habit of "disappearing" from track circuiting 

Seeing a t/c go clear when you know it isn't is a bit disqueiting. Yes, I have watched it. 

[Sir TophamHatt]

I used more than recommended on my layout.

The locos that stuttered a lite at points, there was no stuttering after application.

 

I need to test more over a year or so but I'm happy graphite here and there, helps more than hinders.

[Pacific231G]

13 hours ago, Sir TophamHatt said:

I used more than recommended on my layout.

The locos that stuttered a lite at points, there was no stuttering after application.

 

I need to test more over a year or so but I'm happy graphite here and there, helps more than hinders.

This is definitely a case where experimental evidence is far more important than any theory.

The arguments about carbon's relatively low conductivity compared with relevant metals are a red herring as we're looking at a very thin carbon layer (possibly even graphene?) or more likely just filling pitting and scratches that would otherwise be occupied by air.

[Michael Hodgson]

15 hours ago, Pacific231G said:

I imagine the carbon content of steel rails and wheels may supply that automatically . Actually it's a not uninteresting question. Railways seem to have had endless problems with lightweight railcars not making sufficiently good contact* with the rail to operate track circuits safely so I guess it's not a problem confined to us. 

 

 

 

I don't think this one made good contact with track circuits.  An early prototype for rubber traction tyres. 

 

[Matt C]

I use one of these ( borrowed from SWMBO's art supplies.)

 

https://www.jacksonsart.com/caran-d-ache-grafcube-graphite-stick-15mm-9b?channable=0044a569640031313036333835&___store=jacksonsart_en&gclid=CjwKCAjwiOv7BRBREiwAXHbv3ADg_9hNk4rco2B5KnReO8blzcGPyL6TcDrkFsrD3ZHYe0yfIdPUwhoCP4oQAvD_BwE

 

Its a solid 15 mm block of artists high grade graphite. Started using it on 3 lines through a long tunnel which constantly needed cleaning, involving some dismantling of scenery to get too,  since using it the cleaning has gone from often to ' when did I last do it ???' the block has been going for well over a year ( now over the full layout) and ive not even made a dent in it. General performance much improved. Never mind the science, it just works

[Tankerman]

Some of this discussion reminds me of a saying of one of the older electricians, he had spent 22 years in the RN, including WWII and the rest in the dockyard, when I started my apprenticeship at 16 years old. "In theory, practice and theory are the same thing, in practice they are very different."