Filing Bullhead Rail turnout V's, switch rails and Carbon Rod tie-bars

[Collett]

Always wary of posting to these forums as I don't want to teach Gran'ma how to suck eggs, but here's a couple of things I learnt recently, plus a really interesting material I'm looking into.
 
I've always been confused and confounded by the standard EMGS/Scalefour instructions about how to file V rails for turnouts from Bullhead rail.  First file down one side of the rail to the desired angle/ratio, then bend the angled section back to the straight line so the web is bent, and then file across the whole width of the rail to the required angle.
 
My problem has always been that bending the angled section seems to go every which way, and trying to bend it back ends up in a distorted mess.  However, as an experiment I tried to modify the order and have had success with it.

• Bend the rail to the desired angle
• Cut the bent section with a razor saw so it's approximately in line with the rest of the rail - CAREFUL, this leaves very jagged tongs of metal from the rail head and foot
• File back the jagged ends and finish the cut straight with the rail length
• This effectively gets you to point 'b' on the diagram, filing then proceeds as before

 

Bending the rail before filing makes it easier to handle and get the desired set on the rail.

 

Again, filing the switch rails in the "approved" manner requires the rail foot to be retained when 'planing' away the inside of the switch rail, then bending the rail before filing the back of the switch rail.  This has been frustrating mainly because I have never been able to find small flat files with a "blind" edge that would avoid the rail foot.  Some while ago I bought one of those four sided diamond sharpening blocks for sharpening chisels and kitchen knives and yes, with a little bit of brute force and ignorance, it has been possible to removed the cutting edge from one side of a flat file with no notable ill effects to either file or sharpening block.  This modified file now allows me to plane down the rail head and web without damaging the rail foot.

 

Now having my V and switch rails sorted, I was looking at ways to improve on the tie-bars and stretchers between switch rails.  The turnouts under construction are the SMP plastic base kits, 3' radius with a 1:5 V.  I have seen some interesting results from copper clad fibre-glass used vertically, but I'm presently investigating the use of carbon rods and tubes as used by the model aircraft fraternity. 

 

These are very impressive materials.  I purchased a sample of four lengths (1m each) of 0.28mm rod (4mm/ft = 8/10"), 0.5mm rod (4mm/ft = 1.5"), 0.7mm tube (4mm/ft = 2") with 0.3mm I/D and 1mm tube with 0.5mm I/D.  The supplier is easycomposites.co.uk.  The 0.3mm rod is flexible, but the 0.5mm rod is surprisingly rigid under compression, the 0.7mm and 1mm tubes are also very strong under compression but they do have a tendency to split lengthways if pushed against a sharp object.

My intention is to use the rod and or tube as tie-bars between the switch rails.  I'm still working on connection methods, drilling the tie-bars and reinforcing the join with a short length of brass tube seems favourite at the moment but I will update with some photos when available.

[micknich2003]

I have never had a problem fileing Switch Rails etc. I look forward to hearing more of your "Carbon Rod" stretchers, though, I see a problem in fixing them to the switch rails.

[Flying Pig]

easycomposites say their carbon rods are electrically conductive: http://www.talkcomposites.com/1845/Carbon-Fibre-Rod-Electrical-properties. Isn't that going to be a problem when using them as stretchers?

[Collett]

It seems it depends on whether the carbon is in contact with the switch rail or the resin.  Good point though, I made some searches and kept getting a "no it doesn't" response.  Potentially if the rod or tube interface is set with a suitable Araldite insulation then it might negate the problem.  Will have to experiment. 

[Collett]

Work in progress on the SMP point - First experiments with the carbon rod tie-bar - insulated.  A bit of a fiddle but very strong and I like the look in preference to the moving sleeper - needs some black insulation though.  Early tests show that a fairly 'course' 4mm wheel rim isn't fouling on the insulation.  It ain't perfect but it's progress.