Track and Turnouts

[johnmand]

Track Gauge Narrowing

Has anyone else experienced the narrowing of the gauge of C&L steel Flexitrack some time after laying? In two instances investigation of derailments of one or two items of stock (admittedly with B-B on the lowest allowable) on straight track has shown that the gauge of the track laid on cork in one case and on Exactoscale foam in another with dilute PVA adhesive has narrowed by a few thou for about 12 inches in a 1 metre length, but nowhere else. The gauge was not checked when first laid (why would it be?)

I seem to remember this phenomenon being discussed I think on P4_Talk obout two years ago and the writer stating he had solved the problem by applying a hammer and blunt chisel to the centre of the plastic sleepers involved!! I don't remember any follow-up of this or of any explanation of how the narrowing occurred. Is there now a known reason for the prob, is there a less drastic way of regaining gauge, or has the prob disappeared?

Regards, John Anderson

[grovenor-2685]

Much of my C&L flexi measures around 18.75, its OK only on straight track. All my curves have reverted to ply and rivet but I don't currently have any problems with the C&L on straight sections. Interestingly a piece I have on the workbench that has never been laid measures 18.82
Regards
Keith

[Russ Elliott]

I've detected gauge narrowing on plastic flexi on Somersham. The track affected is ancient (K&L) flexi. The track is almost straight (or very gently curved), and was laid with thin PVA. There is no sign of curling timbers. The affected TG is approximately 0.15mm (and possibly slightly greater) undergauge. I do not know how accurate the TG was before laying.

I suspect that slightly different formulations of the plastic, how much its plasticisers evaporate over the years, and the tool ejection temperature, will all play their part in any gauge narrowing, in either the short or long term. Use of solvent glue, e.g. Evostick, to stick track to trackbed is also likely to exacerbate the dimensional stability of the plastic.

I can just about live with 0.15mm undergauge with wheelsets at 17.8mm BB, but it does mean the tyre roots are uncomfortably tight to the railhead corner.

I've not noticed any short or long term gauge narrowing of ply timbers laid in the same way on the same (cork) trackbed, and will be rather cautious in the future in using plastic flexi - certainly I would check its TG at time of purchase.

In the days of Ratio trackbase (notoriously undergauge even when new), Dave Lowery took a powerful soldering iron and passed it over and close to the tops of the sleepers, to widen the TG. I guess it would work only on unlaid flexi.

The experts on C+L flexi are the Slattocks gang. Here's (snapped by Tony Williams, I believe) how they overcame their problems:

[LesGros]

Much of my C&L flexi measures around 18.75, its OK only on straight track. All my curves have reverted to ply and rivet but I don't currently have any problems with the C&L on straight sections...

I am thinking of using C&L flexitrack to save time building the layout I have in mind, which will have sweeping curves and bends down to about 1.1metre radius. I am somewhat concerned about the gauge narrowing mentioned earlier.

What is the concensus about the limitations of C&L flexi ? eg, what is the minimum practical radius before narrowing creates a problem?

regards

[John Bateson]

Les,
The minimum practical radius depends on the wheelbase and the ability of the wheels to move sideways in their exleboxes. If there is little or no sideplay then the radius must be larger. This is an exercise in 3 variables (wheelbase - radius and sideplay) for a courageous soul to create a Digest.
It also depends on the distance between wheels, a 9F may go around a bend where an LNER F6 2-4-2 will not.
I think the common recommendation is
a) phone a friend - find somebody who has the same engines as you propose to use
b) add gauge widening commensurate with decreasing radius anyway - I use the Exactoscale guages which can gibe 10', 20' and 30', on a few curves below 1000mm I use 30' and 20' or 10' on radii between 1000 and 1500mm
c) experiment

I have reservations about the C&L track which I think tightens up on the gauge when used in a curve - so I now don't use it, I actually glue Exactoscale chairs to ply sleepers, very boring but quite therapeutic at times.

John

[grovenor-2685]

What is the concensus about the limitations of C&L flexi ? eg, what is the minimum practical radius before narrowing creates a problem?

One thing we are pretty short of on here is concensus . You already got my view, straight. You might get away with curves in the 4m plus radius range, 1.1 m, no way.

If I was starting again i would use Fasttrack rather than C&L, the problem then is that any sections using ply and rivet will need packing up. If you are going to use P4track Co. kits or C&L thick timbers you are OK.
Regards
Keith

[LesGros]

Thanks John and Keith,
I begin to see a little more light over the potential minefield. It occurs to me that using Society ply sleepers doubled could perhaps allow mixing rivet/ply contruction and plastic chair with Exacto 1.6 ply sleepers in a pane. This perhaps being a method to retain the flexibility of the use of rivets whilst avoiding awkward packing problems.
Has anyone tried to do it this way, and if so, how successfully? I ask because at this point, I have only Society sleepers and rivets and some plastic chairs to play with, and It is not too late to change course and use thicker sleepers for the new layout.

regards,

[Russ Elliott]

Agree with John and agree very strongly with Keith. If you do insist on using C&L flexi, check its TG isn't already undergauge even when straight from the packet.

I see no virtue in mixing different timber technologies within track panels, except perhaps near baseboard joints.

Thin-ply timber doubling is fun, for underballasted switch and crossing areas, but needs to be planned thoroughly.

Matching the rail heights between adjacent timber technologies is a precision process.

[Andy C]

Many moons ago I was building P4 pointwork using C&L for a Rochdale MRG club layout, Brewery Lane Sidings. The points were laid tp gauge - and I was pretty meticulous about it as well, but on returning to the layout on the next club night they were in places narrow to gauge.

In the end we put it down to tension in the curved stock rail, despite pre bending it, pinning and weighting the rail, which whilst the butanone was still curing just pushed it slightly under gauge. Thankfully the P4 track co pips on the sleepers seem to have cured the problem, but to be honest i wouldnt touch a C and L point components ever again as a complete item.

[jim s-w]

Hi All

We too had gauge narrowing with C&L many moons ago (on squishy track bed). However this was pre Brain and he did tell me that his predeccesor used all sorts of stuff in his plastics. I dont have any experience of newer C&L but i would say be wary of experiences from long ago as the product is different now (or at least I am told that)

Cheers

Jim