Code 75 fishplates - Curve issues.

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Hi everyone.
I'm in the process of building my first layout and I'm at the track laying stage.
I'm using code 75 streamline (peco) and I'm having difficulty with curves and flex track.

When I get to a curve, I start by making sure the previous two rails are equal (one not sticking out further than the other)I add the code 75 fishplates/joiners and join the next length of flexi track. All good so far but for example, if 30cm down the new stretch I need to start a curve, immediately one rail (depending on left or right curve) pops out of the fishplate where I joined the track.
I understand why it does this but the fishplates although all new, don't seem to hold the track firmly in place like the set track code 100's do that I use for the fiddle yard (those fishplates always seem quite stiff) and as soon as I start the curve a little sown the track, one rail easily slides out.
The first few lengths I've done I ended up soldering the rails to the fishplate but this is awkward and not ideal.
I've watched loads of videos and seen ones where the join is in the curve and rails are staggered by a good 15cm or so, some videos as mentioned where they solder the track to each side of the fishplate etc but I must surely be doing something wrong. Is there a step I'm missing?
If fishplates/joiners are loose, a I supposed to clamp the with pliars to hold the rail better? Going to rob a pair from work tomorrow to try it anyway lol!

As said, this is my first layout - I assumed with flex, the track would be anchored at the join by fishplates/joiners to the previously laid length and if I added a curve somewhere into the new length, it would reflect at the end of the the new length where I would then have to cut off the pretruding rail (making it equal with the other rail before adding the next length and repeat!
Any help appreciated!
Mike

One day I'll settle on a trackplan….
but likelihood is it won't be today!
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Hello Mike.  You shouldn't need to crimp the fishplate. All you need to do is hold the rail (which is due to pop out) near the fishplate with your pliers before you start to curve the track.  This should prevent it from sliding out. However, if either or both rails do move a bit, simply grab each rail in turn with your pliers and slide them back into position.  The rails in flexi track can be slid along in the chairs.
Terry

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Just as Terry said Mike, works a treat every time.

I also like to temporarily pin the track to the baseboard at this stage to keep things in place as the track goes down.

Good luck and have fun.

Bill

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And you don't have to make the rail joins even. When I do a curve, I join the tracks together in a straight line & solder the fishplates, then bend - of course, I remove some sleepers & fit them back later by sliding under the rails.

Ron
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Hi Mike,

Ah, the joys of flextrack.

One of the issues when curving track is that the ends want to stay straight. Ron's suggestion of staggered spacing works well as long as the rails can be moved along the sleepers. Works best if you stagger the joints by a third or half the length of the flextrack (minimum 10 sleepers). No issues for me in HO as common practice was to stagger the rail joints anyway. EM is a bit different, there I use GWR rail lengths and PCB ties either side the joints.

Some suggestions (that I have used in the past):

1. Spray the track with primer (rattle can red or grey). It fills in the gaps between rail and sleeper, when curved it stays curved. PITA to work with though.

2. Curve the joiner, You need to make some cuts on the inside radius (the side and about 1/3-1/2 of the foot). Best way to do this is to slide the joiner onto some scrap rail, clamp in place, and use a needle saw/small triangular file (or the Dremel with a thin cutoff disc, much faster). Bend the rail to the desired radius, slide off the joiner, and use. Solder in place just to make sure (and fill in the gaps).

3. Bend to desired radius, anchor in place using some push pins (who am I kidding, use lots!), remove 2 ties about 3 inches from the end, replace with soldered PCB ties, Cut-off the end.

4. Use one of the commercial curved templates that hold the track in place, and use track pins as well as glue.

5. Really drastic approach - go hand built. That way you curve the rail, then fit the sleepers. Fiddly, as the chairs need to be slid on the rails for UK track. OK for a short length of track, if you have yards of it then fuhgeddaboudit.

6. Potentially even more drastic - use large radii for the curves (3-4 feet). Trying to curve flextrack to fit 18"-24" radii can be …trying.

7. Throw in the towel, cry "Uncle" and use Setrack (Peco 100 with code 75-100 transitions at the ends).

My current method for HO and EM - splice and stagger the joints and use PCB ties to anchor the rail every 10 or so ties. Belt and braces approach. And no joiners (metal or plastic). The prototype didn't use them except on changes in rail code. Latest project is an HOn3 cameo, short enough to justify 100% hand-built track. And it has prototypical scale 20"-27" radii curves. If it gets longer then some flextrack will be used on the straight bits, available weathered (and stiff as a board).

Nigel





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Mike

The tightest radius on my layout is 24 inches (storage approaches shown above) and I have no problems with Code 75 using most of the methods listed by the guys - Traksetta gauges and pins every 4 inches or so.  At this radius, I try to lay one piece of track.

Bear in mind though that 24 inch radius curves give you 2 x pi x radius as the circumference of a circle = 2 x 3.14 x 24 = 151 inches approx or 38 inches nearly for a 90 degree curve.  This implies that, at 24 inch radius, any 90 degree curve will require a join.  Going down to 21 inch radius means you can do a 90 degree curve in one piece (36 inch) of track but, visually, that may not be a compromise you want in a scenic area. 

Outside of storage, I try to keep curves at 48 inches or larger - the greater the radius, the less tendency there is for the ends to spring and the joiners to fail.

Barry

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  • Pliers holding the track near the join while you curve the new section but be sure to use flat blade ones, fine track is fragile.
  • Moving to larger radii when you possibly can;
    That was my solution for all my visible sections but then for hidden sections there is a case to be made for as tight as will work
Pinning track is a great way to go when precise shape / appearance are less critical. It's occurred to me that a simple screw on jig spanning both sides of the rail join will keep that section aligned while you start the curve a little further along the new section. It will still be necessary to hold the outside rail while bending.

Once you have a decent section fixed in place the jig can be removed and the join will equilibrate with the newly installed section's curve. It could be made from 3mm MDF maybe 40mm long in the track direction




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I don't often pipe up these days but I've found that a 2 inch piece of hardboard screwed down through clearance holes across the end of the straight you are *curving* from helps, and allows you to tap back a recalcitrant length of rail without  moving your  previously  laid track.
Doug

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[user=1632]BCDR[/user] wrote:
Hi Mike,

 And no joiners (metal or plastic). The prototype didn't use them except on changes in rail code. .

Nigel.
Sorry Nigel, can't agree with you there.  If you mean fishplates, every piece of British track was joined to its neighbours with fishplates. I don't know what the current situation is with continuously welded rail.

Terry
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My experience suggests the curve radius is important.

If the curve is tight, then "kinks" can often occur at rail joins and yes indeed, they are the very devil to sort out.

If you do have to use tight curves (make sure all your stock is able to negotiate the tightest curve first !), then I tend to use a fresh bit of track for the whole of the curve - if possible !  Naturally, if your tight curve is longer than a metre, you can't do that but that would make it a pretty long curve !

Normally, when I'm introducing a curve into a length of trqack, I start at the fishplates and tack 2 or 3 sleepers down then, holding the rails firmly with my fingers - or pliers - I work away from the join leaving the rails to slide in or out of the "free" end of the track.  The inner rail will slide out whilst the outer will slide in.  As long as you ensure the rails are kept well in the fishplate, you should have no problem.

A word of caution - in Cyprus, I suspect you may have to allow for rail expansion so will need to either use a purpose made "expansion section" or leave slight gaps between rail ends within the fishplates.

'Petermac
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Hi Terry,

Quite right, and I use brass etched ones in my 4mm modeling. Not quite the same thing as the rail joiners used in model railways, which are not amenable to curving. Fish plates are joint bars here (which is probably a better description).

Continuous welded rail - different system to allow for expansion. Termed ribbon rail over here.

Nigel

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How do they allow for expansion on welded rail ?

'Petermac
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Hi Mike,

Slightly divergent from your question but it relates to joining rails. The issue with track  templates (commercial or DIY is that the curvature is usually uniform  (I have yet to see a commercial curved template with easements/transitions at the  end). Transition curves are what we should be  aiming for if we want  really smooth running, especially with tangent (straight) track entering  or leaving curves with tight radii. It should be possible to make a template in wood or plastic that has a transition curve, but I suspect that unless you have standardized curves you would be making a lot of templates. I did find a reference to DIY adjustable templates for transition curves - Transition Curve Templates - the MRH Forum

This may seem a  bit esoteric, but model trains (and the real ones) don't like  transitioning directly from a straight (or curve) into a curve (or  straight). What is used is a decreasing or increasing  radius curve. You can do this manually with pencil and paper or use software (Templot for example).  This is an issue I'm facing with my current narrow gauge project which has S-curves scaling down to 21"-24" radii (basically, what should an easement look like in an S curve with 2 different radii?). It's another  argument for using as large a radius as possible (≥48"). Most of us don't have the space for that. This is one of the real advantages that flextrack has when following what is basically a spiral. There is a lot of math behind the determination of a transition curve, most of it unnecessary.   NMRA Data Sheets D3a and D3b.3 (search NMRA easements) have some interesting methods.

One thing nobody has mentioned is that cutting the webbing of flextrack really helps when addressing tight curves.

Nigel




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I agree with Nigel regarding the benefits of ensuring accurate easements and curve transitions having spent the time and effort learning to use basic Templot.

This is worthwhile even if you're not building your own track, simply because of the way it handles curving correctly and then gives you the ability to print pinpoint accurate templates to lay the track on. That removes the need for using any curve templates.

In its simplest form you can design a length of flex to start say at radius 6' for the first 6" then decline evenly over next 2' down to radius 5' and continue to the end. Select and print.

To illustrate I ran up this double track configuration with a similar declining transition curve, the second lower track being derived from the first. Took about 1min. Working from a printout the pair could be accurately laid together.

Not sure how easily this could be done otherwise other than trial and error.



PS. this is just a snip of my Templot screen plot, the actual accurate printout is different.









 


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:thumbs :thumbs :thumbs

Like Colin I use Templot for all my track designs (hand built or commercial offerings). Saves messing around with a lot of trigonometry when laying out easements. Going from a straight (tangent) to a 24" curve was ok in the days of road roller wheel treads and under gauged wheels, modern stock is a lot less forgiving (especially if you use fine scale wheels). Diesels and carriages with short wheel base bogies are usually less of a problem.

Nigel

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[user=6]Petermac[/user] wrote:
How do they allow for expansion on welded rail ?
Pandrol or other high-tension clips, concrete sleepers and deep ballasting.  These combined absorb the stresses which would otherwise lead to expansion.  
For each force there is an equal and opposite force.  If one is able to introduce the potential to exceed one force with its opposite then victory is yours.  

If you mean fishplates, every piece of British track was joined to its neighbours with fishplates. I don't know what the current situation is with continuously welded rail.
See above.  


Traditional jointed track required fishplates (a/k/a joiners) at every rail end.  In British practice this was normally every 60 feet though some rails were 45 feet leading to a different "beat" pattern as wheels passed over them.  


There were also areas where two adjacent 60-foot rails were welded again altering the sound of trains passing over.  


It was also common practice to trim the ends of worn 60-foot rails to create 45-foot or other odd-length rails for use in sidings where low speed and (often) lesser use permitted greater wear and ter to be tolerated than on fast main lines.  


Code 75
It can be tricky but there are plenty of helpful suggestions posted already.  I always try to trim the rails to give parallel ends if only to avoid odd-sounding "beats" as trains pass over non-aligned joints.  There are some spots where having such joints has been the easiest way to get track laid around a curve however.  


Cyprus
When I laid track outdoors in Australia I made the elementary mistake of failing to allow for expansion.  Luckily, perhaps, I received my first rude reminder before too much track was down and a deft trim of the ends removed the heat-buckle.  Since that time I allowed for both the laying temperature and expected operating temperature range.  Tracklaying in 15 - 25C I allowed 1.5mm expansion gaps; if cooler I allowed 2mm and if warmer I allowed just 1mm because the railws were already slightly expanded.  2mm sounds a lot and did give rise to some loud "clickety-clacking" but was never an operational problem.  


My track there was Peco Code 100; code 75 would respond the same way but having less plastic in the base and, crucially, the "chairs" holding the rails it may not tolerate such extremes of temperature.  I ran trains in near-freezing conditions and on days when the air temperature reached 48C but the track - some of which was in full sunlight - hit a finger-searing 57C as measured by thermometer.  


One other rule I adopted was never to run trains fresh from storage (which was an air-conditioned 21C) on hot days.  Cool wheels placed on very hot rails can lead to disaster.  

Rick
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[user=1753]Gwiwer[/user] wrote:
Cyprus
When I laid track outdoors in Australia I made the elementary mistake of failing to allow for expansion.  Luckily, perhaps, I received my first rude reminder before too much track was down and a deft trim of the ends removed the heat-buckle.  Since that time I allowed for both the laying temperature and expected operating temperature range.  Tracklaying in 15 - 25C I allowed 1.5mm expansion gaps; if cooler I allowed 2mm and if warmer I allowed just 1mm because the rails were already slightly expanded.  2mm sounds a lot and did give rise to some loud "clickety-clacking" but was never an operational problem.  

  I ran trains in near-freezing conditions and on days when the air temperature reached 48C but the track - some of which was in full sunlight - hit a finger-searing 57C as measured by thermometer.  
And there I was thinking you were in suburban Melbourne, sounds more like the Simpson Desert!

The issue of expansion gaps is pertinent anywhere ranges of temperature might be found and timely for me to check as I move to track laying.

The available data is instructive:

Alloys of the type used for track have linear expansion coefficients of approx 18 ppm per degree C. so for 1m of flex (as an approximation) 1 degree change will cause a length change of 0.000018 x 1000mm = 0.018mm

For the 50 degree range you had outdoors that gets up to about a mm but I suspect that for more normal situations it's not something to worry too much about. I've had long flex on my layout indoors here with no detectable seasonal change but then the temp range is only 10C at worst, summer to winter, thanks to the situation.

Colin

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And there I was thinking you were in suburban Melbourne, sounds more like the Simpson Desert!


It felt like it at times!  Melbourne gets hot.  Very hot indeed.  Several days most summers reach the low 40s.  The weather system which brings that heat is a hot, dry and very windy one.  The north wind drives bushfires which start all too easily in those conditions.  Very occasionally the temperature reaches higher levels and touched 48C in our sun-trap backyard on a few occasions.  Metal absorbs heat meaning the rails were exposed to those high temperatures and became very hot indeed.   I found it educational to check the rail-head temperature and was surprised at the reading I got.  57C.  On three quite separate occasions over ten years.  

Peco were suitably impressed when I dropped them an email to advise their track was coping in those conditions; their reply was to the effect that whilst they sold (and still sell) decent amounts of track in Australia it wasn't designed for that sort of heat.  They apparently tested it to around 40C.  

Adelaide also gets hot and can be a little hotter than Melbourne.  It can be every bit as dry too with relative humidity down to around 5% or less.  The closest I've been to the Simpson was Alice Springs and around the MacDonnell Ranges which reached around 42C.  It gets up to 50C easily in the open desert sun. 

For most purposes rails can be left just far enough apart to slip a sheet of paper between.  That's much less than 1mm.  Many of us have some system to maintain fairly constant indoor temperature and humidity be it insulation, central hating or even smart heating.  So long as the rail ends are not butted tightly together all should be well.  My Australian layout was large, outdoors and in an extreme location weather-wise with everything on it from track to trains, even the Aussie-design Morley controller which had a cooling fan, being used well outside its design parameters.  

But it worked, and mostly it worked well.  There were points I couldn't always change in extreme heat because the blades expanded differently to the stock rails.  I never ran trains brought straight from the air-conditioned store-room; they were allowed to "warm up" before being placed on the tracks.  No train was allowed to stand in the sun nor to be parked anywhere for more than a few minutes on hot days to avoid any risk of distortion.  

I found some thick polystyrene blocks in a skip one day and took them for insulated covers placed over the layout when not in use.  I found I could then leave trains outside underneath them in safety where previously everything had to be taken out and brought back in for each session.  They also kept a lot of dust and dirt off, and the rain which I could never entirely keep from getting in.  

It's almost five years now since that layout closed.  I promised to write a book and hoped it might be ready for that fifth anniversary.  It's still coming but another project has overtaken it.  It'll get done one day.  

Rick
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Summer!

No need to tell me, we're just on the back-end of summer in Melbourne; our 41st since settling here so we're getting used to it.

Typical Melbourne, no two summers are ever the same and this time we barely had a "$tinking" hot Northerly to speak of. Still we managed to get virtually no rain for 3 months and lots of mid 30C days so hot and dry enough. The various thunderstorms clearly thought Doncaster East was not on the map as they all dodged around us, drowning everyone else!  At one point we had a forecast of 30-60mm over 3 days for the Eastern Suburbs and we got 2mm! Enough to dirty the car.

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Looking at the expansion coefficients, flex track would need cutting into probably 3 sections to accommodate the changes in length of the brass rails over a ΔT of 20°C. The expansion of the plastic used for the sleepers is much greater than the rails. that's why the webbing between the rails should be removed.

Edit: Hang on a 'sec, that doesn't sound right (lunch, glucose in brain, one or 2 neurons firing).

Brass, ΔT of 20°C:

Brass 1m long - 1.000374m (ΔL 0.374mm)
Nylon12 1m long - 1.00161m (ΔL 1.161mm)

I use a Dremel cut-off disc when insulating rails - 0.6mm thick. So having around 0.5-0.6mm gaps would allow for a lot more than a ΔT°C of 20° (around 32.5°). Nylon (or whatever plastic is used for the sleepers) is I suspect where the issue is.

North American track prior to ribbon rail normally used staggered rail joints (normally half a track section of 39 feet).

Nigel

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