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Improving conductivity through fish plates


PMW
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My view is that fishplates should be used to align rails and should not be relied on for conductivity (tarnish, paint, dirt and loosening will degrade conductivity).  You are partly right about droppers.  Conventional wisdom is to use droppers for every piece of track, connected to a buss.  This is going to be the most reliable method of ensuring the whole layout gets power.

 

John

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I thought the idea of the fish-plates was also to accommodate some thermal expansion. When I resumed modelling back in the 1980s I made a small 009 layout which had all the rails snug-fitted. It stood in the corner of the room and the sun got on it and caused the rails to expand and buckle. Two lessons learned there: allow a small gap in the rail ends, and keep the layout away from the sun.

 

If you suspect you have poor conductivity through a fishplated connection, a dash of switch cleaner will soon prove that one way or another. Or just apply a little IPA with an eye-dropper.

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49 minutes ago, AdamsRadial said:

I thought the idea of the fish-plates was also to accommodate some thermal expansion. When I resumed modelling back in the 1980s I made a small 009 layout which had all the rails snug-fitted. It stood in the corner of the room and the sun got on it and caused the rails to expand and buckle. Two lessons learned there: allow a small gap in the rail ends, and keep the layout away from the sun.

 

If you suspect you have poor conductivity through a fishplated connection, a dash of switch cleaner will soon prove that one way or another. Or just apply a little IPA with an eye-dropper.

 

I tend to agree.  You do want to leave a small gap to allow for expansion.

 

John

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2 hours ago, mkrob said:

You could solder the track at the fish-plates like our American friends seem to do. Are you using Flexi-Track?  

 

https://www.youtube.com/watch?v=qUD5rNXNuS4

Don't forget that for the most part American layouts are going to be permanent fixtures, in air-conditioned rooms; temperatures will be more stable than in UK houses, there might not be such a problem with rail expansion and the layout is not going to be moved (either for storage or exhibition).

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8 hours ago, F-UnitMad said:

Don't forget that for the most part American layouts are going to be permanent fixtures, in air-conditioned rooms; temperatures will be more stable than in UK houses, there might not be such a problem with rail expansion and the layout is not going to be moved (either for storage or exhibition).

Putting that aside you have the issue of fishplates NOT being a secure electrical contact unless you solder them. Once solder to the rail you lose any ability of expansion and/or contraction whether it be in an airconditioned room or not! There is always expansion and contraction.
Khris

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2 minutes ago, d00m said:

Has anyone put in prototypical expansion joints?  They tend to have bonding wires across them, so it wouldn't be too difficult to add a dropper wire...

Surely if you don't solder them up solid (or glue!), then they will slide slightly anyway. Put the droppers in and connect to a bus and the job's done.

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I always solder mine and, so far, haven't experienced any expansion problems.  But - I generally have small exhibition layouts.  However, I've also done this on my permanent HO layout which is 12' x 10' and no problems here either.  It is in a room in the main house and doesn't suffer from severe temperature variations which might have a bearing.

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22 hours ago, PMW said:

Has anybody ever used conductive grease on fish plates to improve the conductivity?

 

I would regard conductive grease as grease that happens to be somewhat conductive, rather than a good conductor that also happens to be greasy.  And that's before you get in to the question of applying grease to (or close to) a surface on which you will be relying on metal-to-metal contact for traction...

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19 hours ago, mkrob said:

You could solder the track at the fish-plates like our American friends seem to do. Are you using Flexi-Track?  

 

https://www.youtube.com/watch?v=qUD5rNXNuS4

Don't do this! I did it and had dreadful problems with thermal expansion. The only time I would do this is on a small layout or one that is kept at a constant (ish) temperature. 

Droppers to each track section is the only way to go. Rail joiners will work loose or otherwise stop working.

Ian 

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With over 300 pieces of sectional track droppers to each one is not an option. With the need for thermal expansion neither is soldering, I always use a feeler gauge to leave a gap of 1/32" between tracks. By my very rough calculation a 26 foot loop of nickel silver track has the capacity to expand by more than an inch with a ten degree temperature change, and it will be subject to changes of at least that. 

 

2 hours ago, ejstubbs said:

I would regard conductive grease as grease that happens to be somewhat conductive, rather than a good conductor

 

There are conductive greases that are very highly conductive, more so than solid copper strand. I used to use it in the line of business, and using such products on metal to metal contacts can reduce resistance across a connection in excess of 99%. OK they are very expensive (my preferred product is 8463 Silver Paste, about £2500 per kg) but a whole layout would only use a few grams and not only does it reduce electrical and thermal resistance to virtually zero it disperses static build up from induction motors and prohibits rust or tarnishing. There are other products which are almost as good at a fraction of the price. 

 

It seems such a no brainer to me, I know commercial slot car tracks often do it yet I have never heard of anyone doing it on a railway layout. 

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i  have only ever had one connector go awol during my centuries of modelling .I got a pair of pointed nose pliers and just crimped it gently .Problem solved,

My phone engineer gave me some wire connectors that were full of grease which i presume is similar .They work fine on my layout though a bit messier .

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48 minutes ago, PMW said:

With over 300 pieces of sectional track droppers to each one is not an option. With the need for thermal expansion neither is soldering, I always use a feeler gauge to leave a gap of 1/32" between tracks. By my very rough calculation a 26 foot loop of nickel silver track has the capacity to expand by more than an inch with a ten degree temperature change, and it will be subject to changes of at least that. 

 

 

I think you've got your calculations wrong. An inch of expansion sounds enormous over that distance.

According to http://www.nealloys.com/pdf/nickel-silver-770.pdf , coefficient of expansion for Nickel Silver is 9.3*10^-6, which is 0.0000093. Multiply that by 10 for each degree of temperature change = 0.000093.

The total length is 26', which in inches is 312, so expansion is 312*0.000093 = 0.03". That may not sound like a lot but if the rails are all butted up together or soldered, it is enough to cause a problem. This online calculator will help: https://handymath.com/cgi-bin/arc18.cgi & shows the above expansion would give a deflection of 0.3".

In English, this is a big problem.

Rail may also not be Ni-Ag 770. It may well be a different alloy which is more susceptible to expansion.

 

Just because you do not like the sound of it, this does not make droppers to each rail "not an option". It is an option but just not one you would prefer if you can avoid it.

It is not wrong to look for alternatives, but don't dismiss valid options you don't like until you have a better alternative.

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3 hours ago, Pete the Elaner said:

Just because you do not like the sound of it, this does not make droppers to each rail "not an option".

 

it does in my language .... :P plus the sheer volume of wiring under the baseboard would be hideous. I may not have chance tomorrow but sometime this week I shall do some tests on resistance across a typical block without then with grease and look at the results. 

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Is this DCC?  I don't even like copper grease on Car battery terminals, nice and clean metal to metal is best.  On  Inside layouts I have never had any problems with Peco Fishplates on code 100 Peco track with DC.  Some of it is several yards from the feed, like a 11ft X 5 ft oval test track with one feed and a 1 amp overload cut out.

Up the amps to 2 amps and the fishplates start failing, I have had steel fishplates red hot on 2 amps. as in 2 X 1amp controllers running 3 loco Triang Transcontinental lashups.    DCC can be 4 amps.   If its DC I wouldn't bother with droppers, just wire plenty of sections maybe a feed every 4 yards and run trains  If its DCC follow the experts advice and start drilling and soldering so every single bit of rail is connected to the bus and hope the layout is usable before you decide Morris Dancing/ Darts/ Fishing/Stamp Collecting/ Bird watching is a less frustrating hobby.  Best of luck fault finding if you don't chunk it up into power districts. 

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Trying to solve a problem that isn't there? I've only had one instance where fishplates failed to effectively conduct current and that was on a large 20' x 20' layout with handbuilt track using fishplates not designed for the rail section I was using. Cured with single stands taken from flex soldered across the joint. My current layout, garage sized, uses matching Peco track and fishplates. As I don't like wires soldered to the sides of the rails, power is fed to the fishplates, but only one for each section. Despite the tracks being spray painted, misted with water then flooded with dilute glue when ballasting, and finally given a further waft of spray paint there are absolutely no problems with conductivity.

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13 hours ago, DavidCBroad said:

If its DCC follow the experts advice and start drilling and soldering so every single bit of rail is connected to the bus...


It really depends.

I connected nearly every piece of track and my layout has ZERO dead spots.

It's in a room that sees 10°C up to 20°C.  Never had a problem with buckling track either.

 

Next time I build, I will go for soldering every two or three pieces of track.  I can always add more if I need to but in my experience, it seems like extra work for no real gain.  I think the apparent need to solder every piece of track is nothing more but a myth.  Go slow, double check connections and you shouldn't get any short circuit faults.

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The design philosophy behind my layout, Cwmdimbath, a South Wales 1950s BLT, is KISS, Keep It Simple, Stupid, a reflection of my ability with a soldering ironr and desire to avoid the 'stall' of previous layouts and get it into a state of running with basic scenery in a short time.  Electrical simplicity was vital, and as the layout lives in a rented flat, it must sit on top of furniture and supports so that it is not fixed to the walls, so I did not wish to have droppoers and have to get awkwardly underneath the layout to attend to broken electrical joints (I'm getting on a bit and not as lissom and lithe as I once were, and I wanted the stock to live on the layout without having to be put away while the boards folded out of the way.  I wanted, as many men my age do, a semi permanent erection on my side of the bedroom, and that's what I've got).

 

So, as well as using Peco rail joiners to align adjoining sections of rail, I use them to conduct electrical current.  In conjunction with insulfrog points (I  can see them all shaking their heads solemnly) the current goes where the points switch it to.  The rail joiners act as fishplates, and an expansion gap has been included at rail joints to assist them in this, but I will install bridging wires should any of them fail to conduct electricity; likewise the point blades.  In 4 years of frequnet running with a temperature range of perhpas 10 or 15 degrees Celcius (I prefer my bedroom cooler than the rest of the flat), I have had no failure of conductivity from a rail joiner, nor any problems caused by them 'fishing' during expansion or contraction, and I like the clickety clicks (I've slit gaps in the railheads but not through the rail to enhance this sound effect). 

 

I've had to bridge wire around two of the insulfrog turnouts to maintain conductivity, and others have needed attention to the closure of the blades to the stock rails, where carbon builds up and prevents proper closure.  But KISS has worked well for me.  No doubt there will be more failures over time, but dropper connections fail over time as well, and I can easily deal with problems if they arise.  It works!  My alignments are good, electrical performance is very reliable, and my running is near perfect, getting nearer wth each minor tweak. 

 

A layout that doesn't work properly is a pointless thing no matter how many turnouts it has.

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14 hours ago, DavidCBroad said:

nice and clean metal to metal is best.

 

but it isn't, unless the contacts have been very highly polished the actual connection between the two is much less than the total surface area. Conductive grease fills the tiny gaps between the contacts to ensure current can flow freely across the whole contact and eliminates arcing which is a major source of heat at terminals. 

 

10 hours ago, Neil said:

Trying to solve a problem that isn't there?

 

Hopefully so, but every review I read tells me how rubbish fish plates are at passing current. My layout will be DCC++ at 2a

 

I'll run some tests during the week to see what I decide to do. 

 

 

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1 hour ago, Sir TophamHatt said:


It really depends.

I connected nearly every piece of track and my layout has ZERO dead spots.

It's in a room that sees 10°C up to 20°C.  Never had a problem with buckling track either.

 

Next time I build, I will go for soldering every two or three pieces of track.  I can always add more if I need to but in my experience, it seems like extra work for no real gain.  I think the apparent need to solder every piece of track is nothing more but a myth.  Go slow, double check connections and you shouldn't get any short circuit faults.

I've just converted my layout from DC to DCC. Apart from removing the isolating fish plates were possible, I've taken all feed that came back to the control panel to a central feed to the new control position. I do not have a BUS on my layout. I refer to is as the tree method. Multiple branches off a central core. 
I've found a couple of areas where the DCC feed is questionable and have added extra feed in, apart from that no alteration has been required. Picture shows some of the work mid conversion. 

20200907_133308.jpg

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