Hi,

I had an intermittent contact track problem and this is how I think I will fix it and retrofit existing contact tracks as needed. I'm happy for any replies of suggestions or improvements.


In the above picture the unmodified c-track isolated contact rail is intermittently touching the next track and making contact. I searched the internet for this problem and only found it mentioned on this YouTube video by Model Train Fun starting at 37:21 minutes (https://www.youtube.com/watch?v=2FMWxEPm__Y ). Model Train Fun suggested trying different track sections. I will do that moving forward, however for track already soldered to wires, I don't want to switch out different track sections. My c-track is not screwed down to the layout, but is sitting on top of a sound deadening carpet underlay (Ikea Stopp Filt), which allows a little bit of movement. I wonder if there would be intermittent contact if the track were firmly attached to the layout?


What ended up working was gluing a piece of paper between the track ends. In the picture above I'm about to slide a paper under the rail.


Here is after the glue dried and paper is trimmed back.

As an improvements I want to 1) find material other than paper that will hold up to isopropyl alcohol used to clean the track and 2) trim a better track profile into the insulator.

As an example of the variability in the gap between rails here is another unmodified joint with a generous gap.


I guess what caught me off guard was assuming that all c-track joints always have a gap between the rails, so I wasn't looking at the rail gap when trying to find source of problem.

Take Care,
Chris

I cut a small piece of electric tape and put between, I had to do this in several places on my layout.

All my 15 degree R3 pieces have this problem, and also a couple of straight tracks.

For those who can't do it on the back of an envelope!

https://goodcalculators....al-expansion-calculator/


A few common metals with their coefficient. Z gauge is nickel but I don't know what HO uses. If it is stainless there are different coefficients for different alloys. It most likely will be a 400 series alloy.

https://amesweb.info/Mat...-Coefficient-Metals.aspx


Don't forget to calculate the track base. The plastic will have a higher coefficient than the rail. Also factor in your layout base material. Probably lower. It's most likely the track base plastic which has the greatest coefficient.

Hi,

Thanks for all the great ideas. I tried one more thing, cut from Marklin c-track insulators, that seems pretty stable but is a lot of work cutting and trimming. I think I will try the idea of painting the track ends with something like varnish or liquid electrical tape. I tried filing and a rotary tool first, but I was not able to make a smooth cut nor was I able to control the depth of cut very well.

I was able to get two of these L-shaped insulators from one c-track insulator.

Had the same problem , just gently shaved the edge off the end of the rail with a Dremel cutting disc , problem solved , a file could also be used as stated in the thread earlier.

Feels like a good approach is to paint on an insulating lacquer on the ends where you have the contact tracks.
Then in the future, if and only when you find a false positive problem, then remember to look at the joints between track pieces and if needed cut the joint open again with a rotary and maybe insert a thin styrene piece which can then be painted and glue in place.