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Offline IsItDigitalAlready?  
#1 Posted : 03 May 2015 20:07:11(UTC)
IsItDigitalAlready?

United States   
Joined: 01/03/2015(UTC)
Posts: 30
Location: Nevada, Reno
After a bit of investigation prior to permanently installing the track on my layout - a 4'x8' M-Track digital design, with a Roco Z21 - I have come to the following conclusions:
  1. The conductivity of the track components - the center conductor and the rail/roadbed assembly - is similar to nickel-silver rail.
  2. The center rail contact resistance between adjacent track sections is negligible.
  3. The contact resistance of the rail joiners (and the incidental contact of the adjacent roadbed edges) is high and variable/intermittent.
As a result, I am encouraged that my layout concept can be achieved, but only if the rail contact resistance problem - item #3 - can be solved.

I would appreciate hearing from anyone who has addressed this issue, including what they tried and how it worked.

It may help you to know that I am using M-Track of many vintages, 1950s thru the end-of-production. Naturally, the condition varies from decrepit to nearly new. The results noted above apply to all the track tested so far. I would say there are two primary sources of the problem. The first is the imperfect mechanical contact achieved by the rail joiners, and second, corrosion or oxidation. I have some ideas about how to address these factors - and I have ample "scrap" track to experiment with - but I am sure I am not the only one to have ever faced this situation. I am looking for a systematic solution that does not involve running a separate feeder to each track piece, although I am inclined to install multiple feeders for reliable long-term operation.

All suggestions will be greatly appreciated, and will earn you Engineer's Rights on the layout.

Bob
Bob
Cold Springs (Reno), in far Western Nevada
It's all Gordon's fault!
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Offline H0  
#2 Posted : 03 May 2015 20:32:09(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: IsItDigitalAlready? Go to Quoted Post
I am looking for a systematic solution that does not involve running a separate feeder to each track piece, although I am inclined to install multiple feeders for reliable long-term operation.
Usually recommendations vary between "one feeder track per meter" and "one feeder track every two meters". Feeding every track can be heard sometimes, but I think that is more than enough.

Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline SteamNut  
#3 Posted : 03 May 2015 20:52:28(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
I have soldered additional ground to solve problem areas on my analog layout (never had to add additional positive wires), in retrospect I should done this every 3 meters as soldering the bottom of M track and joining the wires is easy - Fred
Offline Webmaster  
#4 Posted : 03 May 2015 21:08:38(UTC)
Webmaster


Joined: 25/07/2001(UTC)
Posts: 11,161
M-track conductivity problems are usually related to oxidized and/or bent track joiners while the centre rail is usually reliable.
Similar K-track problems can be related to both joiners and the small copper strips connecting the centre rail.
The C-track is supposed to overcome these conductivity problems with track joints, but even there track joining problems may occur.

The good thing about M-track is that you can solder track ground connection cables to it easily directly onto the railbed...
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
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Offline IsItDigitalAlready?  
#5 Posted : 03 May 2015 22:04:18(UTC)
IsItDigitalAlready?

United States   
Joined: 01/03/2015(UTC)
Posts: 30
Location: Nevada, Reno
Dear HO, SteamNut, and Webmaster,

Thanks for pitching in. I should have warned everyone that I am a retired aerospace engineer, and would like to see if there is a way to directly address the rail joiner issue. Once I do that, I figure I can calculate appropriate feed point criteria rather than having to cut and try, so to speak. I have been searching for contact treatments (silver conductive grease, conductive paste, etc.) and contact improvers (springy shims?), but am not sure what has the best probability of success. I also don't want to spend a lot of money buying samples of potentially hazardous/toxic materials. So that's one avenue I would like to pursue.

I had not really thought thru the idea of bonding the railbed together. I suppose if one leaves perhaps 2cm of slack between the rail sections, track maintenance would still be possible. Accommodation for make-up sections would be necessary, I suppose. And I would guess that 18AWG wire would be suitable, if it were fed every couple of meters - but has anyone done that?
Bob
Cold Springs (Reno), in far Western Nevada
It's all Gordon's fault!
Offline carlos.rivas.16752  
#6 Posted : 03 May 2015 22:55:35(UTC)
carlos.rivas.16752

Spain   
Joined: 08/04/2015(UTC)
Posts: 303
Location: Vigo, Spain
Originally Posted by: IsItDigitalAlready? Go to Quoted Post
I have been searching for contact treatments (silver conductive grease, conductive paste, etc.) and contact improvers (springy shims?), but am not sure what has the best probability of success.


I´m using a german product named Kontakt 60 to spray the pukos in order to prevent rust and improve conductivity. It works fine. And I´m using lighter fluid to clean the rails.

Also watch carefully for bent track joiners and replace them.

Regards
Carlos
My blog both in Spanish and English: https://grunewiesen1965.wordpress.com
Offline IsItDigitalAlready?  
#7 Posted : 03 May 2015 22:58:58(UTC)
IsItDigitalAlready?

United States   
Joined: 01/03/2015(UTC)
Posts: 30
Location: Nevada, Reno
Originally Posted by: carlos.rivas.16752 Go to Quoted Post
Originally Posted by: IsItDigitalAlready? Go to Quoted Post
I have been searching for contact treatments (silver conductive grease, conductive paste, etc.) and contact improvers (springy shims?), but am not sure what has the best probability of success.


I´m using a german product named Kontakt 60 to spray the pukos in order to prevent rust and improve conductivity. It works fine. And I´m using lighter fluid to clean the rails.

Also watch carefully for bent track joiners and replace them.

Regards
Carlos


Um ... I do not know the meaning of "pukos"
Bob
Cold Springs (Reno), in far Western Nevada
It's all Gordon's fault!
Offline H0  
#8 Posted : 03 May 2015 23:01:36(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Pukos: centre rail studs.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
Offline Tom Jessop  
#9 Posted : 03 May 2015 23:27:31(UTC)
Tom Jessop

Australia   
Joined: 14/12/2002(UTC)
Posts: 800
Location: Newcastle NSW Australia


I have always soldered my "M"track both on the centre contact & the ground side . I use the Dremel to remove paint from the bent over tab which holds the rail in place & likewise on the inner end of the centre contact . Done with 7 or 8 lengths of track for easy moving . I used telephone wire for the join after I stripped the insulation off , one end had a tail which connected to a heavy cable [building power cable ] for the main feed . Use a air gun to blow away any dust after Dremel use . A clean up of the running surface of the rails with Trackmagic [ naptha based product from the UK ] works wonders , I think ZAP has some similar product . At least where you live in Nevada you would not have problems with humidity like most of us do , I live 100 meters from the largest salt water lake in Australia & unless I run a engine & a few cars at least every few days I end up with a few dead spots .


Cheers Tom in Oz .
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Offline el Gato Gordo  
#10 Posted : 04 May 2015 22:15:25(UTC)
el Gato Gordo

United States   
Joined: 05/03/2015(UTC)
Posts: 4
Location: Colorado, Colorado Springs
Ah, yes, Tom - but my brother doesn't want to solder his track. As much as he and I move about, it could be a real pain to disassemble, with perhaps much damage to track. I recently tore down my first N scale (44x96) layout, on which I had soldered all the joins. There is no doubt that soldering makes a better electrical contact, But it was a pain, and some turnouts were lost in the process. Even so, I soldered again on my new (48x114) layout. "Bob" is looking for a workaround to avoid the permanence of solder.

The good news is this thread is giving us ideas, such as using brass shim stock or inserting wire in the joiner to tighten things up. Thanks for all the responses! Any new ideas, please keep them coming - and I'm sure "Bob" will publish what eventually works for him.

Cheers!
Gordon
Offline SteamNut  
#11 Posted : 05 May 2015 00:16:53(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
I am sorry if I wasn't clear on my post but you can solder the ground wire to the underside of M track on any part that is metal. You do not have to this on every section only every 3 feet or so. This allows you to disassemble the track easily especially when the socket system is used to join the wires together. In my experience you do not have to solder rail joiners together, however the track will have to be cleaned on occasion I do mine once a year with little used spots a bit more.
Offline IsItDigitalAlready?  
#12 Posted : 11 May 2015 19:29:47(UTC)
IsItDigitalAlready?

United States   
Joined: 01/03/2015(UTC)
Posts: 30
Location: Nevada, Reno
I am a bit pressed for time at the present, but I wanted to let others know that I obtained some 0.002" stainless steel foil to see if that could be used to improve the connection resistance. Initial test (one test) shows a drastic reduction in resistance. I cut a 5 mm x 3.5 mm piece, folded up 0.5 mm on the 5 mm edges, and slipped it into the rail joiner, then slipped the rail inside that when connecting two pieces of track. Resistance went from 4-5 ohms to 0-1 ohms for two pieces of "new" 5106 gerade Gleisstuecke (one rail only). More experiments when I get time in June - I have some other foils (Copper, Brass) to try. This does not address the existing (and possibly future) corrosion component of the joint, but I will look into that, too.
Bob
Cold Springs (Reno), in far Western Nevada
It's all Gordon's fault!
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