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laying track

Posted: Thu Mar 05, 2015 12:17 pm
by mcnaugg
I am starting to put down track which is to be permanent. Previously I had fastened the track with pins and found on a number of occasions that my "hammer" work let me down and I hit the rail instead of the pin with the result that there were a number of bumps in the track. The base board is 16mm chipboard and the track is laid on 3mm cork.
I am using a Digitrax DCC system and having tested the layout using the original pinned track I decided to relay the track using wood glue to fasten the cork to the baseboard and then the track to the cork. I am also using Insulated track joiners to split the track into blocks etc.
I am using Nickel Silver track which I must admit is a mixture of recovered Peco/ Lima/Hornby although I have a full box of new unused Hornby track which I was keeping for the mail layout.

My problems is that I am getting false triggering of the block sensors due to a resistance between the common rail and the "monitored" rail. Being a Digitrax system I am using GCA block sensors etc and they seem to trigger if there is a resistance of less than 50Kohms between rails. This didn't happen when the track and cork underlay was pinned down. The glue I am using is a common brand here in South Africa (Alcolin Cold Glue) which is advertised as a multipurpose glue suitable for wood, cardboard, paper and craft projects etc and is also water based. I have lifted a short length of track still on the cork and I measure ± 40Kohms between the rails but a similar length of un-mounted track shows no resistance and does not trigger the block sensor. The track was laid about 36 hours before I connected the sensor wires so I would have thought that the glue would have been dry. I have also put a piece of track and underlay in the sun to see if that makes any difference.

Has anybody else had a similar problem or is it just me? I have been quite liberal with the glue because it dries clear and the track I have laid so far looks perfect.


Re: laying track

Posted: Thu Mar 05, 2015 1:35 pm
by End2end
From what I understand, one of the ideas of DCC is NOT having to have block sections.
Use a pin or ball-pein/ball-peen hammer along with a pin vice, rather than a large or claw hammer and cover each rail either side of where your hammering with some plastic or thick card.
Hope it helps

Re: laying track

Posted: Thu Mar 05, 2015 2:28 pm
by alex3410
i have never bothered but you can split your layout into sections with DCC to help with fault finding - if you keep it as a complete circuit then you have to hunt through the whole thing if something goes wrong but my layouts have never been large enough to worry about this.

i believe you can also do something similar for automation to enable the system to detect the location of the locos

Re: laying track

Posted: Thu Mar 05, 2015 5:06 pm
by mcnaugg
Perhaps I should have indicated that my Digitrax system is connected to a PC which will run the locos on predetermined routes and also schedules(if required). So blocks are needed in one form or another so that the software knows where each and every loco is. In my case my basic track requires a DMU to run between two terminal stations plus one in the middle. The DMU will (and does) slow down on approach and then stop in each station. After a period of time (fixed or random) it will leave the station and carry on to next, again slowing and then stopping. Again after a period of time it will then reverse and go back to the previous station and so on.
So my circuit has two sensors at either end of the block (Station) so with three stations I have 6 sensors. The sensors can be current sensors ( the track is physically isolated on one leg and connected to a current sensor card) where the current drawn by the loco is used to indicate the loco position. This is the type I am using. There are also IR sensors which I also have but need a lot more wiring and there are also RFID sensors(similar to the chips inserted into dogs etc). No Doubt there are other types available.
I chose the current type after trying the IR sensors as they proved to be a bit easier to set up but I never counted on the fact that there could be a electrical resistance problem with the glue I was using. As I said at the beginning I placed some track that I had lifted with the cork still in place in the sun and there seems to have been some improvement in the resistance reading across the track. Maybe I should just use the glue in spots rather than glue the whole length down.

I used a pin hammer or as mother called it a toffee hammer, along with a pair of long nosed pliers to hold the pin during the process. I also found that due to the soft cork underlay it was easy to knock the pin in to deform the sleeper which also caused a slight depression in the track. I did think of making a jig that would straddle the track with a sliding drift so that I couldn't knock the pin in too far or damage the track but I no longer have access to a full workshop so that idea fell by the wayside. I still think that glue is the way to go but wondered whether anybody else had the electrical resistance problem. Also perhaps I should change the type of glue.

Re: laying track

Posted: Thu Mar 05, 2015 9:36 pm
by Albert
Give it time to dry out thoroughly and you might be OK. Set glue could still have quite a high water content.

Failing that I'd suggest epoxy -- not the expensive 'tube of araldite' option but something like the stuff that's sold in quite big quantities for boat building and the like. .

As for using pins I'd suggest using a decent size nail with the point filed flat to act like a setter. Then you just need to use a small pin hammer and a bit of delicacy.


Re: laying track

Posted: Thu Mar 05, 2015 10:10 pm
by Dad-1
Still damp glue could be part of your problem.
How are the track feeds attached ? I can't believe there will
be any interaction through the sleepers, but are bare connecting
feeds within the glue zone ?

Geoff T.

Re: laying track

Posted: Sun Mar 08, 2015 5:14 pm
by mcnaugg
The problems seems to have cleared itself by allowing plenty of time (a couple of days) for the glue to completely dry out. The resistance now is in the region of 60 to 130 K ohms depending on the length of the individual blocks. At these values there is insufficient current to operate the Block sensors.

I always solder the cable directly to the rails so it's conceivable that there are paths for a leakage current. In the past I have always used two wires (rip cord) each soldered to the track. Even though one rail was common I would still solder one wire pair to the common rail just to ensure that I had a good contact all round. The downside was that I had multiple "common track" wires to common together.
To do this I drilled a hole in the centre of the track and brought the two up through the hole and then passed them under the track rails to solder them on the outside of the rails. I was always reluctant to solder the track joiners in case I wanted to make changes so I have started to solder wire straps across the joints one or two sleepers away from the joiners and only using one "common" wire. So far it seems to be working.

I checked the glue known here as No Nail glue and that is also water based. I am reluctant to use an epoxy type of glue as it is so permanent. With the white cold wood glue it can be released by wetting it. Takes time but it can be done. Also when putting the track down there is plenty of time to check the alignment of the track etc. On the straight sections I have been using pins lightly tapped through the track "hole" and fishing line to align the track.

I'm about ready to start the next section so the proof of the pudding they say.

Re: laying track

Posted: Mon Mar 09, 2015 8:30 am
by mjb1961
Hope it all works for you ,ive just laid my track on my new layout ,pinned it to the board ,but I'm having problems with trains stalling on the points,they are only stalling on the siding,I've lifted them and fitted them with wired fishplates but it hasn't really made that much difference ,,,,,,

Re: laying track

Posted: Mon Mar 09, 2015 4:14 pm
by mcnaugg
Could it have anything to do with the frogs i.e. insulated or not?

Re: laying track

Posted: Mon Mar 09, 2015 9:19 pm
by mjb1961
mcnaugg wrote:Could it have anything to do with the frogs i.e. insulated or not?

Probably ,they are hornby insulfrog points ,but to be honest one or two of them are a little bit dodgy,I've been messing about for a couple of hours tonight ,taking pins out ,putting pins in ,one minute the flying Scotsman crawls over them no problem then on the way back it stalls ,the 08 class crawls along nicely but the 03 is having none of it ,it drives you mad ,but regarding insulfrog ,I don't think hornby do electrofrog so I would have to mix it with peco ,anyway I'll persevere ,hopefully getting running to a satisfactory level ,,,thanks mjb

Re: laying track

Posted: Tue Mar 10, 2015 9:51 am
by RAF96
mjb1961 wrote:... and fitted them with wired fishplates but it hasn't really made that much difference ,,,,,,

Wired fishplates won't fix problems if the fishplates are loose as the wires are attached to the problem. To check for bad fishplate joints put your thumb on the rail joint. If its warm or even hot then the fishplate needs tightening by squeezing them with pliers if disconnected or by tapping them with a flat bladed screwdriver and a hammer..

The ultimate solution is to wire across the joints or wire each track piece to a bus. Don't solder your rail joints together or you lose any expansion capability.