woodenhead Posted March 14, 2016 Share Posted March 14, 2016 I have a problem that looks like a momentary short on a point. Just spent half an hour staring at a long point thinking it was the issue when I realised the locos only jerked on it when pulling a train and when light engine were perfectly fine. With just a single coach in tow I realised it was the preceding medium point, as the first set of wheels on the coach hit the part of the points where the blades are I can hear a sizzle and the train will jerk until momemtum takes it forward. The point is isolated all round with its own feed, none of the wires are touching and it appears to be coaches (Farish Blue Riband mk1s) that spark the issue. Any thoughts on this anyone, I think at the moment swapping out the point sounds like the best plan. Realised just how bad my eyesight is again when I tried to really focus on the track, that new O gauge class 15 from the Little Train Company looks even more a bargain at the moment. Link to post Share on other sites More sharing options...
woodenhead Posted March 14, 2016 Author Share Posted March 14, 2016 Having run a coach through the problem point and a couple others using my finger I can hear the wheels scrape on something in the dodgy point but not on the others. Swap it out tomorrow I think. Link to post Share on other sites More sharing options...
DCB Posted March 14, 2016 Share Posted March 14, 2016 It is probably the back of the flange on the coach shorting shorting the open point blade to the running rail Both point blades will be at Frog polarity unless you have snipped wires and have the frog electrically separate from the blades. so running rail and adjacent open point blade are at opposite polarities. I get this with 00 electrofrog and my old Duchess makes a wonderful sight as she bangs over the point with blue sparks flying. Insulfrog, snipping the point blade to frog wires or tweaking the blade or if they are tight the back to back measurement on the coach wheels should solve the problem. Changing to 0 gauge with on board battery power and radio control is a better solution Link to post Share on other sites More sharing options...
woodenhead Posted March 15, 2016 Author Share Posted March 15, 2016 I agree O gauge with on board batteries does sound like the best solution. Link to post Share on other sites More sharing options...
RMweb Gold roundhouse Posted March 15, 2016 RMweb Gold Share Posted March 15, 2016 A few of us bought a batch of Farish mk2's in NSE livery last Autumn. Every one of them derailed on Peco code 55 turnouts but the earlier released blue grey mk2's didnt. We found that the back to back of the wheels on all of the NSE coaches were incorrect. However we didnt get any shorting as the turnouts have had the frogs isolated and the blades wired to the stock rails. This isnt easy to do insitu but worth checking the back to backs of the wheels especially if they are of a more recent batch of coaches. Link to post Share on other sites More sharing options...
woodenhead Posted March 15, 2016 Author Share Posted March 15, 2016 As it seems to be just the one point causing this (though I am now going to have to check a couple of other areas) I'll swap out the point for a long one which is something I wanted to do anyway. Didn't think that tolerances in N gauge were that close though to have to think about isolating the blades from the frog and wiring them separately, certainly not with my soldering skills. Link to post Share on other sites More sharing options...
woodenhead Posted March 15, 2016 Author Share Posted March 15, 2016 Definitely a Mk1 Blue Riband issue - tried some Dapol NPCSS and no issue, at one point I thought my Q1 was also doing it but I think it just needed a bit of running. What should the back to back measurement be, I've a digital measure I am dying to use. Link to post Share on other sites More sharing options...
Crosland Posted March 15, 2016 Share Posted March 15, 2016 Run the layout in the dark and look for the sparks. That will tell you where the problem is (which axle and which bit of track). As you say the gaps on Peco points are huge, compared to say 2mm FS. It's more likely that the wheels need adjusting on that one coach. Link to post Share on other sites More sharing options...
DCB Posted March 15, 2016 Share Posted March 15, 2016 I got tired of measuring back to back and as I model the GWR I made up a Go/No Go gauge for checking back to back. Mine is 00 and one end is 14.2mm and the other 14.5 If the wheelset fits the small end and does not fit the large end it is within my tolerance of 14.2 to 14.5mm. Simples. It took a few attempts to get the gauge right but it saves a lot of time and eye strain checking Link to post Share on other sites More sharing options...
RMweb Premium dhjgreen Posted March 15, 2016 RMweb Premium Share Posted March 15, 2016 What should the back to back measurement be, I've a digital measure I am dying to use. This has to be any easy question to answer, right? I could only find widely differing views especially of the DCC concepts 7.65mm B2B gauge. http://85a.co.uk/forum/view_topic.php?id=1334 If you feel like reading this from 5 years ago, it gives some of the thinking and offers a dimension. I offer no guarantees. Link to post Share on other sites More sharing options...
Crosland Posted March 15, 2016 Share Posted March 15, 2016 I haven't read the Templot thread, so apologies if I am repeating what it says. Back-to-back assumes the flange thickness is standard across all manufacturer's and models - not neccessarily the case. The crucial dimension is from the back of one wheel to the outside face of the flange of the other wheel. Link to post Share on other sites More sharing options...
RMweb Premium dhjgreen Posted March 15, 2016 RMweb Premium Share Posted March 15, 2016 I haven't read the Templot thread, so apologies if I am repeating what it says. Back-to-back assumes the flange thickness is standard across all manufacturer's and models - not neccessarily the case. The crucial dimension is from the back of one wheel to the outside face of the flange of the other wheel. You would need to read it, it is a blog discussion about B2B and does give all the gory details. Link to post Share on other sites More sharing options...
woodenhead Posted March 27, 2016 Author Share Posted March 27, 2016 Mooching around York today and there in front of me was the DCC Concepts stand with a table full of back to backs. £13 plus some points later and I am the proud owner of a brass back to back for N. Get home and find that nearly every coach is out, Farish was no problem resetting but Dapol proved to be a case of two wheel types. One Dapol wheel type with a plastic barrel resets easily, the other which I think is N earlier design as its on all my oldest (but oddly not on the auto coaches) have a metal barrel and adjusting the back to back cost two wheels. Going to order some Farish coach wheels to swap them out with from Hattons tomorrow, no point messing around. Tested the stock I've been able to adjust and so far all is good, couple of jerking locos but that was on plain track and they probably need lubricant and running. All these years I thought it was just the locos needing regular running and it was the coach back to backs. I am one happy modeller tonight, also helped that at York a couple of splendid models had the odd problematic issue and it shows even the best can have problems some of the time so I shouldn't be so hard on myself. Link to post Share on other sites More sharing options...
RMweb Premium dhjgreen Posted March 28, 2016 RMweb Premium Share Posted March 28, 2016 Just be aware that some people find the DCC concepts gauge to be a little large for their track/wheel combination. Link to post Share on other sites More sharing options...
woodenhead Posted March 28, 2016 Author Share Posted March 28, 2016 Just be aware that some people find the DCC concepts gauge to be a little large for their track/wheel combination. Might explain why nearly every coach was out, but other than the older coaches it seems to have cured my track shorting issue on the points. Link to post Share on other sites More sharing options...
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