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Chamby

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  • Location
    : Cornwall
  • Interests
    Great Central London Extension 1948-50;
    Cornish Railways;
    Swiss metre gauge.

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  1. @tender‘s proposal would work if the switch blade not in use was electrically isolated when the other route was selected. There are two potential issues for me with this modification however: Firstly, albeit very unlikely, as @martin_wynne points out, contact could possibly occur at either end of the blade rail, if this happened simultaneously it would cause a short. This would be dependent on the locomotives wheelbase being just the right length to bridge the staggered shorts, of course - so perhaps a theoretical issue for most. Secondly, the electrics get a bit more complicated and at least two switches will be needed, one for the frog as per usual, and one that switches the frog’s selected polarity to the live blade rail. Depending on how you have wired the layout, the type of point motor you are using, and whether you want other functions such as signalling operating from the point motor switches, this may be impractical. Has anyone actually tried this yet?
  2. That section is C&L, the thick sleepered version. I purchased a box of it before the PECO bullhead rail came out. I have used PECO elsewhere, the main visual difference is that C&L has a smoother finish on the sleeper tops so reflects light differently even when it’s all painted the same colour. It is also easier to lay straight sections because the webbing is continuous under both rails so it doesn’t bend so readily... but needs cutting on one side for curves. It’s nice stuff to use though. For filling in the six foot, I used dry ballast and droppered on diluted PVA. It dried overnight, even in the deeper vee.
  3. Yes, but I’m struggling re: joining the dots!
  4. Hi John, A question for you re: the ballasting: are you purposefully leaving a 'valley' between the two running lines? The reason I ask is because I have recently been asking myself the same thing. At the time you are modelling, it was common for ballast to be levelled between the tracks. The inner shoulders are more typically associated with more modern ballast tamping machines. Of course there were always exceptions and you may have already researched this for the lines you are modelling, but it might be worth checking photo's of the right location/time if you haven't already. A second consideration is the cess, that bit between the ballast shoulder and the green stuff. Have you given any thought to what may lie there? I have based my track profile on the former Great Central line which had a clearly defined cess between the ballast shoulder and the 'sodding' laid inside the boundary fence. I was fortunate to find an engineering diagram showing a cross-section of M,S&LR embankments and cuttings whilst browsing on t'internet, which I used as a guide. To represent the cess, usually formed using a finer material than the ballast, I have used sand from the beach at Portmellon Cove - our dog likes swimming there and she brings home a regular supply in her fur, leaving it all over our boot room when we rub her down! I used Woodland Scenics medium grey blend ballast in this case, this is the result: (It all needs weathering down a tad, it looks too pristine at the moment!) Best regards, Phil
  5. Hi Nile. Shorting occurs more often when the frog is live because there are more opportunities for rails of opposite polarity to be in close proximity. But shorting can also occur with the frogs in dead mode, for example: On the basis that a picture paints a thousand words... Yes, I have staged these for photographic expediency, but they demonstrate what happens. My apologies for the limited macro capability of the iPhone camera used here! The photo above shows the 'crabbing' effect of the L1 front pony bridging the gap between rails of opposite polarity just before it reaches the frog. Note the back of the flange touching the opposite rail, the far side of the insulated rail break. This short occurred frequently with both of my L1's and is what first drew my attention to the possible issues. It now doesn't ever happen following the modification, because the electrical rail breaks have been relocated to where the rails are farther apart. Epoxy insulation on the inside of the rails would also work here. Apologies for the poor depth of field in the photo above, which shows a 'Princess Coronation' fitted with the flangeless trailing bogie wheels that enable it to negotiate tighter radii. You can make out, despite the blurring, that when running on the curved track, the wheel 'hangs out of gauge' and can short across the top of the rails of opposite polarity on the straight road, before encountering the frog. I have two Princess Coronations and seven A3's with this arrangement, some are fine, others will short intermittently. It seems to depend on whether the flangeless wheel actually sits on the rail or is suspended above it. Epoxy on the inside of the rail wouldn't work here, it would need to obscure the top of the rail and that would extend the length of the dead section. Incidentally, the rear driving wheel also shows just how close the back of its flange is to the straight rail which is an opposite polarity at this location. As has been said many times, it only needed the rail breaks to be moved a bit farther away from the frog, like in the FB electro frog turnouts, for the problem to disappear. I have observed this too. The laws of physics suggests it may(?) be something to do with centrifugal force? At higher speeds and therefore higher inertia, the locomotives wheels are pushed harder against the inside face of the outside rail. You can imagine with the Coronation above, that the flangeless wheel might 'hang out' farther as the loco travels faster through the curve. As we all know, drive too fast on too tight a radius, and the centrifugal force will even cause the loco to fall off... on the outside of the curve of course. There appears to be considerable variation between apparently identical models... have a look at your one example, the Clan, do the trailing bogie wheels actually touch the top of the rail? Some do, some don't. I notice that you have very few Hornby pacific's on your list and you haven't tried the L1 either. Trust me, other forum users do know what we're talking about here, because we found out the hard way and I hope that the above photo's communicate at least some of the issues clearly. Phil Edit: Just to clarify, I am still buying and using these points for the scenic sections of my layout, but I do now always make the previously mentioned modifications. They still represent a relatively straightforward way for a non-trackbuilder to acquire fine-scale bullhead turnouts in OO gauge.
  6. Hi PMP. Absolutely, checking the back-to-backs is always the first step. But there are other situations where problems can occur and significantly these are almost always encountered when using the turnouts curved track. These include: # double-pivot pony trucks that cause the wheels to ‘crab’ at an angle when traversing curved track, therefore the flanges ride at an angle against the inside of the rail and this widens their profile, reducing the effective back-to-back. If the bogie ran true then the back to back would be fine, but when running at an angle it is enough to short at the unifrog. A number of Hornby locomotives feature this pony design, the L1 front bogie being a particularly notorious example. (There is a locomotive-based solution to this particular characteristic described elsewhere on the forum). # long rigid wheelbase loco’s where again, the outer wheels track at a slight angle on the curved rail, enough to short out the unifrog - this time due to the length of an inflexible chassis. # the flangeless trailing bogie wheels favoured by Hornby on many of their 4-6-2 locomotives. These ‘hang’ over the outside curved rail and can short across the top of the adjacent rails of opposite polarity. # some RTR stock has wheels fitted with a slightly bulbous back profile, that are proud enough to cause a short. Some of these features give intermittent problems, some can be exacerbated when there is a curved approach to the turnout rather than a straight one, because the curve seems to ‘set up’ the angle of approach to the turnout slightly differently. It is such a shame that the isolation breaks either side of the frog weren’t placed just a millimetre or two farther away from the nose, it would have avoided all these issues. That’s essentially what you are doing when modifying the points either electrically, or with epoxy/varnish insulation. It would be easy to moan on about this being a PECO problem, but the reality is that it is nearly always a combination of PECO’s very tight electrical tolerances around the unifrog and the RTR’s manufacturers’ design approach that affects the running characteristics, and the two solutions fall foul of each other when they meet up.
  7. Yes, it is a classic ‘catch 22’. Those most at risk, the elderly, have most to fear and least to gain from the tourism re-start. But those still of working age have most to gain and are less at risk themselves. That’s the eternal dilemma with this virus!
  8. You have described very well the theory and the marketing concept behind the unifrog. But as this thread has highlighted, that is not everyone’s experience when they actually do wire up the frog, which it sounds like you have not yet done. Seriously, it will depend upon what you are running through the turnout. A lot of stuff, it works absolutely fine, as intended, no problem. However some other stock can encounter the shorting out problems that others have described in this thread. Your choice is therefore between keeping the dead frog and accepting that some loco’s will need a prod if they stall on the dead bit (mostly likely short wheelbase stuff) OR wiring up the frog to improve electrical continuity - but then some wheels might create a short because of the unifrog design. So as designed, it’s an ‘either/or’ situation. If you want both the smooth running provided by electrical continuity and to avoid the shorting out, then that’s where the modifications come in. Of course there is a third option, to leave the point unmodified, wire in the frog, but don’t run anything that you find shorts out on it.... Nobody’s telling you that you have to modify these turnouts, we’ve just explained how to do it if you find yourself in the same situation as us, and want to do something about it.
  9. Here in Gods Own Country, folks have been remarkably compliant with the social distancing rules and respecting others... and they still are. Probably something to do with the age demographic here, a good proportion of the residents are in an ‘at risk’ Category. There is much angst and wringing of hands in Cornwall at the moment about the unfettered return of the emmets after 4th July, when much of the tourist infrastructure is due to re-open and the allegedly plague-riddled, rubbish dumping hoardes finally arrive to infest our nice quiet fishing villages and beaches! We’ve got used to having the place to ourselves, and a very pleasant interlude it has been too!
  10. No-one that I know of. Quite possibly, no-one at all. People who are in the market for these turnouts are unlikely to be enamoured by dead frogs. I think this is a classic case of somebody at PECO coming up with a clever concept, then squeezing the tolerances too hard to try and make it workable in practice, then Introducing it on totally the wrong product. The EMGS turnout, using the bullhead rail and produced for them by PECO in electrofrog format, is exactly how the 16.5mm gauge version should have been specified.
  11. I know they have gone up in price a lot, but you’ve just confirmed that Hornby pacific’s are as expensive as an O gauge loco these days!
  12. Hi Rob, Yes, using varnish is a 'quick fix' but the problem will return with wear, or it may give rise to stalling problems as you are creating a 'dead section'. It also won't last long if you use a track cleaning rubber! The modifications, I agree, are rather more tedious, but they do give you both a permanent resolution and better electrical continuity. Nice ballasting, by the way...
  13. Hi Dave, Gilbert, The photo below (of an unmodified turnout) shows exactly where shorts can occur. Different Loco's or stock seem to short out at different places... Certainly the first thing to do is check your back-to-backs. Then look for where the wheels might be being pushed against the nearby rail with the opposite polarity, it could be any one of the three places indicated below, where rails of opposite polarity are close to each other. Problems mostly occur when stock is taking the curved route. As mentioned before, loco's with a short double-pivot front pony truck such as Hornby's L1 or P2 are particularly prone, also Hornby Pacifics with the flangeless trailing pony truck wheels that swing out of gauge on curves, and some Loco's with long wheelbases. For some reason I still haven't fathomed, I have one Bachmann Deltic that does it too, but not others. The modifications I make are shown on page 46 of this thread. RFS above has kindly provided a link above. Essentially, I convert the turnout to an electrofrog format. The Unifrog can short out in any one of the three places ringed red: usually it is caused by the back face of a wheel flange touching the opposite polarity rail. Hornby's flangeless training pony wheels on their Pacific locomotives can also swing outwards on the curved rails, bridging the gap and creating a short. With the unifrog, it is the frog nose, and the two check rails aside of it that change polarity when the frog is thrown. The modification makes all the adjacent rails the same polarity as the frog, and moves the electrical breaks further away from the frog.
  14. I’ve lost track of what month it is, thanks to lockdown, let alone what day of the week... Is it April 1st today?
  15. Also: 5807 - 12/34 to 1/39 (Yeadon) 5808 - 6/34 to 9/38 (Yeadon) 5141 - 12/29 to 1/37 and 7/37 to 11/38 (Yeadon) Shedbash shows 5798, 5807 and 5808 spotted at Retford (GC) 36E on Sunday 20th February 1938.
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