While thinking about something else the other day it suddenly hit me that the actual movement I was looking at was 1mm and there would not be that much strain on the joint. Why not just solder the throw bar to the point blades and be done with it? a WTF moment if you will.
so, 1 minute to drill the hole in the middle, 10 seconds to file a bit extra off the copper clad board, and a quick run with the soldering iron later and there we go. The NMRA track gauge even has a thingy to get the point blades the right distance apart.
'The old 3 hole with the new 1 hole (trust me as the photo is a bit crap)'
'2 minutes and we are done'I assume it will last, and if it doesn't its not hard to replace. It might not work with the heavier code 55 rail, but should be fine with the wiggly code 40.
5 comments:
hmm. At the risk of sounding over-engineered....
To ensure there's no danger of both flanges touching the point rails at the same time they would have to be quite a way apart.
Perhaps another solution is to use the finest guitar string from that music shop on the Square bent in a U shape and soldered to the foot of the rail afer being bent through the pc tiebar, copper underneath. That fine guitar string is tiny but quite stiff so you could get away without having to solder to the copper surface underneath; it is finer gauge than the peco pin, plus it solders a lot easier.
Or , perhaps with such small movement soldering to the copper as well would still allow sufficient flex although you probably wouldn't need to do that.
The advantage of this is you could keep the point rails close which would look make your fine trackwork look even finer.
Quentin
Hmm, I'll have to have a think about this, but I can't quite see where you are comming from. the wheels can touch both the point blade and running rail at the same time as the electric polarity is the same.
The guitar string won't be strong enough to throw the point blade, and theres also the possiblity that the point blade will climb out of plane and cause derailments.
From the photo, I reckon the set-up you have built is a good design. The moving sleeper will prevent the point blade rising up - that causes enough trouble for S wheels and wagons going over a blade, never mind TT ones. The key test is whether there is enough flex in the blades and ability for the moving sleeper to move 'along the rails' as well as from side to side to prevent the solder breaking. The proof is in the eating - or in this case, multiple switching of the points by the motor or mechanism that will actually do it. Some point motors can introduce new stresses that can break the solder at point blades. It helps having Cabbage on hand to fix them when it happens at exhibitions.
sorry, didnt explain myself properly.
Im thinking go back to your earlier idea drilling three holes, one in centre for the throw activation, and one each for fine guitar string U shaped 'pivots' that are soldered to each point rail just along top of the throwbar at each end, and bent flat under the throwbar, whose copper surface is gapped somewhere in middle of course for elec isolation.
Firm bending of U against throwbar will ensure point rail doesnt rise relative to the running rail, as throwbar will be locked from vertical movement by the rails. Same as your new system, but rails pivot on throwbar rather than rigidly soldered to it.
These U pivots are just a replacement of the Peco pins you mention earlier I think. Peco pinsd I find annoying to solder, must be the black coating. Fine guitar styring is not only very fine but nice and shiny and solder sticks to it instantly, like phosphor bronze which is what it might be perhaps.
My thinking is of the two point blades being electrically isolated, so each point blade is same polarity as its adjacent rail, rather than point blades soldered as a single unit electrically, which means the opposite rail would be different polarity, thus requiring both wheels shouldnt contact the point blades at the same time and so they have to be far apart from the 'other' rail. A smaller gap is possible with above method as it wont matter if wheels touch point rails and adjacent rails simultaneously as each point rail is isolated, so each is the same polarity as its adjacent running rail. But this means you'll have to gap both rails before they reach the frog.
Just an idea. I use the system for my points and they work well, S scale but teh string is so fine I figure itd work in TT just as well. I like the look of small gaps as possible in points.
Quentin
woops just looked at your photo again and I see you gap the pc board anyway so my overengineered solution re polarity of rails is redundant. tsk. Must be the solder fumes having their cumulative effect (I must read the warning label some time.)
However if flexing causes solder joins to fracture maybe the over engineered solution might be a runner....
Quentin
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