Templot Club Archive 2007-2020                             

topic: 3834S4 discussion about ready to use P4 turnouts
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posted: 9 Dec 2020 17:34

from:

DerekStuart
 
United Kingdom

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I'm puzzled.
Why are people on the S4 forum trying to promote the manufacture of ready to lay P4 turnouts?

Aside from the technical challenges of tolerence, outlined by Martin, there's still the re-wheeling (often requiring chassis modifications, especially for steam). Someone has got to **WANT** to go to P4 and not just see it as one of many options.

But the biggest killer to this point is prototype accuracy. When the World's railways restrict their tracks to 'short, medium and long' turnouts, in both straight and curved, then fair enough. Until then, a limited use of pre-set turnouts geometry will look little different to a wider version of 00 set track.

The irony is that the USA might be the only place where a limited choice of turnouts would work and that is gauged with H0 any way.

Moan over.
Derek

posted: 9 Dec 2020 20:31

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi Derek,

I think the attraction of the pointwork kits is that they provide an entry to the world of track building, a way to get started in P4. After successfully assembling a couple of turnouts kits and a wagon or two, modellers will know if P4 is for them, and think about doing more of it themselves.

It is not necessarily true that building kits restricts you to a "set-track look". If the kits can be assembled curved, it's possible to consider a reasonable "flowing" trackplan from only a restricted range of crossing angles. I have just posted about this in RMweb:
 
 http://www.rmweb.co.uk/community/index.php?/topic/160234-new-range-of-simple-to-assemble-00em-gauge-pointwork-kits/&do=findComment&comment=4225265

This proposed Finetrax range strikes me as very promising. It's not perfect, lower-tech than the Exactoscale kits, but it might enable many more to create Templot track plans with some hope of being able to build them. Let's not put folks off before they have even started. :)

cheers,

Martin.

posted: 9 Dec 2020 21:31

from:

DerekStuart
 
United Kingdom

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Hello Martin

As ever, you make a good point. Incidentally, your graphic showing the tiny difference of curve Vs straight common crossing nicely compliments your recent reply to me on a very closely related question (re producing different crossings).

I am not at all trying to knock this new maker- but I really think the way to encourage people into P4 is to get them used to making track in other gauges first and I suspect this is how 99.9% arrive at P4. Ironically, I am in the 0.1% as apart from trying to badly make a turnout in 009/H0e many years back, my first turnout was P4.

If I could add, however, that the proof of the cast common crossing is interesting and I wonder if it could be adapted for those looking at flat bottom rail; a built crossing doesn't look much like a casting!

Please don't think I'm trying to put people off; only questioning the calls from some on S4 for them to run before they can walk.

All the best
Derek

posted: 9 Dec 2020 21:34

from:

DerekStuart
 
United Kingdom

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PS

Rather than ask this on your RMW thread and confuse some...

You (and other experts) have taught us to make a nice and smooth running turnout, where you cannot feel the transition from crossing/ knuckle/ wing. Yet you can most definitely feel it on the prototype. Of course I'm familiar with the issue of scaled mass, but what exactly causes that jolt/ sound?

Thanks
Derek

posted: 9 Dec 2020 22:00

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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DerekStuart wrote:
Rather than ask this on your RMW thread and confuse some...
You (and other experts) have taught us to make a nice and smooth running turnout, where you cannot feel the transition from crossing/ knuckle/ wing. Yet you can most definitely feel it on the prototype. Of course I'm familiar with the issue of scaled mass, but what exactly causes that jolt/ sound?
Hi Derek,

Are you sure you can feel it? I suspect that most of what you feel is in fact the wing front rail joint. Rail joints are the weakest point in any track, and have to be constantly packed and fettled to eliminate any dip. If the rest of the track is smooth-running long-welded rail, it is likely to make the rail joints through pointwork more noticeable.

If there is a bump running over a crossing, there are two possible reasons:

1. Wear. Our models don't tend to wear down the rails, but real trains do. Especially over switches and crossings where the load is often being supported on less than the full rail width. If the crossing has worn down significantly more than the rails leading to and from it, you are going to feel the effect. A bit like a pothole in the road, and each bump increases the wear.

2. The 1:20 coning angle on the wheels. The nose of the vee is taken down below the level of the wing rails, so that a 1:20 coned wheel can sit firmly on both at the same time. But that means the wheel must drop a fraction as it runs along the wing rail, and rise again after it lands on the nose and runs back up to full height along the vee rail.

The vehicle suspension and a comfy seat should take care of that, and it's not much -- about 3/16" -- but you are bound to feel something.

cheers,

Martin.

posted: 9 Dec 2020 22:18

from:

DerekStuart
 
United Kingdom

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Thanks Martin

Perhaps it's not so much the feel, but the sound- certainly more than just a normal rail joint, so your observation about crossing wear is probably the cause.

I noticed it more in some locations than others, so perhaps areas of high wear?

Thanks again. I really can't wait to get back to making track.... It's good for my blood pressure.

Derek



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