Scalefour Forum

Hello - I want to design a fiddleyard where of course space saving is one of the main criteria.

All my stock I design to be able to go round a 4 foot curve, which is 1219mm. I have a question - what is the most space saving turnout with a minimum radius of 4 feet? I don't need it to look in any way prototypical.

Prototype points, as they appear on the Society templates, have a "closer radius" and a "switch radius". The turnout with the "closer radius" not less than 1219mm is the A6, where the radius is 1240mm. The A switch radius, whether the turnout is an A4, A5, or A6, is said to be 1928mm.

Am I right to infer that the "closer radius" is the radius through the closure rail area?

It would seem the A6 point is closest to what I want if I'm copying the prototype, though I don't need to for appearance. I have made a successful A6 point so I know it's practical for me. But maybe I could design one that has the radius that little less, at (say) 1220mm?

So supposing I was to design one: - from my experience building points, I know that the switch is where most derailment problems are likely to occur, so I think it might be advisable to stay with the A switch, even though the radius is so much greater than my 4 foot - but, given a model overscale joggle, what length would a switch be to have a 4ft radius equivalent? - or would that be to invite disaster? Obiviously, if I designed a turnout with 4ft radii through both switch and closure, I would make one and test it before committing it to layout plans.

I was looking for a layout planning sub-forum but couldn't find one. Maybe I should ask this question on Templot Club too or instead... Anyway thanks in advance if anyone has any thoughts.

I cannot help with your specific query Julian but if space is limited it might be better to consider alternative fiddle year designs such as cassettes, traversers or sector plates. Any size of turnout will always take up some space which will reduce the length of the storage roads. One of the methods mentioned will remove this disadvantage.

Terry Bendall

Terry Bendall wrote:I cannot help with your specific query Julian but if space is limited it might be better to consider alternative fiddle year designs such as cassettes, traversers or sector plates. Any size of turnout will always take up some space which will reduce the length of the storage roads. One of the methods mentioned will remove this disadvantage.

Terry Bendall

I had a quick play in Templot and an A6 (radius 1205mm) plus reverse curve to achieve a parallel track on the turnout side is about 485mm long. So a considerable saving can be made. Chris Gough made a driven traverser for Cadhay Sidings https://www.scalefour.org/forum/viewtopic.php?f=9&t=3774&start=200#p70543

Any design depends on the size of the yard, so some further detail may assist those giving advice.

HTH

Would it help to copy a Peco turnout, scaling up the lengths by 18.83/16.5? Peco stuff has a good record for getting models round curves and is systematically shorter than scale turnouts with the same crossing-angle.

Do you actually need conventional switches? If the turnout is not seen, would a stub turnout do?

I'm not sure if this saves length, but it might be easier to make. Stub turnouts work well as an alternative to n-throw switches.

If you are used to building your own points, design one using two curves superimposed on top of one another.
The tightest curve being 4ft.

You can do this in Templot.

What other requirements do you have for the point?

An A6 standard straight point gives a radius of 47.4" radius an A6.25 gives 52.4" radius.

Gordon A

Thank you for those responses already. Terry - yes, I haven't discounted a traverser or whatever. Windander the fiddleyard is at a very early stage of design, not even drawn yet. The layout proper is a prototype place and is fixed in my mind. It will feed under a bridge into the FY on two tracks (that are bi-directional) and, (this is now all flexible, an * denotes what might change) I'm thinking I'll want four* storage roads the length of 4* carriages, the gap between each track yet to be determined. The locomotive that brought the train in will draw forward onto a loco+tender length traverser and then set back, using the scenic part of the layout as part of its shunt to get to the head of the next departing train using either track. Some shunting moves will involve stock being propelled from the scenic part onto the FY, and this is where the reverse curve may become an issue. The 485mm length to a parallel track is very useful information - track how far apart? I'll have to learn to use Templot...

So a traverser for the whole thing may well be easier, but I'm interested to know about a minimum length turnout all the same. I'm rather confused about the various radii for an A6 quoted - Winander 1205mm, my 1240mm and Gordon's 47.4" (which is pretty much what I wanted). Think Guy I'll stick with normal switches, and thanks for the thought re scaling up Peco.

I'm by no means an expert with Templot but I get the same figures as Gordon with an A6 turnout having a radius of 1205mm (47.4") and a length of 267.65mm

John

For minimum length turnouts use them in Y configuration. eg If you superimpose a Left hand A6 over a right hand A6 then omit the straight track you get a Y point which is much shorter but has the same radius.
(Or you can keep the straight track and build it as a 3 way!)

Julian Roberts wrote:The 485mm length to a parallel track is very useful information - track how far apart?

I think we are all agreed on dimensions (from Templot) of an A6 despite using different units. The track centres are standard 12" to the foot minimum for running lines, a scale 44.67mm between centre lines.

One thing to consider is that running line clearance between tracks gives very little room to handle stock if adjacent roads are full. Spacing further apart will ease the reverse curve.

best wishes,
Richard

Referring to traversers, I happened across this on RMWeb the other day in which Mikkel refers to Linear Sliding Guides. I am toying with the idea of them myself.

Guy Rixon wrote:Would it help to copy a Peco turnout, scaling up the lengths by 18.83/16.5? Peco stuff has a good record for getting models round curves and is systematically shorter than scale turnouts with the same crossing-angle.

Do you actually need conventional switches? If the turnout is not seen, would a stub turnout do?

I'm not sure if this saves length, but it might be easier to make. Stub turnouts work well as an alternative to n-throw switches.
3688542938_da56f53147_o.jpg

Guy,

Where is the five way stub point please?

Gordon A

steamraiser wrote:Guy,

Where is the five way stub point please?

Gordon A

https://model-railroad-hobbyist.com/node/10584 is where I found it. That article says: "I came across this post because I was researching the location of an unusual five-way stub switch, reputedly in New Zealand and associated with the Rimutaka Incline railway. But after considerable searching I have not been able to identify the actual location. The only available pics that I can find suggest that the tracks are active, presumably in connection with a railway museum or heritage train."

It’s given me food for thought for space saving and increased length of storage yards. Not sure how practical it would be for running at a scale 60 mph though. Reading through the article, it looks as though some of our own Tony Wilkins’ work is featured a bit further down.

Philip

Julian Roberts wrote:All my stock I design to be able to go round a 4 foot curve, which is 1219mm. I have a question - what is the most space saving turnout with a minimum radius of 4 feet? I don't need it to look in any way prototypical

Hi Julian,

Templot has a setting for this:



Using the 1:24 short model switch and a generic-pattern V-crossing, I think this is the shortest practical straight turnout for 48" radius in P4 in Templot.

For 48" radius you can get down to 1:5.62 for the crossing angle. The length is as shown on the 10mm grid.

1:24 means it uses the same size switch blades as an "A" switch, if you have a filing jig or buy them ready-made.

If you could spare a little more space, I would go for the 1:32 switch (same as "B") instead for an easier switch deflection in hidden sidings.

cheers,

Martin.

Martin Hello thank you for seeing this thread. That's brilliant. I've established there is 35mm between tracks on the Kettlewell turntable/traverser which is a good benchmark for me. Now I need to establish what the length would be with this turnout to the fouling point on parallel track at that 35mm spacing, assuming the same 48" radius reverse curve. I'm happy with A switches by the way from actual operating experience.

I will need to learn to use Templot to create this layout. I think it is more achievable than my St Enoch idea last summer. However simply to establish the above information will enable me to design the offstage requirements and general concept before getting down to the fun stuff.

(I wonder how this non prototype short model switch compares with a Peco point scaled up to gauge.... )

Hi Keith thanks also for your suggestion. It's possible I could turn Martin's model turnout into a Y as you suggest. I haven't fully thought out everything: coaches as well as shorter vehicles will need to be propelled and the problem may be buffer locking with those radii. For that reason I may need two straight roads and two turnout roads.

I will need to make a test reverse curve (mimicking the Martin's turnout plus return to parallel) to check buffers of shorter vehicles and pilot locos don't lock. A traverser would avoid all this thinking and save space but I find trackwork more interesting than carpentry!

Guy Rixon wrote:

steamraiser wrote:Guy,

Where is the five way stub point please?

Gordon A

https://model-railroad-hobbyist.com/node/10584 is where I found it. That article says: "I came across this post because I was researching the location of an unusual five-way stub switch, reputedly in New Zealand and associated with the Rimutaka Incline railway. But after considerable searching I have not been able to identify the actual location. The only available pics that I can find suggest that the tracks are active, presumably in connection with a railway museum or heritage train."

Thanks for the reply Guy.

Julian - traversers are not all about carpentry - there's potentially a pile of electromechanics too!!! Happy to have a chat about mine at some point.

David - I thoroughly recommend the type of sliding guides referenced in your post. Generally they have much less slop than drawer runners and as a result I've found them much easier to mechanise accurately once the runners are set up parallel. the downside is that without the drawer runner slop you definitely do need to get them parallel!

CDGFife wrote:Generally they have much less slop than drawer runners and as a result I've found them much easier to mechanise accurately once the runners are set up parallel. the downside is that without the drawer runner slop you definitely do need to get them parallel!

Hi Chris,

If you do something like this, there is no need for great precision in the runners:


Using a single cord instead of the two shown makes it easier to set up a constant tension in it, before clamping the board attachments to it.

Cords and pulleys: https://jimmygreen.com/1007-Standing-Rigging

cheers,

Martin.

CDGFife wrote:David - I thoroughly recommend the type of sliding guides referenced in your post.

Thank you, Chris, and also to Martin. Very useful.

Martin Wynne wrote:

CDGFife wrote:Generally they have much less slop than drawer runners and as a result I've found them much easier to mechanise accurately once the runners are set up parallel. the downside is that without the drawer runner slop you definitely do need to get them parallel!

Hi Chris,

If you do something like this, there is no need for great precision in the runners:

traverser_tensioners_level.png
Using a single cord instead of the two shown makes it easier to set up a constant tension in it, before clamping the board attachments to it.

Cords and pulleys: https://jimmygreen.com/1007-Standing-Rigging

cheers,

Martin.

You might be lucky and get a drawing board en route to the tip, or perhaps its a few years to late now

There will be loads of ways of tackling a traverser but I must point out that anything that slides has the potential to be a disaster. Try and do it any other way first. If it needs precision parts then you're probably about to do it wrong. A thorough understanding of kinematic design is required.

Cassettes are a much safer solution.

DaveB

I don't see why anybody would need to mechanise a fiddle-yard traverser. Why not just slide it by hand?

Further, and picking up Dave B.'s point, why not make it as a multi-road cassette? This would have have slightly better ergonomics than separate, train-sized cassettes that have to be lifted over each other, but the precise part of aligning with the exit tracks would be the same.

It's now going to look as if I've wasted everyone's time. Hopefully it isn't the case. I've only recently built this A5 Y point for Calderside "kickback sidings" which are an addition to the fiddleyard, sitting behind the layout. (The fiddleyard by the way is a traverser/turntable that works to all intents and purposes perfectly, used for many exhibitions. It was described by John Stocks in the Snooze some time ago, I'll edit this to say which number if I find out.)(I should add that is a significantly engineered and quite heavy piece of kit - no half thought out iffy stuff here!)

Like the turnout Martin showed it is 190mm from the blade tips to the crossing V. The fouling point with two of my coaches (57ft I think) is 300mm (or 1 foot) from the blade tips. I haven't worked it out yet but suspect the fouling point would be the same for the tighter straight point. However two running lines leading up to these points will need to be wider apart than the normal 6 foot way to give room for the fanning out tracks so this may not be the answer for me.

Doing an A5 wyed means that the radius is much larger than the curved road of a straight A5, which is why I made my above suggestion of using two curved roads, keeps the 4 ft radius but shortens the switch a lot, and increases the crossing angle, it won't be a 1:5 anymore. Mind you I think A5 is a bit tight, I would use A6 curved roads in the same way.
Below on the left, is a turnout built using B7 as a basis using the same principle. Compared to the standard B7 on the right the length is reduced by 30%. And of course it diverges to the clearance point in a similarly reduced distance.

davebradwell wrote:There will be loads of ways of tackling a traverser but I must point out that anything that slides has the potential to be a disaster. Try and do it any other way first. If it needs precision parts then you're probably about to do it wrong. A thorough understanding of kinematic design is required.

Cassettes are a much safer solution.

DaveB

I'm absolutely inclined to agree with this Dave - for myself. However here is the write up that was in the Snooze describing our traverser and turntable