Masokits etched chairs turnout construction for Kyle of Lochalsh

Discuss the prototype and how to model it.
davebradwell
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Re: Masokits etched chairs turnout construction

Postby davebradwell » Sun Nov 01, 2020 9:53 am

Yes Martin, I add on the gauge widening when choosing my drills to get the right check gauge. It's perhaps an odd way to do it but I go over the whole thing with vernier and drills after construction to see what I've ended up with. Thanks for confirming the check figure is constant.

DaveB

Julian Roberts
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Re: Masokits etched chairs turnout construction

Postby Julian Roberts » Sat Nov 07, 2020 5:08 pm

Thanks for the ideas re drill shanks Dave and confirmation of standards Martin. It's problematic actually measuring things even with a digital vernier.

Now I've got some Masokits stretcher bars on and they work fine. But the blade clearance is 0.9 on the first switch, and 0.85 on the second. Clearly I'm doing something Mike Clark hasn't thought I might. I think it's because I've left the foot of the blade as chunky as possible. By filing the stockrail side of the blade only as far as the web, not half way through it, at the tip. So that the rail is flat at the tip where it fits against the stock rail, but no thinner than needed. So, more filing needed on the running surface of the blade than normal perhaps.

As far as I can work out, even if I had a BB of 17.47, and 0.35 flanges, the blade gap would have to be 0.66 for there to be any conflict. I've gauge widened the whole switch by 0.1, so the gap would have to be 0.76 to conflict. So I think I've got enough room. Anyway 3 test vehicles go through without any problem. I can't test my very deviant loco that does have narrow BB till I've gapped and wired all this up.

Anybody any thoughts? Certainly I like the look of the small gap, I always think the prototype looks smaller than our 1.4mm gap, though I'm sure that's just some visual trick of the eye.
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20201107_161600 narrow blade gap.jpg
20201107_161600 narrow blade gap.jpg (94.96 KiB) Viewed 2253 times

Julian Roberts
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Re: Masokits etched chairs turnout construction - stretcher bars

Postby Julian Roberts » Sun Nov 22, 2020 8:21 pm

I expressed some doubt a while back as to whether the Masokits stretcher bars were too stiff, but I have found they operate perfectly. Here is a video showing they open and shut the blades all the way along the planing length, with a robust but light feel when operating the wire, which will in time be hooked up with a proper mechanism actuated by a lever frame.



The main thing about attaching them is not soldering up the whole switch solid. Preparation is quite intensive. As best as I can I remove any slightest trace of solder from where the stock rails solder to the slide chairs. I coat the stock rail, slide chairs, underneath and back of switch blades with several coats of permanent marker pen ink. The blades before being fixed down to chairs are given a tiny dab of solder where the stretchers attach to them, while the rest of the front of the blades is also covered in permanent marker.
20201025_161119.jpg
Switch blade prepared, a rather too generous dob of solder


With the blades then fixed to the chairs, the stretchers (which I file a little with a V shape where they fix to the blades to look more like the real thing, slightly less noticeable) are held in place under the rails with the blade held against the stock rail. A small piece of paper gives clearance where the bars go under the stock rails. The main thing now is to get no solder behind the blade - any trace will upset the fit against the stock rail. So long as the blade is held against the stock rail with the piece of paper interposed the solder hasn't run round behind.

20201105_172855.jpg
Basically showing the soldering up moment, though blade not against stock rail


A fairly quick dab of the iron onto where the blade has been tinned does it. Then onto the other blade, similarly held against the stock rail.

20201103_131057.jpg
All fixed up


My problem in the previous post came slightly overtinned blades and from being too delicate at this point - the bars are robust and won't disintegrate. Titanium tweezers help get a good join to the blade and seated properly into the web. The blades now open roughly the normal amount.

I've found after four points and four point kits that I've got far more of the plain track chairs than I need, but not quite enough of some of the point components - the check rail chairs and block chair halves are not generously enough supplied.

Here is what is gernerally seen to be a notoriously liable to derail 6 wheel van fully at home, so I'm pretty happy at how these are turning out (pun) :o .



Two videos of these two turnouts in action


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grovenor-2685
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Re: Masokits etched chairs turnout construction

Postby grovenor-2685 » Sun Nov 22, 2020 9:33 pm

Excellent job Julian, those blades are a really good fit. I have found Masokits stretchers a bit frustrating, I do one that comes out just right then the next will play up and not solder together properly but you seem to have cracked it.
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Re: Masokits etched chairs turnout construction - stretcher bars

Postby Julian Roberts » Sun Nov 22, 2020 10:01 pm

Thanks Keith!

I saw someone else saying somewhere, what I've found, there's no need to hold back on the solder when assembling the stretchers, so that's what makes them strong. Though there is the bit of filing to do at that point, that's the longest bit of work I think...

Just completing previous post, here is a photo of the tandem switches, and my 782 negotiating each road video



Worth saying, that the optional actuating part of the stretcher bars isn't live to either blade, potentially a very useful feature.
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20201114_172607.jpg

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Re: Masokits etched chairs turnout construction - irregular curving single slip

Postby Julian Roberts » Tue Dec 01, 2020 9:19 pm

My first diamond of any kind, this is a single slip for my Kyle of Lochalsh project, with a gentle curve on both through roads, and with an approx 1:9 crossing at one end, and approx 1:7 at the other.

Single slip as built.PNG

55216 ambaile.PNG

Single slip view.PNG

Tony Wilkins' thread on bullhead turnout construction alas leaves Slips for a future instalment, so I'm taking the Digest notes as a guide but going my own way with my own mistakes. I started with the two Vs, and then followed my previous practice of getting the whole acute crossing done. Looking at the Exactoscale diagrams and my two photos of the slip at Kyle, the rail joint is much nearer the centre of the whole diamond, so I made these rails that length. There is a straight section at the switch between the set (which is on the other rail) and the stockgauge.

20201129_203821.jpg
Acute crossings and knuckle/wing/closure rails done
20201129_203821.jpg (28.48 KiB) Viewed 1827 times


Making the first stockrail was simple enough, but it took me a modelling whole day to get the two point rails making the first K. I could see the logic of doing these first another time but now I've got to fit these into the quite short length. Even filing the point rails correctly took me one complete failure (too short by the time I'd got the angled bit right).

20201130_210809.jpg


Now the other stock rail is positioned. I'm slightly guessing for which chairs to use of the types supplied on the Masokits etch. These are not all correct I see already. I'm slightly surprised that our Society doesn't have a photo to which to refer. The plan view from Exactoscale is very useful though I'm not absolutely confident what they look like side-on. Anyway I don't suppose it matters an awful lot in the context of a layout, but each chair is a choice, it would be nice to get the one nearest to correct! As it is, I have the above photos to go on, which I suppose is good enough really.

20201201_183629.jpg
20201201_183629.jpg (29.3 KiB) Viewed 1826 times


Amazingly useful info just posted by James Dickie. viewtopic.php?f=5&t=7277

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Will L
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Will L » Tue Dec 01, 2020 11:59 pm

You might be interested in reading the relevant bit of our Digest Sheet 23.6.2 Advanced Turnout Construction. Link downloads a PDF. The really relevant bit is on the second page under the heading Diamonds and Slips and goes into details on K crossings.

davebradwell
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby davebradwell » Wed Dec 02, 2020 9:43 am

I suggest you bend the check rail very sharply, Julian, despite knowing the prototype bend radius. This is a difficult area and the test is to see if a wagon can be pushed down the wrong way. I usually cheat with the filed bits too, making them just a little longer and sharper than the prototype blunt nose. Success seems to hang on a few thou' here and there so an awakening for anyone at all blase about b-b setting. Keep sighting through the flangeways.

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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Wed Dec 02, 2020 2:57 pm

Hi Will thanks yes that was what I was referring to but I haven't laboured the point about where I was following the recommended order of service and where I was departing from it.

In fact I think now I should have started with the obtuse crossing as being all curved it hasn't got to line up with the Vs in straight lines.

Hi Dave thanks for that advice. I was wondering that very thing, whether to cheat with sharper point rails.

The photo shows the distance a wheel travels unchecked.
20201202_143913-1.jpg
Travelling left to right RH wheel unchecked for 5mm or so

The obtuse crossing is 1:7.5. The instructions referred to above say 1:8 is the prototype largest number crossing possible but already here there is 5mm unchecked travel. I assume in S4 the unchecked travel would be less?

I haven't figured out yet what the BB will do, whether a blasé attitude below or above the recommended amount will be an awakening :?

Well I'll be finding out soon....!

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Will L
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Will L » Wed Dec 02, 2020 3:58 pm

Julian Roberts wrote:Hi Will thanks yes that was what I was referring to but I haven't laboured the point about where I was following the recommended order of service and where I was departing from it....
...The obtuse crossing is 1:7.5. The instructions referred to above say 1:8 is the prototype largest number crossing possible but already here there is 5mm unchecked travel. I assume in S4 the unchecked travel would be less?

I haven't figured out yet what the BB will do, whether a blasé attitude below or above the recommended amount will be an awakening :?

Well I'll be finding out soon....!

Good, I just wanted to be sure you were aware of the issue. Dave's points are all about minimising the possibility of wagons going the wrong way (small wheels are more prone) and does demand that the match between the BtoB and the dimension across point of the central check rail pair is as close as possible. Doing this on a curve only makes the problem worse. Of course there is such a thing as a switched crossing...

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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Wed Dec 02, 2020 5:53 pm

Will L wrote: and does demand that the match between the BtoB and the dimension across point of the central check rail pair is as close as possible.


Will thanks for your advice - I'm not understanding this sentence, sorry to be thick; any chance you could sketch what you mean?

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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Tony Wilkins » Wed Dec 02, 2020 10:38 pm

Julian Roberts wrote:In fact I think now I should have started with the obtuse crossing as being all curved it hasn't got to line up with the Vs in straight lines.

Hi Dave thanks for that advice. I was wondering that very thing, whether to cheat with sharper point rails.

The photo shows the distance a wheel travels unchecked.
20201202_143913-1.jpg
The obtuse crossing is 1:7.5. The instructions referred to above say 1:8 is the prototype largest number crossing possible but already here there is 5mm unchecked travel. I assume in S4 the unchecked travel would be less?

I haven't figured out yet what the BB will do, whether a blasé attitude below or above the recommended amount will be an awakening :?

Well I'll be finding out soon....!


Hi Julian.

Regardless of whether slips are straight or curved, I always start with the acute crossings as these for me are the reference points.
With S4 dimensions the flangeways being 0.1mm narrower than P4 means that for a 1:8 crossing the gap will be 0.8mm shorter (the difference x the angle). To some extent this discrepancy can be countered by making point rails thinner at the tips and therefore that bit closer to the knuckle. Another critical dimension here is the track gauge, which must not have any widening. Your picture (which hasn't copied over) shows the gauge touching both knuckle rails, which is as it should be. However the knuckle bends do need to be exactly opposite one another and I am not entirely convinced that they are. This is a difficult area to gauge accurately.
The K crossing check rails should be installed using the check rail gauge or better still a pair, one on each arm of the rail.
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Tony.
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby grovenor-2685 » Thu Dec 03, 2020 12:57 am

Tony Wilkins wrote:However the knuckle bends do need to be exactly opposite one another and I am not entirely convinced that they are.

Yes, if the timbers are at right angles to the centreline, which they appear to be, then both knuckles should be centered on the same timber, the top one is, the bottom one isn't.

Is that metal strip a correct gauge? It doesn't look it, maybe you are just using it for a straightedge and the bottom knuckle is not fixed yet.
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Thu Dec 03, 2020 7:55 am

Hi Tony and Keith

Thank you for your helpful comments. Yes the timbers are done by Templot and look to be at right angles at the centre of the obtuse crossing.

So the unchecked distance is say 4mm even in exact scale or a foot in reality! So running depends on perfect alignment.

Yes I had another 2 goes at the opposite stock rail.
20201202_175843.jpg

The gauge block was made for me, being 45mm long.

20201202_183514.jpg


I found myself wondering what the radius of the curvature of the bend at the centre of the crossing should be? Success with this 3rd attempt seemed to be partly to do with curving it over a 10mm drill shank. Sighting along the route (only one point rail installed so far) looks much better than the completed first K crossing.

Templot now shows 3 lines for the common crossing knuckle bend. That feature would be very useful here.

ted.stephens
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby ted.stephens » Thu Dec 03, 2020 9:28 am

Here is an extract from an old p'way drawing, SRE 42L, showing details of a 1:7 1/2 obtuse crossing. The radius is given as 4' 8 1/4".
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SRE42L 1 in 7.5 Obtuse Crossing.JPG

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Will L
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Will L » Thu Dec 03, 2020 11:44 am

Julian Roberts wrote:
Will L wrote: and does demand that the match between the BtoB and the dimension across point of the central check rail pair is as close as possible.


Will thanks for your advice - I'm not understanding this sentence, sorry to be thick; any chance you could sketch what you mean?

What I was on about is well illustrated by the drawing posted by Ted Stephens. Because the check rails are bent to a radius to form the centre diamond the check gauge at the centre of the point will necessarily be less than elsewhere.

The problem here is that the tolerances in these circumstances get progressively smaller as the angle gets greater. As we know, on the prototype they wont go above 1:8 and its far easier to have tight control over tolerances at full size.

The sensitivity to going the wrong way is significantly affected by both the unchecked distance and the difference between the check gauge and the BtoB at the centre of the diamond. So the bigger the radius of this bend the more likely you will get problems. We also need to remember that the bigger the difference between the effective check gauge and the BtoB of a given wheel set the greater the likelihood of wheels going the wrong way, so in this specific circumstance we want the BtoB to be as tight to the check gauge as possible (i.e. at the low end of the tolerance). As BtoB varies from wheel set to wheel set, if problems do occur it will tend to be specific vehicles. Even then it will depend on how the vehicles centre line relates to the track centre line. i.e it is most likely to affect wagons being pushed by a vehicle behind, particularly given the extra tolerance between tack gauge and wheel gauge we get form P4 standards.

So from the point of view of reliability, this is perhaps one occasion when we might not want to follow prototype practice too closely. Firstly because we can afford not to blunt the angled ends of the running rails, as this reduces the unchecked distance, and we are nothing like so worried by the thin end getting damaged /worn. Secondly, by bending the check rails as sharply as possible, therefore reducing the length of under gauge section at the centre of the diamond.

This also explains why gauge widening should not be applied.

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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Thu Dec 03, 2020 1:57 pm

That's great Will. Thank you I now understand. Interesting that my previous blasé attitude that less than 17.67 is OK seems to be an advantage here. I was not expecting that - rather, I expected the opposite.

Lots to think about here and try out.

Interesting you don't mention the curve of the stockrails. The crossing will be wide to gauge between the asterisks. I'm wondering whether to relay the first stockrail now...! - as the second one looks so much better when sighting along the route.

I'm wondering what the prototype criteria was for the curves in stock and checkrails.

Thanks so much Ted for posting the image. Exactly what I needed!!

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Will L
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Will L » Thu Dec 03, 2020 4:16 pm

Julian Roberts wrote:...Interesting you don't mention the curve of the stockrails. The crossing will be wide to gauge between the asterisks...

In that position over such a short length I can't see there is any problem. Gauge widening over the whole diamond would be a totally different proposition.

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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Tony Wilkins » Thu Dec 03, 2020 4:22 pm

Hi Will.
Even the prototype had problems with obtuse crossings as is well known and have done their best to reduce the numbers.
I found an entry in the BR rule book a while back forbidding the stopping of goods trains whilst shunting with a slip or diamond under the train as there was a risk that if a wheel set stopped on the middle of the obtuse crossing, it could go the wrong direction when reversed.
I will see if I can find the number.
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby grovenor-2685 » Thu Dec 03, 2020 7:13 pm

Will L wrote:
Julian Roberts wrote:...Interesting you don't mention the curve of the stockrails. The crossing will be wide to gauge between the asterisks...

In that position over such a short length I can't see there is any problem. Gauge widening over the whole diamond would be a totally different proposition.

You can't measure the guage there anyway. :)
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Sat Dec 05, 2020 9:55 am

davebradwell wrote:I suggest you bend the check rail very sharply, Julian, despite knowing the prototype bend radius. This is a difficult area and the test is to see if a wagon can be pushed down the wrong way. I usually cheat with the filed bits too, making them just a little longer and sharper than the prototype blunt nose. Success seems to hang on a few thou' here and there so an awakening for anyone at all blase about b-b setting. Keep sighting through the flangeways.

DaveB


Is it possible to make a 1:7.5 obtuse crossing proof against the wheelset going the wrong way I wonder. What angle do you have Dave? On test I find no vehicle actually goes the wrong way unless I push it sideways, in which case at the last moment it can.

I also wonder if it's possible to get a finer point on the point rails using steel rail? With my NS rail a tip that has any strength comes to pretty much the blunt point mark on the Templot template.

Would seem I will have to have a rule on this layout just as the rule Tony mentions above, no stopping on the single slip. Though hopefully slip road itself won't be any problem.

Photo shows the only problem so far. Crab loco (on push mode, gear grub screw undone) going backwards here the rear driving wheel flangeback was catching on the point rail making the loco give a slight hop. Very small amount of filing on non running side of point rail gauge corner has cured the issue.

But certainly not absolutely confident about this crossing yet! I'll have to set up a test track long enough for the Crab and a couple of vehicles, wired up for power.
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20201205_131231.jpg

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Martin Wynne
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Martin Wynne » Sat Dec 05, 2020 2:11 pm

Julian Roberts wrote:Is it possible to make a 1:7.5 obtuse crossing proof against the wheelset going the wrong way I wonder.

Hi Julian,

The problem with fixed K-crossings is with small wagon wheels, especially when being propelled (pushed), not loco wheels. Larger wheels have a longer length of flange below the rail top.

In P4 I would have built 1:7.5 on a curve as a switch-diamond with moving K-crossings. Maybe with exact-scale flangeways (S4) it would be possible fixed, but you are on the prototype limit for fixed K-crossings where there is curving:

In radius down to:   the flattest angle for a fixed K-crossing is:

60 chains ( 3960ft )........1:8
30 chains ( 1980ft )........1:7.75
20 chains ( 1320ft )........1:7.5
15 chains ( 990ft )..........1:7.25
12 chains ( 792ft )..........1:7
10 chains ( 660ft )..........1:6.5
below 10 chains............1:6
 
This information is dated 1943 for the GWR, and similar rules can be assumed for other companies. For modern Network Rail the rules are even more restrictive.

Martin.
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Tony Wilkins
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Tony Wilkins » Sat Dec 05, 2020 4:13 pm

Hi Julian.

I can add little to Martin's comments other than to state that the slip roads are not where the problems lie.
My own experience with Steel and n/s rail is that steel rail has less strength than n/s at really thin sections. This however occurs at the tip of switch blades. Point rails for obtuse crossings should never get that thin. 0.1mm or 4 thou is thin enough for me rather than the normal 0.25mm.

Martin.
Thanks for republishing this information. I have taken the liberty of copying the data into my track construction thread (with acknowledgements) so it is available there too.

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Tony.
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Martin Wynne
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Martin Wynne » Sat Dec 05, 2020 5:32 pm

Tony Wilkins wrote:Point rails for obtuse crossings should never get that thin. 0.1mm or 4 thou is thin enough for me rather than the normal 0.25mm. Martin. Thanks for republishing this information. I have taken the liberty of copying the data into my track construction thread (with acknowledgements) so it is available there too.

Hi Tony,

Normal for REA bullhead blunt point rails is 1/2" nose = 0.17mm , rather than the 3/4" (0.25mm) for blunt vee nose. (GWR is 11/16" for both.)

You are welcome to the info -- it's actually in the K-crossing help notes in Templot, and has been there for about 20 years. :)

cheers,

Martin.
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Re: Masokits etched chairs turnout construction for Kyle of Lochalsh

Postby Julian Roberts » Sat Dec 05, 2020 7:21 pm

Hi Martin and Tony

Thank you for answering my questions, and giving me and anyone reading this such helpful information. I'm not absolutely sure if this below is all the information required to say what the radii of the crossing is. No doubt designing it on the 1905 25 inch OS map isn't a foolproof thing to do.

Radius of single slip.PNG
Radius of single slip.PNG (8.99 KiB) Viewed 1358 times

Radius of single slip 2.PNG
Radius of single slip 2.PNG (6.4 KiB) Viewed 1358 times


Notwithstanding, so far I don't find any problem. The tender being pushed is 400g or so, to simulate a heavy train in front of the wagon being propelled. I've done the same thing on the other road, train both ways round. I'll add some rails each side of the crossing to test a longer train. I wonder if anyone can suggest how to further test the issue on the bench.



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