Mid-Cornwall Lines - 1950s Western Region in 00

[checkrail]

Love that curved pointwork and look forward to seeing the final arrangement.  All the best.

[Keith Addenbrooke]

8 hours ago, St Enodoc said:

As Father Christmas and Rudolf prepare at St Enodoc for their work tonight, Veronica and I wish you all a very Merry Christmas and a Happy New Year from our home to yours, wherever you may be.

 

“and also with you.”  
 

Thanks for another year of sharing progress on this great project.  Here’s to 2023, Keith.

[St Enodoc]

1 hour ago, Barry O said:

Iam still looking forward to the appearance of the Shackleton!  Hat, coat see you later!

Baz

You will have a long wait.

[St Enodoc]

1 hour ago, 5BarVT said:

I think you’re right about the straight - it looks odd to me.  A slight curve will look better, but might (will?) affect clearance points on P1/loco spur.  Are either of them tight?

Paul.

Thanks Paul.

 

Appearances are deceptive. Most of the tracks around there are at 60mm centres. There's just under 50mm centre to centre between the two straight bits of track so there shouldn't be any problems. The only possible parallel moves are to/from Platform 1 and between the goods yard and the Loop/carriages sidings. Only one of P1/loco spur/P2/P3 can see a train at a given time.

 

Next time I'm in the railway room I'll play around with the versine rule and see whether I can get a smooth curve in place of the straight while still maintaining the clearance. That will probably be to the accompaniment of the commentary from the Melbourne Cricket Ground on Monday.

[FarrMan]

As Christians, we do not celebrate Christmas, so I will wish John and all on here Season's Greetings. Thanks for all your contributions on this thread, whether informative, whimsical or plain funny.

 

Lloyd

[acg5324]

Merry Christmas John and Veronica.

[drduncan]

Merry Christmas 

Duncan

[Clive Mortimore]

On 18/12/2022 at 15:00, Clive Mortimore said:

Ah Robert there is more than one way to peel a potato (vegan friendly).

 

I lied about having a RSO, it is a TSO but I have now made a RSO and a RF diagram 16 to go with it. The RFs were only allocated to the WR and would have been in service during Sainty's modelling period.

 

The RSO

 

The RF corridor side.

 

 

The RF kitchen side.

 

The pair together.

 

The TSO and RSO together. The TSO is made from bits sent to me by Sainty and there could well be some bits from other conversions in the RF that started life with John.

 

Happy Xmas every one.

 

 

[St Enodoc]

A nice walk this morning to work off some of yesterday's excess calories, followed by the first session from the Melbourne Cricket Ground and the start of the Sydney-Hobart Race was a good introduction to this afternoon's work. I had a good play around with the alignment of the connections to both P1 and the loco spur and there are now, therefore, rather more lines on the board than there were before. A mixture of calculating radii using the versine formula and some trial and error with the templates has resulted in alignments that are a lot better, I think, than they were when I started.

 

I'll have another play tomorrow before I ink in too many extra lines...

[drduncan]

How does a versine ruler actually work?

Duncan

[St Enodoc]

5 hours ago, drduncan said:

How does a versine ruler actually work?

Duncan

Very good! I should have said versine formula rather than versine rule.

[St Enodoc]

Today I went back to the original locations for the four points in the approach track and drew the inner radii as far as the locations where they are parallel to the baseboard edge. For each of the three platforms and the loco spur, I drew tangents a chord that intersected both tangents at the same angle. Finally, I drew in the centre line for a circular curve joining the tangent points. The resulted in even more lines on the baseboard than before.

 

All this gave me enough information to calculate the radius of each curve and the versine, which will let me set out the curves on the baseboard (more lines!). I will probably adjust these a little more to make the track centres as consistent as possible before locking in the design.

 

@drduncan I didn't actually use the versine formula at all this time, relying instead on similar triangles and Pythagoras' Theorem!

Edited December 27, 2022 by St Enodoc

[drduncan]

7 hours ago, St Enodoc said:

Very good! I should have said versine formula rather than versine rule.

I wasn’t trying to be pedantic (this time admittedly…); so how does a versine formulae work and what can I or others do with it?

D

[1466]

6 minutes ago, drduncan said:

I wasn’t trying to be pedantic (this time admittedly…); so how does a versine formulae work and what can I or others do with it?

D

My apologies for taking this off topic; but I’ve tried your  link to rtr conversions to EM without success . Can you check it’s correct , please ? Thank you kindly .

[St Enodoc]

33 minutes ago, drduncan said:

I wasn’t trying to be pedantic (this time admittedly…); so how does a versine formulae work and what can I or others do with it?

D

In full-size railway engineering it's used to check deviations from the correct radius of a curve, so that it can be adjusted during maintenance. I've used it in the opposite way to help set out curves on models but that's more tricky because there are usually two unknowns - the radius and the versine or offset itself. Trial and error can give a good enough answer in the smaller scales.

 

If you want to know more, try this link:

 

https://pwayblog.com/2016/05/09/the-versine-formulae/

 

or hope that a friendly PWay engineer will drop in here...

 

[St Enodoc]

33 minutes ago, 1466 said:

My apologies for taking this off topic; but I’ve tried your  link to rtr conversions to EM without success . Can you check it’s correct , please ? Thank you kindly .

You're right, this is well off topic. Private messages are better for this sort of query.

[drduncan]

10 minutes ago, St Enodoc said:

In full-size railway engineering it's used to check deviations from the correct radius of a curve, so that it can be adjusted during maintenance. I've used it in the opposite way to help set out curves on models but that's more tricky because there are usually two unknowns - the radius and the versine or offset itself. Trial and error can give a good enough answer in the smaller scales.

 

If you want to know more, try this link:

 

https://pwayblog.com/2016/05/09/the-versine-formulae/

 

or hope that a friendly PWay engineer will drop in here...

 

I think I’ll stick with Templot….

D

[St Enodoc]

A nice glass of port with the last of the Stilton has helped me work out that I've been overthinking the approach track problem.

 

The original setting out was fine except for a section of straight track on all the roads as they ran parallel to the double slip.

 

The version I showed a couple of days ago had fixed this except for Platform 1. Because it was now the only straight section, it looked worse than when all the tracks did it.

 

What I've done now, on paper not on the boards yet, is to set out a single circular curve for each track that connects the 760mm radius of each turnout track to the respective straight sections of track running parallel with the loop, from which the carriage sidings spring.

 

Because I've come to this late, and other parts of the alignment (notably the line to Treloggan Junction) are already fixed, there is some fudging needed but only to the extent of about 10mm misalignment from the ideal. This is within a reasonable tolerance for "give" as expounded by my good friend Graham @LNER4479. Here are the "best fit" lines that I sketched out on graph paper at 1/10 scale this evening.

 

Not a versine , similar triangle or Greek philosopher in sight - just some trial and error with common tangents for curves of different radii.

 

Tomorrow, other commitments permitting, I'll get rid of all the pencil lines on the boards (memo to self: buy some more erasers) and draw this in at full size.

 

Wish me luck, as this task is starting to get more than a little tedious...

[Chamby]

3 hours ago, drduncan said:

I think I’ll stick with Templot….

D

 

I think I’ll stick with a drawing pin, length of string and a pencil !

[LNER4479]

You can indeed over think these things. Something to do with bumblebees being incapable of flight, methinks?

 

Just so long as you're not trying to fit a quart into a pint pot (which I'm sure you're not)

 

Merry Christmas 🤗

[t-b-g]

Just to stick a probably unwelcome thought or suggestion into the mix when so much has been done already, I was wondering if there was any merit in having one curved point as trains arrive, then two more curved points, one on each route. The last point could be on one of the now 4 tracks. It might not help in any way but it might just shorten the throat and in my mind, it could improve the look a bit. The 4 curved points one after the other on the same line just looks a little long and ungainly to my eyes.

 

There are probably good reasons why it won't work but I thought I would mention it anyway. 

[St Enodoc]

6 hours ago, t-b-g said:

Just to stick a probably unwelcome thought or suggestion into the mix when so much has been done already, I was wondering if there was any merit in having one curved point as trains arrive, then two more curved points, one on each route. The last point could be on one of the now 4 tracks. It might not help in any way but it might just shorten the throat and in my mind, it could improve the look a bit. The 4 curved points one after the other on the same line just looks a little long and ungainly to my eyes.

 

There are probably good reasons why it won't work but I thought I would mention it anyway. 

Thanks Tony, that's a very fair comment. An early version of the plan had exactly that configuration but I changed it to get more length on platforms 2 and 3. On summer Saturdays there was at least one 15-coach train from Newquay to Paddington, which following my 60% rule means that my representation will be 9 coaches (plus two 4-6-0s) long. The downside is the reduced length of plain track between Pentowan and Treloggan Junction. There's always a trade-off but operability has to take precedence!

[St Enodoc]

I cleared all the pencil lines from the boards today, leaving just those lines that I'd inked in prematurely, which made the picture much easier to see.

 

Of course, what was on the board didn't match precisely what was on last night's sketch but I followed the same principle and set out the curves direct on the baseboard.

 

I resisted the temptation to ink the new lines in straight away - I'll redraw the 1/10 plan tonight to check the common tangents and curve centres first.

 

Instead, I trimmed the ends of the existing Treloggan Junction trackbase and the Pentowan baseboard nearest to Polperran. That gave me a first sight of how the whole Treloggan Junction - Pentowan section will look.

 

 

 

I'm a lot happier with this than I was this time yesterday, so I hope progress will speed up again now.

[FarrMan]

On 27/12/2022 at 08:08, St Enodoc said:

In full-size railway engineering it's used to check deviations from the correct radius of a curve, so that it can be adjusted during maintenance. I've used it in the opposite way to help set out curves on models but that's more tricky because there are usually two unknowns - the radius and the versine or offset itself. Trial and error can give a good enough answer in the smaller scales.

 

If you want to know more, try this link:

 

https://pwayblog.com/2016/05/09/the-versine-formulae/

 

or hope that a friendly PWay engineer will drop in here...

 

Versines. That had me trying to remember my highway engineering curves, though it is only a few years since I was teaching it, obviously not very successfully! It brought back memories of the first time I was teaching it, a long time after having used it in practice. Rather than the versine itself, we tended to use the distance from the intersection point (of the two straights at either end of the curve) to the mid-point of the curve. The formula for this used the trig form of a Secant (the reciprocal of a Cosine), which was usually abbreviated to Sec. Having difficulty remembering what a Secant was, I guessed which it was a reciprocal of wrongly getting an obviously wrong answer, and found myself asking the class if anyone had secs on their calculators!

 

Lloyd

Edited December 28, 2022 by FarrMan
Grammar

[St Enodoc]

Right, here's the revised 1/10 plan.

 

I've found circular curves that fit, albeit at the expense of coming down to about 45mm track centres at the double slip by using a 1600mm radius curve for Platform 1. That should be OK as I should be able to squeeze out an extra mm or so by exploiting the "give". I also had to make the curve into Platform 3 a compound curve, as I can't move the point closer to Treloggan Junction.

 

I think this will be as good as it gets, so I'll have another look in the morning before marking out the baseboards (again).