Mid-Cornwall Lines - 1950s Western Region in 00

[FarrMan]

6 minutes ago, Keith Addenbrooke said:

 

I don't use much maths in my present job, so find it hard to keep up with my kids, so I've taken a lunchtime maths test to see if I could work out for myself how @FarrMan's calculations work.  Starting with 'Ra', 'Rb' and 'D' (which I understand) I think I'm OK with the derivation of 'Db' and 'Ta,' but I've got a reversal in my formula for 'Tb'...? Have I missed something:

 

 

 

 

Sorry, not much to do with trains.  Just curious, Keith.

It is a while since I marked any Maths exams, and I was once told by an SQA external verifier that I was 'a hard marker'. That was just after a student had asked me, on receipt of his results, 'do you ever fail anyone'!

 

I am not sure where the difference between us is re the third part. My formula for Ta is just the same as yours, except that I have expressed it slightly differently due to the limits of the keyboard. The formula for Tb was necessary because without that, you do not have Ta or Tb.  You have come at it a slightly different way to how I did, but the result is the same.

 

Full marks, and an 'Excellent Work' for it!

 

Lloyd

[Keith Addenbrooke]

1 hour ago, FarrMan said:

It is a while since I marked any Maths exams, and I was once told by an SQA external verifier that I was 'a hard marker'. That was just after a student had asked me, on receipt of his results, 'do you ever fail anyone'!

 

I am not sure where the difference between us is re the third part. My formula for Ta is just the same as yours, except that I have expressed it slightly differently due to the limits of the keyboard. The formula for Tb was necessary because without that, you do not have Ta or Tb.  You have come at it a slightly different way to how I did, but the result is the same.

 

Full marks, and an 'Excellent Work' for it!

 

Lloyd

 

Thank you - it was question 2 ('Tb') where I think I have a different answer: your original shows:

 

Tb = Sq Rt of (Rb*Rb) - (Db*Db)

 

whereas I get:

 

Tb = Sq Rt of (Db*Db) - (Rb*Rb)

 

As you say above, Tb is needed to calculate Ta.  Either way, I suspect the class who opted for music so they could listen to the records instead are probably glad they skipped maths.  Hope the family house move has gone well today, Keith.

[FarrMan]

14 minutes ago, Keith Addenbrooke said:

 

Thank you - it was question 2 ('Tb') where I think I have a different answer: your original shows:

 

Tb = Sq Rt of (Rb*Rb) - (Db*Db)

 

whereas I get:

 

Tb = Sq Rt of (Db*Db) - (Rb*Rb)

 

As you say above, Tb is needed to calculate Ta.  Either way, I suspect the class who opted for music so they could listen to the records instead are probably glad they skipped maths.  Hope the family house move has gone well today, Keith.

Keith

 

You are, of course, correct. I hadn't read your response well enough. I had it right on the spreadsheet, but put it the wrong way round when explaining it. I go to the bottom of the class. I enjoyed both music and maths, though the maths got a bit boring doing so many examples when i had picked it up after the first few.

 

Family house move not left Linlithgow yet. Apart from emptying lots of plastic boxes and generally getting things ready, my main part does not start until they reach Tomatin and my daughter in law comes here to Farr to pick me up to help unload. Then tomorrow morning moving the rest of our own stuff from where we lived until a couple of months ago (only a mile away from here) to their house in Tomatin. Then Friday night preparing a handle for his spiked roller (for a concrete floor screed), either using a broom handle or the arms of an old rotary clothes line! Should have peace again Saturday afternoon.

[Chamby]

2 hours ago, Keith Addenbrooke said:

 

Thank you - it was question 2 ('Tb') where I think I have a different answer: your original shows:

 

Tb = Sq Rt of (Rb*Rb) - (Db*Db)

 

whereas I get:

 

Tb = Sq Rt of (Db*Db) - (Rb*Rb)

 

As you say above, Tb is needed to calculate Ta.  Either way, I suspect the class who opted for music so they could listen to the records instead are probably glad they skipped maths.  Hope the family house move has gone well today, Keith.

 

All this algebra stuff is going right over my head.  My calculations got as far as:

 

Tb R (not Tb).  That is the question...

 

I’ll stick with my trusty tracksetta’s for laying out curves, and my eye...  

[St Enodoc]

7 hours ago, Keith Addenbrooke said:

 

Thank you - it was question 2 ('Tb') where I think I have a different answer: your original shows:

 

Tb = Sq Rt of (Rb*Rb) - (Db*Db)

 

whereas I get:

 

Tb = Sq Rt of (Db*Db) - (Rb*Rb)

 

As you say above, Tb is needed to calculate Ta.  Either way, I suspect the class who opted for music so they could listen to the records instead are probably glad they skipped maths.  Hope the family house move has gone well today, Keith.

That's right Keith (which Lloyd has confirmed) because Db must by definition be greater than or equal to Rb.

 

Have a gold star.

[St Enodoc]

6 hours ago, FarrMan said:

Family house move not left Linlithgow yet. Apart from emptying lots of plastic boxes and generally getting things ready, my main part does not start until they reach Tomatin and my daughter in law comes here to Farr to pick me up to help unload. Then tomorrow morning moving the rest of our own stuff from where we lived until a couple of months ago (only a mile away from here) to their house in Tomatin. Then Friday night preparing a handle for his spiked roller (for a concrete floor screed), either using a broom handle or the arms of an old rotary clothes line! Should have peace again Saturday afternoon.

So Farr so good then (sorry).

[St Enodoc]

I hadn't made any progress on Porthmellyn Road signal box for a few weeks but last night I cleaned up the filler where I'd joined the two roof sections together. Once I've scribed the slate joints back in, I'll be ready to do more.

 

In the railway room today, the first job was to ease out the blade gaps slightly on the two points that had remained in place at St Enodoc station, as these were a bit tighter than my current standard. Once I'd done that I painted the rails, rail joiners and bare copperclad timbers on all the new track and points, then left it to dry.

 

While the paint was drying, I turned to St Enodoc Down end again and had a go at the tangents on the three reverse curves.

 

Here are the three curves with the radii marked.

 

I took the tangent tool, lined it up on the top track (the Loop) and marked the ends of the tangent.

 

After that, I completed the tangent.

 

I marked the position on each curve where the tangent was offset by 5mm...

 

...and found the mid-point between these marks, which represents the tangent point itself.

 

How did that go in comparison to Lloyd's spreadsheet?

 

Well, here are the results, numbering the three curves from the top:

 

Curve 1: Ra = 822, Rb = 1159, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 133.

 

Curve 2: Ra = 762, Rb = 1219, offset = 2.5 so D = 1984 and Ta + Tb = 100, compared with the measured value of 82.

 

Curve 1: Ra = 762, Rb = 1219, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 139.

 

Overall, I don't think this has turned out too badly I think, given the inherent inaccuracy of measuring the distances between the lines and the thickness of the pencil lines themselves. For the final marking out I'll use the calculated values.

 

Ballasting next!

 

 

Edited June 28, 2023 by St Enodoc
Images restored

[Stubby47]

37 minutes ago, St Enodoc said:

Ballasting next!

 

Surely you need to lay the track first ?

[Keith Addenbrooke]

1 hour ago, St Enodoc said:

I hadn't made any progress on Porthmellyn Road signal box for a few weeks but last night I cleaned up the filler where I'd joined the two roof sections together. Once I've scribed the slate joints back in, I'll be ready to do more.

 

In the railway room today, the first job was to ease out the blade gaps slightly on the two points that had remained in place at St Enodoc station, as these were a bit tighter than my current standard. Once I'd done that I painted the rails, rail joiners and bare copperclad timbers on all the new track and points, then left it to dry.

 

While the paint was drying, I turned to St Enodoc Down end again and had a go at the tangents on the three reverse curves.

 

Here are the three curves with the radii marked.

 

I took the tangent tool, lined it up on the top track (the Loop) and marked the ends of the tangent.

 

After that, I completed the tangent.

 

I marked the position on each curve where the tangent was offset by 5mm...

 

...and found the mid-point between these marks, which represents the tangent point itself.

 

How did that go in comparison to Lloyd's spreadsheet?

 

Well, here are the results, numbering the three curves from the top:

 

Curve 1: Ra = 822, Rb = 1159, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 133.

 

Curve 2: Ra = 762, Rb = 1219, offset = 2.5 so D = 1984 and Ta + Tb = 100, compared with the measured value of 82.

 

Curve 1: Ra = 762, Rb = 1219, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 139.

 

Overall, I don't think this has turned out too badly I think, given the inherent inaccuracy of measuring the distances between the lines and the thickness of the pencil lines themselves. For the final marking out I'll use the calculated values.

 

Ballasting next!

 

 

With these short tangents, I guess knowing a measurement for Ta + Tb also helps check the tangent will be long enough to avoid buffer locking on the reverse curve (before being able to play test it with rolling stock on the actual track)?

 

If my pencil lines on plywood could be as neat as these, I’d be tempted not to ballast the track and leave them showing  .

[St Enodoc]

2 hours ago, St Enodoc said:

I hadn't made any progress on Porthmellyn Road signal box for a few weeks but last night I cleaned up the filler where I'd joined the two roof sections together. Once I've scribed the slate joints back in, I'll be ready to do more.

 

In the railway room today, the first job was to ease out the blade gaps slightly on the two points that had remained in place at St Enodoc station, as these were a bit tighter than my current standard. Once I'd done that I painted the rails, rail joiners and bare copperclad timbers on all the new track and points, then left it to dry.

 

While the paint was drying, I turned to St Enodoc Down end again and had a go at the tangents on the three reverse curves.

 

Here are the three curves with the radii marked.

 

I took the tangent tool, lined it up on the top track (the Loop) and marked the ends of the tangent.

 

After that, I completed the tangent.

 

I marked the position on each curve where the tangent was offset by 5mm...

 

...and found the mid-point between these marks, which represents the tangent point itself.

 

How did that go in comparison to Lloyd's spreadsheet?

 

Well, here are the results, numbering the three curves from the top:

 

Curve 1: Ra = 822, Rb = 1159, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 133.

 

Curve 2: Ra = 762, Rb = 1219, offset = 2.5 so D = 1984 and Ta + Tb = 100, compared with the measured value of 82.

 

Curve 1: Ra = 762, Rb = 1219, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 139.

 

Overall, I don't think this has turned out too badly I think, given the inherent inaccuracy of measuring the distances between the lines and the thickness of the pencil lines themselves. For the final marking out I'll use the calculated values.

 

Ballasting next!

 

 

Now I'm not so sure. Because the offset [D - (Ra + Rb)] is so small it's very hard to measure accurately, as mentioned above, and a small variation makes a big difference. Also, because the two centres are off the edges of the board, I can't construct the two right-angled triangles and hence I don't think I can actually locate the tangent points, which is the aim of the exercise.

 

Lloyd @FarrMan and/or Keith @Keith Addenbrooke, please would you mind either a) pointing out what I'm missing or b) suggesting a method that I can use? Otherwise I think I might have to stick with my graphical method, which should be accurate enough considering the width of my pencil and pen lines.

 

Thanks.

[St Enodoc]

33 minutes ago, Keith Addenbrooke said:

With these short tangents, I guess knowing a measurement for Ta + Tb also helps check the tangent will be long enough to avoid buffer locking on the reverse curve (before being able to play test it with rolling stock on the actual track)?

 

If my pencil lines on plywood could be as neat as these, I’d be tempted not to ballast the track and leave them showing  .

I use DG couplers, Keith, so buffer-locking isn't an issue. I don't think I could use loose couplings with 30" radius curves in 00 at all, with or without tangents.

[KingEdwardII]

8 minutes ago, St Enodoc said:

because the two centres are off the edges of the board, I can't construct the two right-angled triangles

This is the kind of reason that I prefer to do all the geometric wrangling on the computer and print out the results. It has its downsides, of course, in that you need to do the mapping between computer and real world very carefully - in both directions, especially given the lack of "squareness" of typical rooms. But laying the track to follow the printouts gets me good results.

 

Yours, Mike.

[St Enodoc]

1 minute ago, KingEdwardII said:

This is the kind of reason that I prefer to do all the geometric wrangling on the computer and print out the results. It has its downsides, of course, in that you need to do the mapping between computer and real world very carefully - in both directions, especially given the lack of "squareness" of typical rooms. But laying the track to follow the printouts gets me good results.

 

Yours, Mike.

Each to their own, Mike! I prefer to work with pencil, eraser, straight edge and curve templates. That gives me good results - good enough for what I need, anyway - too!

[Dr Gerbil-Fritters]

3 hours ago, St Enodoc said:

Well, here are the results, numbering the three curves from the top:

 

Curve 1: Ra = 822, Rb = 1159, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 133.

 

Curve 2: Ra = 762, Rb = 1219, offset = 2.5 so D = 1984 and Ta + Tb = 100, compared with the measured value of 82.

 

Curve 1: Ra = 762, Rb = 1219, offset = 5 so D = 1986 and Ta + Tb = 141, compared with the measured value of 139.

 

Overall, I don't think this has turned out too badly I think, given the inherent inaccuracy of measuring the distances between the lines and the thickness of the pencil lines themselves. For the final marking out I'll use the calculated values.

 

Ballasting next!

 

Spiral easements as well?

 

I would fetch my coat, but it's that cold today I'm already wearing it.

Edited April 16, 2021 by Dr Gerbil-Fritters

[Clive Mortimore]

One the beauties of us mere mortals in using Peco track and tension lock couplings, is accuracy of track alignment is not a problem. If it looks right and the trains don't fall off what is the hassle? 

 

For those who enjoy enjoy calculating their track curves, tangents etc keep doing so as the hobby is supposed to be fun. We all have different aims and ideals.

[Keith Addenbrooke]

On 16/04/2021 at 11:54, St Enodoc said:

Now I'm not so sure. Because the offset [D - (Ra + Rb)] is so small it's very hard to measure accurately, as mentioned above, and a small variation makes a big difference. Also, because the two centres are off the edges of the board, I can't construct the two right-angled triangles and hence I don't think I can actually locate the tangent points, which is the aim of the exercise.

 

Lloyd @FarrMan and/or Keith @Keith Addenbrooke, please would you mind either a) pointing out what I'm missing or b) suggesting a method that I can use? Otherwise I think I might have to stick with my graphical method, which should be accurate enough considering the width of my pencil and pen lines.

 

Thanks.

 

There will be engineering answers for situations where the centre of a curve cannot be easily identified for triangulation (eg: line along a sea wall!), but I’m afraid I don’t know them, sorry.  Whatever technique was used for marking out curves of a constant radius to be joined here seems to have given a neat result too of course, though I understand that can be done without knowing the centre point.
 

I’ve had a play over lunch, but I’m afraid all I’m coming up with is what I think you’ve already done

 

Once again, this is easier to draw (or prove) when centres are known.  I think at this point I have to concede the limit of my knowledge, although I suspect there’s an obvious answer I’m not seeing either, Keith.

 

 

Edited September 26, 2022 by Keith Addenbrooke
Edited for text only as photos no longer available.

[Stubby47]

This would also work.

 

[lofty.ian]

On 15/04/2021 at 12:15, FarrMan said:

I will be interested to know the results of your comparison.

 

Re transition curves, I might have a spreadsheet that does that already for roads. I produced it for my use in marking Highway Engineering exams. I was a great help to me to identify where they had gone wrong!

 

With regard to Chamby's comment about looking along the curve to check that it is smooth, reminds me of my road setting out days, where we would calculate the appropriate setting out data, and then set out with steel tapes (fibre tapes stretch - not as accurate) and theodolite reading to at least 20 seconds if not 5 or 1 second accuracy, so that it should have been spot on. ( an angle of one second gives an offset of about 1mm at 100 metres!) Then we looked round the curve that we had set out and adjusted it for smoothness by eye! These days they normally use GPS for setting out - supposed to be accurate to within a couple of mm. I'm sure that the old hands especially still eye it in for final adjustments.

 

Lloyd

Brings back memories of early computer systems (1970s). I was involved with D of Transport (or was it MoT?) programs for Highway Design (BIPS) which calculated horizontal and vertical alignments.  They had the 'occasional' hiccup.  One plotted out the results and looked at them by eye before passing them on.

St Enodoc - you are safer sticking to pencil and paper.

[FarrMan]

22 hours ago, St Enodoc said:

So Farr so good then (sorry).

The better one is that when someone asks you if you have come from far, you just say yes.

 

Anyway, exhausting day and DEFINITELY ready for bed.

 

Lloyd

[St Enodoc]

10 hours ago, Dr Gerbil-Fritters said:

 

Spiral easements as well?

Yes, where I have room, but here I don't.

[St Enodoc]

10 hours ago, Clive Mortimore said:

One the beauties of us mere mortals in using Peco track and tension lock couplings, is accuracy of track alignment is not a problem. If it looks right and the trains don't fall off what is the hassle? 

 

For those who enjoy enjoy calculating their track curves, tangents etc keep doing so as the hobby is supposed to be fun. We all have different aims and ideals.

DGs are a form of tension-lock, so I agree there. However, there's no difference in terms of alignment between Peco, SMP or any other make of flexible track.

[St Enodoc]

8 hours ago, Stubby47 said:

This would also work.

 

Yes but you need to know at least one of the centres.

[St Enodoc]

I tidied up the ballast at St Enodoc Up end today.

 

There is a distinct change in the colour of the ballast, as the brand I used originally (Chuck's Ballast) is no longer available and I couldn't get a match. A weathering wash will tone it down in due course.

 

I won't do any more work here until I've completed the Down end trackwork and built the lever frame and uncoupler/hand points control panel.

 

In the meantime, using a bit of wrong-road running, St Enodoc can act as a temporary 5-road fiddle yard, primarily for the china-clay trains, although I might run the branch freight as well next time it comes round in the sequence. There will need to be some hand shunting too, until the Down end trackwork is laid.

 

Here are the long clay train and short clay train ready to depart, with the other short clay train wagons in a siding.

 

As a result of these changes, I've also updated the local working instructions to reflect the new arrangements.

Edited June 28, 2023 by St Enodoc
Images restored

[St Enodoc]

Today is ANZAC Day, the anniversary of the Gallipoli landings in 1915, on which date we remember all Australian and New Zealand servicemen and servicewomen who gave their lives in armed conflicts. This year, most states and territories were able to hold dawn services and marches, although in most cases with reduced numbers.

 

Not much railway action since last week, as we went away for a few days to celebrate Veronica's birthday at Port Stephens, which is a couple of hours' drive north of here. We enjoyed glorious autumn weather, although the clear skies meant that it got a little chilly after sunset. We walked a lot, ate a lot and drank a little lot, not necessarily in that order.

 

Today I did just one smallish job in the railway room, which was to cut away the front edge of the Porthmellyn Road baseboards so that when St Enodoc Down end is constructed there will be a clear gangway about 600mm wide. The jigsaw, with a long blade to cut through the surface and the joists at one go, made short work of this.

 

 

Here's the end result. You can see that where the cut is hard up against the L-girder I scuffed the timber a little - fortunately, without the blade jumping or breaking. In due course, this will get finished with a profiled MDF fascia. I haven't decided what colour to paint that yet. Suggestions on a postcard please.

 

I will cut more away at the Up end once I've built the boards carrying the single line to Treloggan Junction. This will also involve fairing in the edges of the fixed boards and the lifting flap, which will let me finalise the lengths of No1 and No 2 Spurs and replace the Hornby Dublo buffer stops with Lanarkshire ones..

 

Once I'd finished that, I had a dry run of the last half-dozen or so trains in the Friday sequence, anticipating our next running session in three weeks' time.

Edited June 28, 2023 by St Enodoc
Images restored

[5BarVT]

My favourite is a darkish grey (think unfitted wagons).  Mine happens to be Dulux Urban Obsession which has a slight brown tinge giving a bit of warmth.  I like it because it’s less stark than black but doesn’t impart any colour bias.

Paul.