Templot Club Archive 2007-2020
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posted: 23 May 2011 19:44 from: Brian Nicholls
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Hi Martin, I thought this the best and only place to post my query. First let me state that, I know not what the new pug will do regarding half diamonds, so if this posting is premature and in error, I apologise. Whilst making an irregular switch diamond for New Street and updating the guide document on that subject, I came across a problem that may not have been addressed in the new pug. If you get two Vee crossing angles that are different, such that one is less than 1 : 8 and the other is greater than 1 : 8, then Templot may well generate a diamond that is as shown in the screenshot below, in other words a mixed diamond !! As I envisage, it may be necessary to put in a drop down menu that asks if you want to change to a “normal half diamond” or a “Switched half diamond” after converting to the half diamond. It would be nice if this decision were automatic, but the problem there is that it would depend upon which half of the full diamond crossing was generated first, unless a prior drop down menu boxes gave the option as one converted in the first instance. I mention this in the hope that it may correct a problem that is (and I have) experienced in Templot 0.91c. All the best, Brian Nicholls. 1853_231442_520000000.gif  |
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posted: 23 May 2011 20:15 from: Paul Boyd
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Hi BrianAs I envisage, it may be necessary to put in a drop down menu that asks if you want to change to a “normal half diamond” or a “Switched half diamond” after converting to the half diamond.This is already there in 0.91c in the Real -> K-crossing options menu, where you have a choice of fixed or moveable K-crossings. If you set the required option before starting the diamond, you'll get whichever option you want regardless of crossing angle. The default is set to automatic which is why you have the results you're seeing. But... where you have two diamonds with different crossing angles like that, you're going to have a sharp change of angle in one of the roads at the K-crossing, aren't you? |
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| Last edited on 23 May 2011 20:15 by Paul Boyd |
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posted: 23 May 2011 20:48 from: Martin Wynne
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Hi Brian, Paul, I'm aware of this problem and accordingly I have made a slight change in TDV -- the automatic change now takes place at 1:8.125 instead of 1:8. Brian, the two K-crossings should always be the same angle, otherwise you will get a sideways jolt in the running. However, to be strictly mathematically correct for the irregular diamonds there should be a very slight difference between the two angles. Which means that wherever you set the limit there is a rare chance that the two K-crossings will fall each side of the limit. See for example this result of make diamond-crossing: 2_231537_170000000.png  The half-diamond on the right has a K-crossing angle of 1:8.1 -- i.e. below the new limit and therefore it has fixed K-crossings. To match exactly the one on the left has a K-crossing angle of 1:8.13 -- i.e above the new limit and therefore it has switched K-crossings. This is going to be a fairly rare occurrence, but I have a note in the book to fix it. I think the best solution will be to ignore the limit for the second half-diamond and ensure that it always matches the first one, regardless of the angle. But it's not in there yet -- another hole waiting to be fixed.  regards, Martin. |
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posted: 24 May 2011 00:10 from: Brian Nicholls
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Martin Wynne wrote: Hi Brian, Paul, Hi Paul ; Martin, Many thanks for the response. As Martin said, I thought there may be a slight problem in this area, just my luck to fall into it. On my New Street layout I have an irregular Diamond, that has the following basic data: One Plain track straight, running from top right to bottom left at an angle approximating 45 degrees. One curved track, at track centre-line radius at peg = 8671.53 ( 341.4 " ) almost on the same angle but curving gently across the straight track, this is very similar to the screenshot in my posting but if you imagine it at approx 45 degree angle instead of horizontal. The Vee crossing at top end crossover is 1 : 9.5 The Vee angle at lower end crossover is 1 : 6.91 Clearly this falls right into the category of a mixed diamond, now obviously, because of the ‘flatter’ angle at the top, then the full diamond crossing must be treated as “Switched Diamond Crossing” otherwise I may run into all sorts of other problems if I made the crossing as a normal fixed K-crossing. As you may see that’s my dilemma, I also have a double slip with almost the same characteristics at little further on in the layout. Paul Boyd wrote: But... where you have two diamonds with different crossing angles like that, you're going to have a sharp change of angle in one of the roads at the K-crossing, aren't you? Paul, I’m not necessarily convinced of this, the method I use to construct these awkward (complex) formations is to use constant radius guide curves (or straights where applicable) which follow and mimic the plan tracks as close as possible, (so far I have not come against a formation that I could not do this). Therefore, as the build of the crossings progress, I snake onto these guide curves and the passage through the acute K crossing point is smooth and not kinked in either direction, this appears to be irrespective of the angles at those crossing points. I have no real way of telling what the acute angles are or if they are the same or different, I do have a suspicion that the guide curves may make the K angles the same, I think I shall have to get an accurate protractor and measure them some time, or spend a lot of time doing the maths. I am sure of one thing though, when the full diamond is constructed, all the rails of the two roads, follow the guide curves exactly all the way through and are a perfect match. BTW, many thanks Paul for the advice about the K crossing options in 0.91c. Thanks again for the messages. All the best, |
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posted: 24 May 2011 05:02 from: Martin Wynne
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Brian Nicholls wrote:The Vee crossing at top end crossover is 1 : 9.5Hi Brian, The V-crossing angles are largely irrelevant. Only if the K-crossing angles span the limit will you get a mixed diamond. They probably don't. Why not join the development group and try it again in TDV? Apart from solving the angle question you will see how much easier it is to create irregular diamonds. You don't have to abandon 091c, TDV installs separately. regards, Martin. |
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posted: 24 May 2011 16:44 from: Brian Nicholls
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Hi Martin, Many thanks for the response, sorry if I’ve taken you away from coding on this topic, but thought I would mention it so that it may be incorporated in the new pug before it arrives. I see your up with the lark again this morning posting at 05:02, I was still in dreamland at that time.  Martin Wynne wrote: The V-crossing angles are largely irrelevant. Only if the K-crossing angles span the limit will you get a mixed diamond. They probably don't. Although I can partially understand what you are getting at here, I was firmly under the impression that it was the Vee crossing that determined the “flatness” of a diamond and hence the acuteness of the K crossing angle, as these are a product of the Vee. I fully understand that as the K angle gets flatter, so also does the gaps in the crossing rails, and beyond a certain point the gaps become untenable as far as the severity of wheel drop and wheel to rail contact impact energy, and hence resorting to a switched k crossing resolves the problem. Regarding my own New Street diamond, details as show in the previous posting, when I first made the template of this diamond, I did end up with a mixed diamond, half fixed K and half switched K, so therefore, Templot though it should be a mixed diamond, and it appears Templot takes the limit information of 1 : 8 from the Vee crossing of the turnout that was used to convert into a half diamond and decides what version of K crossing to generate, unless I am mistaken. Any how, it’s not worth debating this any further as I’m sure you have more important things to think about than this, also from what you say, the new pug will be able to generate irregular diamonds at the drop of a hat. Martin Wynne wrote: Why not join the development group and try it again in TDV? Apart from solving the angle question you will see how much easier it is to create irregular diamonds. As regards to the TDV, although I have been eagerly waiting to get my hands on sketchboard in particular, due to my inexperience with Templot (only used it for the past 14 months) and only just starting to get the hang of it, I had so far resisted the urge to get an advanced copy, and to join the development team. However, since the TDV installs separately, and having received, one might almost say an invitation to do so, and having reflected upon what has been said and written over the last several days about the new pug and TDV, I have decided to give it a go and see what changes/improvements to the program have been done and how easy it will be to use the program in the future. Also if I can be of assistance in providing feedback, good or bad, that will help further improve things. I’m sure I shall find a way of bending or breaking it. Having stated the above, I hereby gratefully request that you add my name to the list of the development team, and I make the following declaration: I confirm that: a. I will not share the downloaded code with anyone or distribute it or copy it anywhere other than on my own computer. b. the computer on which I will install the code is my own personal property and under my full control. c. before selling, lending out, disposing of or otherwise ceasing to have access to the computer, I will delete all of the downloaded code from the computer. d. my computer has access to the internet. In addition on a personal note, I will also undertake to provide feedback and report any functions that I find to either not be performing properly or have faults and those that have enhanced the system, and will if requested provide a general synopsis of my findings on the use of the new system to that date. Am now looking forward to trying the new code.  All the best, Brian Nicholls. |
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posted: 24 May 2011 16:55 from: Martin Wynne
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Brian Nicholls wrote:Am now looking forward to trying the new code.Hi Brian, Thanks for joining. You are now purple, and you can download TDV from: topic 1500 regards, Martin. |
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