Templot Club Archive 2007-2020
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posted: 15 Mar 2010 18:43 from: polybear click the date to link to this post click member name to view archived images |
Hi all, If a length of plain trackwork is made by placing sleepers in a straight jig (based on Templot sleeper spacings) and then attaching one rail (by whatever is your chosen method) to those sleepers, then if that piece of trackwork is removed from the jig and subsequently curved and placed over a curved Templot Template then can anyone tell me if the Sleepers will now match the positions on the curved template assuming: 1. A curve of constant radius, or 2. A transition curve. Many thanks. Brian Tulley. ps. Is this the accepted normal method of producing curved trackwork (either with or without the use of a jig) - i.e. by producing a straight length with one rail fitted, curving it then fitting the second rail? |
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posted: 15 Mar 2010 19:00 from: Dellboy
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polybear wrote: Hi all, Brian In the real world providing the outside rail (of the curve) is the rail soldered first then the sleeper spacings will be correct. This is based on a standard 60 foot track panel. The inner rail (of the curve) would have to be suitably shortened to maintain square rail joints at the end(s) of the panel. Templot should reflect the resultant sleeper spacings on a curved template but I do not know if this is the case. Derek |
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posted: 15 Mar 2010 20:00 from: Martin Wynne
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Dellboy wrote:Templot should reflect the resultant sleeper spacings on a curved template but I do not know if this is the case.Hi Derek, Unfortunately no, it doesn't.  You are correct that the sleeper centres should be measured along the long rail on a curve. Specially made and drilled "short rails" (usually 3 inches shorter than the standard rail length) are introduced on the inside rail when the joint stagger has exceeded 1.1/2 inches. It has not (yet) been possible to introduce this feature in Templot, partly because of the complexity for S-curve transitions (where the short rail swaps sides), but mainly because of the effect of the much smaller than prototype model radii. For example, a 60ft scale outer rail on a 1200mm radius in EM requires every inner rail to be only 59ft long. That's a lot more than an occasional 3" short rail on the prototype. I made the decision therefore to run the sleeper spacings along the track centre-line for all curves. This means that if you build half-track and curve it, the spacing won't match the default templates exactly. Provided you build the outer rail first, your track will be correct*, the template will be slightly out. *edit: but see my next message. Those for whom this discrepancy matters can adjust the sleeper spacings by creating a set of custom plain track settings for a suitable range of radii, and use the appropriate setting as required. Someone may care to do that and share the files?  If you also want to reproduce the joint stagger and occasional short rail, this can be done by overlaying partial templates. regards, Martin. |
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posted: 15 Mar 2010 20:13 from: Martin Wynne
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I wrote: if you build half-track and curve it, the spacing won't match the default templates exactly. Provided you build the outer rail first, your track will be correct That assumes of course that you are using the correct jig. You can't use the jig for straight track and bend it to any radius -- curves have more sleepers per rail length and need their own jig. Some notes about the radius limits for 24, 25 or 26 sleepers per 60ft length are in the Templot program notes for the plain track settings. regards, Martin. |
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posted: 15 Mar 2010 20:28 from: Dellboy
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Hello Martin I suspected as much. It appeared far too complex to me for Templot to be able to generate sleeper spacing other than based on centre line. As you say we are generally dealing in much tighter radii although there are of course some very tight curves on the Railways where all the low (inner) rails are special lengths, each cut & drilled to suit. Derek |
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posted: 15 Apr 2010 17:36 from: Templot User
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Posted by email by Andrew Jukes ___________________________ Hi Martin Not a big issue for the reasons you explain, but I understood 3 inches was another one of those Western peculiarities. The 1956 edition of 'British Railway Track' says: "It is not usual to provide short rails of odd lengths and the general practice is to shorten the rails by the distance between fishbolt holes so that when cut there is only one additional hole to be drilled. This distance is 5" for the new standard flat bottom track, and for British Standard bull-head track it is 4.5". Special short flat bottom rails are, therefore, 59' 7" in length, and bull-head specials are 59' 7.5" long, except on the Western Region where specials 3" shorter than the full standard length are used". Regards Andrew |
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