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posted: 24 Aug 2011 12:25 from: Paulr1949
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Hello again I am currently creating a plan in O-gauge FS which requires a right-angled curve to get from Fiddleyard to main platform on L-shaped boards. In this curve is a LH A-5 semi-curved point - the turnout road from this leads to the main platform, the main road to a runround loop. The main curve radius is approx. 51 inches, but the information screen is now flashing minimum radius of 25.1 inches (637mm). Looking at the info in the storage box it tells me track centre-line radius = 1288.06 (constant radius) resultant switch radius (centre-line) = 931 approx. resultant turnout radius (centre-line) = 637 approx. ------------ switch radius (rail gauge-face) = 3374.0 turnout radius (rail gauge-face) = 1274.45 So I appear to have a switch radius of 3/4 of the track centreline radius and a turnout radius of either 637 (half the centreline radius) or 1274mm (about the same). It doesn't look like 25 inches/637mm on the plan. Which is right - or is it me just being thick again? Box file attached - my intention is either to split template 15 (main approach) and create a transition curve or to change template 10 to a RH point for entry into the fiddleyard (but I was hoping to create a 3-way p;oint here to enable at least 2 sidings to be "long"). Or I could just move 13 & 15 down a bit. Thanks in advance for any help Paul |
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Attachment: attach_1152_1596_MJB_11_08_24_1224_32.box 152 | |||
posted: 24 Aug 2011 13:02 from: Martin Wynne
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Hi Paul, The minimum radius is indeed 637mm. You can ease it to 685mm by changing to a generic V-crossing, and to 707mm by changing to a 9ft switch instead of the A switch. To see it, try tools > make split > make plain track turnout road > on internal geometrical radius, which produces 719mm radius. re the1274.45mm dimension -- the line you missed in the data is this: "equivalent straight template dimensions BEFORE curving:" That dimension would apply to a straight A-5 turnout. It's not a good idea to put a short turnout such as an A-5 in such a sharp ruling curve, the radius will be far too tight. Your main road curving at 1288mm is already near the bottom limit for 0 Gauge, so to have a turnout diverging from the inside it will need to be a very long turnout, such as a D-12. You can ease the radius a little by changing to a generic type of V-crossing. (Or curviform, according to the needs of the connecting geometry.) regards, Martin. |
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posted: 24 Aug 2011 14:28 from: Paulr1949
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Martin Wynne wrote: Hi Paul, Hi Martin I agree, and will have to think again. I think I can ease the main curve a bit. I tried making the turnout on the outside but could not get everything lined up to my satisfaction thanks Paul |
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