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posted: 11 Mar 2013 21:47 from: julia click the date to link to this post click member name to view archived images |
Can anyone suggest how to make a Joggle - I am not sure if that is the right term for it, but it's the term used in the 2mm scale track book - in a piece of flat bottom rail? Thanks J |
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posted: 11 Mar 2013 22:09 from: Martin Wynne
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Hi Julia, Joggles are not usually made in flat-bottom rail because the rail section is too stiff. Most flat-bottom switches use the chamfered style of planing in which the stock rail is machined: 1679_261348_250000001.jpg The above pic from the excellent collection of Michael Davies in the Image Gallery, the large hi-res version is at: gallery/1679/original/1679_261348_250000001.jpg Lots more pics at: http://85a.co.uk/forum/gallery_view.php?user=1679#gallery_top Chamfered planing looks like this (this diagram is for bullhead rail): 1932_021155_110000000.gif The problem with chamfered planing is that it is very difficult to do in model form. Almost all model rail section has a significantly over-scale web thickness, which limits the scope for tucking the switch rail under the head of the stock rail. And it is very difficult to make the undercut planed angle on the stock rail head using only hand tools. The angle on the switch rail top, and its height, also need to be precisely matched to the stock rail. I have never seen a model version of chamfered planing in the smaller scales, although there is always a first time of course. Anyone? regards, Martin. |
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posted: 12 Mar 2013 02:26 from: Trevor Walling
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Hello, As a matter of general interest is the ballast shown in the photographic image limestone? Thanks. trustytrev. |
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posted: 12 Mar 2013 11:14 from: GeoffJones
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julia wrote: Hi Julia Joggle is the term used in my copy of British Railway Track so I think that is a reasonable authority for the the use of the term. The techniques for making joggles described in the 2mm book, which include using it for FB rail, work well in that scale and I think they would probably work in 4mm scale, although you might need to use a vice rather than pliers to press the rail. It would be easy enough to try as it only requires a few scraps of brass and a short length of rail. The form of chamfering illustrated by Martin is designed to minimise the removal of steel from the stock rail in order to maintain its strength. Luckily this aspect of rail strength is much less of an issue for modellers so we can use a version where most of the foot of the stock rail is filed away in a simple taper and the switch has a matching taper. Regards Geoff |
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posted: 12 Mar 2013 12:13 from: Phil O
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Hi Julia "Joggle" is a standard engineering term where a double set is introduced into the metal whether it be sheet, bar or section. When I worked in the dockyard as a boilermaker we used joggles in sheet or plate trunking and ducting to allow one piece to slide inside or outside the next section. Phil |
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posted: 12 Mar 2013 12:56 from: Andy Crow
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Trevor Walling wrote: Hello, With the colour and sharpness of the individual pieces, it is more likely to be feldspar (granite). Andy |
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posted: 12 Mar 2013 17:39 from: Robert Preston
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Andy Crow wrote:
Don't think it's granite, the grain size is too small. The red colouration looks superficial and could come from rust. The fracture, grain size and greenish tinge makes me wonder if it isn't markfieldite (a microdiorite from Charnwood). Robert |
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posted: 12 Mar 2013 20:20 from: Glen Suckling
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Don't think it's granite, the grain size is too small. The red colouration looks superficial and could come from rust. The fracture, grain size and greenish tinge makes me wonder if it isn't markfieldite (a microdiorite from Charnwood). It seems that we all agree on an igneous rock (ie. definitely not limestone). The comment on grain size is a valid point as is the possibility of rust discoloration. Feldspars tend to be pink rather than the orange that I am seeing here which nornally indicates the presence of iron. I would opt for granodiorite in view of some of the darker pieces. Of course identifying rock from a photograph is always tricky and to really confuse things we may actually be looking at a blend. Glen |
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posted: 12 Mar 2013 21:11 from: alan@york click the date to link to this post click member name to view archived images |
It could be limestone: this does not look very different to what I have seen in quarries (eg Carboniferous limestone in the Avon Gorge). There is also an admixture of other stuff: paper, and gunk, which doesn't help. Ballast is reused, and there may be admixtures from other wagons. It is likely to be "local" crushed stone, so if you know the location, a better guess could be made. alan@york (geologist in a previous career) |
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posted: 13 Mar 2013 09:54 from: Trevor Walling
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Hello, I seem to have opened a can of worms with my question.I suppose the "local" location would have a major bearing on the type of material used due to the quantities involved.I know limestone can be discolored due to iron oxide in the vicinity where the limestone is quarried as that is the case in the NW Lancashire/South Cumbria area where I live.I would imagine quarried material would have been transported by the railway company involve at the time of construction. trustytrev. |
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