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  • The Plug Track functions are experimental and still being developed. Some of the earlier pages of this topic are now out-of-date.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.
  • The Plug Track functions are experimental and still being developed.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.

How to ... using the Templot rail filing jigs

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Martin Wynne

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These rail-filing jigs can be 3D-printed for any crossing angle 1: 0.5 to 1:20 and for any REA semi-curved switch size A to F and corresponding straight switches.

The jigs are intended to be FDM printed using toughened PLA-Plus filament to resist filing -- the same material as is used for the timbering bases. The cost of filament is under £1 per jig for the vee rails and under £2 per jig for the switch blades. Suitable filament is:

https://www.amazon.co.uk/gp/product/B07FQ75QG2

The overall size of the crossing jigs for most angles is 90mm x 50mm. The thickness can be set as required -- the default is 19mm. The switch jigs are necessarily longer but can be printed diagonally on the bed if necessary on most FDM printers.

The large opening in the middle allows the jig to be clamped on the corner of a table, if holding it in a bench vice isn't convenient.

Using all-threads with double wing nuts makes it easy to hand tighten without needing any other tools ( screwdriver, spanner, socket) on the head, but obviously any ordinary M6 (6mm) bolts will do, such as widely available roofing bolts.

The square holes are slightly undersize -- firmly push the bolt through the hole to create a close fitting bolt which will help to align the two halves.


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n.b. that's grey FDM filament, not a resin print.

The jigs are used by clamping the rails in the slots with the M6 bolts, with enough rail protruding on the filing surface to be filed off at the required angle. The assembled jig can be held in a bench vice, or G-clamped onto the corner of a table through the large opening in each one.

Before finally tightening the bolts, check that both halves of the jig are flush with each other along the filing surface.

Use a good quality 2nd-cut engineer's flat file, and lightly finish with a flat 400-grit sanding block. The file will barely harm the jig, but the sanding block can do, so it is used lightly just to remove the filing scratches from the metal, so that the rails can fit snugly together.

Unless it is a very expensive file, it is unlikely to be dead straight. Looking along it you will likely detect that it is fractionally curved. If so, use the convex side for best results on the jig.

While filing, brush away the filings between every few strokes. The file itself won't harm the jig, but rubbing metal filings into the surface will do. Fully disassemble the jig after each use, so that you can remove any filings or other debris from the slots. The jigs will last for a great many filed rails, but being plastic, they need to be treated with care -- otherwise you will soon be printing a replacement. :(



1. The crossing jig makes both point and splice vee rails by turning the rail the other way up. They are opposites for the opposite hands of a V-crossing.

For Templot plug track and COT track, you don't make a pre-assembled vee. The vee rails are inserted separately into the chairs.

The point rail forming the nose of the vee goes on the straight-ahead main side (MS) of the crossing. The splice rail goes on the diverging turnout-side (TS) of the crossing and fits snugly against the point rail. This is important to allow the rails to fit properly in the 3D-printed chairs.

The larger edge of the rail is the head (top) of the rail -- the rails won't fit in the chairs upside-down. Be sure to identify which hand you need before fitting the rails in the jig, and which side of which rail needs to be filed.


After filing, in 4mm/ft scale the point rail should be blunted back to a width of 0.25mm (10 thou) at the tip by trimming with sharp snips and sanding smooth. When correct it should slide into the "A" chair and stop with the nose just on the far edge of the chair. Check it is the right way up and hand for the "A" chair, LH and RH chairs are handed.

The splice rail is not blunted back, but it's a good idea to remove the tiny feather of metal which remains from the rail web at the tip. The rail should slide up to the point rail and fit snugly against it.

The rails will only fit snugly if they have been filed using filing jigs exactly matching the crossing angle -- hence including the jigs in Templot.

This below is how the filed vee point rail fits in the plug track "A" chair. This is for a Left-hand V-crossing looking towards the vee nose and showing the main-side (MS) wing rail:


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More information about the above diagram is at:

https://85a.uk/templot/club/index.php?posts/8369



2. The switch blade back jig should be used first to prepare the backs of the blades. Again turning the other way up for the opposite side of the switch. The final tip of the blade will be at exactly 20mm from the end of the jig, so you probably want to start with the rail at about 19mm from the end of the jig before filing. After filing, mark it at 20mm with a permanent marker.

Do not tighten the bolt too much at this end of the jig, just firm it up by hand. Otherwise the rail may be forced up out of the slot.

This is the blade back jig for size B switch blade backs. For which the planing length (filed length) in 4mm scale code 75 rail is 29.3mm:

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3. The switch blade front jigs are separate jigs for left and right switch blades. This "left and right" refers to the sides of the switch looking from the toe, NOT the hand of the turnout.

Insert the rail with the back already filed so that the mark is again exactly 20mm from the end. The jig is designed to accept the angle filed on the back at that rail position. That's the theory. In practice because of FDM printing variations you might find tweaking it a little forward or back fits best. Again do not clamp too tightly at this end.

The process of filing the back of the blade may have caused the rail to curve slightly where it is filed. If so, gently straighten it in your fingers before doing the front of the blade.

The jig allows you to file across the head of the rail at 20 degrees, producing a sharp tip at the toe and leaving most of the rail foot intact. Make sure you have the correct rail the correct way up. The filed end will be sharp -- keep some Elastoplast handy. :)



If you mark along the rail with a marker pen before starting, you can see where you have filed. For code75 bullhead rail in 4mm/ft scale, the filing should run out at a filed length (planing length) of 29.3mm from the tip for B blades, i.e. at 49.3mm from the end of the jig. Mark this position on the blade.

Here is a handy chart of blade planing lengths and deflection angles for different switches:

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More prototype info about switch blades is at:

https://85a.uk/templot/companion/real_track.php#planing_types



4. The final task is to make a very slight inwards bend in the switch blade at that position, i.e. towards the centre of the track, until the filed top front running edge aligns in a straight line with the remainder of the rail. This is best seen by eyeing along the rail, but don't poke yourself in the eye with the sharp tip.

For the curved switch blade, do this first before curving the rail to match the template.

There are likely to be some burrs on the filed edges which can be fettled with fine abrasive paper. Do this on the bottom of the blades before assembly, and after assembly for the running top of the blade so that it blends in nicely against the stock rail.

Martin.
 
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I hope it's OK to post this here, I've not seen much elsewhere about using these handy jigs. I know it's not beyond the wit of man to build a suitable jig, but I'm renowned for bodging such things and hate miter joins, so I reckon these are genius, especially as I will be able to do the switch blades too.

I've now had a few goes at printing a C&L code 131 1:7.5 crossing vee filing jig and I'm getting close to having one I can use. Because I've done a lot of FDM slicing and printing, and because I didn't understand what all the other settings on the export tab do, I've been just exporting to CAD.
The jig settings are not retained between Templot sessions and default back to code 75 so I have to overwrite them again each session; so make a note of the settings you use :)
Here's what I'm using:
Capture.JPG

Note you put in half the rail height (ish), which does make sense based on the text next to the value. Also, you must enter these values manually, they are not yet linked to the rail settings anywhere else in Templot. As has been stated elsewhere, print thin jigs until you have the rail sitting snug in the groove or you will be just wasting time and plastic.

Lastly, the code lettering on the STL output is too fine to print on our old CR-10 with a 0.4mm nozzle, but that's hardly an issue for me as I'm only working with one code.
 
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I may well have made a newbie error, but after filing two rails, the vee seems to be exactly twice the angle I need for a 7.5 turnout? I'll load it into CAD and check and edit this post when done.
Tim, it's difficult to see from the photo but, I think You just need to slide one rail down the other to form the Vee so that the main running rail has the tip and the turnout rail slide up to it. e.g. the tip of the main-road veered rail forms the actual bee angle!

1733584999212.png
 
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Anyone know where the latest or last slicing profiles are located for filing jigs and fdm timbers? I have just updated my fdm printer and lost the working templot profiles I had...
 
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If you use the Templot 3D-printed filing jigs the vee rails will fit together very snugly and do not strictly need fixing. In the FDM-printed bases with loose-jaw chairs the dropper wires (24swg TCW) are attached to the rails before assembling them, and the rails are effectively fixed by pushing the dropper wire into the dropper wire retaining ridges:

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And if necessary retained there with some suitable sealant, such as children's modelling clay from the pound shop. This handy stuff looks and feels like brightly coloured Blu-Tack, with the difference that if left for a few days it loses its stickiness and dries out to a blob of rubbery material. Which is ideal for sealing things but can be removed easily if necessary.

Dropper wire: RS PRO 0.56mm Tinned Copper Wire, 24 AWG 91.3m Reel | RS

Here is my provisional jig for soldering dropper wires to the underside of rail, where they will be almost invisible. As you can see no expense has been spared:

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Four 2p coins glued to a bit of wood with a gap between them for the rail. A 1p coin glued on top to support the dropper wire. A blob of Blu-Tack to stop the rail sliding, and another blob to hold the wire while it is soldered. The ink marks on the rail show the chair positions which must be avoided, and also confirm you have the rail upside down. It works fine, but I'm intending to create a proper resin-printed equivalent.

But if preferred the vee can be fixed solid after assembly:

Resin chairs: these will resist soldering temperatures briefly, so the vee can be soldered in situ. The neatest result is using low-temperature SMT paste (138degC). It's expensive, but a tub lasts forever if kept in the fridge, and it is useful for lots of modelling jobs:

SMDLTLFP50T3 | CHIPQUIK SMD LTLF Lead Free Solder Paste, 50g Tub | RS

Just a smear with a cocktail stick into the web of the (cleaned) point rail after inserting it in place. Slide the splice rail up to it and touch the rails with a dry soldering iron. The SMT paste will flash and lock the vee rails together invisibly.

FDM (COT) chairs: same process but using epoxy adhesive instead. FDM filament won't resist soldering temperatures.

Martin.
 
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