Manufacturing

The development of the railway has included CAD drawing and design computer software; a lot of thought was put into this engineering. Naturally, concepts developed in those places have been inherited by hardware. Any apparently arbitrary design features in the hardware probably are the result of earlier engineering decisions.

These notes can be read in sequence, which yields a bottom up approach to manufacturing; and, ultimately, this is what must be done in the workshop. Alternatively, the notes can be read via the links below, which offer a top down view which may help with comprehending the structure of what is described. The links for assemblies usually lead to images, which, also, are very helpful.

Tooling
Interface Plate Drilling Jigs
Module Assembly Jig
Socket Liner Tool
Jigs To Be Made

Module
Main Frame
Interface Plates
Blank
Drilling
Attachment Blocks
Attachment Assembly
Location Pins
Pin Assembly
Fitting
Ribs
Liner
Washer
Blank
Socket Drilling
Components
Frame Sides
Platform
Attachments
Blank
Locators

Legs
Leg Tubes
Leg Clamp
Leg Clamp Sleeve
Leg Foot
Components

Track

In the railway design computer code, the distance between the end plates along the leftmost blue track is known as the size vector of the module; and the angle between the plates is the turn.

These jigs do not exist but probably are a good idea.

• Interface Pin Assembly Tool
  Probably this is simply a piece of round stock with a hole in the end that accepts a pin, but keeps the pin poking out. This tool then can be used in a press or vice.
• Platform Templates
  When more than a very small number of modules of the same design are to be made, it is worthwhile to make a durable shape template from the paper template used on the module assembly jig. The precise nature of such templates is yet to be determined.

• Interface Blank
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  This is cut from a 1-1/2 x 1-1/2 x 1/8 aluminium angle. The length for the single track interface is 6-1/2 inches, for the double track, 16-1/2 inches, the 10 inch difference is the centreline spacing of the two tracks. The ends of the blank must be square since the module frame sides are located by this interface.


• Interface Plate Drilling
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  Place the locator positioning jig on the outside of the blank and drill #13 holes in the blank, one for the single track interface, three for the double track interface. The centre hole marks the centre of the long interface, but is not used otherwise in manufacturing. The other holes are offset 1/4 inch from the centreline of the associated locator, and are used to position the locator drilling jig. Deburr the holes.

  For each locator, i.e., once for a single track interface, twice for a double track interface, do as follows

  • Place the locator drilling jig on the inside of the blank and bolt to the blank using the centreline marking hole made using the positioning drilling jig.
  • Drill five holes in the blank as indicated by the jig. Those on the same face as the bolt are 1/4 inch (or #E), and #13. The three on the other face are all #19. Deburr the holes.


• Attachment Blocks
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  These are simple oak blocks that are glued to the ends of an interface plate. When the module frame is assembled the frame sides are glued to these these blocks, which forms the main frame perimeter. The blocks are cut from nominal 1 x 2 oak board and are 1-3/8 long; the latter dimension should make the installed block essentially flush with the top edge of the interface plate. The faces that are to be glued must not be contaminated with dirt, finger-marks, etc., since the glued joints are important for frame strength.


• Attachment Assembly
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  An interface plate requires an attachment block to be glued flush to each end with epoxy. This glueing must be done after both interface blank completion and drilling. The corner of the block installed in the crotch of the interface plate blank should be chamfered if necessary to ensure good seating. The areas on the interface plate to be glued should be cleaned and roughening with emery cloth to ensure good glue adhesion. The block should be clamped to both faces of the plate during epoxy cure.


• Location Pins
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  These are purchased items that are installed in an interface plate. However, an alternative design exists for these pins, which would be made in the workshop. These pins have a longer engagement taper, and a short full engagement diameter, which is thought to be more suitable for module interface location. Also these alternative pins have an internal thread, and they are attached to the interface plate with a screw. None of these pins has been made.


• Interface Location Pin Assembly
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  Each interface plate locator requires a locating pin to be installed into the locator #13 hole. A multi-locator interface plate requires a locating pin for each locator. Installation must be done with care to avoid damage to the aluminium by the steel pin. High strength Loctite should be used on purchased pin installation, low or medium strength Loctite on the alternative pin threads.


• Socket Liner
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  The socket liner is a piece of tube 1-1/4 diameter x 0.058 wall. The ends must be square, and the length 1.25 inches. This liner is best finished in a lathe, and an adequate lead-in provided for a leg.


• Socket Washer
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  This is a steel washer at the bottom of the socket that spreads the load put on the rib by a leg. This is a purchased item, being a 1-1/4 diameter fender washer. The centre hole size is not important; suitable washers may be identified as AJB or AJC, the B/C specifies the centre hole size.


• Rib Blank
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  This is cut from a 2 x 2 Pine board. The length for the single track interface is 6-1/2 inches, for the double track, 16-1/2 inches, the 10 inch difference is the centreline spacing of the two tracks. The ends of the blank must be square since the module frame sides are located by this interface.


• Socket Drilling
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  The leg socket holes are drilled in a rib blank on a drill press using a 1-1/4 inch Forstner bit. It is necessary to use a carbide-tipped bit. On the prototype modules a standard hardware shop Forstner bit was used and this was ruined rather quickly by the heat generated by the cut. The first ribs made were oak; however, even pine, as used later, gets the cutter very hot. The holes lie on the centreline of the rib and are 1 inch from the end of the rib, which puts them on 4-1/2 or 14-1/2 inches centres according to the width of the module. The socket holes should be square, and the hole depth must be adequate to ensure the socket liner does not protrude above the rib. A good target depth is 0.02-0.03 inches greater than the sum of the length of the liner and the thickness of the load bearing washer


• Frame Sides
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  Frame sides are stock 1-1/2 x 1/8 aluminium bar. The length obviously varies according to the module arc length, and less obviously varies with the curvature of the module. The outer side of a curved main frame is longer than the inside side. This difference can be important when purchasing the frame side material because a standard length from a supplier is 12 feet, i.e., exactly twice the nominal arc length of a standard module. On the prototype double track 71 inch arc length module, for transportation convenience, the 12 feet long material was cut, by the supplier, to yield pieces 73 inches long and the remainder. This was acceptable because the longer side length is about 72-1/4 inches.

  The frame sides must be curved using slip rolls, or somesuch, and cut to a precise length, before installation. However, this is done, more or less, at module assembly time; no basic work is required.


• Platform
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  Module platforms are made from 1/4 Baltic birch, and they are conceptually very simple, being just a shape. The prototype platforms were traced from the module assembly jig paper templates using carbon paper - an old fashioned technology associated with typewriters for those who have not heard of it. The prototype platforms then were cut out using a powered jig saw. At the time of writing it is guessed that the best way to mark the outline of a platform is to create a template; but this is a development item. It is very useful to mark the primary track centreline on the platform at each end, small notches were used on the prototypes. These marks assist greatly in positioning the main frame when it is being prepared to be glued to the platform. Positioning blocks clamped onto the platform also are hugely useful when the frame finally is offered up to the platform with the glue in place by helping to avoid smearing the glue.


• Attachment Side Blank
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  The prototype side blanks are 3 inches wide and the length of the module, as required. The thickness depends on the material used. The prototypes are of poplar (1/4 inch), Baltic birch (1/8 inch), and Luan (3/16 inch). It is intended to try 1/8 inch double sided tempered hardboard, which has been recommended highly by a fellow steamer. These sides are cut from a 4 x 8 sheet.


• Attachment Side Locators
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  These locators are small pieces of wood that are glued in pairs in three places to the side blanks, in the middle and at each end. The platform is held in place by, and in between, the locators during glueing of the sides to the platform edge.


• Leg Tubes
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  The legs tubes are cut from standard 1-1/8 and 1 inch telescoping tubing with a wall thickness of 0.058 inches. The 1-1/8 tube is 21-1/8 inches long, and the 1 inch tube is 24 inches long. After cutting, the tubes must be carefully de-burred at each end, thoughly cleaned, and checked for smooth assembly. The 1-1/8 tube should be roughened with emery cloth at one end in preparation for glueing to the leg clamp.


• Leg Clamp
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  The leg clamps are purchased items.


• Leg Clamp Sleeve
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  The leg clamps are made for 1-1/4 inch diameter tubing. This means that the clamp must be sleeved with 1-1/4 diameter telescoping tubing in order to accept the 1-1/8 leg tube. The sleeve is 2-1/8 inches long, and must be de-burred and roughened with emery cloth inside and outside in preparation for glueing.


• Leg Foot
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  A leg foot comprises two purchased items. These are a standard rubber foot for a 1 inch tube, and a 1 inch diameter steel fender washer, which spreads the load imposed by the leg tube.


• Interface Plates
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  These are the ends of the main frame of a module. Two are glued to two frame sides to form the frame perimeter.

  

  
  Fitting
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  Multi-track interfaces may not mate nor separate easily due to lack of machining precision. At the time of writing there is a lack of information to guide best practice. On the prototype modules some success has been achieved by opening the pin socket holes on the secondary track locator to 0.257 inches (#F) or even 0.261 (#G). On one module the socket holes on the primary locator also have been opened up as a (not useful) experiment, but it is hoped that this can be avoided, by precise hole positioning, because single track locators work well without this modification.

  If the secondary track locator socket is drilled larger than 0.25 inches (#E), then the interface primary end should be marked PL as in the image.


• Ribs
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  These are the internal spacers of the main frame of a module. Three are glued to the inside of the frame perimeter. The ribs also house the leg sockets.

  

  The assembled rib. The separate aluminium item is a tool to press the liners into the sockets; this is used in a bench vice or other press.

   Rib Components
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  This image shows the rib assembly components: one end of the drilled blank, 1-1/4 od liners, and 1-1/4 diameter fender washers. The washers shown are identified as AJB and are about 0.046 inch thick; the liners are 1.25 inches long; and the holes are drilled to about 1.31 deep. After assembly, it is important that the liners do not protrude above the surface of the rib so that the ribs can lie level with the frame sides during frame assembly. The surfaces to be glued have not been prepared, by roughening with emery cloth, in this image.


• Main Frame
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  The main frame is assembled in the Module Assembly Jig from two Interface Plates, three Ribs, and two Frame Sides.

  

  A computer model for the module is produced by the computer railway design software. A full-size - and amazingly accurate! - paper template is produced from this model by a commercial drawing printer (Staples). This paper template is installed in the jig located by pivots on the jig interface plates. This template indicates the required angular position of the interface plates, which then are held in place during construction by blue clamps, two of which can be seen on the right of the image. The aluminium module interface plates are loaded into the jig.

  The frame sides now are curved using slip rolls or other mechanism until they conform to the template lines. This process is accurate enough that it is possible at this point, i.e., before assembly, to cut the sides to their finish lengths. After suitable surface preparation, the sides are glued with epoxy to the interface plates using clamps during cure. These clamps are not shown in the image since this operation was complete when the image was taken.

  The image shows the last operation, where the three wood ribs are being glued in place. Whenever glueing, or other potentially damaging operation, is being carried out on the template, the template is protected with waxed paper, some of which can be seen in the image. The leg socket holes are out of sight since the frame is right side up.

  The module shown being assembled was the first double track module to be made; accordingly, assembly proceeded with caution, one step at a time. The epoxy glue has a cure time of at least six hours, which became an overnight wait. Clearly there is room for assembly time reduction, mainly doing all the glueing at once. Using a quick-set glue probably is a bad idea, both because those varieties are not as strong as the extended cure epoxy, and because the open time is not adequate to allow careful module assembly. The epoxy used, J-B Weld, has an open time of about 30 minutes, this time also depends on the temperature.


• Attachments
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  Module configuration clearly is arbitrary; once a main frame and a platform are assembled the module structure is strong and rigid; finishing is a matter of application requirements. The prototype modules have sides glued to them to attempt derailing containment; the prototype double track module has sides that extend above the target rail-head level and below the main frame to provide some protection if the modules are stacked.


• Module
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  The main frame is assembled from a Main Frame, a Platform, and any Attachments that are desired.

  

  This image shows the first prototype module having plain side attachments glued in place. The sides are positioned vertically on the platform by the locators glued to the sides. Locators just can be seen in the image on the right and left sides of the interface plate.

  

  This image shows the first prototype double track module, complete except for its track; the other prototype modules are to the left. The legs are incomplete.


• Legs
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  A leg is assembled from Leg Tubes, a Leg Clamp, a Leg Clamp Sleeve, and a Leg Foot.

  The lower, thinner, leg tube carries the rubber foot on one end; the load bearing washer being inserted into the foot to spread the load from the tube, followed by the tube. It is important for this tube (actually, all the telescoping tubes) to be clean and burr-free before assembly to avoid surface damage, and possible jamming.

  The upper tube carries the clamp. The sleeve is glued into the appropriate part of the clamp, followed immediately by the tube being glued into the sleeve. The glue is the epoxy used throughout module assembly. Any surplus glue on the inside of the tube or clamp must be removed so that it does not interfere with the lower tube's sliding into the upper tube.

  During prototype development there was a significant problem due to the fit between the upper tube and the clamp being too tight. A different clamp, especially if it were designed for a 1-1/8 diameter tube, would be quite acceptable, or better. But the current clamp was the only one that could be found despite considerable searching. Most sleeves required hammering (!) to assemble them in the clamp; the nylon clamps seemed to be able to absorb the hammering and very tight fit, but it was a disturbing thing to be doing. Turning the outside of the tube and dry-fitting to a better fit probably is a good procedure.

  

  An assembled leg.

   Leg Components
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  This image shows the components of a leg before glueing and assembly, except that the load-bearing washer and foot are shown already installed.


• Track
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  This section has not been written.