Rail, ties, spikes and spiking tool were purchased from SwitchCrafters in Albany, Oregon to make a four foot test track to check operation of moving parts. These include drivers and other wheels, equalization gear, springs, driver rods, etc. In the photo above a six inch wide baseboard precut to four foot length was purchased along with two molding boards that have one beveled edge. The beveled edges were on opposite side. The rail shown here is temporarily layed out on the ties. At this point all the wood and ties were glued down.
In order to obtain accurate track spacing three track gauges were made using the 3D printer. Each gauge has openings that provide access for the spiking tool. Above the track gauges hold the rails in position. The locomotive frame with drivers is shown in place on the rails. The gauge for 1/24th scale is 2.354 inches (59.8 mm). The gauges were accurate to a few thousandths of an inch and worked well in holding the rail in good position.
Above is one of the track gauges in position on the rails. Code 250 rail is used. The gauges are sufficiently tight on the rails to hold them in position within a few thousandths.
The work of spiking the rails was done on the floor as my workbench otherwise is a glass top desk. The spikes are 3/8" inch and two at a time fit into the spiking tool. A hammer is then used to drive the spikes using drive pins that are part of the spiking tool.
A small tweezers was used to handle the spikes during loading into the tool. The tool has holding magnets that keep them in accurate alignment during driving.
The spiking tool works on one side of a rail at a time positioning two spikes during the driving process. The tool is then reloaded and positioned on the other side of the rail and spikes inserted there. The process is then repeated on the other rail of the same tie. Due to the stiffness of the rail and the fact the rails will not be loaded spikes were placed about every 10th tie. The assembly is quite solid. After completion of the locomotive another rail section will be built and ballasted to make it look better for display. The wood base will be thicker and stained and some form of name plate added to describe the model.
Above is the model as currently completed on the finished testbed rail section.
While working to build the test bed rail section the 3D printer was building various parts that will be assembled to make up the back frame section. Above at left are parts still attached to raft and support materials while those at right have been built and removed for previous blogs.
The above parts consist of a pair of equalizer mounts at left, two sets of equalizer bars at bottom center, four sets of equalizer pull rods that connect to the truck spring front, two sets of truck spring saddle front mounts at center right top and one set of truck spring saddles at right. Still to be built will be two sets of truck spring leaves and spring clamps that will be similar to those built for the locomotive drivers. All these parts look good prior to removal. A couple of parts did not print correctly and had to be rotated to a different alignment to get good results.
Above are some of the major component parts of the back frame. At top is the frame side pair with an internal sacrificial support frame that was built all together. After assembly of the front and rear spacer parts the sacrificial support frame will be removed by cutting it away at the attachment points at the inside of the frames. The frame insides will then be trimmed and sanded to remove any material not needed. The interior will be hidden after locomotive firebox insertion by the clinker chute that runs down between the frames.
At left upper is the rear mount for the trailing truck springs. The springs will be attached near the outer edge well outside the frames and truck wheels. This mount spans and surrounds the frame sides inside, outside and top. At left bottom is the front spacer which includes the trailing truck pivot mount at left of the part and the front firebox mount at right.
The small round part at right upper with the two cones is the trailing truck centering device. This part contains a spring that pushes the cones outward. The trailing truck will have push rods that will be centered inside the cones and push the spring inwards. When the truck is centered the cones will be held by the housing and keep in position. If the truck moves either direction it pushes a cone inward and the spring provides a centering force to restore the truck back to center.
The bottom right corner part is the back spacer for the side frames and includes the tender drawbar attachment pin and tensioner pad. The drawbar pin will be a machine screw. The tension pad will not be implemented fully in prototype manner which calls for a wedge to be inserted at the tender end of the drawbar to pull the tender tightly to the locomotive frame pad.
The trailing truck design is essentially complete and it too will be built along with the rear firebox mount to enable a fit check of most parts together. A pair of rear spacer extension cab mounts will also be printed and attached to the frame rear outboard of the frames.
A number of pivot pins will be done using machine screws and fit checks done a various sub-assembly levels before gluing parts together. The correct alignment and fit of the equalization bars, pull rods and springs will dictate the final position of the truck spring mounts. They will be very close to prototype positions but will likely need tweaking a bit to get good fit and operation.
Some preliminary detailed design work is being done on the front pilot truck. Wheels, axle and bearings are completed. The pilot truck has a pressure driven centering device integral to the frame which may or may not be implemented depending on how well the 3D printer can do the small parts needed. Other small parts have come out fairly well so this looks promising.
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