r_i_straw
June 21st, 2004, 04:34 AM
Two Microtrain Z or Nn3 freight truck frames and eight Marklin metal wheel sets are required. I have built brass side frame inserts using two methods. The simpler one involves drilling #73 holes for the axle points to poke through and into the plastic side frame cones. The contact inserts rest against the outside of the wheels and ride on the axle just inside of the points. The more complex but better method is to form cone bearing races in the brass strip and fabricate something like that used in the side of the Kato N scale Mikado trucks. I use an aluminum block with a dimple hammered into it and a steel cone punch that I ground down from an old drill bit while spinning it in my Dremel tool. The point has to be rounded a little so it will not tear through the brass stock. I first make a bearing point in one end of a strip of .01" brass.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aao.sized.jpg
Use a divider to measure the wheel spacing on the MT truck frame. With one point of the divider inserted into the first hole, mark the location for the second hole using the other point of the divider.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aap.sized.jpg
Use a sewing needle mounted in a pin vice to open up a good center point for the punch or drill. I did this for two side frames side by side. File or grind away most of the strip leaving only a small area around the holes and a connecting piece between them that clears the cross brace on the truck.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aaq.sized.jpg
Solder a length of fine wire (such as wire from Richmond Controls on their micro-bulbs) to each of the brass plates. Next removed the insulated wheels from the 8 Marklin wheel sets. The axle on the inside of each wheel is cut off leaving a stub axle about 3/32” (2.3mm, .09") long. Insert these into a 3/16” (5.3mm, .02”) piece of Evergreen .08” diameter styrene rod with the inside is drilled out with a #74 bit. Note: The stub axles should not be long enough to touch each other on the inside of the tubing.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aar.sized.jpg
The bearing cones pressed into the brass strip require a little more clearance in the plastic truck frame so I drilled out enough material on the inside to accept them. Assemble the trucks with the side plates mounted outside the wheels and the needle points in the bearing cones. If you use the more simple drilled hole method, the axle points extend through the clearance holes to rest in the plastic bearing cones in the truck side frames.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aas.jpg
Wire the jumper wires from the side frames to the appropriate motor contacts.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aau.sized.jpg
This is a Bachmann 4-4-0 tender from a locomotive that I converted to Nn3.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aao.sized.jpg
Use a divider to measure the wheel spacing on the MT truck frame. With one point of the divider inserted into the first hole, mark the location for the second hole using the other point of the divider.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aap.sized.jpg
Use a sewing needle mounted in a pin vice to open up a good center point for the punch or drill. I did this for two side frames side by side. File or grind away most of the strip leaving only a small area around the holes and a connecting piece between them that clears the cross brace on the truck.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aaq.sized.jpg
Solder a length of fine wire (such as wire from Richmond Controls on their micro-bulbs) to each of the brass plates. Next removed the insulated wheels from the 8 Marklin wheel sets. The axle on the inside of each wheel is cut off leaving a stub axle about 3/32” (2.3mm, .09") long. Insert these into a 3/16” (5.3mm, .02”) piece of Evergreen .08” diameter styrene rod with the inside is drilled out with a #74 bit. Note: The stub axles should not be long enough to touch each other on the inside of the tubing.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aar.sized.jpg
The bearing cones pressed into the brass strip require a little more clearance in the plastic truck frame so I drilled out enough material on the inside to accept them. Assemble the trucks with the side plates mounted outside the wheels and the needle points in the bearing cones. If you use the more simple drilled hole method, the axle points extend through the clearance holes to rest in the plastic bearing cones in the truck side frames.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aas.jpg
Wire the jumper wires from the side frames to the appropriate motor contacts.
http://www.railimages.com/albums/Modeling-stuff-and-train-room/aau.sized.jpg
This is a Bachmann 4-4-0 tender from a locomotive that I converted to Nn3.