Making maximum traction trucks. part 2

The bore in the Romford/Jackson gear wheel is 1/8" as are the flanged bearings. The Romford/Jackson wheels come fitted to 2mm axles and gauged for HO. Ideally the axles should be all steel but without a lathe I can't do the machining that would be needed. So I use hard brass tube from the hobby shop. I reckon it's ok for my tram models because my models are lightweight, won't be pulling 100 wagon trains, won't be running continuously, run slowly and added to that I use the long axle bearings so the wear is distributed over a quite large area. Anyway so far hard brass has not shown any signs of wear. I just have to remember to keep a drop of oil on the bearings.

I am using HO scale wheels and the back to back dimension for HO is 14.55mm +0.05mm -0.15mm. I add 15.5mm to that to get the back to back for O scale using HO wheels. The difference between 16.5mm and 32mm. So I end up with a back to back that should be 30.05mm +0.05mm -0.15mm. 30mm is near enough and suits me just fine.

I use the nesting brass tubes you can get from the hobby shop. I started off with the 1/8" OD hard brass tube and selected the next tube down in size that nested inside the first. I cut 4 pieces of the smaller size to a length of 28mm as the insulated hubs on the wheels stand proud of the rear of the wheel by almost 1mm.


Then I cut the pieces of 1/8" tube to a length of 25mm and slid the smaller tubes inside the larger. I soldered the two tubes together on the ends. The top photo shows the stages of construction.


The bore on the inner tube is too small to allow the 2mm axles to be inserted so they needed to be drilled out. This is where a lathe would be handy but my method works just as well if a bit slower. The advantage of using tube here is provided everything is set up reasonably accurately a 2mm drill will track down the dead centre of the axle and give me a wobble free wheel.


The table of the drill press was checked to make sure it was still horizontal and a 1/8" hole was drilled through a piece of nice flat pine. Then I sawed a narrow slot down the pine and through the centre of the 1/8" hole. With an axle inserted into the hole I used a G clamp to close up the saw cut which grips the axle. This trick will hold the axle tight enough to drill out the centre but at the same time not mark the surface in any way which would interfere with smooth running.

I cut the wheel sets in half so I ended up with wheels and stub axles still attached. The fit into the axles was firm. Just too tight to do it by hand so I used the drill press as a wheel press as can be seen in the next photo.

All the wheels have been pressed into one end. The other end will be done after the axles are assembled on the trucks. Each unit was lightly clamped into the drill press chuck and given a spin to check for wobble. None so far. I checked the blackening on the wheels with a multimeter and the coating is conductive but I will polish it off the rear of the wheel where the pickup springs will rub just to be on the safe side.