< Motion Plates etc.>

The motion plates for the William are plane mild steel plates combined with brackets which carry the expansion link. We can tackle with them in the same way as the main frames.

The brackets for the expansion link are made of BMS flat bar. First the window was cut out by drilling, sawing and filing.

The triangle shape was end-milled on the rotary table.

Both motion plates were temporary combined with headless copper rivets and end-milled together.

The grooves which hold the slide bars are cut by a Woodruff cutter, using the slide bar material as a gauge to get correct width.

The motion plates have rectangle slots which clear the radius rods. Start with drilling in the both end, open the window with a fret saw and finally file to desired shape.

The bracket is put on the correct position of the plate, clamped and countersunk through the hole in the plate. Then the bracket is drilled and tapped.

A mild steel angle is employed to fix the motion plates onto the frames. The angle is trued up in the four-jaws before using.

Bushes for the expansion links were turned from a phosphoric bronze rod and press fitted to the brackets.

I employed BMS flat bar with desired width and depth for the slide bar. In this case I don't have to do much more than cutting the slant shape on the both end. I prepared a jig which tilts the job in correct angle during cutting.

The excess areas in the both ends for clamping will cut after the operation.

There are holes in the frames which indicate the position of the expansion link. Holding the link bracket of a motion plate with a round bar inserted through the positioning holes in the frames, the motion plate is set vertical with a try-square and clamped to the frames. Then drill through the frames and bolted together. I added holes for 2mm positioning pins.

Lining the slide bar. Note a pair of brass square posts which hold the slide bars in correct height from the frame. Then the slide bars are glued to the cylinder rear cover.

A counter sink is made in the bolting face of the cylinder cover through the slide bar. Then the cover is drilled and tapped.

After positioning and clamping a cylinder block, drill through the frame and make a counter sink on the cylinder. I added holes for positioning pins again.

The cylinder block is drilled and tapped. Note the nut on the tap as a stopper. Depth of the hole should be decided carefully according to the plan. If the bottom is too closed to the main bore, the bore will be distorted when tapping.

Position of the slide bar depends on the thickness of the cylinder gasket. So we have to prepare them here. They were made of 0.2mm paper, printed by CAD and cut with a knife.

The rear end of the slide bar is fix to the motion plate with a brass angle. The angle is fix to the motion plate by iron rivets, then bolted to the slide bar.

All of wheels and rods were mounted to the frames and lubricated, then the chassis is tested on a curved track. The weight of the chassis is 13kg. With this adhesion, the wheels should rotate smoothly without slipping. Close your eyes and slowly push the loco with a finger. If you feel a tightness then open your eyes and check the position. Repeat this operation and if the position is always the same, the position is "hot spot" to be eliminated.

It needed following adjustment to have satisfactory result.

  1. The angles which hold the slide bar to the motion plate are slightly distorted with riveting, and push the slide bar toward inside. Then I corrected the shape with a flat file.
  2. The inner rear edge of the slide bar had sometimes touched the con-rod. Then I cut the edge slantwise.
  3. A connecting rod was slightly curved and prevented smoothness. So I carefully straighten them.

Rolling and rolling... Now is a time when I look like a small boy to my wife !