< Complete Chassis >
The photo shows casting parts for the trailing frames, from left to right, back equalizer bracket, trailing spring support and equalizer end bracket. The first two types were cast with cores so as to mold entire shape. The last type is too small to cast with core.
I started with the back equalizer brackets. After cutting the bolting face, both sides of the slit are milled to a desired width.
There are nine holes for bolts. First I opened the central one hole and fixed the casting to the frame. And then drill through the rest eight holes from the frame. Six bolts of them also fix the reinforcement casting in opposite side.
Next is the trailing spring supports. As the photo shows, two faces were cut by end mill in a time. Note two steel bars to avoid slipping of the job in cutting.
I made dummy oil pots from round brass bar and screwed them down into the castings. The studs and nuts are also dummy parts.
In case of the prototype, the spring supports are fixed by hammer bolts which have steep countersunk heads with no recess. I modified a kind of countersunk screw turning its head angle from 90 to 60 degree.
For the modified screws, I made a countersink cutter from a drill rod. It was hardened with propane gas torch but tempered with electric furnace, rising temperature to 230 centigrade and cooling immediately. Electric furnace makes such heat treatment much easier.
The casting was bolted onto the trailing frames. The plate under the bracket is slipping plate for laminated leaf springs.
The equalizer end casting has no hole, so I opened square hole. First I drilled four corner and center holes. After that I opened it to square profile by end mill and files.
The bracket was mounted to the frames.
The photo shows rear frame casting that closes the trailing frames at their ends. That of the prototype is one body casting. But I separated top plate so as to ease casting. The tunnel at center bottom of the casting is coupler pocket.
First I finished the bottom face, and then I cut back and both side faces.
The top plate has six studs to fix itself onto the bottom casting. Against the studs, shallow recesses were cut on the casting, in order to make height of the studs even. The casting plate on the back side is tender buffer catcher.
The main frames and trailing frames were connected again. And the rear frame casting was secured between the trailing frames. Again I checked out rear frames' height and symmetry during the assembly.
Coming back to the main frames, front butter beam, front bottom plate and the pilots were put on the front frame casting. All of them are laser-cut parts.
The chassis was completed.