< Start Erection of Frames >
Key seat cutting will be necessary in future for driving and coupling wheels. So I prepared lathe slotting attachment that makes it easier. I utilized cylinder block casting reservoir for the William. Key seat cutting tool is hold in a stem. The stem moves to and fro through bushes at each end of the casting's bore. To ensure precise key-cutting, the stem and the bushes have to be finished very close fit.
The steel base stack is to raise the casting to the lathe center height. Note two pins under the base stack. The pin's diameter is equal to the lathe cross-slider's groove width. They make the unit always parallel to the lathe headstock. For that purpose, we should do boring of the casting after securing the unit with the pins.
The boring tool is that I made for William's cylinder boring, with a tip made from old HSS drill.
The phosphoric bronze bar that I used for bushes was terrible material. Its elastic character captures drill as if it is press-fitted into the material. The photo shows before and after cutting. Material color changed reddish by high temperature in cutting.
Inner and outer diameter of the bushes should be finished at a time, so as to ensure true concentricity.
The stem is made from silver steel round bar. The slit is cut with metal saw. The stem has a clean hole at the center to hold cutting tool. The hole is opened with drill and finished with small boring bar. Also a cross screw hole is opened in the collar glued on the stem. It is for a screw to secure cutting tool.
The link is made from bright mild steel bars. The bracket is made from ground steel angle. In the picture, the link is fixed with pins and E-rings. But I replaced them with bolts and nuts, in order to make the linkage tight.
I received several castings from a foundry's engineer. First I finished 100 mm angle plates which will be vital for many works. Mount on the lathe cross table and fly-cut each square face. The fly-cutter is a knife tool in the tool post which is hold in four-jaw chuck.
[Truing Up of axlebox slit]
The main frame thickness is 12mm, so hornblock is not necessary. But laser-cut section is wild and tapered, so I trued up the section with end mill. I utilized four of the 100 mm angle plates to hold the pair of frames rigidly. The end mill's diameter is 21 mm. The slit depth is 60 mm. It is beyond the capacity of my milling machine. Therefore I cut every 5 mm depth until the bottom. Finally, I cleaned the cutting face with an oil stone.
The main frames material is cold (bright) steel bar. Its residual stress caused me a great deal of trouble. First I tried to true up top edge of the frames. I cut only 0.2 mm surface, then the top edge warped convexly (left hand picture). After that I trued up the axlebox slit. When I released the chuck after cutting, the slit was deformed in bell-bottom shape, on the other hand the frames' warp disappeared (center picture). So I had to do truing up again (right hand picture). As a result, I got 0.2 mm wider slit than I designed.
I think laser cutting edge includes tensile force, while the inside material includes compressive force. If we remove the edge, then the material extends immediately. We should better ask local factory to anneal whole job before any cutting.
The hornstays are laser-cut, too. Before fix them on the frames, bolting face is cleaned by endmill. Opposite face in the frame is also cleaned.
All of stretchers and buffers between the frames are made of cast iron. First of all, front and back end castings are built on, so as to join both frames. The picture shows those castings. The bigger and complicated one is front buffer casting.
[Front buffer casting]
I have to cut front, top, bottom, and side faces. Width of the casting is around 200 mm. Only X-axis of my milling machine can cut this length. The photo shows cutting top and front faces. After that, the job was reversed and top face was cut.
The photo shows cutting side faces. First, two angle plated are fixed on the machine stage truly square in each. Then top and front faces of the casting are push against the two faces of angle plates, and secured with suitable clamps. Then the side face can be cut truly square to both front and top faces.
[Rear stretcher casting]
The casting is enough small to handle in the lathe. First, the bottom face was turned in four-jaw chuck. Then each side face was fly-cut as the photo shows. Note a DTI in the tail stock that was to cut each side face truly parallel.
[Main frame twisting]
I checked the main frames again and found that one of them was slightly twisted. Then I tried to true it up again. I fixed the rear end on milling machine's table, held the other end with large clampers, and then gave an opposite twist to the frame. After many times of powerful motions, the twist was disappeared.
[Combination of two frames]
Mark out one hole in each side of a casting, punch, drill and tap them. Then build on the casting between frames with one screw in each side. Adjust angle of the casting on a flat surface, and clamp them. The photo shows how to make the front face of the casting square to the main frames. For this operation, I utilized combination of straight and square rules.
Then counter sink the casting through all of holes in the frames. The photo shows a portable hand drill that I used. Note a brass tube around the drill bit as 'stopper'. After that, disassemble, drill and tap the rest of holes.
Reassembled main frames. The whole length is around 1 meter. Rear frames of 0.5 meter length will be bolted on them.