< Driving Wheel Cutting 2 >
Looking back now, the leading wheel contour looks weak for its thin flange. So I modified the wheel contour for driving wheels as the red line in the illustration.
In the same way as the leading wheels, the wheel contour is cut due to calculated locus of the tool tip. Note the ring on the face plate was cut to the same diameter as the wheel, so as to utilize the ring as a gauge of wheel diameter.
The backside radius of the flange is cut from backside. After that, tread taper is cut, front edge is chamfered, and whole contour is finished with fine file and emery cloth. Finally, sharp edges around the counter weight and spoke backside are removed by file.
The spigot is turned down to a diameter of first and third driving wheels' center hole. And then, the first and third driving wheels are cut in the same way as the second driving wheels.
A serious problem happened when I cut the driving wheels. It started with a strange noise from the lathe backgear. Before long, the noise became louder and finally the lathe spindle stopped suddenly. I checked and found the backgear was jammed on the spindle. I made sharp impacts upon the gear but they could not make the gear turn. I was obliged to disassemble the headstock. First I removed the main spindle as the photo shows. The backgear is still remained in the gearbox.
The backgear is swung by a lever under the main spindle. The lever drives eccentric spindle of the backgear. Note an oval hole under the lever. I guess cast iron chips came through the hole and slipped into the backgear spindle. I had better close the hole.
The backgear spindle could not be drawn from the jammed gear. So I employed 12mm bolt and nut to push out the spindle. I utilized the die holder as a sleeve. Incidentally, the other gears in the headstock have gunmetal bushes around the spindles, but only the backgear have no bush.
The photo shows the damaged spindle. You can see terrible scratch around the spindle. I have no spare part so I had to use this again. I removed burr around the scratch by fine file and scoured the spindle with metal polishing paste. And then the head stock is assembled again.
Cutting driving wheels were completed at length. The question is how to build them up accurately.