< 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.
