Harold Hall
Crossing Out Clock Wheels using a Rotary Table. Harold Hall
Photograph 1 shows the spokes of a clock wheel being machined, with the length being controlled by the X axis stops and their width by the Y axis stops. First, one side was machined using the X axis stops and one of the Y axis stops. Then, repeated for the other Y axis stop making the second side. The rotary table was then moved through 72 degrees for each spoke.
Photograph 2 shows the boss and outer diameter being machined using the rotary table and the same X axis stop positions, as was used for the spokes. The table was also set against one of the Y axis stops, either will do.
I started approximately in the middle of the curved being made and the rotary table rotated first one way and then the other, in each case stopping (visually) just short of the spoke already made. The reason for starting in the middle was to avoid the possibility of turning the rotary table the wrong way and hitting the spoke.
Photograph 3 shows the wheels as they came of the rotary table, with just a little cleaning up needed.
The setting up process was as follows
1 Using a centre in the machine spindle and a centred plug in the bore of the rotary table. Set the rotary table concentric with the machine spindle and secure the rotary table onto the machine table.
2 Similarly, with a centred plug in the holding fixture, set the fixture concentric with the machine spindle, making it concentric with the rotary table also. Add wheel blank.
3. Traverse table in the X direction equal to half the boss diameter plus half the cutter diameter and set the first table stop.
4. Traverse the table in the X direction by the spoke length minus the cutter diameter and set second stop
5. Traverse the table in the Y direction by half the spoke width plus half the cutter diameter and set the first Y axis stop.
6. Traverse the table in the Y direction, but opposite to that in 5, by the spoke width plus the cutter diameter and set the second stop. Take note of backlash in the feed when setting this stop.
7. The wheel can now be machined as described above.
Whilst not set for the clock wheels,Photographs 4 and 5 show the X and Y stops fitted to my milling machine.
Metalworking
Workshop Processes
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All pictures can be clicked on to provide a larger view
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