Leave the body firmly clamped on the faceplate but remove the cutter holder placing
this in the tapping jig (Sk. 1). The holder should be fixed in the jig using the
screws engaging in the grove that was produce by drilling the 6mm hole. The centre
drilled impressions should also be visible at the working end.
Place the jig into a vice on the milling machine table and align the centre drilled
end of the cutter holder with a centre placed in the machines spindle. To do this
mount a small centre in the drill chuck and lower it into the centre with the vice
only loosely clamped to the table and with that done, clamp the vice to the table,
Photograph 5. Take up the backlash in the appropriate direction in the X axis leadscrew,
then remove the centre and feed the table by precisely 11mm. Centre drill, drill
5.2mm diameter, Photograph 6, and tap M6.
Remove the cutter holder from the jig, which has now served its purpose, and return
the holder to the body still on the faceplate. Align the partial M6 thread with the
partial 6mm diameter hole by screwing in an M6 grub screw. With that done, again
clamp the holder in the body using the two M4 grub screws and produce the 10mm diameter
counter bore as shown in Photograph 7.
The curve surface in the cutter holder produced by the counter bore needs to be extended
deeper to allow the holder to move for cutting different diameters. To do this, loosen
the cutter holder and move it forward 11mm, still with the grub screw engaged with
the M6 thread and 6mm hole, and carefully extend the curved surface as seen in Photograph
Return the cutter holder to the full in position and rotate the complete assembly
to permit the 14mm counter bore to be made on the other side. Place a short piece
of 6mm diameter rod in the drill chuck and use this in the pre drilled 6mm hole to
align the body for counter boring. Counter bore 14mm diameter.
Remove the body from the faceplate assembly, which has now also served its purpose
and can be dismantled. However, do not remove the cutter holder from the body before
scribing a line on one end to represent the line to which the flat has to be machined.
This does not need doing with any degree of accuracy as it is used more for alignment
than to detail the amount to be removed.