Body S2 This is the only other item that needs special attention, Cut a piece of
steel 92 mm long mount in the four jaw chuck and set to run true. Drill and tap M8,
remove reverse and centre drill the second end. Fit a hex head screw gripping this
in the three jaw chuck and supporting the other end with the tailstock centre. Turn
the outer diameter to 44 mm.
Once more, accurately mount in the four jaw chuck and support the outer end with
a fixed steady. Turn the internal diameters and thread in the first end, turn end
on end and repeat for the second end and through bore 26 mm diameter. The book mentioned
earlier details this sequence in more detail.
The remaining items for this are S3 to S7 and S9 and S10, all being relatively simple
with only the collet (S7) worthy of some comment.
Place a piece of 16 mm steel in the three jaw and with about 30 mm projecting. Face
the end and turn the 6 mm bore by 17 mm deep. As concentricity is vital bore this
hole rather than using a 6 mm drill. Next turn the taper, ideally using the top slide
still set at 12 ° from making the collet chuck body (S8). Drill and tap the M4 hole
and part off. Make the four slits in the collet using a similar system to that detail
below for the larger collets.
Large Collet Chuck Assembly (AS 5)
Adapter L1 With a piece of 25 mm in the three jaw chuck, face end and drill through
10 mm diameter. To minimise the amount of machining required when eventually mounted
on the threaded stub mandrel later, pre bore the 17 mm bore at 16 mm, also a little
short on depth, say 27 mm. Similarly machine the 22 mm outer diameter oversize at
Remove from the chuck, turn end on end and replace holding it on the 23 mm diameter
just turned. Bore through at 10.5 mm a close sliding fit on the end of the spindle.
Similarly, bore for the 1/2" x 20 TPI thread, also the 1/2" x 2 mm deep bore, Photograph
21. This bore replicates the locating bore in the drill chuck that can also be fitted.
Make the 20 TPI thread.
Turn the 22 mm diameter and skim the 25 mm outer diameter to ensure that it is running
true. Do take the absolute minimum off else it will reduce the thread outer diameter
beyond what is acceptable. If your three jaw is not reasonably accurate then use
the four jaw so that the 25 mm diameter can be set to run true. Make the 25 x 1 mm
thread, Photograph 22.