With the assembly positioned, first, using a tipped tool, machine the side of the
vice stepping down the face in increments of around 1/8". Follow this by machining
the fixing face doing this also in stages.
Rotate, and repeat for the other side. For this side though now add a HSS end mill
and finish machine the two surfaces with a depth of cut of around 0.002", setting
the saddle stop at this position. With that done rotate once more and finish machine
the two faces of this side also, Photograph 13. At a depth of cut of 0.002" the cutter's
helix prevents it taking an over wide cut. Having done that the milling operations
Move the jaw to the fully open position and the vertical slide parallel with the
lathe's axis and drill for the operating screw, Photograph 14. First, drill at the
size required in the jaw (6mm) then at the tapping size hole through the vice end
only. Note that the tailstock should be used to feed the saddle for the drilling
operation. When taking the mock up picture I overlooked placing the moving jaw against
the rear of the vice, also showing the feed being applied by the tailstock.
Whilst still on the lathe, place the tap in the drill chuck and tap the vice body.
Being cast iron the chuck should provide sufficient grip for the operation or at
least to get the thread started on course, which is essential.
The feed screw
Do turn the part with the outer end supported by the tailstock centre, reason detailed
later, otherwise it is a relatively straight forward item to make. However, so that
the vice works correctly it is essential that the thread does not wander along the
length of the screw. This is not as easy as may first be thought. Using a tailstock
die holder would seem the approach to take but at this diameter it is unlikely that
the chuck will have sufficient grip. The easiest way out of this is to machine the
part from hexagon bar material, if this is not available then the thread can be initially
screw cut and then just finished off with a die.
The latter is the way I would take myself except for the fact that I like to keep
to metric threads but have a lathe with an imperial leadscrew. The way that I chose
to make the thread was using a die in a guided die stock, these perform the task
with ease even if making very long threads