Fine downfeed mod for HF 12 speed DrillMill |
The first mod I made to my drillmill was to add a fine down feed to the z-axis.
After tring several other approaches, the easiest was to add a worm gear to
the existing feed mechanism. This had the advantages of allowing use of
the existing speed handles for drilling or the fine feed for milling. I
first made several castings for the gear blank and worm mounting baracket, I also
cast a knob, using one form my 7x10 minilathe as a pattern. The worm gear
was cut using a 1/2-13 spiral flute tap as a hobb. This was bored to
provide a press fit on the existing depth stop coller, the stop pin is removed
from the side of the headstock. |
I used a simple brass bushing forthe worm screw in the mounting bracket, and a simple
center pin on the other end I have notice some alignment
problems after continued use and may replace this with a set of ball bearings
on each end. |
drawings for the simple down feed mod |