I need to make a 32t helical gear to mate with my 8TPI acme leadscrew. I ha
ve a couple of questions for those here who know way more than I do.
I need to mill slots into my 8TPI acme blank. It's just an old Sheldon lead
screw that fits nothing I have. I figure I'll cut 4 or 6 groves on my mill.
My question is where should the leading edge be in relation to the center
line of the blank. My gut tells me that the cutting edge should on the cent
er line so the cutting edge is 90 degrees. If the center of the slot is cen
tered instead the cutting edge will not be at a 90 degree angle. Does this
Second, the diameter of the blank. The circumference of 32 teeth divided by
Pi gives me a dia of 1.27. Following a different method, adding three teet
h divided by DP of 25.13 gives me a diameter of 1.39
Color me confused. Can anyone here answer these questions please?
BTW the gear will be brass. I've made a jig to hold the blank in my tool po
st and hob will be in the lathe chuck. I intend to run the lathe as slow as
I can and feed the gear blank into the hob slowly until I get enough teeth
to operate my thread dial. I may do it in my mill, holding the blank in my
vice and hob in my collet holder, depending on which one rotates the slowe
st. Thanks in advance for any feedback/suggestions
6 years ago