No offense to you or anyone else but I had put you and most of those
who typically spend an inordinate amount of time humping your leg into
my bozo bin quite some time ago. Simply, I felt it a waste of too much
my time reading that
stuff on the newsgroup. And so with that in mind please do feel free
to mail me if you have a question or even if you just want to shoot
the breeze I will try and get back to you fairly quick.
Anyways, the video link you referenced is of someone using a profile
tool and specialty lathe attachment in order to cut primary clearance
and helix into a soft (probably m2 hss) blank in order to produce a
hob--easily spotted in the video is that the attachment has a a cam-
action motion to produce a form relief--not
readily apparent is the "half nut" which is acting as a lead screw to
generate the helix--if you notice, he keeps it engaged with his hand
on the black knob the whole time except at the very end where he
finally opens it up presumably in order to move re-position the
carriage to the starting point for another pass.
As to finished gear quality, you need to understand that a hobbed gear
is a "generated form" and so the actual gear quality isn't nearly as
dependent upon the hob as one might at first think and so even though
the hob will have a nasty surface finish from relieving it at such a
low surface speed I would think that after hardening it should produce
a perfectly servicable gear though pretty sure I do recall most if not
all commercial hobs as having been ground all-over.
Anyways where upon the higher classes of gear ( or involute spline )
are required then your part processing methodology normally moves from
hobbing soft material then hardening to hobbing a hardened work piece
and then after that to hobbing a soft blank oversize followed
hardening and subsequent finish grind
using form grinding wheels on a gear grinding machine, the wheel
itself having thread mill" sort of profile..
If you look closely at this video you will see a clear shot of the
wheel form while dressing is being carried out at about 1:02 :
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.