Posted by BillS on December 16, 2006 at 20:07:41:
In Reply to: Re: hobber recommendation posted by Bob M on December 14, 2006 at 03:02:07:
Hob slide motion is in a direction parallel to the work piece axis.
I'm not sure how many square cut cycles there are, but I believe one of them goes something like this:
(1) Machine starts and hob slide feeds parallel to work axis to cut teeth, (2) stops and raises workhead above cutter, (3)retracts hob slide to starting point and waits for part to be changed. (4)After part changes, machine starts and workhead drops to cutting depth and hob slide feed engages to repeat cycle at (1). I believe this "square cut cycle" can be used with auto-loading equipment.
I'm not aware of earlier B-C hobbers equipped with tangential feed, where the hob cutter moves along its axis. Maybe someone can advise us on this point.
There is hob shifting (same motion direction as in tangential feed) that shifts the hob only when "out of cut" during retraction. This distributes wear along the length of the hob. Even on a manual machine, the hob should be shifted at intervals during a production run to even out hob wear.
You're right about plunge. That's motion of the workpiece axis toward the hob spindle and is used to throat worm gears. Any machine can be manually moved in this direction but the automation is well worth it if you intend to throat a lot of worm gears.
I wonder if there is a "square" cycle for throating?