HOB Cutting machine

The point of this video is what? That one can use it to make their own gear hob / make gears? How good would the gears be? Good enough to put in an automotive gearbox?

Jon Banquer San Diego, CA

Good video. People still have skills to make clever tools.

Fred

The point of this video is what? That one can use it to make their own gear hob / make gears? How good would the gears be? Good enough to put in an automotive gearbox?

Jon Banquer San Diego, CA

Jon,

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 :

Cheers,

Hope all is going well for you.

Sorry for the delay. I'm working long hours. I sent you off an e-mail from work to your precision machinist hotmail account explaining what I'm looking for.

Jon Banquer San Diego, CA