Re: Questions on adding rigid tapping....
How quickly does your spindle come up to speed? How fast does it reverse speed? Would it be practical for you to use TC tapping? I run TC tapping on my "hobby" grade mills and it works fine. The hard part was modifying my CAM software to generate a good "drilling" operation. I picked an RPM inside the edge my power band and adjusted my signal voltage so it was dead on at that speed. I do just about all my tapping at that RPM. I tap in high gear in aluminum, and low gear in most steels and it works just fine. Once I had a template that worked inside the power requirement range of the mill I just copied it and adjust the increment for all my most commonly used tap pitches. Now I just apply the template (style) I need to the operation and move on to the next one. I've even done blind holes when drilled to have a few threads extra depth clearance, and after doing some test cuts to see how much the maximum over travel was during reversals. It will probably never be as good as rigid tapping and I tap at a pretty low RPM, but it works. I could tap faster and get further into the power band, but even this is far superior to walking the finished work piece over to the drill press an tapping with the tapping head. (I have two drill presses with "permanently" mounted tapping heads and my two most commonly used taps loaded.)
Bob La Londe
http://www.YumaBassMan.com