On Sat, 21 Dec 2024 at 04:55, johnd <jo...@autoartisans.com> wrote: > > Thanks. Is there a minimum number of slots assuming the spindle speed is > stable?I've not had issues with 60. My friend has far less.
The issue is that the spindle speed is _not_ stable, as rigid tapping has a stop and reverse. It's catching that that is critical. So you definitely need quadrature, to be able to tell when the spindle changes direction. And then you need to think about how much "electronic backlash" you can afford at the tap. With 60 teeth you have about 6 degrees of positional uncertainty. With a 24 tpi / 1mm pitch tap that's about 0.0007" or 0.02mm axial error. The tendency will be for the tap to rub on the lower thread flank as it backs out. If you use a floating tap holder then this won't be a concern. I think you are just about OK at 60, but going any less I think that a floating holder would give better threads. But consider also the backlash in the Z-axis drive, there is probably some, even if not very much. That will have the same effect. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1912 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
