On 11/13/2016 03:34 AM, Gene Heskett wrote: > On Sunday 13 November 2016 00:21:24 Jon Elson wrote: > >> On 11/12/2016 08:29 PM, Gene Heskett wrote: >>> Back again; >>> >>> I stuck the 2nd one back in, right way to, but I guess it did not >>> survive the reversed polarity, it can only pull down about half a >>> milliamp. I have 7 more of them so I will use new ones for the last >>> 2, A/B. >>> >>> But watching the one in the index position, I note that they stay in >>> the last state, but does that affect the index adversely? >> Yes, they have a flip-flop that is driven by a comparator >> that checks the difference between the two sensors >> in each unit. So, they DO latch, that is the behavior as >> per the data sheet. >> >> Now, with LinuxCNC, all you need is consistent operation in >> ONE direction only. For instance, in a rigid tapping >> operation, the spindle encoder is synched to the index at >> the beginning of the operation and then the encoder is >> allowed to count up and down as the tap progresses in and >> then backs out. The spindle encoder is NOT resynched during >> the whole operation. >> >> It is pretty clear that the index pulse would pick up the >> opposite side of the hole or notch when running the opposite >> direction, but that should not be a problem as mentioned above. >> >> It also seems that the A-B quadrature might slip one >> quadrature count when the spindle reverses, but would then >> slip the other way when reversing again. And, I'm not sure >> that would actually occur, either. Anyway, a tiny slip in >> the spindle count should not be much of a problem in most cases. >> >> I've rigid tapped thousands of 4-40 holes with combo >> drill-taps without any problem, using the ATS667 sensors. >> >> Jon >> > Not knowing the internal workings as you do, I was somewhat concerned > that there might be enough of a phase angle difference between > directions to loosen a thread, particularly when running the g33.1 in a > peck loop, I don't know the peck cycle. Does it re-synch the spindle each peck, or just stay synched for the entire cycle? I'd kind of guess it just stays synched for the entire cycle, in which case it should not matter. > I think some of my > loose threads are because the tap isn't straight. Well, there is also lag in the trajectory planner (in old versions you could run the TP at 1/5th the servo rate) and backlash and other slack in the machine. > And I keep forgetting > to order a couple 3mm from some other than dewalt/irwin because both of > the $30 ea tap & matching drill kits I've bought have crooked taps, by > about a 20 to 30 thou wobble. Ugh! I buy my taps from MSC or KBC, usually. I use drill-taps for thin stock and do the spot-drill-tap in one cycle. I use spiral-flute taps for other stuff in aluminum. > Z backlash setting accuracy should count > for that too. Oh, i do NOT use backlash compensation. It makes a jerk move on every reversal, and that can cause problems.
Jon ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
