On Tue, 29 Sep 2009 22:02:51 +0100, you wrote: >2009/9/29 Kirk Wallace <kwall...@wallacecompany.com>: > >> I still think your threading problem is due to the Z acceleration issue. >> You may try cutting an air thread that is as long as your Z axis will >> allow. If your thread wanders the same across the thread then I would >> look into your encoder more. If the wander settles to a perfect sync to >> your spindle, then look at the accel problem. > >As always, it is more complicated than this... > >G61.1 helps, but only if I turn down my max accel rate, otherwise it >drives the stepper too fast and it stalls. It is not a complete >solution, either.
?? As an example, I can thread a 1.5mm pitch thread at 1000 rpm using steppers. Acceleration should be set so the stepper can still move reliably without CV. BUT you need to be out of the cut while that acceleration is taking place. I watched your video, but couldn't determine how much lead in you were giving the thread? I've heard the same jittering occasionally, but at a much higher frequency. Air running testing many passes and watching the speed readout, it seems to happen on the full pass that a noise pulse occurred on. My acceleration values are high, BUT I still always start 5mm off the end. Delay on 1st pass for spindle to get to speed, all interim moves are G0's. Spindle here is 1.1kW, I've tried encoders with 90 and 125 ppr per rev and they work fine. Ideally you need to have NO noise on the encoder line. Mine still has a little, and needs a new encoder cable, and shows as odd kicks on the spindle speed readout - even with the spindle stopped. Repositioning the existing cable helped enormously. I think you have two problems, noise and not enough lead in. Steve Blackmore -- ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
