On Sat, 24 May 2008 22:11:47 -0500, you wrote:
>I have set up lathe-type threading on my mini-mill, with a real >quadrature encoder on the spindle. It has 1728 lines, for 6912 >quadrature counts/revolution. So, at 100 RPM, it provides >11,520 counts/second, or 11.52 counts/servo period, assuming a >1 KHz servo update cycle. I didn't think I needed that kind of >resolution or count rate, it was just a one-of-a-kind encoder I >had laying around. I did also see some of this "hunting" >behavior when I first started setting this up several years ago. Jon - I know nothing on how EMC works with spindle index, but hunting that decreases in amplitude and then steadies out in other controls is usually a sign of over correction with too aggressive correction factors in PID controls. Random hunting is usually a poor connection. >Also, if your Z axis is asked to sync to the >spindle in too short a distance, it will reach its accel limit >and suffer some hunting. Shouldn't happen, should be NO hunting in a properly implemented and set up system - it's overcorrecting. It should get up to speed and stay there. The norm is to allow a short pause for the spindle to get to speed before the Z axis moves, that could either be set in the controller (EMC) or in Gcode. A short lead in is normal to allow the Z axis to get to velocity, but how much is machine dependant. Steve Blackmore -- ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users