On Friday, July 15, 2011 02:35:03 AM Andy Howell did opine: > Hello, > > I purchased a used Sieg X2 mill. The previous owner retrofitted it for > CNC using the plans from Hossmachine. > > Its using a Gekko 540 to drive the steppers. > > I've been having problems with it a low feed rates. I was attempting to > do a pocketing operation to create a 0.6 inch hole with a 1/4 end mill. > Each pass ended up offset from the previous one. > > Not understanding what was happening, I substituted a pen for the end > mill, removed the Z axis movement, and drew the following image at > different feed rates: > > http://i52.tinypic.com/28ba821.jpg > > At F20, it looks pretty good. The center is cleared out, followed by the > outer portion. The slower the rate, the greater the positioning error. > > Any idea what might wrong? > > Thanks, > > Andy
I am assuming that you have checked for draggy movement by powering down the amps and turning that axis by hand, but on 2nd thought that doesn't fit very well either. Does this Gecko 540 have a powerdown mode that reduces motor power when no motion is being done? If so, it looks as if the Y axis amp may be powering down, going into park mode so to speak, based on the D flatted motion of the Y axis. It is possible that the timing capacitor in the 540's Y amp has opened up, smallish electrolytic caps are a bit famous for that failure when operating at logic level voltages. I've never seen a 540 myself, so I have no clue if this is something field repairable, or if its a send it back to Gecko job. I am a C.E.T., so unless its a potted assembly, it is field repairable to me. ;-) This, if that is the case, is one of those failures best found with a "Capacitor Wizard" tester, google for it, the common digital meters capacitor checker will often not be very successful at finding such a failure since it is measuring the capacitance by a method that may even heal the problem for a short time. Had I not fixated on the D flatted motion, I would have recommended that you post a drawing showing your grounding and shielding interconnects, but I'll just suffice to say it should all be a star format, all grounds come back to one center point, but are not otherwise interconnected by cable shielding. The shielding should only be 'grounded' on the end of the cable nearest this center point. My motor cables are shielded, but the shielding stops at the motor end of the cable connector and does not continue on to the motor itself. Cheers, gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) A man who fishes for marlin in ponds will put his money in Etruscan bonds. ------------------------------------------------------------------------------ AppSumo Presents a FREE Video for the SourceForge Community by Eric Ries, the creator of the Lean Startup Methodology on "Lean Startup Secrets Revealed." This video shows you how to validate your ideas, optimize your ideas and identify your business strategy. http://p.sf.net/sfu/appsumosfdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
