Background: My 20" x 40" DIY CNC table has a 14" x 30" machinable area and has been in hobbyist service for 7 years, always using Mach3 v3.043.066.
My PC is 64-bit. 3Ghz, 3GB RAM, Windows 7 Pro (had been XP years back), Mach3 Kernel speed has always been 25Khz, parallel port driven BOB. B.O.B. is CNC4PC C1R10.
For XY axis: Keling KL-4030 Drivers, Keling KL23H286-20-8B 425 in/oz stepper motors, powered by KL 350-36, 36 volt, 9.6A Switching power supply. XY gantries are timing belt driven, Z gantry is ACME Lead Screw driven. All axis use V-groove bearings on aluminum linear rails. I recently modified the .75" x .75" aluminum rails by adding anodized V-Rails to them while maintaining their basic dimensions. Recent "pull" tests of the X and Y gantries with timing belts removed showed the X-gantry required between 3-1/2 to 4 lbs of pull to move through full travel. The Y-gantry required 2 to 2-1/2 lbs of pull to move through full travel. The pull required prior to the V-rail upgrades are unknown but believed to have been a few pounds more for each axis. The XY timing pulleys are 1" diameters, so the stepper motors have more than sufficient drive torque for their loads. Stepper driver's heat sinks are only ever slightly warm. With the V-rail additions, the XYZ axes travels are smooth with very low mechanical slop.
Calculated XY resolution is .0008". As such, I am trying to determine why diagonal bit travels have visible stair-stepping and why some circular pads one straight circuit traces have their upper and lower sides slight offset from each other. From what I've read in researching this forum, this could be due to motor tuning, velocity vs acceleration vs CV Control settings. CV Control settings have always be defaults, with only two items checked: CV Dist Tolerance=180units, G100 AdaptiveNubsCV.
I'll post a reply with the XY Motor Tuning screenshot but this post includes back lit photos of recent isolation routed PCB showing areas of interest for feedback.
The isolation routing was done using a .005" dia. tip, 60 degree engraving bit, 20,000 RPM, Feed Rate 15 IPM, D.O.C. of .006", through 1 mil copper clad board 1/16" thick.
X-CircleTracking-1 photo shows upper and lower half of solder pads are slightly offset in the X-axis and this does also occur when trace and pad are aligned on the Y-axis. Is this an acceleration issue?
X-CircleTracking-2 photo shows vertical and horizontal traces routed are nice, smooth and straight (expected behavior) with diagonal portions of these traces show stair-stepping. Some stair-stepping is expected but on the order of .001", or so I think. Is this also an acceleration issue?
P1000687-c photo, A board I did about 6 years ago, does not show the same degree of stair-stepping.
I'm wondering whether since reducing the XY axis friction with the V-rail modification is the a factor in the root-cause of what is now happening.
Thanks for your feedback and let me know if I can provide further information.