Gecko 320 Testing & Tuning results
Posted by
Kenneth A. Emmert
on 2007-09-19 08:38:13 UTC
Gecko Tuning X-axis-
One of the reasons for my CNC adventure is to work with Scale and
measurement data towards a goal of true closed-loop. I have done
the initial mounting and testing on X-axis using a 1 micron
Certified High Precision Scale. I'll cover what was used for
equipment in my testing and early results. System installed was a
standard CNC retrofit kit supplied by Industrial Hobbies.
Scale- Foic Certified High Precision Glass Scale 0.001mm resolution
+/-0.003mm deviation within 500mm travel, repeatability +/-0.001mm
the metric equivalent to 0.00004"
Gecko 320 Servo Card
Rockford ¾" Precision Rolled Ballscrews specified at 0 to .003 +/-
deviation per foot
2,000 count encoder; ballscrew shaft mounted with a 4 to 1 reduction
Industrial Hobby High Performance Servo motors
I was unable to measure any backlash from the double nut ballscrew
at 0.001mm registration. Ball nuts are set at approximately 100lbs
of torque as per IH specifications.
These are initial results while not definitive they are suggestive.
Perhaps group members will suggest other testing parameters.
Gecko 320 unit grossly tuned Damp and Gain were set in the 11
o'clock position. Testing done was with using Mach 3 software.
With these settings it became clear that system would not hold a
repeatable Zero point. System was variable in repeatable accuracy
and deviation showed increase in measurement deviation as table was
operated in both directions multiple times.
In tuning I was able to get a consistent and repeatable Zero
registered to within measurement system deviation specifications.
While ballscrew deviation in length was only grossly tested within
18.5" travel; it did not exceed 0.0015" at any point.
Ken
Kenneth A. Emmert
SMW Precision
One of the reasons for my CNC adventure is to work with Scale and
measurement data towards a goal of true closed-loop. I have done
the initial mounting and testing on X-axis using a 1 micron
Certified High Precision Scale. I'll cover what was used for
equipment in my testing and early results. System installed was a
standard CNC retrofit kit supplied by Industrial Hobbies.
Scale- Foic Certified High Precision Glass Scale 0.001mm resolution
+/-0.003mm deviation within 500mm travel, repeatability +/-0.001mm
the metric equivalent to 0.00004"
Gecko 320 Servo Card
Rockford ¾" Precision Rolled Ballscrews specified at 0 to .003 +/-
deviation per foot
2,000 count encoder; ballscrew shaft mounted with a 4 to 1 reduction
Industrial Hobby High Performance Servo motors
I was unable to measure any backlash from the double nut ballscrew
at 0.001mm registration. Ball nuts are set at approximately 100lbs
of torque as per IH specifications.
These are initial results while not definitive they are suggestive.
Perhaps group members will suggest other testing parameters.
Gecko 320 unit grossly tuned Damp and Gain were set in the 11
o'clock position. Testing done was with using Mach 3 software.
With these settings it became clear that system would not hold a
repeatable Zero point. System was variable in repeatable accuracy
and deviation showed increase in measurement deviation as table was
operated in both directions multiple times.
In tuning I was able to get a consistent and repeatable Zero
registered to within measurement system deviation specifications.
While ballscrew deviation in length was only grossly tested within
18.5" travel; it did not exceed 0.0015" at any point.
Ken
Kenneth A. Emmert
SMW Precision