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General Mach Discussion / First Post - Help with setup issue?
« on: May 25, 2009, 04:46:41 PM »
Hello Everyone,
I'm new here and could use some help. I've been working on an X2 CNC conversion for some time now. I have no prior CNC experience. I have some machining experience so I'm comfortable using a manual mill or lathe. I'm just starting to learn Mach3 and g-code.
My X2 CNC conversion is almost operational however, I discovered a problem while testing this afternoon. While checking position repeatability I discovered the X axis is traveling .006" short of what Mach3 is reporting on the DRO.
My test setup is simple. I've clamped blocks a fixed distance apart, 2.000". The DTI has a 0.099" diameter ball end. The indicator is set to read 0" at the starting block. It travels 0.001" after contact to get to a 0" reading. I wrote some simple g-code to move the X axis from 0.000 at the starting block to the end block (2.000" away). By changing the distance little by little until the DTI reads 0.000" (at the end block) I found that distance needed to be 1.906". I put a dwell in so I can read the DTI at the end block before it returns the table to the original position. The repeatability is fine. It returns to within 0.0005" on both ends repeatedly.
Here's my breakdown.
Start = 0"
Reported distance traveled = 1.906"
+ DTI travel to 0" = 0.001"
+ indicator ball dia. 0.099"
Actual Distance traveled = 2.006"
Over travel of 0.006" per the Mach3 DRO
I've also tried the above test with blocks set 3.000" apart with the same 0.006" over travel reported by the Mach3 DRO.
By using my Shuttle Express to jog at 0.001" per click I found that the DTI doesn't move til about 0.006" of reported travel when changing directions.
So, would this be the backlash on the X axis?
Thanks for the help,
Dan
I'm new here and could use some help. I've been working on an X2 CNC conversion for some time now. I have no prior CNC experience. I have some machining experience so I'm comfortable using a manual mill or lathe. I'm just starting to learn Mach3 and g-code.
My X2 CNC conversion is almost operational however, I discovered a problem while testing this afternoon. While checking position repeatability I discovered the X axis is traveling .006" short of what Mach3 is reporting on the DRO.
My test setup is simple. I've clamped blocks a fixed distance apart, 2.000". The DTI has a 0.099" diameter ball end. The indicator is set to read 0" at the starting block. It travels 0.001" after contact to get to a 0" reading. I wrote some simple g-code to move the X axis from 0.000 at the starting block to the end block (2.000" away). By changing the distance little by little until the DTI reads 0.000" (at the end block) I found that distance needed to be 1.906". I put a dwell in so I can read the DTI at the end block before it returns the table to the original position. The repeatability is fine. It returns to within 0.0005" on both ends repeatedly.
Here's my breakdown.
Start = 0"
Reported distance traveled = 1.906"
+ DTI travel to 0" = 0.001"
+ indicator ball dia. 0.099"
Actual Distance traveled = 2.006"
Over travel of 0.006" per the Mach3 DRO
I've also tried the above test with blocks set 3.000" apart with the same 0.006" over travel reported by the Mach3 DRO.
By using my Shuttle Express to jog at 0.001" per click I found that the DTI doesn't move til about 0.006" of reported travel when changing directions.
So, would this be the backlash on the X axis?
Thanks for the help,
Dan