Z axis jog moves spindle only incrementally

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10 years 9 months ago #69344 by norbertfarquharsh
Thanks for previous help but I am lost again and even thought I had sent this problem in but see no record of it on My Topics list.

I had to start over on this machine due to a complete computer crash and some other problems but at least the help given me before let me avoid some of the problems as this time I set it up with gantrykins so it went fairly well.
The machine is a gantry with xylotex hardware. It is up and running with limit switches on all axes. After I got it all running, I wrote a small program (attached, firstone.ngc) which was to try movement on all axes and it worked fine. Then I wrote another (new8.ngc) one try canned cycles and found that I could not make the Z axis feed in the correct direction. I could not get the program to work any way so decided to reverse the axis polarity. Note that the X and Y axes have their home switches on the negative end and the Z axis switch is now on the positive end.
At that point, there were all sorts of problems. FOr example. homing was in the wrong direction, which I corrected by changing the sign on the Home Search Velocity and inverted the feed direction but then the axis did not want to jog. I tried changing the table travel signs to no avail. All the setup to this point had been done with Stepconf.
This morning I edited (with gedit) the gantry.ini file and noted that the Max Limit on Z was only 0.1. I changed that to 8.0 and then the axis would jog, but homing did not work properly; that is, when Home All was chosen, only Z homed. And there were other quirks, So I went back to Stepconf and saved things and the .ini and .hal attached are from after that.

Thanks in advance for any help you can give me.

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10 years 9 months ago #69363 by Rick G

noted that the Max Limit on Z was only 0.1. I changed that to 8.0

It would be more common to have the Z axis home at 0.
In which case if there is 8" of travel on your Z axis the range would be 0 to -8.
Code:
[AXIS_2] TYPE = LINEAR HOME = 0.0 MAX_VELOCITY = 2.85001824012 MAX_ACCELERATION = 30.0 STEPGEN_MAXACCEL = 37.5 SCALE = 6400.0 FERROR = 0.05 MIN_FERROR = 0.01 MIN_LIMIT = -0.01 MAX_LIMIT = 0.01 HOME_OFFSET = 0.000000 HOME_SEARCH_VEL = 0.500000 HOME_LATCH_VEL = -0.078125 HOME_IGNORE_LIMITS = YES HOME_SEQUENCE = 0

Rick G

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10 years 9 months ago #69391 by norbertfarquharsh
Rick,

Thank you very much for your reply.
I am not certain if I understand your first point about the homing at 0. All axes are homed at zero, but the X and Y home at the negative end as I understand it as when I jog away from home the positive jog is used and in G code programs positive numbers are used to move away from home. Conversely, the Z axis homes at the positive end as the negative jog button moves the spindle away from home and in G code negative numbers are used to move the spindle away from home
One thing that is confusing is that if I put those numbers into Stepconf, it does not change the numbers in gantry.ini. That is one reason that I finally resorted to direct edits of the file. I just tried it again and the values in stepconf are 0.0 and -8.0 but that is not what is written in the .ini files. Probably I am doing something wrong.
However, when I edited the gantry.ini file with gedit and changed the Axis 2 MIN_LIMIT to 0.0 and the MAX_LIMIT to -8.0.
The axes home properly but the Z axis gives "Can't jog joint 2 further past min. soft limit (or, alternately max) when the other jog direction is tried.
I do appreciate your help as it certainly confuses me.
Latest gantry.ini attached

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10 years 8 months ago #69422 by Rick G

changed the Axis 2 MIN_LIMIT to 0.0 and the MAX_LIMIT to -8.0.
The axes home properly but the Z axis gives "Can't jog joint 2 further past min. soft limit


O.K. using gedit on the z axis change
Code:
MIN_LIMIT = 0.0
to
Code:
MIN_LIMIT = 0.01

and try that.

Rick G

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10 years 8 months ago #69454 by andypugh

norbertfarquharsh wrote: However, when I edited the gantry.ini file with gedit and changed the Axis 2 MIN_LIMIT to 0.0 and the MAX_LIMIT to -8.0


The max limit must be > min limit.

Try
MIN_LIMIT -8.0
MAX_LIMIT 0 (or 0.01)

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10 years 8 months ago #69496 by Rick G

The max limit must be > min limit.

Yup, should have had my coffee first.
Code:
MIN_LIMIT = -8.0 MAX_LIMIT = .01 HOME = 0.000 HOME_OFFSET = 0
I have found that setting the max limit slightly beyond the home position (.01 instead of 0.00) sometimes prevents the soft limit error.

Rick G
The following user(s) said Thank You: cahlfors

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