Homng moving away from home
- TarHeelTom
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Now my X axis moves in the right directions when jogging, but when I ask it to home, it moves away from the homing switch, instead of towards it.
Any ideas?
hal and ini are attached.
thanks
Tom
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- TarHeelTom
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See linuxcnc.org/docs/html/config_stepconf.html
extract from same
Home Search Velocity
The velocity to use when moving towards the switch. If the switch is near the end of travel, this velocity must be chosen so that the axis can decelerate to a stop before hitting the end of travel. If the switch is only closed for a short range of travel (instead of being closed from its trip point to one end of travel), this velocity must be chosen so that the axis can decelerate to a stop before the switch opens again, and homing must always be started from the same side of the switch.
If the machine moves the wrong direction at the beginning of the homing procedure, negate the value of Home Search Velocity.
Home Latch Direction
Choose "Same" to have homing back off the switch, then approach it again at a very low speed. The second time the switch closes, the home position is set.
Choose "Opposite" to have homing slowly back off the switch. When the switch opens, the home position is set.
regards
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- TarHeelTom
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Sure wish the documentation had a search function.
Tom
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- TarHeelTom
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Things are almost to the point where I need to start fine tuning.
Is there a write-up in the forum which discusses tweaking all the numbers?
I'm still getting the occasional following error, etc, in preliminary work.
Also need to tweak the numbers which set the jog speed, etc. Would like to have some more background here on going about these is a systematic way.
Thanks
Tom
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First the basics, without the base-thread speed set properly everything else fails
wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Twe...ftwareStepGeneration
also the previous link I gave has more info
linuxcnc.org/docs/html/config_stepconf.html
The below explains the .ini file settings, I set my jog well below the max velocity for the axes, since I want to use it to go to a position in a controlled fashion. A high figure very often leads to joint errors in use.
linuxcnc.org/docs/html/config_ini_config.html
As a rough rule of thumb set you axes max velocity at 80% of the theoretical max and the [TRAJ] MAX_LINEAR_VELOCITY at 10% less than the axes max velocity.
I like to have a 'soft' acceleration figure, as I find that what leads to more lost steps than any other factor is harsh acceleration figures on an axis which is stopped and run in rapid in the opposite direction (ie what happens at the end of every cut sometimes).
After that it is fine tuning and choice. No-one can tell you what figures you should be running, the motors, the machine, your computer and personal preferences will decide.
regards
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- TarHeelTom
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Going to print all this out, digest it, and start working on tweaking.
Slightly off topic, ran into my old copilot today, who is setting up a shop specifically to build rifle barrels for bench rest target shooters.
Tom
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- TarHeelTom
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I move the X axis off the limit switch (using limit override), then hit the home button.
Creeps down toward the negative limit switch, hits it, then rapids out a bit, then creeps down again until it hits it a second time.
At this point everything stops. The limit switch is open, the home symbol is not turned on, and I get a 0 axis feed override warning message.
Any ideas?
Tom
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- TarHeelTom
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At this point everything stops. The limit switch is open, the home symbol is not turned on, and I get a 0 axis feed override warning message.
Any ideas?
Probably not related, but you might want to uncomment the STEPGEN_MAXACCEL line.
I suspect that the problem might be that the home offset is positive with a negative search velocity, so the home switch position is inside the range (this would only be a problem with a shared home/limit switch, though. Having the home inside the range is OK in principle.
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