Extruder: Add g-codes for get and set extruder step_distance

[ld3300]

Add GET_E_STEP_DISTANCE and SET_E_STEP_DISTANCE to available g-codes. Implemented in response to request for a tunable step_distance to account for difference in hardness levels of filament materials.

Signed off by: David Smith [email protected]

[KevinOConnor]

Thanks.

What's the high-level "use case" you envision for this?

Be aware that some users may wish to disable a stepper (eg, possibly via distance=0.0) and reverse a stepper (eg, possibly via distance=-.001). Doing so would enable #1631 and possibly #950 via [extruder_stepper] config sections.

Separately, the step_distance activation doesn't seem correct to me - I'm not sure why the set_trapq, set_max_jerk, and register_step_generator calls are being made. I'd recommend moving all the low-level logic into stepper:set_step_dist().

Finally, I'd recommend SET_EXTRUDER_STEP_DISTANCE for the command name.

-Kevin

[ld3300]

Hi Kevin,
This came out of the conversation in #2445 so that the step distance can be declared from the slicer to compensate for different filament hardness levels that cause the extruder teeth to sink into filaments differently, therefore changing the step distance property. With the other tickets you mention, I'm unsure if you are suggesting that these changes would positively or negatively affect those. If it would enable those features in a positive way I would probably need to remove the "safety" check I added (I may have accidentally realized how big a difference there is between between 0.007 and 0.004, thank goodness I didn't miss a zero).

I put all those calls in extruder.py because that is also where they are initially called in the init section. I can do it in the lower level set_step_dist, but I have to pass all the params. I added the calls with formulas that looked like they were only called once and were affected by the step distance. set_max_jerk has _step_distance in it's formula. set_trapq is setup using _stepper_kinematics which is calculated using _step_dist.

I might have had in my head that register_step_generator needed to be recalled too. It looks like it does not need to be.

The command name change makes sense. Will implement that.

-David

[KevinOConnor]

Thanks. See my comments below.

-Kevin

[KevinOConnor]

FWIW, I would not add a GET_EXTRUDER_STEP_DISTANCE command. Instead, I'd have SET_EXTRUDER_STEP_DISTANCE report the current step distance if an explicit DISTANCE parameter is not specified.

[ld3300]

Makes sense I will make that change.

[KevinOConnor]

FWIW, I don't think this check is necessary.

[ld3300]

I agree, when I implemented that it was a knee jerk reaction to making a mistake typing in a value too high, but with some of the other uses this might provide the check would only be a hindrance. I will remove it.

[KevinOConnor]

These three lines should be removed.

The set_max_jerk() call configures the micro-controller "min_stop_interval" configuration. That configuration can not be changed at run-time, so it's confusing to alter the setting at run-time. In this particular case, a 9999999.9 disables the min_stop_interval check, so it's redundant to call again anyway.

I understand the set_stepper_kinematics() call is to populate the step_distance to the "itersolve" code. That's fine, but it should be done from stepper:set_step_dist().

The set_trapq() call associates the stepper with a "motion queue". That motion queue isn't changing on a step distance update, so there is no reason to call it here.

Separately, I believe it will be necessary to call toolhead.flush_step_generation() prior to updating the step distance.

[ld3300]

ahh, okay, on the max_jerk I didn't see that check, so makes sense. I will move the set_stepper_kinematics() as suggested. Thank you for note about toolhead.flush_step_generation(). Thank makes a lot of sense. I will make those changes and test to make sure it performs as expected.

[KevinOConnor]

This return statement looks redundant.

[ld3300]

Yes, should have trusted my gut on that one, added it thinking "this isn't useful at all"

[kakou-fr]

could you also patch extruder_stepper to allow set step for mixing ?
i tried, but i always have this error : stepcompress o=0 i=0 c=12 a=0: Invalid sequence

diff --git a/klippy/extras/extruder_stepper.py b/klippy/extras/extruder_stepper.py
index f6d0e9ea..6e780949 100644
--- a/klippy/extras/extruder_stepper.py
+++ b/klippy/extras/extruder_stepper.py
@@ -9,17 +9,39 @@ import stepper
 class ExtruderStepper:
     def __init__(self, config):
         self.printer = config.get_printer()
+        self.name = config.get_name()
         self.extruder_name = config.get('extruder', 'extruder')
         self.stepper = stepper.PrinterStepper(config)
         self.stepper.set_max_jerk(9999999.9, 9999999.9)
         self.stepper.setup_itersolve('extruder_stepper_alloc')
         self.printer.register_event_handler("klippy:connect",
                                             self.handle_connect)
+        # Register commands
+        gcode = self.printer.lookup_object('gcode')
+        gcode.register_mux_command("GET_EXTRUDER_STEP_DISTANCE", "EXTRUDER",
+                                   self.name, self.cmd_GET_E_STEP_DISTANCE,
+                                   desc=self.cmd_GET_E_STEP_DISTANCE_help)
+        gcode.register_mux_command("SET_EXTRUDER_STEP_DISTANCE", "EXTRUDER",
+                                   self.name, self.cmd_SET_E_STEP_DISTANCE,
+                                   desc=self.cmd_SET_E_STEP_DISTANCE_help)
     def handle_connect(self):
         extruder = self.printer.lookup_object(self.extruder_name)
         self.stepper.set_trapq(extruder.get_trapq())
         toolhead = self.printer.lookup_object('toolhead')
         toolhead.register_step_generator(self.stepper.generate_steps)
+    cmd_GET_E_STEP_DISTANCE_help = "Get extruder step distance"
+    def cmd_GET_E_STEP_DISTANCE(self, params):
+        gcode = self.printer.lookup_object('gcode')
+        step_dist = self.stepper.get_step_dist()
+        gcode.respond_info("%s E step distance: %f" % (self.name, step_dist))
+    cmd_SET_E_STEP_DISTANCE_help = "Set extruder step distance"
+    def cmd_SET_E_STEP_DISTANCE(self, params):
+        gcode = self.printer.lookup_object('gcode')
+        dist = gcode.get_float('DISTANCE', params, 0.)
+        self.stepper.set_step_dist(dist)
+        step_dist = self.stepper.get_step_dist()
+        gcode.respond_info("%s E step distance set: %f" %
+                                           (self.name, step_dist))

[ld3300]

@kakou-fr I think that would be a good feature and would probably be useful to a lot of people. It falls outside of this pull request, and will likely be outside my abilities (though I will give it a look). Please start a new issue for the request with a good description of how you would expect it to perform. This feature will allow setting the step distance for any extruder by name, so in that aspect it should be helpful.

[kakou-fr]

@ld3300 I am waiting the final version of your patch, redo test, and after I will post an issue for mixing If the final version doesn't work

[ld3300]

Okay, I've made those changes, and everything seems to be working for the original intent. I was hoping it would also work for #1631, but doing a negative step distance causes klipper to crash pretty hard when a move is attempted. The log also just cuts off. Included if it gives any clues.
klippy.log
I'm not sure where to look for the source of that issue.

[KevinOConnor]

Thanks. FYI, I also made a couple of minor changes on top (commit 336af2f and 7717758).

-Kevin

[ld3300]

Thank you.