docs: Update Pressure_Advance.md to use tuning tower
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
parent
b8a6160646
commit
c794e11c67
|
@ -13,58 +13,64 @@ uses the second feature (reducing blobbing during cornering) as a
|
||||||
mechanism for tuning.
|
mechanism for tuning.
|
||||||
|
|
||||||
In order to calibrate pressure advance the printer must be configured
|
In order to calibrate pressure advance the printer must be configured
|
||||||
and operational. The tuning test involves printing objects and
|
and operational as the tuning test involves printing and inspecting a
|
||||||
inspecting the differences between objects. It is a good idea to read
|
test object. It is a good idea to read this document in full prior to
|
||||||
this document in full prior to running the test.
|
running the test.
|
||||||
|
|
||||||
Use a slicer to generate g-code for the large hollow square found in
|
Use a slicer to generate g-code for the large hollow square found in
|
||||||
[docs/prints/square.stl](prints/square.stl). Use a high speed (eg,
|
[docs/prints/square_tower.stl](prints/square_tower.stl). Use a high
|
||||||
100mm/s) and a coarse layer height (the layer height should be around
|
speed (eg, 100mm/s), zero infill, and a coarse layer height (the layer
|
||||||
75% of the nozzle diameter). It is fine to use a low infill (eg, 10%).
|
height should be around 75% of the nozzle diameter).
|
||||||
|
|
||||||
Prepare for the test by issuing the following G-Code commands:
|
Prepare for the test by issuing the following G-Code command:
|
||||||
`SET_VELOCITY_LIMIT SQUARE_CORNER_VELOCITY=1 ACCEL=500` and
|
```
|
||||||
`SET_PRESSURE_ADVANCE ADVANCE_LOOKAHEAD_TIME=0`. These commands make
|
SET_VELOCITY_LIMIT SQUARE_CORNER_VELOCITY=1 ACCEL=500
|
||||||
the nozzle travel slower through corners and they emphasize the
|
```
|
||||||
effects of extruder pressure.
|
This command makes the nozzle travel slower through corners and to
|
||||||
|
emphasize the effects of extruder pressure. Then for printers with a
|
||||||
|
direct drive extruder run the command:
|
||||||
|
```
|
||||||
|
TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.005
|
||||||
|
```
|
||||||
|
For long bowden extruders use:
|
||||||
|
```
|
||||||
|
TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.020
|
||||||
|
```
|
||||||
|
Then print the object. When fully printed the test print looks like:
|
||||||
|
|
||||||
For the first print use a pressure advance of zero by running
|
![tuning_tower](img/tuning_tower.jpg)
|
||||||
`SET_PRESSURE_ADVANCE ADVANCE=0.000`. Then print at least 10 layers of
|
|
||||||
the test object. While the object is printing, make a note of which
|
|
||||||
direction the head is moving during external perimeters. What many
|
|
||||||
people see here is blobbing occurring at the corners - extra filament
|
|
||||||
at the corner in the direction the head travels followed by a possible
|
|
||||||
lack of filament on the side immediately after that corner:
|
|
||||||
|
|
||||||
![corner-blob](img/corner-blob.jpg)
|
The above TUNING_TOWER command instructs Klipper to alter the
|
||||||
|
pressure_advance setting on each layer of the print. Higher layers in
|
||||||
|
the print will have a larger pressure advance value set. Layers below
|
||||||
|
the ideal pressure_advance setting will have blobbing at the corners,
|
||||||
|
and layers above the ideal setting can lead to rounded corners and
|
||||||
|
poor extrusion leading up to the corner.
|
||||||
|
|
||||||
This blobbing is the result of pressure in the extruder being released
|
One can cancel the print early if one observes that the corners are no
|
||||||
as a blob when the head slows down to corner.
|
longer printing well (and thus one can avoid printing layers that are
|
||||||
|
known to be above the ideal pressure_advance value).
|
||||||
|
|
||||||
The next step is to increase pressure advance (start with
|
Inspect the print and then use a digital calipers to find the height
|
||||||
`SET_PRESSURE_ADVANCE ADVANCE=0.050`) and reprint the test object.
|
that has the best quality corners. When in doubt, prefer a lower
|
||||||
With pressure advance, the extruder will retract when the head slows
|
height.
|
||||||
down, thus countering the pressure buildup and ideally eliminate the
|
|
||||||
blobbing.
|
|
||||||
|
|
||||||
If a test run is done with a pressure advance setting that is too
|
![tune_pa](img/tune_pa.jpg)
|
||||||
high, one typically sees a dimple in the corner followed by possible
|
|
||||||
blobbing after the corner (too much filament is retracted during slow
|
|
||||||
down and then too much filament is extruded during the following speed
|
|
||||||
up after cornering):
|
|
||||||
|
|
||||||
![corner-dimple](img/corner-dimple.jpg)
|
The pressure_advance value can then be calculated as `pressure_advance
|
||||||
|
= <start> + <measured_height> * <factor>`. (For example, `0 + 12.90 *
|
||||||
|
.020` would be `.258`.)
|
||||||
|
|
||||||
The goal is to find the smallest pressure advance value that results
|
It is possible to choose custom settings for START and FACTOR if that
|
||||||
in good quality corners:
|
helps identify the best pressure advance setting. When doing this, be
|
||||||
|
sure to issue the TUNING_TOWER command at the start of each test
|
||||||
![corner-good](img/corner-good.jpg)
|
print.
|
||||||
|
|
||||||
Typical pressure advance values are between 0.050 and 1.000 (the high
|
Typical pressure advance values are between 0.050 and 1.000 (the high
|
||||||
end usually only with bowden extruders). If there is no significant
|
end usually only with bowden extruders). If there is no significant
|
||||||
improvement after gradually increasing pressure advance to 1.000, then
|
improvement with a pressure advance up to 1.000, then pressure advance
|
||||||
pressure advance is unlikely to improve the quality of prints. Return
|
is unlikely to improve the quality of prints. Return to a default
|
||||||
to a default configuration with pressure advance disabled.
|
configuration with pressure advance disabled.
|
||||||
|
|
||||||
Although this tuning exercise directly improves the quality of
|
Although this tuning exercise directly improves the quality of
|
||||||
corners, it's worth remembering that a good pressure advance
|
corners, it's worth remembering that a good pressure advance
|
||||||
|
@ -72,8 +78,8 @@ configuration also reduces ooze throughout the print.
|
||||||
|
|
||||||
At the completion of this test, update the extruder's pressure_advance
|
At the completion of this test, update the extruder's pressure_advance
|
||||||
setting in the configuration file and issue a RESTART command. The
|
setting in the configuration file and issue a RESTART command. The
|
||||||
RESTART command will also return the acceleration, cornering speeds,
|
RESTART command will clear the test state and return the acceleration
|
||||||
and look-ahead times to their normal values.
|
and cornering speeds to their normal values.
|
||||||
|
|
||||||
Important Notes
|
Important Notes
|
||||||
===============
|
===============
|
||||||
|
@ -91,20 +97,16 @@ Important Notes
|
||||||
[nozzle temperature](http://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide#Nozzle_Temperature)
|
[nozzle temperature](http://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide#Nozzle_Temperature)
|
||||||
prior to tuning pressure advance.
|
prior to tuning pressure advance.
|
||||||
|
|
||||||
* It is not unusual for one corner of the test print to be
|
* It is common for the test print to show different behavior on each
|
||||||
consistently different than the other three corners. This typically
|
corner. Often the slicer will arrange to change layers at one corner
|
||||||
occurs when the slicer arranges to always change Z height at that
|
which can result in that corner being significantly different from
|
||||||
corner. If this occurs, then ignore that corner and tune pressure
|
the remaining three corners. If this occurs, then ignore that corner
|
||||||
advance using the other three corners.
|
and tune pressure advance using the other three corners. It is also
|
||||||
|
common for the remaining corners to vary slightly. (This can occur
|
||||||
* Check for warping at the corners during the test prints (the corners
|
due to small differences in how the printer's frame reacts to
|
||||||
detaching from the bed and rising a small distance upwards during
|
cornering in certain directions.) Try to choose a value that works
|
||||||
the print). If one corner appears warped then ignore that corner
|
well for all the remaining corners. If in doubt, prefer a lower
|
||||||
when tuning. If significant warping is seen throughout the test then
|
pressure advance value.
|
||||||
typical solutions are to reduce the slicer's first layer speed,
|
|
||||||
adjust the bed temperature, and/or to use the slicer's brim feature.
|
|
||||||
Pressure advance itself is unlikely to impact warping, but this
|
|
||||||
tuning test is sensitive to it.
|
|
||||||
|
|
||||||
* If a high pressure advance value (eg, over 0.200) is used then one
|
* If a high pressure advance value (eg, over 0.200) is used then one
|
||||||
may find that the extruder skips when returning to the printer's
|
may find that the extruder skips when returning to the printer's
|
||||||
|
|
Binary file not shown.
After Width: | Height: | Size: 24 KiB |
Binary file not shown.
After Width: | Height: | Size: 20 KiB |
Loading…
Reference in New Issue