mirror of https://github.com/Desuuuu/klipper.git
251 lines
10 KiB
Markdown
251 lines
10 KiB
Markdown
# Delta calibration
|
|
|
|
This document describes Klipper's automatic calibration system for
|
|
"delta" style printers.
|
|
|
|
Delta calibration involves finding the tower endstop positions, tower
|
|
angles, delta radius, and delta arm lengths. These settings control
|
|
printer motion on a delta printer. Each one of these parameters has a
|
|
non-obvious and non-linear impact and it is difficult to calibrate
|
|
them manually. In contrast, the software calibration code can provide
|
|
excellent results with just a few minutes of time. No special probing
|
|
hardware is necessary.
|
|
|
|
Ultimately, the delta calibration is dependent on the precision of the
|
|
tower endstop switches. If one is using Trinamic stepper motor drivers
|
|
then consider enabling [endstop phase](Endstop_Phase.md) detection to
|
|
improve the accuracy of those switches.
|
|
|
|
## Automatic vs manual probing
|
|
|
|
Klipper supports calibrating the delta parameters via a manual probing
|
|
method or via an automatic Z probe.
|
|
|
|
A number of delta printer kits come with automatic Z probes that are
|
|
not sufficiently accurate (specifically, small differences in arm
|
|
length can cause effector tilt which can skew an automatic probe). If
|
|
using an automatic probe then first
|
|
[calibrate the probe](Probe_Calibrate.md) and then check for a
|
|
[probe location bias](Probe_Calibrate.md#location-bias-check). If the
|
|
automatic probe has a bias of more than 25 microns (.025mm) then use
|
|
manual probing instead. Manual probing only takes a few minutes and it
|
|
eliminates error introduced by the probe.
|
|
|
|
If using a probe that is mounted on the side of the hotend (that is,
|
|
it has an X or Y offset) then note that performing delta calibration
|
|
will invalidate the results of probe calibration. These types of
|
|
probes are rarely suitable for use on a delta (because minor effector
|
|
tilt will result in a probe location bias). If using the probe anyway,
|
|
then be sure to rerun probe calibration after any delta calibration.
|
|
|
|
## Basic delta calibration
|
|
|
|
Klipper has a DELTA_CALIBRATE command that can perform basic delta
|
|
calibration. This command probes seven different points on the bed and
|
|
calculates new values for the tower angles, tower endstops, and delta
|
|
radius.
|
|
|
|
In order to perform this calibration the initial delta parameters (arm
|
|
lengths, radius, and endstop positions) must be provided and they
|
|
should have an accuracy to within a few millimeters. Most delta
|
|
printer kits will provide these parameters - configure the printer
|
|
with these initial defaults and then go on to run the DELTA_CALIBRATE
|
|
command as described below. If no defaults are available then search
|
|
online for a delta calibration guide that can provide a basic starting
|
|
point.
|
|
|
|
During the delta calibration process it may be necessary for the
|
|
printer to probe below what would otherwise be considered the plane of
|
|
the bed. It is typical to permit this during calibration by updating
|
|
the config so that the printer's `minimum_z_position=-5`. (Once
|
|
calibration completes, one can remove this setting from the config.)
|
|
|
|
There are two ways to perform the probing - manual probing
|
|
(`DELTA_CALIBRATE METHOD=manual`) and automatic probing
|
|
(`DELTA_CALIBRATE`). The manual probing method will move the head near
|
|
the bed and then wait for the user to follow the steps described at
|
|
["the paper test"](Bed_Level.md#the-paper-test) to determine the
|
|
actual distance between the nozzle and bed at the given location.
|
|
|
|
To perform the basic probe, make sure the config has a
|
|
[delta_calibrate] section defined and then run the tool:
|
|
```
|
|
G28
|
|
DELTA_CALIBRATE METHOD=manual
|
|
```
|
|
After probing the seven points new delta parameters will be
|
|
calculated. Save and apply these parameters by running:
|
|
```
|
|
SAVE_CONFIG
|
|
```
|
|
|
|
The basic calibration should provide delta parameters that are
|
|
accurate enough for basic printing. If this is a new printer, this is
|
|
a good time to print some basic objects and verify general
|
|
functionality.
|
|
|
|
## Enhanced delta calibration
|
|
|
|
The basic delta calibration generally does a good job of calculating
|
|
delta parameters such that the nozzle is the correct distance from the
|
|
bed. However, it does not attempt to calibrate X and Y dimensional
|
|
accuracy. It's a good idea to perform an enhanced delta calibration to
|
|
verify dimensional accuracy.
|
|
|
|
This calibration procedure requires printing a test object and
|
|
measuring parts of that test object with digital calipers.
|
|
|
|
Prior to running an enhanced delta calibration one must run the basic
|
|
delta calibration (via the DELTA_CALIBRATE command) and save the
|
|
results (via the SAVE_CONFIG command). Make sure there hasn't been any
|
|
notable change to the printer configuration nor hardware since last
|
|
performing a basic delta calibration (if unsure, rerun the
|
|
[basic delta calibration](#basic-delta-calibration), including
|
|
SAVE_CONFIG, just prior to printing the test object described below.)
|
|
|
|
Use a slicer to generate G-Code from the
|
|
[docs/prints/calibrate_size.stl](prints/calibrate_size.stl) file.
|
|
Slice the object using a slow speed (eg, 40mm/s). If possible, use a
|
|
stiff plastic (such as PLA) for the object. The object has a diameter
|
|
of 140mm. If this is too large for the printer then one can scale it
|
|
down (but be sure to uniformly scale both the X and Y axes). If the
|
|
printer supports significantly larger prints then this object can also
|
|
be increased in size. A larger size can improve the measurement
|
|
accuracy, but good print adhesion is more important than a larger
|
|
print size.
|
|
|
|
Print the test object and wait for it to fully cool. The commands
|
|
described below must be run with the same printer settings used to
|
|
print the calibration object (don't run DELTA_CALIBRATE between
|
|
printing and measuring, or do something that would otherwise change
|
|
the printer configuration).
|
|
|
|
If possible, perform the measurements described below while the object
|
|
is still attached to the print bed, but don't worry if the part
|
|
detaches from the bed - just try to avoid bending the object when
|
|
performing the measurements.
|
|
|
|
Start by measuring the distance between the center pillar and the
|
|
pillar next to the "A" label (which should also be pointing towards
|
|
the "A" tower).
|
|
|
|
|
|
|
|
Then go counterclockwise and measure the distances between the center
|
|
pillar and the other pillars (distance from center to pillar across
|
|
from C label, distance from center to pillar with B label, etc.).
|
|
|
|
|
|
|
|
Enter these parameters into Klipper with a comma separated list of
|
|
floating point numbers:
|
|
```
|
|
DELTA_ANALYZE CENTER_DISTS=<a_dist>,<far_c_dist>,<b_dist>,<far_a_dist>,<c_dist>,<far_b_dist>
|
|
```
|
|
Provide the values without spaces between them.
|
|
|
|
Then measure the distance between the A pillar and the pillar across
|
|
from the C label.
|
|
|
|
|
|
|
|
Then go counterclockwise and measure the distance between the pillar
|
|
across from C to the B pillar, the distance between the B pillar and
|
|
the pillar across from A, and so on.
|
|
|
|
|
|
|
|
Enter these parameters into Klipper:
|
|
```
|
|
DELTA_ANALYZE OUTER_DISTS=<a_to_far_c>,<far_c_to_b>,<b_to_far_a>,<far_a_to_c>,<c_to_far_b>,<far_b_to_a>
|
|
```
|
|
|
|
At this point it is okay to remove the object from the bed. The final
|
|
measurements are of the pillars themselves. Measure the size of the
|
|
center pillar along the A spoke, then the B spoke, and then the C
|
|
spoke.
|
|
|
|
|
|
|
|
|
|
|
|
Enter them into Klipper:
|
|
```
|
|
DELTA_ANALYZE CENTER_PILLAR_WIDTHS=<a>,<b>,<c>
|
|
```
|
|
|
|
The final measurements are of the outer pillars. Start by measuring
|
|
the distance of the A pillar along the line from A to the pillar
|
|
across from C.
|
|
|
|
|
|
|
|
Then go counterclockwise and measure the remaining outer pillars
|
|
(pillar across from C along the line to B, B pillar along the line to
|
|
pillar across from A, etc.).
|
|
|
|
|
|
|
|
And enter them into Klipper:
|
|
```
|
|
DELTA_ANALYZE OUTER_PILLAR_WIDTHS=<a>,<far_c>,<b>,<far_a>,<c>,<far_b>
|
|
```
|
|
|
|
If the object was scaled to a smaller or larger size then provide the
|
|
scale factor that was used when slicing the object:
|
|
```
|
|
DELTA_ANALYZE SCALE=1.0
|
|
```
|
|
(A scale value of 2.0 would mean the object is twice its original
|
|
size, 0.5 would be half its original size.)
|
|
|
|
Finally, perform the enhanced delta calibration by running:
|
|
```
|
|
DELTA_ANALYZE CALIBRATE=extended
|
|
```
|
|
This command can take several minutes to complete. After completion it
|
|
will calculate updated delta parameters (delta radius, tower angles,
|
|
endstop positions, and arm lengths). Use the SAVE_CONFIG command to
|
|
save and apply the settings:
|
|
```
|
|
SAVE_CONFIG
|
|
```
|
|
|
|
The SAVE_CONFIG command will save both the updated delta parameters
|
|
and information from the distance measurements. Future DELTA_CALIBRATE
|
|
commands will also utilize this distance information. Do not attempt
|
|
to reenter the raw distance measurements after running SAVE_CONFIG, as
|
|
this command changes the printer configuration and the raw
|
|
measurements no longer apply.
|
|
|
|
### Additional notes
|
|
|
|
* If the delta printer has good dimensional accuracy then the distance
|
|
between any two pillars should be around 74mm and the width of every
|
|
pillar should be around 9mm. (Specifically, the goal is for the
|
|
distance between any two pillars minus the width of one of the
|
|
pillars to be exactly 65mm.) Should there be a dimensional
|
|
inaccuracy in the part then the DELTA_ANALYZE routine will calculate
|
|
new delta parameters using both the distance measurements and the
|
|
previous height measurements from the last DELTA_CALIBRATE command.
|
|
|
|
* DELTA_ANALYZE may produce delta parameters that are surprising. For
|
|
example, it may suggest arm lengths that do not match the printer's
|
|
actual arm lengths. Despite this, testing has shown that
|
|
DELTA_ANALYZE often produces superior results. It is believed that
|
|
the calculated delta parameters are able to account for slight
|
|
errors elsewhere in the hardware. For example, small differences in
|
|
arm length may result in a tilt to the effector and some of that
|
|
tilt may be accounted for by adjusting the arm length parameters.
|
|
|
|
## Using Bed Mesh on a Delta
|
|
|
|
It is possible to use [bed mesh](Bed_Mesh.md) on a delta. However, it
|
|
is important to obtain good delta calibration prior to enabling a bed
|
|
mesh. Running bed mesh with poor delta calibration will result in
|
|
confusing and poor results.
|
|
|
|
Note that performing delta calibration will invalidate any previously
|
|
obtained bed mesh. After performing a new delta calibration be sure to
|
|
rerun BED_MESH_CALIBRATE.
|