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docs: Improve description of delta stepper acceleration limits 

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-07-19 12:27:32 -04:00
parent c4b8d3ea8b
commit 17a3e25036
2 changed files with 13 additions and 14 deletions
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10
config/example-delta.cfg
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@ -81,16 +81,10 @@ kinematics: delta
# This option must be "delta" for linear delta printers. # This option must be "delta" for linear delta printers.
max_velocity: 300 max_velocity: 300
# Maximum velocity (in mm/s) of the toolhead relative to the # Maximum velocity (in mm/s) of the toolhead relative to the
# print. This limits the velocity of the toolhead relative to the # print. This parameter must be specified.
# print - at the extreme end of the print envelope the delta axis
# steppers themselves may briefly exceed this speed by up to 3
# times. This parameter must be specified.
max_accel: 3000 max_accel: 3000
# Maximum acceleration (in mm/s^2) of the toolhead relative to the # Maximum acceleration (in mm/s^2) of the toolhead relative to the
# print. This limits the acceleration of the toolhead relative to # print. This parameter must be specified.
# the print - at the extreme end of the print envelope the delta
# axis steppers may briefly exceed this acceleration by up to 3
# times. This parameter must be specified.
max_z_velocity: 200 max_z_velocity: 200
# For delta printers this limits the maximum velocity (in mm/s) of # For delta printers this limits the maximum velocity (in mm/s) of
# moves with z axis movement. This setting can be used to reduce the # moves with z axis movement. This setting can be used to reduce the

17
docs/Kinematics.md
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@ -211,13 +211,18 @@ With delta kinematics it is possible for a move that is accelerating
in cartesian space to require an acceleration on a particular stepper in cartesian space to require an acceleration on a particular stepper
motor greater than the move's acceleration. This can occur when a motor greater than the move's acceleration. This can occur when a
stepper arm is more horizontal than vertical and the line of movement stepper arm is more horizontal than vertical and the line of movement
is near that stepper's tower. passes near that stepper's tower. Although these moves could require a
stepper motor acceleration greater than the printer's maximum
configured move acceleration, this would only occur when the stepper
is moving a small amount of mass. (The stepper would essentially only
be moving the mass of the tower carriage.) Therefore, these brief
periods of high acceleration are considered harmless.
Klipper does enforce a maximum ceiling on stepper acceleration that is However, to avoid extreme cases, Klipper enforces a maximum ceiling on
three times the maximum acceleration of a move in cartesian stepper acceleration of three times the printer's configured maximum
space. (Similarly, the maximum velocity of the stepper is limited to move acceleration. (Similarly, the maximum velocity of the stepper is
three times the maximum move velocity.) In order to enforce this limited to three times the maximum move velocity.) In order to enforce
limit, moves at the extreme edge of the build envelope (where a this limit, moves at the extreme edge of the build envelope (where a
stepper arm may be nearly horizontal) will have a lower maximum stepper arm may be nearly horizontal) will have a lower maximum
acceleration and velocity. acceleration and velocity.