From 2ee42997e4b8ac4d8ca84cc53ecc9859baafbbbd Mon Sep 17 00:00:00 2001 From: Kevin O'Connor Date: Wed, 19 Jul 2017 19:09:14 -0400 Subject: [PATCH] docs: Update Kinematics.md with regards to stepper torque limits It is not necessary to limit stepper acceleration - only the limiting of stepper torque is important. Signed-off-by: Kevin O'Connor --- docs/Kinematics.md | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/docs/Kinematics.md b/docs/Kinematics.md index 8e5d5806..8f12524a 100644 --- a/docs/Kinematics.md +++ b/docs/Kinematics.md @@ -18,12 +18,12 @@ rapid jerking of the head can cause disruption of recently deposited filament. Limiting speed changes of the print head (relative to the print) reduces risks of disrupting the print. -It is also important to enforce a maximum acceleration of the stepper -motors to ensure they do not skip or put excessive stress on the -machine. Klipper limits the acceleration of each stepper by virtue of -limiting the acceleration of the print head. Enforcing acceleration at -the print head naturally also enforces acceleration at the steppers -that control that print head (the inverse is not always true). +It is also important to limit acceleration so that the stepper motors +do not skip or put excessive stress on the machine. Klipper limits the +torque on each stepper by virtue of limiting the acceleration of the +print head. Enforcing acceleration at the print head naturally also +limits the torque of the steppers that move the print head (the +inverse is not always true). Klipper implements constant acceleration. The key formula for constant acceleration is: @@ -213,10 +213,10 @@ motor greater than the move's acceleration. This can occur when a stepper arm is more horizontal than vertical and the line of movement 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. +configured move acceleration, the effective mass moved by that stepper +would be smaller. Thus the higher stepper acceleration does not result +in significantly higher stepper torque and it is therefore considered +harmless. However, to avoid extreme cases, Klipper enforces a maximum ceiling on stepper acceleration of three times the printer's configured maximum