diff --git a/docs/FAQ.md b/docs/FAQ.md index e3e3b163..31d4efab 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -20,8 +20,8 @@ Frequently asked questions 17. [Will the heaters be left on if the Raspberry Pi crashes?](#will-the-heaters-be-left-on-if-the-raspberry-pi-crashes) 18. [How do I convert a Marlin pin number to a Klipper pin name?](#how-do-i-convert-a-marlin-pin-number-to-a-klipper-pin-name) 19. [How do I cancel an M109/M190 "wait for temperature" request?](#how-do-i-cancel-an-m109m190-wait-for-temperature-request) -20. [How do I upgrade to the latest software?](#how-do-i-upgrade-to-the-latest-software) -21. [Can I find out whether the printer has lost steps?](#can-i-find-out-whether-the-printer-has-lost-steps) +20. [Can I find out whether the printer has lost steps?](#can-i-find-out-whether-the-printer-has-lost-steps) +21. [How do I upgrade to the latest software?](#how-do-i-upgrade-to-the-latest-software) ### How can I donate to the project? @@ -442,6 +442,24 @@ terminal tab and issue a FIRMWARE_RESTART command to clear the Klipper error state. After completing this sequence, the previous heating request will be canceled and a new print may be started. +### Can I find out whether the printer has lost steps? + +In a way, yes. Home the printer, issue a `GET_POSITION` command, run +your print, home again and issue another `GET_POSITION`. Then compare +the values in the `mcu:` line. + +This might be helpful to tune settings like stepper motor currents, +accelerations and speeds without needing to actually print something +and waste filament: just run some high-speed moves in between the +`GET_POSITION` commands. + +Note that endstop switches themselves tend to trigger at slightly +different positions, so a difference of a couple of microsteps is +likely the result of endstop inaccuracies. A stepper motor itself can +only lose steps in increments of 4 full steps. (So, if one is using 16 +microsteps, then a lost step on the stepper would result in the "mcu:" +step counter being off by a multiple of 64 microsteps.) + ### How do I upgrade to the latest software? The general way to upgrade is to ssh into the Raspberry Pi and run: @@ -484,21 +502,3 @@ needed for a software change to take effect. When upgrading the software, be sure to check the [config changes](Config_Changes.md) document for information on software changes that may require updates to your printer.cfg file. - -### Can I find out whether the printer has lost steps? - -In a way, yes. Home the printer, issue a `GET_POSITION` command, run -your print, home again and issue another `GET_POSITION`. Then compare -the values in the `mcu:` line. - -This might be helpful to tune settings like stepper motor currents, -accelerations and speeds without needing to actually print something -and waste filament: just run some high-speed moves in between the -`GET_POSITION` commands. - -Note that endstop switches themselves tend to trigger at slightly -different positions, so a difference of a couple of microsteps is -likely the result of endstop inaccuracies. A stepper motor itself can -only lose steps in increments of 4 full steps. (So, if one is using 16 -microsteps, then a lost step on the stepper would result in the "mcu:" -step counter being off by a multiple of 64 microsteps.)