From 82efed5e2a330e36dc9fa755c5ec9ddd89e71816 Mon Sep 17 00:00:00 2001 From: christian mock Date: Mon, 18 Feb 2019 04:35:58 +0100 Subject: [PATCH] docs: added an answer to the FAQ about detecting lost steps (#1265) Signed-off-by: christian mock --- docs/FAQ.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/docs/FAQ.md b/docs/FAQ.md index d9585566..0f1eea53 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -21,6 +21,7 @@ Frequently asked questions 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) ### How can I donate to the project? @@ -452,3 +453,21 @@ 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.)