{"action":"created","issue":{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/3570","repository_url":"https://api.github.com/repos/MarlinFirmware/Marlin","labels_url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/3570/labels{/name}","comments_url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/3570/comments","events_url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/3570/events","html_url":"https://github.com/MarlinFirmware/Marlin/issues/3570","id":149413191,"number":3570,"title":"E step handling, calibration and extruding with USB","user":{"login":"Alex9779","id":6394581,"avatar_url":"https://avatars.githubusercontent.com/u/6394581?v=3","gravatar_id":"","url":"https://api.github.com/users/Alex9779","html_url":"https://github.com/Alex9779","followers_url":"https://api.github.com/users/Alex9779/followers","following_url":"https://api.github.com/users/Alex9779/following{/other_user}","gists_url":"https://api.github.com/users/Alex9779/gists{/gist_id}","starred_url":"https://api.github.com/users/Alex9779/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Alex9779/subscriptions","organizations_url":"https://api.github.com/users/Alex9779/orgs","repos_url":"https://api.github.com/users/Alex9779/repos","events_url":"https://api.github.com/users/Alex9779/events{/privacy}","received_events_url":"https://api.github.com/users/Alex9779/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/labels/Hardware%20Support","name":"Hardware Support","color":"006b75"},{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/labels/Hosts%20&%20Protocols","name":"Hosts & Protocols","color":"eb6420"},{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/labels/Potential%20bug?","name":"Potential bug?","color":"eb6420"},{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/labels/Support%20Question","name":"Support Question","color":"cc317c"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":6,"created_at":"2016-04-19T10:11:59Z","updated_at":"2016-04-19T12:21:26Z","closed_at":null,"body":"I am trying to calibrate my E steps for a day now and I have strange strange issues.\r\nI used the bleeding edge of last nights RCBgFix, I used RC5 and I used RC4 all with the same results.\r\n\r\nWhat I do is I mark the filament measured from a fixed point, in my case the top of the extruder, then I extrude and measure where the mark moved.\r\nMy calculation for the new E step is [current e steps] * [target extrusion distance] / [real extrusion distance].\r\n\r\nSo my first issue or question is how the firmware does handle a change of E steps?\r\nI doe what described above, then I move the E axis then I calculate and change the E steps and move the axis again.\r\nApparently there is something going on because a test showed me this.\r\nI changed the E steps to a too high value and moved the axis to 10mm, the real length extruded was 12mm. Then I change the steps and move the axis again but the extruder retracted and my mark was at the now set 11mm.\r\nIs that an intended behaviour?\r\n\r\nMy second issue is that when doing this process with USB over OctoPrint I am somehow not able to get any reliable results.\r\nI used the built in extrusion method of OctoPrint, it uses two commands to extrude, first \"G91\" for relative followed by the extrusion command \"G1 Ex F300\" in my case. And also I tried with scripts like this one:\r\n```\r\nG21 ; set to millimeters\r\nG90 ; use absolute positioning\r\nT0 ; select extruder 0\r\nG92 E0 ; zero the extrusion distance\r\nG1 E100 F400 ; extrude 100mm\r\nG92 E0 ; zero the extrusion distance\r\n```\r\nor this one:\r\n```\r\nG21 ; set to millimeters\r\nG90 ; use absolute positioning\r\nM83 ; relative extrusion\r\nT0 ; select extruder 0\r\nG1 E100 F400 ; extrude 100mm\r\n```\r\nBoth had the same result. With the shown 100mm extrusion I get to a maximum of about 92mm extruded no matter how high I set my E steps. I didn't do it very high only for about three iterations, for example I started with\r\n417.5\r\n417,5*100/91=458.8\r\n458.8*100/99=463.4\r\n463.4*100/91=....\r\nI increased but the extruded distance decreased...\r\n\r\nIf I try extrusion from OctorPrint and set the E steps to 417.5 which seems to be right in my case at least with LCD and changing nothing I get right that what I want, and I extrude 10mm with OctoPrint I get 10mm, if I extrude 50mm I get less, about only 41mm, and if I extrude 100mm I get much less...\r\n\r\nAm I doing something wrong? Are there calculations made I do not know of?\r\nHow am I supposed to do this process?\r\n\r\nI am totally confused. Can I still print with OctoPrint at this stage as the value sent with USB are strange?"},"comment":{"url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/comments/211897055","html_url":"https://github.com/MarlinFirmware/Marlin/issues/3570#issuecomment-211897055","issue_url":"https://api.github.com/repos/MarlinFirmware/Marlin/issues/3570","id":211897055,"user":{"login":"Alex9779","id":6394581,"avatar_url":"https://avatars.githubusercontent.com/u/6394581?v=3","gravatar_id":"","url":"https://api.github.com/users/Alex9779","html_url":"https://github.com/Alex9779","followers_url":"https://api.github.com/users/Alex9779/followers","following_url":"https://api.github.com/users/Alex9779/following{/other_user}","gists_url":"https://api.github.com/users/Alex9779/gists{/gist_id}","starred_url":"https://api.github.com/users/Alex9779/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Alex9779/subscriptions","organizations_url":"https://api.github.com/users/Alex9779/orgs","repos_url":"https://api.github.com/users/Alex9779/repos","events_url":"https://api.github.com/users/Alex9779/events{/privacy}","received_events_url":"https://api.github.com/users/Alex9779/received_events","type":"User","site_admin":false},"created_at":"2016-04-19T12:21:26Z","updated_at":"2016-04-19T12:21:26Z","body":"Ok did G1 E50 F50 and then the extrusion is the same and with the 417.5 E steps also 50mm.\r\nSo does the motor skip steps? But the sound of it is ok, power too low?"}}