<p>On the reprap wiki it says using Znnn it sets a new axis position.  But then it says &quot;No physical motion will occur&quot;. What would the line <code>G92 E0</code> be used for?</p>

[{'answer_id': 4828, 'author': 'Mick', 'author_id': 3953, 'author_profile': 'https://3dprinting.stackexchange.com/users/3953', 'pm_score': 5, 'selected': True, 'text': '<p>The <code>G92</code> command is used to set the start position (origin) of one of more axes (including the current extruder) to any arbitrary value. The command <code>G92 E0</code> is often used to perform retraction and nozzle priming. For example, the following commands are often used in start-gcode sequences (prologues) to prime the current extruder by extruding a small amount of filament:</p>\n\n<pre><code>G92 E0     ; Reset the extruder\'s origin\nG1 F200 E3 ; Extrude 3 millimetres of filament\nG92 E0     ; Reset the extruder\'s origin\n</code></pre>\n\n<p><a href="http://reprap.org/wiki/G-code#G92:_Set_Position" rel="noreferrer">RepRap Wiki: G92: Set Position</a></p>\n'}, {'answer_id': 13935, 'author': 'Davo', 'author_id': 4922, 'author_profile': 'https://3dprinting.stackexchange.com/users/4922', 'pm_score': 3, 'selected': False, 'text': "<p>To supplement the accepted answer, and answer a question in the answer's comments (which should not be there), consider the E value as another axis - the axis of the filament.</p>\n<p>If you executed:</p>\n<pre><code>G92 E0     ; Reset the extruder's origin\nG1 F200 E3 ; Extrude 3 millimetres of filament at a rate of 200 units per second\n</code></pre>\n<p>and then went on to printing, the first filament move would have to take you from E3 to whatever E value the next move specified.</p>\n<p>If the next move assumed starting at E0, you'd already be 3 mm further along, and the first move would probably be a retract, so for example, if the next printing move was:</p>\n<pre><code>G1 Xnnn Ynnn E0.5 ; Extrude 0.5 millimetres of filament\n</code></pre>\n<p>then <strong>instead of extruding 0.5 mm, you would actually retract 2.5 mm</strong>, to get from 3.0 to 0.5. Just like moving in a negative direction on any other axis.</p>\n"}]
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