<p>Suppose I want to to print several copies of a large, flat object, such as a hollow frame. If I make an STL file consisting of several copies floating just above each other then my 3D printer's software happily generates supports for the upper objects to sit on, as shown below:</p>

<p><a href="https://i.stack.imgur.com/XbxbGm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/XbxbGm.png" alt="enter image description here"></a></p>

<p>My question is, is this a crazy idea? If it will work it seems it has several advantages. I can print more copies at once than if I tried to fit them next to each other on the platform, and if one of the prints fails the ones below it will still be OK. It doesn't take that much more filament than printing them all separately.</p>

<p>I'll probably try it at some point just to see what happens, but it's not something I've heard of people doing before, so I'm wondering if there's a good reason why it won't work or would otherwise not be a good strategy.</p>

[{'answer_id': 851, 'author': 'tbm0115', 'author_id': 98, 'author_profile': 'https://3dprinting.stackexchange.com/users/98', 'pm_score': 2, 'selected': False, 'text': '<p>According to the RepRap.org <a href="http://reprap.org/wiki/G-code" rel="nofollow noreferrer">list of G-Code commands</a>, see <strong><a href="http://reprap.org/wiki/G-code#G0_.26_G1:_Move" rel="nofollow noreferrer">G0 &amp; G1: Move</a></strong>:</p>\n\n<blockquote>\n  <p>The <code>Ennn</code> command is <em>The amount to extrude between the starting point and ending point</em>. </p>\n</blockquote>\n\n<p>However, according to <strike><a href="https://github.com/daid/Cura/issues/385" rel="nofollow noreferrer">this</a></strike> a discussion, that is now deleted from GitHub, about the Cura slicing engine:</p>\n\n<p>The <strong>E</strong> values are in <em>absolute mode</em>, so perhaps the firmware is attempting to move the stepper motor to the absolute position (which is almost 50% through your print). This may lead to clogging or skipping depending on how hot your extruder is at that point.</p>\n\n<p>As a last resort, you can perform a Boolean subtract on your model of the section that\'s already printed and re-slice the model to print the remaining bit. Then glue, or ABS weld, the remaining piece to the main print. I\'ve done this in the past, it\'s not super glamorous, but it gets the job done if the part doesn\'t require a lot of structural integrity.</p>\n\n<p><strong>I was incorrect with the following statements with regard to the Cura slicing engine:</strong> </p>\n\n<p><s>It\'s been a while since I\'ve looked at 3D printer G-Code, but from what I remember, <strong>E</strong> values can be the bane of any manually written G-Code. Usually the slicing engine generates the <strong>E</strong> value as an incremental step value throughout the G-Code (at least this was true for Skeinforge and early MakerWare, please verify this). So, if the value is incremental and depending on the controller, this value could be lost or corrupt if a new print is initialized.</p>\n\n<p>I would hope, that if you\'re using a slicing engine\'s <em>custom G-Code</em> input, that the software would be able to compensate situations like this and reformat your provided G-Code to match the value of <strong>E</strong> or any similar command.</s></p>\n'}, {'answer_id': 863, 'author': 'Tom van der Zanden', 'author_id': 26, 'author_profile': 'https://3dprinting.stackexchange.com/users/26', 'pm_score': 1, 'selected': False, 'text': '<p>Is the hotend temperature set correctly? If you only preheat the hotend but then turn it off, it will behave exactly as you described (while you\'re above <code>EXTRUDE_MINTEMP</code> it will behave normally, but once the temperature drops too low it will continue doing the XYZ-moves, but stop extruding). Perhaps you need to add a <code>M109</code> command to set the temperature properly.</p>\n\n<p><a href="https://3dprinting.stackexchange.com/questions/850/no-extrusion-when-trying-to-resume-failed-print-with-manually-edited-gcode/851#851">In his answer</a>, tbm0115 mentions absolute and relative coordinates. Whether absolute or relative coordinates are used is set using the <code>G90</code>/<code>G91</code> commands and will always be the same for all axes (XYZ and E). He also mentions that:</p>\n\n<blockquote>\n  <p>so perhaps the firmware is attempting to move the stepper motor to the absolute position (which is almost 50% thru your print). This may lead to clogging or skipping depending on how hot your extruder is at that point.</p>\n</blockquote>\n\n<p>This shouldn\'t happen, as extremely long extrude moves are ignored by Marlin. When the printer encounters</p>\n\n<pre><code>G1 F3600 X210.390 Y105.771 E4104.65185\n</code></pre>\n\n<p>it performs only the XYZ-part of the move, but doesn\'t move the extruder (assuming the printer was reset and the current extruder position is 0). However, it does update the internal value for the extruder position, so the next move happens normally. Perhaps missing the initial extrude segment isn\'t a big deal, but if you want the print to resume perfectly where you left off, you should add a <code>G92</code> command to the beginning to initialize the extruder position correctly, for example:</p>\n\n<pre><code>G92 E4104.4\n</code></pre>\n\n<p>(but the exact value depends on the last extruder position in the previous layer).</p>\n'}, {'answer_id': 1198, 'author': 'skidoo', 'author_id': 1846, 'author_profile': 'https://3dprinting.stackexchange.com/users/1846', 'pm_score': 2, 'selected': False, 'text': "<p>I know this is an old thread but I have been running into similar issues with my delta machine with Marlin firmware.  </p>\n\n<p>Not all printers running Marlin ignore large <code>E</code> (extruder) moves.  G-code has always (even in CNC machines) run commands from were the motors are now, to the value in the G-code line.  For example, <code>G0 X10</code> will move the X motor 10 units.  The units are set through <code>G20</code> or <code>G21</code>. </p>\n\n<p>When your machine has lost power, you need to re-home all axes in order for the machine to know where it is.  If you don't, it will likely think that it currently is at 0, 0, 0, 0.  Then when you have the line, </p>\n\n<pre><code>G1 F3600 X210.390 Y105.771 E4104.65185 \n</code></pre>\n\n<p>it will try to go from 0,0,0,0 to 210.390, 105.771, 0, 4104.65185 at the feed rate of 3600. Therefore it is always good to home after power loss and add a <code>G92 E4104.4</code> (last line ran before power loss) even if your machine may not need it.  </p>\n\n<p>Good habits make for less mistakes. </p>\n"}]
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