<p>I'm trying to print large objects (around 1 meter squared) with polycarbonate pellets. The problem is sometimes the print cracks. It is not due to delamination as it is a shear crack across multiple layers. I know the ideal scenario is to have a heated enclosure but I cannot do that due to the size. Any suggestions?</p>
<p>I am using a robotic arm (KUKA KR360) with a custom extruder. That is why I can't build the enclosure. As for the temperature, they are 230 to 260 °C. Nozzle is 10 mm.</p>
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<p><em>I like the idea of directed heat. I might try that.</em></p>

[{'answer_id': 18438, 'author': '0scar', 'author_id': 5740, 'author_profile': 'https://3dprinting.stackexchange.com/users/5740', 'pm_score': 1, 'selected': False, 'text': '<p>Printing polycarbonate requires a high end 3D printer that is suitable for the task.</p>\n<p>From <a href="https://www.simplify3d.com/support/materials-guide/polycarbonate/" rel="nofollow noreferrer">Simplify3d support</a> we learn that:</p>\n<blockquote>\n<p>... requires very high temperatures for printing and will <strong>exhibit layer separation if printed at too low of a temperature or with excessive cooling enabled</strong>. Polycarbonate is frequently <strong>best printed on a machine that has an enclosed build volume</strong> and is capable of handling high bed and extruder temperatures.</p>\n</blockquote>\n<p>High temperatures and enclosed build volume are key to print polycarbonate without cracking or delamination.</p>\n<blockquote>\n<p>Any suggestions?</p>\n</blockquote>\n<p>Note that NASA has successfully printed ULTEM (even higher temperatures needed) <a href="https://ntrs.nasa.gov/citations/20170000214" rel="nofollow noreferrer">using open source hardware</a>. They have used infrared lamps directed at the build plate, this may be an option if a full enclosure is not possible. Also people seem to get good results with draft shields for printing ABS on non enclosed printers. Key is that a constant elevated temperature is created near the print, whether that works for such a large size remains to be seen. Best solution would be enclosing the printer.</p>\n'}, {'answer_id': 18439, 'author': 'Criggie', 'author_id': 12956, 'author_profile': 'https://3dprinting.stackexchange.com/users/12956', 'pm_score': 0, 'selected': False, 'text': '<p>Sounds like your problem is cooling, which would be mitigated by an enclosure to eliminate draughts and hold a higher air temperature.</p>\n<p>I made an enclosure using parts-on-hand and some printed PLA joiners.  It doesn\'t have to be fancy or expensive to work well.</p>\n<p>Details are at <a href="https://3dprinting.stackexchange.com/a/18406/12956">https://3dprinting.stackexchange.com/a/18406/12956</a></p>\n<p>Next step is to sew some thermal &quot;curtains&quot; as sides and top.  As it is I simply hang some coats around the frame in the short term, and use a Pi camera inside to monitor the progress from remote.</p>\n'}]
['https://3dprinting.stackexchange.com/questions/18437', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/31095/']