<p>I'm printing with opaque grey PETG on glass. The intention is to produce a house number plate, so a shiny, production quality finish on the bottom. For this reason, extruding at 245&nbsp;°C with a bed at 95&nbsp;°C, to give a perfect glass finish with no filament lines showing. Smaller test versions have been very promising; this seems to be the maximum temperatures before warping or a severe elephant's foot arises.</p>

<p>However when printing the full-scale version, areas of the first layer of filament seem to go completely "transparent"; there seems to be filament there - you can feel the filament "comb" when you run your finger over it, and it feels a similar thickness to its neighbours.</p>

<p>On the attached photo you might think that those gaps are simply not printed yet, however you can see on the top right corner that it's actually started on the next layer.</p>

<p><a href="https://i.stack.imgur.com/JYOVA.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JYOVA.jpg" alt="print"></a></p>

<p>What could be causing this? Is it a blockage which is interrupting flow, and maybe insufficient filament is being "stretched out"? Or maybe it could be something to do with temperature? Could it be insufficient layer height (I'm using 0.2&nbsp;mm, but 0.24&nbsp;mm on first layer, increasing further reveals filament lines, but tested higher and lower on smaller scale with success).</p>

<p>I've tested a range of extrude and temperatures and chosen the temps with the best results; but when I "go large" this always seems to happen. I've also calibrated the bed height using the 3 point adjustment screws on this printer (Qidi X-Plus). (The transparent areas are actually occuring in the center where the smaller test prints where working perfectly, so don't know how it could be to do with this). </p>

[{'answer_id': 12003, 'author': 'Krista K', 'author_id': 20086, 'author_profile': 'https://3dprinting.stackexchange.com/users/20086', 'pm_score': 1, 'selected': False, 'text': "<p>PETG becomes transparent when the layers completely fuse. Translucency is from incomplete adhesion or voids left. Try small increases to flow or print width to get slightly better fill - or slow the speed (but speed might not affect how much material is output).</p>\n\n<p>Also, I see the top surface has a pattern on it. My FDM printer always does a similar thing and it will take tuning to get it smooth. If you see the pattern repeating consistently, it is possible the extruder stepper (or its driver) is starting to fail. I've had that too.</p>\n"}, {'answer_id': 12005, 'author': '0scar', 'author_id': 5740, 'author_profile': 'https://3dprinting.stackexchange.com/users/5740', 'pm_score': 3, 'selected': True, 'text': '<p>Are you using Z-hop? Is there any play in the Z-axis direction? It appears that parts of the first layer are printed much thinner than other parts.</p>\n\n<p>What can happen if there is a little play in the Z-axis direction that the nozzle doesn\'t return to the same level after a Z-hop movement (e.g. backlash in the leadscrew nuts).</p>\n\n<p>The "transparent" printed part appears thinner, this must indicate that the Z positioning is not up to par.</p>\n'}, {'answer_id': 12021, 'author': 'ventis', 'author_id': 12416, 'author_profile': 'https://3dprinting.stackexchange.com/users/12416', 'pm_score': 1, 'selected': False, 'text': '<p>there are a lot of variable at play here, when are there not in the 3D printing world. Given that I don’t know the answer to your question although very interested to learn how you solve it eventually I will mention the things you can do ,maybe you have to eliminate or identify what parameter is the fault cause.</p>\n\n<p>Things I would eliminate - \n1 bed temperature discrepancies - move the origin cycle of the print or rotate it to see that the problems are physical rather  than software. If the faults occur at the same place on a reoriented print then I would say you can eliminate nozzle and bed temps as well as material inconsistency.</p>\n\n<p>May also be worth trying the print from a different complier I often find a piece prints differently and there fore better from this or that printer app.</p>\n\n<p>2 could cooling be the issue? What if you hold a heat gun on the extruded parts to slow down cooling I have done this on tricky parts to get better binding, could be similar issue.</p>\n\n<p>3 print a raft or test piece and see what happens to transparency with heat - if the material properties change as a result of temperature you could investigate why the temp is changing at the points in the print that are relevant -</p>\n\n<p>Not sure that these ideas are that original but the fewer variable you need to consider the faster you will work out what to do about the rouge one </p>\n\n<p>Regards</p>\n'}]
['https://3dprinting.stackexchange.com/questions/11967', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/19946/']