Hello, after printing many objects without problems, I got serious problems with the largest part I have printed up to now. It is a box with 110x190 mm ground surface and 100mm height. The walls are 3mm thick. The box is printed from transparent Bendlay ABS filament at 230°C over a PET tape covered heat bed set to constant 120°C temperature. My M90 was running in a heated chamber with 44°C inside temperature. During printing developed several cracks between the layers, obviously caused by thermal shrinkage of the ABS material. The first crack is about 10mm above the surface, but also far above from the glass plate developed cracks. What are your experiences about such large objects? Is there a way to avoid this cracks ( reduced bed temperature after first layer, better inter-layer connection by higher extruder temperature, special filament types, other box design ...???)? Finally, when traying to remove the box from the glass plate, I broke the glass plate :-( Can I replace it by some standard, common glass plate or have I to look for some special glass? Cheers, Gerd https://reprap.org/forum/read.php?292,316281,316281#msg-316281 Mon, 05 Oct 2026 14:45:52 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?292,316281,321121#msg-321121 https://reprap.org/forum/read.php?292,316281,321121#msg-321121 GerdH Mendel90 Fri, 07 Mar 2014 05:30:02 -0500 https://reprap.org/forum/read.php?292,316281,318838#msg-318838 https://reprap.org/forum/read.php?292,316281,318838#msg-318838 Ralph.Hilton Mendel90 Sun, 02 Mar 2014 22:45:15 -0500 https://reprap.org/forum/read.php?292,316281,316450#msg-316450 https://reprap.org/forum/read.php?292,316281,316450#msg-316450
The datasheet of the transparent ABS quoted 225 to 240°C printing temperatures. So I tried 230°C, which worked fine for small objects.

But the box must not be transparent or from ABS (btw, if the infill is not solid, it looks not very transparent, more like crushed ice).
I still have a spool of green PLA. Or has natural PLA even better characteristics?]]> GerdH Mendel90 Wed, 26 Feb 2014 11:04:15 -0500 https://reprap.org/forum/read.php?292,316281,316372#msg-316372 https://reprap.org/forum/read.php?292,316281,316372#msg-316372
Something that size and shape would be challenging in ABS. Would natural PLA be suitable for your application?]]> nophead Mendel90 Wed, 26 Feb 2014 08:21:23 -0500 https://reprap.org/forum/read.php?292,316281,316287#msg-316287 https://reprap.org/forum/read.php?292,316281,316287#msg-316287
As for replacing the glass, apparently picture frame glass is 2mm and people here have had success in getting their local picture framer to cut 200x200 sheets for them.
I use 3mm thick SORLI mirror tiles from IKEA, which are already 200x200 (albeit with rounded corners) and are £6 for four. It takes a little longer to get up to temperature given the extra thickness, but I have been printing on it with no problems. Having lots of tiles means I can clean off and prepare spare ones with PET tape and just swap them over when the tape eventually degrades without interrupting my printing too much.]]> QuackingPlums Mendel90 Wed, 26 Feb 2014 04:30:44 -0500 https://reprap.org/forum/read.php?292,316281,316281#msg-316281 https://reprap.org/forum/read.php?292,316281,316281#msg-316281
after printing many objects without problems, I got serious problems with the largest part I have printed up to now.

It is a box with 110x190 mm ground surface and 100mm height. The walls are 3mm thick. The box is printed from transparent Bendlay ABS filament at 230°C over a PET tape covered heat bed set to constant 120°C temperature. My M90 was running in a heated chamber with 44°C inside temperature.

During printing developed several cracks between the layers, obviously caused by thermal shrinkage of the ABS material. The first crack is about 10mm above the surface, but also far above from the glass plate developed cracks.

What are your experiences about such large objects?
Is there a way to avoid this cracks ( reduced bed temperature after first layer, better inter-layer connection by higher extruder temperature, special filament types, other box design ...???)?

Finally, when traying to remove the box from the glass plate, I broke the glass plate :-(
Can I replace it by some standard, common glass plate or have I to look for some special glass?


Cheers, Gerd]]> GerdH Mendel90 Wed, 26 Feb 2014 04:20:35 -0500