Hello everybody. I’m doing a print right now that requires a pause to insert some steel weights inside of it. They slip right down without and effort and only weights 3g a piece. This is a technique I’ve used many times before without incident. However, I’m abruptly having an issue where the next layer after the pause seems to be slightly misaligned and a gap is being left. It is only paused for about thirty seconds and chamber temperatures are being maintained at 50-55 so I do not think it’s part shrinkage from cooling. Wall finish quality is very important on these parts so this isn’t an acceptable quality. Does anybody have any idea what could be done to remedy the issue? I suspect it is mechanical with something being loose after 1200hrs of print time on this machine. The offset and gap is consistent in it’s orientation as well.
I often use the same technique for embedded weights, fastening hardware and magnets when making functional parts, so I totally understand what you’re trying to achieve.
I’ve not experienced this with PC, PETG, ASA or PLA when stopping a print midpoint to insert hardware. I have to wonder if this is perhaps something peculiar to ABS.
To rule out that the filament is what is causing this, one could perform a simple test. Print a cylinder and cube primitive of similar height to your model for the sake of time and filament savings. Pause the print midpoint to simulate the insertion of hardware. Then restart the print and see if this mimics the phenomena. To do this test properly, you would have to test it with other filaments too in order to rule out ABS as the culprit.
Possible theory
I do have a another theory. Since this is ABS, which we know is picky about temps, placing the hardware inside the cavity might cause the hardware itself to act as a heatsink, temporarily altering the thermal properties of the surrounding filament. To test this, you could create two test cases:
In the first case, use hardware at room temperature.
In the second case, let the hardware rest on the build plate during the print so it reaches the same temperature as the filament.
When you pause, place the room-temperature hardware into the cavity of test model #1 first. Then, place the pre-heated hardware (from the build plate) into the model #2 cavity last. Resume the print and observe the results.
If you decide to perform such a test, please share the results with the community so we can all benefit.
I’ve done this previously with ASA to insert steel reinforcement into a model bridge
Hmm… This is something I had not considered. I’ll run this test possibly later this week and post the results. I hadn’t considered the thermal mass to be significant enough to matter but perhaps the high shrinkage rates of ABS paired with the greater temperature difference is producing a noticable effect.
