Guys,
Im having trouble printing large prints reliably.
My models are produced in Fusion360 and sliced within Cura. I tend to print larger prints directly from the SD card (rather than via Octoprint).
My latest problem is the part shown below. Printing for about 30 hours and then its appears as though the stepper motors lost accuracy in the z-axis and everything then turns to custard!
I have attached a section and model image of the part - It stands just under 190mm high and has about a 150mm DIA at its widest.
The part is made from PETG and printed at 75% infill - because its a structural part.
I have also included a part of the timelapse within the zip file to show what happens… Essentially I got a great print until such time as I didnt! At that point I had a few hours of spagetti plastic around my part! When I got to it this morning the print head was still travelling over the part as though it was printing in the correct place but somewhere along the line one layer failed to adhere to the one below it.
My first thought was that I maybe had a hollow somewhere in my model, but the section analysis would suggest that thats not the case.
For heavier models such as the one you are printing inertia becomes a large factor for bed slingers like the Ender 3.
This can manifest as a skipped or unreliable step in the Z-axis, extra pressure on the springs (cumuatively causing under extrusion) or the print itself can slip from the plate.
If you only have to print one more I’d say to kick the print off from where it failed and super flue to together!
Liam
I’m with @Liam on this - looks like layer shifting, which when happening 30hrs-in will make it quite a nuisance to debug by iterating on settings.
You mentioned that it’s a structural part, so if super-gluing isn’t an option I would try thinking about designing the part in a way that can be printed in smaller sections and then fitted together. Given it’s somewhat cylindrical one way could be to split the neck and bell sections, and then attach them using a thread (which you would need to design into the models).
Here’s a very rough sketch of what I mean - I hope it makes sense:
Now I know its likely to be a physical constraint rather than something Im doing wrong I’ll change my thinking with the parts.
The thread is a great idea - never crossed my mind. I’ll trty the super-glue idea and see how it goes, fail in that I’ll introduce a threaded joint.
On a somehwat different but related thought, would a resin printer suffer from similar (or othe) issues for these kind of parts? I dont print hundreds of these kind of things, but the slow speed is somewhat frustrating. On the whole I do like the Ender 3, especially for smallwe parts, but Im wondering if I may have the wrong machine for these kind of things.
I use my machines for much smaller brackets and fill the rest with 2020 extrusion, DAR or other suitable materials. So the 3D printed part is really just an adapter.
A resin printer might be an option but comes with its own constraints - much messier, typically smaller build volumes ect.
For parts like this where they are tall it is likely to take a similar amount of time.
Working in parts that you might be able to grab from a hardware store ought to be the real time saver!
Liam
It could be that your Z axis binds up at that level for some reason, then skips a few layers once it overcomes that, leaving a gap in layers that will produce spaghetti. Have you run a quick test print of say, a rectangular prism that reaches that high, and watched for any irregularities? Have you taken a look at the path the printer takes in Cura to confirm there aren’t any weird gaps due to a slicing error?
Before I saw the video I was going to mention that there doesn’t seem to be a large flat surface for the bed to grip, but it seems your adhesion is not the issue, and it’s more about what’s happening up top.
I think you’re on the money here. What he could do is a print with 2 flat surfaces for the adhesive. If that works, make 2 pieces like Jacob says. Maybe you could get away with just an extruded cut and extruded boss…unless you really want a threaded join.
