Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
Hi all.
I was printing a file that had two objects on the plate, one much taller than the other. I was surprised to visit the printer and find the first, taller object completed and the printer spewing filament into mid-air. This happened because the printhead collided with the first-printed object and couldn't reach the plate to start the second one.
I'm surprised that this is allowed, given that PrusaSlicer is set for my printer (Mini+) and it should know the dimensions of the stock printhead assembly. Is there a way to specify a "bounding box" of required clearance around the printhead within PrusaSlicer?
I'm also using OctoPrint, so if PrusaSlicer lacks this ability but OctoPrint has it, please let me know.
Thanks!
RE: Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
You didn't upload a 3mf project file, so everything is speculation. I suspect you used Sequential Printing (Print Settings→Output options) because otherwise the printer would be laying down layer by layer for each object (which can't cause the issue you described) and not finish one first. Yes, you have to make sure that the hotend doesn't collide with the printed objects. The clearance is defined by Radius and Height for Extruder clearance in the Sequential printing dialog. The print preview will show you the outline of the exclusion zone. When they're too close together, the print preview will also give you a warning.
But there are a number of issues, and I really wish this function was a lot more intelligent than it is. For one, I never figured out how the Height option works, the explanation makes no sense to me. I just set it to a very high value and be done with it. You also need to consider the order in which objects are printed and ensure they're printed from front to back. You can check the tool path in the Preview and make changes to the order by dragging the parts in the parts list into the correct order.
As I said, it works but it should be a lot more fool-proof.
RE: Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
Thanks for the reply. I have made no changes in PrusaSlicer other than to choose my printer and filament, so whatever the defaults are is what I use. It looks as though sequential printing is off. Also, it's only a checkbox on my system. When is the dialog with further settings supposed to appear?
And on further review, the collision may not have happened. In the past when I had a model in FreeCAD where an object was offset from 0 in Z, PrusaSlicer still put it on the plate. But those had only one object. In this case, PrusaSlicer shows the second object floating above Z, and auto-generation of supports is off. So maybe it just decided to print the thing in mid-air and there was no physical collision. There would have been, however, had the printer attempted to reach the plate.
This forum won't let me attach the 3mf file.
RE: Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
This forum won't let me attach the 3mf file.
You need to zip the 3mf file in order for the forum to accept it.
RE: Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
Okay, not a sequential printing issue. But yes, if one of the objects is hovering above the print bed, Bad Things will happen… You can use the Split function in the right-click menu to split the object into its parts, so each part will print on the steel sheet.
RE: Can PrusaSlicer warn of object layouts that are impossible to print because of printhead obstruction?
Thanks, guys.
You can use the Split function in the right-click menu to split the object into its parts, so each part will print on the steel sheet.
Oh yeah! Plop, there it goes, right down to the plate. Any idea about that sequential-printing options dialog?