TAZ PRO Constant Air Print

I’ve tried making the same object 5 times and each time it ends in failure. It makes 2 and a half hours of layers before it just keeps grinding into the filament. I’ve had the same settings since my first few successes but now it decides to randomly “print in mid-air” with the drive gear full of ground plastic.
What am I doing wrong? Should I turn off retractions altogether? I need these done by next week!
3 PC Shelf-Rack.stl (58.9 KB)

I don’t see anything about that design that should be retraction-heavy enough to ruin the filament, but the quality on the sides looks absolutely terrible.

I would guess that you’re trying to extrude with some of that messy print right against the nozzle, creating enough backpressure that the filament is stripping.

Should I change the print speed or something else?

I also just looked at this model. Is it even sticking to the bed? This is a printer warp torture test. Long, straight lines with about 7mm of material right on top of it. I can easily see the warping causing the parts to mash into the nozzle as it prints, then catching the nozzle or causing the grinding.

It might succeed if it was done in an enclosed printer, but this design is just not optimized for 3D printing at all. Looking at it I’d guess it’s supposed to hold papers? Make just the side pieces (with breaks in the contact with the bed) and run some wooden slats or dowels between them.

Something like this quick and dirty modification (dowel holes too big, but you get the idea)

This is not a nail for the hammer of 3D printing.