A Broken Arm, on a Stormy Night

A follow up. You read about these things but you just don't believe they could happen to you. I was mostly able to fix my 3D printer after a recent catastrophic failure. And me? I hate fixing things. The big problem turned out to be a cracked extruder arm.

Old... . . . . . New...

You couldn't see the crack from the outside, not like the picture after dismantling above. And the crack didn't stop the idler wheel rotation or the 40 toothed driver wheel, and it didn't keep me from manually applying more pressure to the filament. But it appeared to occur because of too much pressure from the hot end applied via the filament to the arm (and that problem still seems to be occuring!). But changing to an aluminum extruder assembly created an amazing change in behavior (yea Amazon), the proper size extrusions suddenly reappeared, and as if by magic, most builds again became possible!! ...e.g.

... ............

...

So it's not totally fixed. With too many retractions, the Bowden tube gets to hopping up and down, the tubing starts to move in and out of the air fittings, The filament slips and gets progressively damaged. Hence, it breaks or becomes fatally damaged, all symptoms of high friction. So there is still probably some heat creep or something else going on at the hot end. Still, if I clean everything up, avoid high humidity filament, up the hot end temperature slightly, and keep the project size small, I can make things. Here are pictures of 5 objects that I was able to make over the past few days, The one with all the supports shown on the right side, that's the one that killed my machine originally, it posed an extreme number of retractions!! And it took 4 tries to get this success. I should add, the very next project after this success, shown below and already a known albatross (third try, and a cursed bird), failed from filament breakage! That project was also a project with an unusually high number of retractions which I really didn't realize. To add more troubles, we have also been experiencing high humidity here, constant rain. PLA plastic does not tolerate moisture well. It becomes fudge like or like moist clay... and easily broken. The broken filament left in the Bowden tube showed a lot of wear spots (from gear grinding) along the path between the hot end and the extruder motor.. along with that wear a filament breakage, inside the Bowden tube!! I may still spend that 25$ for a new hot end. I'm a cheap skate, but it seems like it is probably worth it. A good thing though, this may have helped cure my "obsessive-impulsive" 3D printing tendencies. .My PhD in science did not help solve this dilemma one darned bit. :) But,I used the "down time" to build 3 bookshelves, do some Spring planting, and mow my farm's fence lines. :)

... The last failed project after the killer, was a hummingbird feeder, shown here, consisting of a top and bottom. The layers of this bottom attempt separated because of a filament breakage but the printer kept on printing... bravo printer! If I hadn't messed with it, I could have glued the halves together. I'm guessing if I shrink it a bit and go to 100% infil to eliminate retractions, it will survive. The base for the feeder failed as shown on the right below... The separated walls are offset from the base.

....

The raft, a before and after picture, it took a lot of force to remove the print on the right, enough to crack the rigid and functional raft!!



The people at Voxelabs (FlashForge) were helpful and very patient as I attempted to get this thing running again. I broke it.... And their printer can do some truly amazing things when the filament path is clear and you don't ask the impossible. So, Henry Wu, wherever you are, thanks for your help. :)

I need to pick projects that don't require 10,000 retractions or take 3 days to compile in Openscad.

May 25, 2022...