Monday, 18 January 2016

Hobbled hobbed bolt

As mentioned in the last post, I ended up with a failed print due to stripping. Turns out stripping can have a number of causes, but left-over PLA in the hobbed bolt is a common one, and since I had stripping before, I should check it. Sure enough:

One Reddit post mentioned misalignment of the hobbed bolt, so I double-checked that it aligned well, and it seemed a bit out of place. Trying with an extra-thick washer made the grip much worse, though, so I quickly scratched that idea and cleaned the bolt again. While cleaning, I noticed there was one side where a piece of metal was crossing the teeth of the hobbing. Maybe that's what has been making those funny "click" noises regularly. 

In any case, putting the bolt back on like it was before didn't give me the nice, smooth extrusion I was used to. Rather, it was difficult to get it to bite, and not even easy to get the filament through. Feels like there is something clogging it. Didn't help that I accidentally left the extruder on 220C for about 20 minutes while doing other things. This is going to be tricky to fix. 

For your amusement: Close-ups of the hobbed bolt. Plenty of stuck PLA, even after attempting cleaning, and one piece of sideways metal.


  1. Ouch, that's a terrible bolt. I've never seen one that bad, you may get a benefit from going to something like (with nuts jammed instead of the head, or a )

  2. I had nothing to compare it with, so I didn't know. It's also from more than three years ago, things may have improved since then. But that piece of metal across it, plus the clicking sound, made me suspicious. New bolt ordered.