Printed this last night in white PLA at 0.2 layer height.

Its a very nice part. The new extruder base is now very close to the hobbed bolt and I cant see the ninjaflex being able to escape around the bolt.

Some observations. It does desperately need modifying to add a groove for the set screw on the hobbed bolt. In the current design the set screw on the hobbed bolt catches and stops the extruder from turning.

The holes on the bottom where it affixes to the powder coated Y arm give a strong fixing once you can get the M3 screws to bite but getting them started is a pain due to varying tollerances of printing precise holes on desktop 3d printers. I would suggest tapering the hole. a slightly wider entrace to allow the screws to gain purchase then tapering to being tighter as they start to bite.

The support material removes very easily but leaves the small dots at the top of the support material attached to the overhang. This means then the hotend is fitted its sits perhaps .5 lower than it did in the ali extruder meaning the z probe needs moving and quite a bit of relevelling. The design looks like it has space to get a sharp scalpel into the gap to trip them off but certainly on mine and looking at the other prints theres not space to do so meaning removing these dots is very difficult and consequently the hot end sits lower.

Only one other comment. Once I'd removed the 20mm M3 bolt which fixes the sprung extruder arm to the stepper motor I found after screwing it back in it didnt seem to have the same bite and consequently the sprung arm tended to slew forward toward the front of the bot when the spring was tensioned. 20mm seems a bit mean. perhaps I damaged the thread on the bolt or the stepper. Perhaps I've rotated the stepper and the new bolthole isnt as good.To fix the problem i've ordered a new set of 23mm M3 cap head bolts. That extra 3mm should bottom out in the body of the stepper and provide a good solid axle.

I will be interested to see how this pla part will hold up on a long print being so close to the hot end.

IMHO 20mm is just too little thread for a good fixing.

Printrbot Flexible Filament Direct Drive Extruder

Printrbot Flexible Filament Direct Drive Extruder

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