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Any idea why I get intermediate under extrusion spots within my prints?

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I had this issue for a while, so thinking it was just a clog I was constantly removing the block and cleaning out the nozzle when it would appear that the atomic pulls weren't doing the trick. When the problem persisted I decided I would swap over to an olsson block and installed the .4mm nozzle... also swapped out with a new temp sensor since the old one refused to separate from the block and broke off.

Im using IC3D black ABS filament at 250 nozzle, 95 bed.

printing at .1 layer height at 40mm/s

Im not sure why but the problem continues. The only other things I can think of are either its a problem with the extruder or the feed tube. I have also noticed that every other print seems to jam at startup and require me to hit the change filament option... when I reload the filament the following print starts up fine. Could anyone offer any advice?


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Kinda disappointed with the lack of response to this. Anyhow I diagnosed it myself since there was no community assistance. In case anyone else has a similar issue I’ll post my findings. It appears it was a faulty feed tube that was causing friction while feeding the filament to the hotend and ultimately would cause underexteusion and nozzle jams. I replaced my PTFE tube with a new one and I haven’t had any issues since. I performed 3 abs test prints at .1 mm layer height and they all came out beautifully.

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