Filament gets chewed by extruder after a number of layers
Running into an issue with extruder chewing up filament after a number of layers. Basically the prints seem to be working fine for a while, but at some point the two cogs eat a groove either side of the filament and it no longer extrudes. I've adjusted the tension on the extruder to only lightly grab the filament (see attachment) but I can't reliably print anything without this happening at some point. When I look at the end of the filament there is a bulge. Is this normal, or could this be a heatsink issue where the heat from the hotend is bleeding into the filament too much causing it to block?
RE: Filament gets chewed by extruder after a number of layers
Looking at the infill at the top, it looks like surfaces aren't adhering well. Notice how strands of the perimeters are being pulled straight across instead of following the curve of the leg. If the temp isn't high enough, adhesion may be poor and you can easily get jams and skips if the flow is interrupted. I'd try increasing temps and slowing speeds down. Perhaps a bump of 10C.
You might be experiencing other heat-related issues, but the part is simple enough and I wouldn't expect a lot of retractions to contribute to heat problems.
RE: Filament gets chewed by extruder after a number of layers
I think what you're seeing on the front most leg is the extrusion stopping, so there are artifacts because of there being little/no filament extruded. The back leg is more representative of how its dialed in. Also, I should have mentioned this is Prusa PLA with 215deg hotend/60deg bed. That said I'll try a higher temp and see if that helps. Thanks!
RE: Filament gets chewed by extruder after a number of layers
Heat creep issues aside, that is a tall, top heavy object. I would do everything I could to increase adhesion and stability.
If there is any wobble in the part, you could get infill issues like that.
I happen to be a fan of brims...
RE: Filament gets chewed by extruder after a number of layers
The unloaded filament stub shows the very typical heat break jam. If it measures 2.2 mm then you'll be better off changing to a stock E3D-V6 heat break.
It seems random, but some us were unlucky and received a bad heat break from Prusa. My printer started jamming after a month or two... and a new heat break fixed it. No other changes.
RE: Filament gets chewed by extruder after a number of layers
@tim-m30
Thanks! I wondered if it was that. Has anyone had luck getting prusa to send replacement heatbreaks, given this seems to be a known issue?
This machine is only a couple of months old and has done less than 50hrs printing.
RE: Filament gets chewed by extruder after a number of layers
You are talking about a $15 part with free shipping...
Prusa has not acknowledged anything is wrong with their design, and it might actually be needed for the MMU.
RE: Filament gets chewed by extruder after a number of layers
You can find the Titanium version for around $20, too. It's even an upgrade (better for the mind, lol).
https://e3d-online.com/catalog/product/view/id/9284/s/v6-titanium-heat-break/