Hi Folks,
I like to get some advise. I bought for our students a new Gear Head Extruder v2, to upgrade our Printrbot Plus-1504. We printing mainly big projects and using therefore 1 mm nozzle. But the print quality give always trouble in pushing with the old (orig.) extruder the filament through the 1mm nozzle. After the update with the Gear Head Extruder v2, we have now a now problem. After 20 min. the print fails, as the gear head grinds of the filament.
It looks like we using the wrong forward speed for the extruder, but all settings are correct ? As described on the Printrbot webpage, we changed the settings inside “Pronterface UI” steps per mm to 127 - Command: M92 E127
M501
M92 E127
M500
M501
We using Cura_15.04.2. and all settings from temperature to running on slow speed seems OK…
I appreciate your support
Regards
Frank
I bet your settings are fine - I’d question whether the hot end is maintaining the desired temperature. 1mm nozzle is a lot of filament to melt in a short amount of time - that will require a lot of heat. If the heater can’t keep up, the filament will get hard to push through and the extruder/hot end will jam.
The old extruder was probably slipping, allowing filament time to melt. The new one is not so forgiving, and the filament ends up losing (getting ground up).
Is the hot end getting enough current? What’s the duty cycle of the heater? (Repetier Host will show me how “hard” the heater is working to maintain the temperature)
If you slowed the print speed right down, I wonder if it would print successfully. I appreciate that defeats the purpose of the larger nozzle - namely to print large objects quickly, but it would confirm my suspicion about the hotend heater not keeping up with the load.
Hi @Alex_Wiebe I think you hit the main point. We using this old hotend for years now and it’s time for a new one. I hope this will change the performance. Thank you for the support.
You need to think about filament extrusion rate in terms of VOLUME FLOW, not speed. Your hot end can only melt filament so fast, simply due to heat conduction limits into the plastic. For example, a standard PTFE-lined hot end may max out around 4-5 mm^3/sec of filament flow with PLA. It is very, very easy to hit these limits with large nozzles. In comparison, hot ends designed for high-flow printing like the E3D Volcano (that are all-metal with a long melt zone) have a much higher flow limit, perhaps ~30 mm^3/sec.
To calculate flow rate from slicer settings:
flow in mm^3/sec =
extrusion width in mm *
layer height in mm *
print speed in mm/sec
(This is accurate enough for understanding extrusion limits. )
For example, printing 0.5 mm width at 0.2 mm layer height at 40 mm/s gives 0.50.240= 4 mm^3/sec, which is generally within the capabilities of most hot ends.
But printing 1.2 mm width at 0.5 mm layers at only 20 mm/s gives 1.20.520= 12 mm^3/sec, which is a far higher actual printing rate, beyond the melt capabilities of most hot ends.
Yes, bigger nozzles make it easier to print fast, but not 3x faster. You need to swap out the hot block to a high-flow model to get high print speeds from big nozzles.
The shredding of the filament is the clue that the feeder gear is stripping the filament before it can melt going through the extruder. The stripped debris then just plugs the everything up. To find a good flow rate, raise the z-axis all the way up, then just feed the filament through the extruder, watching for a clean flow. If the flow curls, its a sign the filament is not being heated all the way through (or extruder damage). If the filament is going droopy, or spurting, then its too hot. Too many retracts in a print can cause the filament to cool during retracts, which will mush the leading filament in the hot end, so the right temp settings is between those two, and set to slightly hot.
Well explained thank you +MidnightVisions
Justva note, manufacturers recomended filament settings are geared towards an extruder with .5 or .4 diameter output. Your project is using 1mm, so when you find a reliable setting please let the community know what your setting are. : )
Good comments. It seems wrong, but slow the print down until it prints well. The taller / wider layers will still lower overall print time, so it will be faster. You can easily bump the filament temp 10-20 degrees depending on speed.
This is why we built the 33 watt high flow and the 90 watt / 24V High Temp hotend… both have a much longer melt zone so big nozzles can live up to the dream. These are much better suited for higher volumetric flow.
Brook
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