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Reply To: Setting Stepper Motor Current (vref) and what it has to do with Belt, Wheel and Extruder tension (among other things)

Forums The Beast V1, V2 and Elevator 3D Printer Support Setting Stepper Motor Current (vref) and what it has to do with Belt, Wheel and Extruder tension (among other things) Reply To: Setting Stepper Motor Current (vref) and what it has to do with Belt, Wheel and Extruder tension (among other things)

#1207
dandan
Participant

Josh. Sorry I missed your post. Our server got corrupted, preventing email notifications. Let me know if you’ve solved this. If you get zero extrusion, first you need to figure out if the extruder is actually working. This can be easily tested by removing your Bowden tube from the hotend, preheating your hotend (allowing the extruder to move) and using your lcd to move the extruder say 100mm. Does the extruder move unhindered?

If it does, is there any torque? If you were to hold the filament before it enters the extruder, does the extruder pull or does it skip with the slightest of resistance?

Commonly, one thing people often overlook is that when an blockage occures, you absolutely NEED to remove any filament from the Bowden tube. Upon blockages, possibly from the hotend, the extruder can chew and deform the filament inside the Bowden tube, making it impossible for the extruder to do its thing. Often people clear the source of the blockage only, completely overlooking the other EFFECT of the blockage which can be deformed filament. Removing the filament from the tube will often reveal very badly deformed filament.

If the extruder seems fine, and Bowden not itself blocked, it’s time to look at your hotend. Primarily hotend construction, look for gaps in construction, specifically between the heartbreak and nozzle and or the Bowden tube and heartbreak. Make sure your Bowden is cut square and when you insert it into the hotend (and extruder) ensure you pull up on the neck of the push fit adapter while pushing down on the tube. This prevents gaps from forming during retract movements.

Another tip if printing with low melt plastics such as PLA and PETG is to consider the effect of the seldom mentioned variable of “heatwork”. Heatwork is the effect of temperature over time. When printing with a heated bed, consider that the filament is likely at ambient temperature before it enters the hotend. This means less hotend heat is required to achieve a viscous material. It also means that filament will soften in the “cold zone” at a lower hotend temperature than it would if the heated bed was turned off. Again, simple solution is to reduce the hotend temperature by up to 20-30 degrees while printing with a heated bed. In my experience, PLA which prints fine at 205 deg without a heated bed running can be reliably printer at 175 with a heated bed active. At some point I’ll devise an experiment to show and graph how heatwork effects filament viscosity in Bowden tube as I’m sure the amount to reduce hotend temperature isn’t linear nor directly equivalent to the increase in ambient temperature caused by the heated bed. Also worth considering with the V2 which has a moving heated bed is that heatwork will have less effect on the viscosity of material as the bed moves further and further from the nozzle during printing. This means adjusting hotend temperature upwards as the z height increases is advisable.

Let me know where you’re at with this so I can assist further.

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