Underextruding After Travel - E3D Volcano Hotend

  • I'm using a new E3D Volcano setup with a Bondtech BMG direct driver extruder and a 0.6mm Volcano nozzle - previously I've only had significant printing experience with a standard E3D.

    Usually the Volcano underextrudes after a travel movement.

    This is a minor imperfection for the most part, except it leaves small gaps in the top layer which would be perfect otherwise.

    I'm using Simplify3D and could use some ideas on what order to troubleshoot. I plan on trying to keep retraction on and add a positive extra restart distance - but further ideas are welcome.

    Is there a way to tweak priming the extruder after travel in firmware based on travel distance?

    From what I understand, pressure advance would deal with the reverse of this problem and it looks like 0.05 pressure advance does make it the slightest bit worse.

    • Thanks

  • administrators

    Pressure advance deals with under extrusion at the start of a move and over extrusion at the end of a move.

  • I'm not sure about simplify but Cura has a scalable prime option that uses more Prime amount when the travel is longer.

    You can also increase your travel and retraction speeds if possible

  • After fighting with under/over extrusion issues with my MK10 hotend, I played with coasting, extra prime amounts, retraction speed/distance, I finally used Pressure advance and it essentially fixed the problem.

    I found that setting the retraction distance lower than normal and the speed around 50mm/s fixes it, using higher retraction distance caused a little under-extrusion in my case.

    I have the advance value at .06, retraction at 1.3mm and speed at 50mm/s.

  • @dc42 Perfect, I guess I had my understanding of it backwards then.

    A 0.05 setting didn't quit work, but I will bump it up and see where I get to.

    The Volcano is a strange hotend to print with, but I do like the larger melt zone - it seems to print more consistently at lower temperatures.

  • I had a volcano for probably 300 hours print time.

    I'ts one of my favorites and it will spit plastic as fast as your machine prints.

    That said, I didn't want to loose the 30+ mm to convert the machine to the E3D setup in order to use the official heat breaks.

    The down sides are figuring out the correct temps and issues at low print speeds.

  • @dc42 said in Underextruding After Travel - E3D Volcano Hotend:

    Pressure advance deals with under extrusion at the start of a move and over extrusion at the end of a move.

    I came very close to a perfect top layer with 0.1 pressure advance, but at the cost of tiny gaps in retraction in the side wall (0.06 or 0.07 is probably the correct value instead of 0.1, so I plan on lowering it).

    Do printer acceleration, jerk, and overall print speed settings calculate into this as well?

    I'll have to check the settings later, but I was thinking I should raise the extruder acceleration as a start.

    Retraction was set at 0.4mm for the Volcano, so I don't think I'm retracting too much. I may also try a little bit of extra restart distance and see how that works.

  • I'm not sure, but I've noticed when printing single layer test cubes, if the acceleration/jerk/speed is too high, the extruder can't build up pressure/material fast enough after a layer change and you get a thin/streaky side/corner, but it goes back to normal shortly after.

    Pressure advance helps this, but after playing around with crazy acceleration settings I think there is a point you can go too far.

    Raising temps and increasing s/mm on extruder can help too.

  • @wyvern said in Underextruding After Travel - E3D Volcano Hotend:

    acceleration/jerk/speed is too high

    What were your config settings for those if you don't mind posting them?

    I dialed pressure advance up to 0.1, which left gaps, but 0.06 is pretty much perfect. It still leaves the same small under-extrusion after travel though - but I think it's set correctly.

    I'll paste my config block below of the settings I used for accel/jerk/speed:

    M201 X1500 Y1500 Z500 E3000
    M203 X24000 Y24000 Z2000 E3000
    M566 X600 Y600 Z700 E1000

  • M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80.00 Y80.00 Z795.00 E110.00 ; Set steps per mm
    M566 X800.00 Y800.00 Z14.00 E120.00 ; Set maximum instantaneous speed changes (mm/min) AKA Jerk
    M203 X8000.00 Y8000.00 Z200.00 E1300.00 ; Set maximum speeds (mm/min)
    M201 X1000.00 Y1000.00 Z300.00 E250.00 ; Set accelerations (mm/s^2)
    M906 X1100.00 Y1750.00 Z850.00 E900.00 I30 ; Set motor currents (mA) and motor idle factor in per cent

    This is mine, still fine tuning it. This is a simple gantry style setup Z motion bed, twin stepper Y axis and single stepper X. The machine is a FT-5R2 with multiple upgrades and frame stiffeners.

    I would say you are a little hot on some of your settings.

  • @wyvern

    Lowered some of my settings to the following:

    M201 X1000 Y1000 Z100 E2000
    M203 X9000 Y9000 Z300 E6000
    M566 X600 Y600 Z50 E600

    Ended up with 0.6 Pressure Advance, the settings above, print speed 60mm/s with outlines and perimeters set to 60% and 70% of that. Retraction had 0.05mm of Extra Restart Distance in Simplify3D and with those settings, everything looked pretty good.

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