Need advise. I use MatterControl host software with Marlin V1 and with autobed leveling

3D Printing
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Need advise.
I use MatterControl host software with Marlin V1 and with autobed leveling setup.
PLA, 0.4MM nozzle, tried temperature 200C, 205C and 210C, direct drive extrusion.
I had an intermittent problem, sometimes printing OK and in a sudden it turn baD. I had tried changing extruder speed from between 50mm/s ~ 30mm/s and also recalibrated the step/unit but problem still the same. I tried tweet around other speed, out layer from 60mm/s to 40mm/s still same. I re-level the bed. I don’t have another set of hot end, can swap to confirm.
The twisted vase I probably consider very happy with my first build.
Any suggestion and pointer is welcome.

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PLA 1.75MM

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Check for temperature fluctuations. It’s possible the temp drops and makes the PLA jam a bit then it clears up once it gets back to temp. I would recommend PID tuning and seeing if that helps. http://reprap.org/wiki/PID_Tuning

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Thanks Mark, I did use PID (I will re-tune it once again later) and the temperature did fluctuate slightly between 5 to 10C, I tried compensate it by setting it higher to 210C. At manual extrusion, in fact 195C is good enough, it run smooth. I suspect jam inside the hot end (no spare unit) or impurity of filament. I did try white color filament, same result intermittent.

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That’s a lot of fluctuation. Usually poeple get no more than 1-2C of temperature variation. Although you can extrude by hand at 195, the pressure still does increase, especially if you are printing quickly and the filament doesn’t have enough time to heat up before being extruded. Your other theories are possible, although I’m not sure a jam would fix itself.

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Your auto bed leveling maybe, check for backlash in your Z

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Try close the screws of the belt poly on the motor shaft , in the axes x, y

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Thanks guys, I will re-tune the temperature and also check the Z backlash, and see what happen. I don’t suspect X or Y. In fact i have some plays or looseness in X axis (drive sleeve), the plays causes the whole printing shift in certain layer and continue and it will repeat itself at some point but not causing this insufficient extrusion. My X axis and Z axis is lead screw drive while Y axis is rack drive, I don’t used belt at all.

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The rack can also cause backlash if not adjusted correctly. Is it a printed rack and gear? With a leadscrew on z it should be better but self leveling gave me endless trouble with print quality. If anything sticks or is loose you see it in the print. Eg if the leadscew backlash mighy not be the problem but if there is any delay in the bed moving up or down you will see it. I built a smart rap with self leveing and redid it so i could level the bed manually.

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Hi Mike, is a metal rack and gear pair(japan manufacture, pretty accurate and stable), good idea to off the auto bed and check, tks.

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You can also oil up the gear that the extruder moves on, I had the same problem but after that it works great on my Zmorph

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You can also oil up the gear that the extruder moves on, I had the same problem but after that it works great on my Zmorph

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Hi Guys, I disable the autobed and it was printing good even before I re-level, re-level the bed and print again, the problem went away. I guess the Z is not responding fast enough with X/Y movement or either Z is having backlash. Thanks Mike for your advise. If it is Z (current XYZ setting of feedrate 50, 200, 4 and max acceleration 5000, 5000, 50) unable to response fast enough, any suggestion value to start with?

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Start at the beginning. First, confirm the voltage on the potentiometer for the extruder motor. references on internet indicate 0.40v for current limit to keep motor from getting too hot. But I provide active cooling to extruder (you can also put heat sink fins on the motor) and with a Bowden tube on my Kossel, I need more power to push the filament. So I have the voltage set higher at about .55v now with active cooling.
For direct drive extruder you should figure out the voltage best for you.

Second, the force of the bearing on the filament pushing into the drive gear/hob bolt can make a difference. Trial and error finding the right force on the filament.

third, temperature is the most important key variable to make sure the hot end does not jam/clog and that the layers do not delaminate. Too hot and the temperature gradient inside the hot end increases and more and more filament is at glass temperature and expands leading to jam/clog. Too low a temperature and the print will delaminate. Also, different filament has different production processes and results in different optimum temperatures.

PLA likes cool and ABS likes hot. Print PLA at as low a temperature as possible. I tested black BuMat at 175 and it delaminated. tested at 195 and it jam/clog my E3Dv5 hot end. ideal temp of about 180-185, with just the right force from the bowden extruder motor, after adjusting the potentiometer voltage to get more force.