Extruding problems

Hi guys,

I have a problem that bother me for 2 weeks. I have a bowden extruding system witch is about 50cm long. My bed level is perfectly leveled, and the extruder is at a decent height from the bed. I know this because I did for too many times the paper test. My filament is sliding smoothly trough the teflon tube and I don't have any obstruction on the fiting tubes. I'm using original E3dV6 extruder, so you can't blame the quality. As extruding system I'm using this one [www.google.ro]: but with some modifications: I'm using this type of gear [www.banggood.com] and an 625ZZ bearing. The gear is very clean and it has all the teeths. The spring is tensioned good enough. My extruder steps/mm is correct set. If I want to extrude 100mm, is extruding 100mm. My extruder feedrate in Marlin is set to 25mm/sec, acceleration is 10000 and Ejerk is 5.0 mm/sec.If I want to extrude in the air everything is perfect, my extruder is not skipping steps. But If I want to print, it start to skip randomly. I increase the motor current and I have same issue. I was carefully to not have the extruder too close to the bed. In Cura, Print speed is set to 60mm/sec and my Infill speed is: 45mm/sec (3.6mm^3).

So what could be the problem? When I watch the gear extruding it look like wants to extrude too much even if I lowered the Infill speed from 60 to 45mm/sec in Cura. Because when it's not printing I don't have skipping steps, I think the only problem is on my slicer settings. But even with lower print and infill speeds I have the same issues. And it's visible that the gear is trying to rotate too fast.

If you have 3mm filament make sure cura is set to that diameter in the settings. It defaults to 1.75mm

Ive had this happen to me a few times with software updates.

It will be wonderfull to be like this. Easy problem. But it's not....I have 1.75 filament and Cura settings for 1.75 filament. So....

I'm using cura 15.4.03. I see that for the first and second layer the printing is slower and it does not skip any steps. But after the second layer it starts to print faster and then start to loose steps.

At 50 mm/sec is still skipping. This is a slow speed and is skipping steps. I can't believe it.

Could it be that your stepper driver is getting too hot and activates thermal protection? Have you tried lowering Vref?

Yes, I tried this also.... still don't solve the problem. I'll try with a smaller gear in diameter. I heard that a smaller gear have more power torque. We'll see.....

Did you check the temperature of your hotend while you are printing? Is it constant and is the duty cycle well below 100%?

If the heating cartridge of the hotend is running at its limit, after some time it can't keep up melting the incoming cold filament and the temperature of the hotend starts going down.

Well.... my hotend temperature is surprisingly good. I mean I don't have devitations bigger than 1 degree Celsius and PID calibration was done two times at 240 degrees. If I extrude in the air when it's not printing I don't have any problems. I think a good experiment will be to start print something and the rising up the extruder from bed and ust print in the air. To see if during the air print is still skipping. I don't know what you mean by duty cycle well below 100%. How do I check this?

The duty cycle is the percentage of time the heating is switched on. In Marlin, it is usually a value between 0 for no heating and 127 (or 255) for full heating. In Pronterface (which I use here) I can see this value for both hotend and heated bed in the same line as the current temperatures are listed.

So I made some experiments. I printed the same part at 0.06mm layer high with 60mm/sec print speed and 80mm/sec infill speed and the print was wonderful. Same thing for 0.1 mm high at 60mm/sec print speed and 60mm/sec infill speed. But, when I print at 0.2 mm layer high with 60mm/sec print speed and 60mm/sec infill speed then the extruder start to skip randomly. I posted some pictures with my settings for 0.2mm layer high. If it's not skippig at 0.06 and 0.1mm I'm thinking is not a hardware problem. What should I change? Thank you.

can you allso post the settings for the 0.06 or 0.1 that are printing ok

The other settings are exactly the same. The only settings I change when i print for 0.06 and 0.1 are printing speed and infill speed. Just these two. And I posted them above: ,, I printed the same part at 0.06mm layer height with 60mm/sec print speed and 80mm/sec infill speed and the print was wonderful. Same thing for 0.1 mm height at 60mm/sec print speed and 60mm/sec infill speed"

If its extruding too much. Lower your 'Filament' Flow %. Mines set at 80% which I'm assuming lowers the amount extruded.

Also, was it working perfect before but then started to skip or is this issue from a new setup. If it was working perfect before was there any changes made? Changed Filament?
I've got a crappy printer and got some crappy filament (many) so I've been fighting ext-ruder problems for years Not that I've learned anything useful from it

Edited 1 time(s). Last edit at 03/02/2017 10:09PM by tgit23.

I solved the problem. I replace my extruder gear with a smaller one in diameter so the motor have more torque. And I loose a bit the tension on the spring and now runs perfecly. Thank you for advices guys