Hi,
I’m hoping you guys can give me a sequence to use to trouble-shoot my extruder issue. I’ll do a “to the point” list of the issue, and then give the long-winded version in the hopes that I don’t omit a clue and give bored people something to read.
I have an acrylic frame i3 clone.
It has a direct drive extruder.
It has an e3d V5 hotend.
Ramps board.
Marlin Firmware (more info way down)
I run it at slower speeds - 35mm/s at most.
I have had it running since August last year.
My esteps/mm were calibrated from the default 160 supplied with the machine (this 160 coincides with what the calculaters gave me) to 164 - Many hours of noob printing like this and everything has thundered along very well.
It now under-extrudes badly, randomly.
After a fail if I check e-step calibration, it is incorrect.
The calibration is always short of supplying the 100mm of filament by a rather large amount (think 50%ish).
After re-calibrating, the print starts well but I get the problem again mid print.
If I re-calibrate immediately I will get another large discreprency.
The amount it is out by is not consistent. ie. each calibration is not always under extruded by say 50%. it might be 60, might be 40 - seems random.
Test cube dimensions are always within 0.5mm of 20mm so It appears to only be an issue on the extruder side of things.
Things I’ve tried…
Stripped/cleaned hot-end.
Swopped drivers around on the Ramps. (perhaps I try swop again?)
Checked tension on the filament - seems good.
Checked Marlin version.
Updated Marlin (see below)
I will check the physical seating of all the power connectors etc. tonight.
Any wise words for me?
Long version… get coffee…
I had my first weird under-extrusion that happened mid print.
I heard my stepper doing the thunk thunk thing and after cleaning everything and stripping the hot-end etc. it turned out that the spool was pushed against the wall. Felt stupid and carried on.
Two days later my first roll of PETG arrived and I tried to print a temp tower. I had all sorts of issues trying to get it to stick/get smooth lines and found that at 255 deg (250 max according to the spool) I could print.
First test cube had slighlty thick, round corners.
Checked e-step calibration and had to move it up to 184. I thought it was a bit odd but figured it might be the new material being more sticky or something.
Cube two was actually something I was proud of. Printed really nicely.
Start printing my first “real sized” prints.
Print one comes out well.
Print two stalls half way giving a Thermal runaway message. I think this might have been an anomaly as it was running at night and a thunder storm came over. We had a bad surge when it happened. Power off, will re-start in the morning.
Repeat print two in the morning - No issues and I’m very happy.
Print three looks amazing but at about 20% completion (maybe 3 hours in) it just under-extrudes like a beast. I killed the printer, left it off for a few hours and tried again. It flopped immediately.
thanks for still reading… 
So I start looking at the estep calibration again. Completely out. but by a huge margin - maybe 50%. I run the bog standard A4988 drivers. They all sit at 800mA so i figured I would try swop them over. I still seem to have the problem.
I discovered that I had Marlin 1.0.0 loaded so I put Marlin 1.1.0 (the one that was officially released a few days ago) on. Same issue. Last night I re-calibrated the e-steps and I was 50% out. So i re-loaded the firmware, restored the failsafe and calibrated. My new value e-step value was 315. Applied this value. Re-test calibration. It’s perfect - exactly 100mm extruded.
Print test block. Starts perfectly, infill goes wonky very quickly and under-extrudes top layers. Re-check calibration and I’m back down at about 40% of the requested travel. So I would now need a value of about 475 which just seems crazy.
any ideas of how what/how to get it figured out would be great.
