# E-steps somehow reset, how could it have happened

## Background

After installing a direct drive extruder (E3D Hemera) to my CR-10S, I calibrated the E-steps so that adequate extrusion would happen; going from ~95 steps/mm to ~390 steps/mm.

I had a couple of days of mostly successful prints. Some under extrusion (or no extrusion) happened here and there, solved by calibrating Vref for my extruder (from 455 mA to ~800 mA). I was then able to print a thing or two.

Then, after a couple of days, I had major under extrusion problems. (To the point that it looked like only the infill was being mostly printed despite using the same slice settings on past successful prints.) I looked up under extrusion causes (temp, bed level, speeds, idler tension, etc) and nothing seemed to apply, except for idler tension, which I cranked up.

Despite being certain that I didn't do anything to reset my step settings (namely resetting EEPROM) I decided that I might as well check to see what my steps are set to. Lo and behold, my steps were back down to 95. No wonder I was under extruding, I was only pushing a quarter of plastic out! Sending an M92 I was able to get the E-steps back to where they belong. Benchy came out with some droopy layers, so I was over extruding. I tweaked the idler tension (since I cranked it tight earlier) and for the most part that seemed to help. I came to have other issues (like a potential clogged nozzle) so I'm not sure how much calibration is needed as plastic isn't feeding, but I digress...

What could have happened to cause my e-steps to reset? The obvious being resetting the EEPROM, which I am most sure I didn't do. Is there anything else that could have happened?

## My setup

Printer: Creality CR-10S

Firmware: TH3D Unified Firmware U1.R2.22 (or one/two versions before it maybe) (firmware is Marlin based)

Extra: OctoPi (Unsure of version, possibly most recent stable release) Other than starting prints, only used to set E steps and G0 commands before problem showed up.

As for future prevention of resetting to 95 steps/mm, I realize I just need to re-flash the firmware setting the E-steps to 390 or something.

• Did you use M500?? – Trish Jan 15 '20 at 15:06
• Yes, a new firmware would be the easiest solution. Marlin does have a CRC checksum for EEPROM contents, though that should first result in a hint to use "M502" and "M500". If you did not "M500" after setting the steps the first time, and did not power down the printer since, that could also cause that. Note that TH3D is based on an obsolete version of Marlin. If you're going to reflash, I'd recommend using Marlin 2.0 – towe Jan 15 '20 at 15:12
• I don't think that I used M500. Though I definitely saved settings to EEPROM through the printer after confirming M92 changed settings yesterday. I think I did the same the first time I used M92, but cannot confirm. – Lux Claridge Jan 15 '20 at 15:18
• I didn't realize that TH3D is basically obsolete. Thanks for the tip! – Lux Claridge Jan 15 '20 at 15:19