Upgrade MK2.5 to MK2.5S  

RE: Upgrade MK2.5 to MK2.5S

what hardened nozzle did you install. you may need 245-250 on PETG with a hardened steel nozzle. steel is that much worse a thermal conductor than brass.  

RE: Upgrade MK2.5 to MK2.5S

I was using 260-265 with a hardened nozzle for PETG on my MK2.5, but I also am using 240 for the brass nozzle.   I switched back to brass for the MMU2.  Easier to setup.  I haven't tried Prusament PETG yet.

David

RE: Upgrade MK2.5 to MK2.5S

There is no way PETG would de-laminate with an extrusion temperature of 230-235 even up to speed of 50 (default PETG PrusaSlicer) with 100% fan.  I'm using given black PETG for MK2.5S upgrade kit and MatterHackers economy PETG and I have melt-blobbing at 240 and have probed to ensure temps.  But I've had something like this happen a while back.

I cracked my thermistor cable when going from MK2S to MK2.5 (currently at MK2.5S).  In my case, I was getting weird chokes and thermal overrun on nozzle (which almost never happens, it is usually the bed) after upgrading to MK2.5.  The wires looked fine but the copper had snapped inside the insulated sheath that is almost impossible to detect on visual inspection.  I found out after I replaced my whole nozzle assembly when the copper simply slipped out of the sleeve from the removed heater block.  Yours could be frayed too, perhaps as a sanity check, test your nozzle temperature with a thermal probe?  While still in pre-heat, take a non-conductive pick and move your wire slightly, check if your temperature reading on your LCD and test nozzle temperature again.  Look for any sudden zeros showing up on LCD when moving the thermistor wire (don't over-do it, the wire is actually very delicate).

Oh and the 9 point calibration.  I believe the MK2.5 and up firmware use slightly different movement specifications, maxed movement speed and acceleration values unless directly specified by the G-code stream.  Likely a common sense quality-of-life update to firmware.