Strange hot end behaviour



  • When testing PC-Max filament, the hot end needs to be between 250 and 275C
    I tried 250C and that worked fine. That was last night.

    Today, simply switched on the machine and it would not go above 200C. Error msg that the temp was rising too slowly.
    Nothing had changed since I switched off last night. Came in this morning and switched it on again.
    It would not go higher. Rebooted. Same story.

    OK, so, time to tune the heater, had not done that yet for the hot end.
    Used the P1 S250 parameters (BTW, is there a max limit? I can enter S260, but not S270. Invalid parameter)

    It ran successfully. But now the heater would not go above 220C. It simply maxed out.
    So I ran it again, with S260 and it failed, as it got too hot.
    Ran it at S250 gaian, failed as well again too hot.
    Now I manually edited the Gain M307 parameters to M307 H1 A220 C70.3 D6.3 B0 S1
    Only thing I changed was the Gain: A181 to A220.

    Now it heats up to 250C again, but a little slower than it used to.

    So, I have 2 questions resulting from this.
    1. Why did it start messing about this morning? (what could be the underlying causes)
    2. What are good starting parameters to do the temp tuning? (I am using an E3D hot end.)



  • 12 volt system or 24 volt? Is it an E3D heater if so what wattage ? Did you ensure all your connections are tight, etc ? Sounds to me like you either have a power supply issue or bad connections which limit the current and cap your max temp. You can check your power supply voltages (after trying to heat) using M122 in the G-Code Console. This will give you min, max and current voltages in the list of details.

    Jeff



  • Lykle the reason you got invalid parameter is that the default Max temp for the Hotend in the FW is 262 degrees (You can change that in the Config.g file is you wish with the M143 command



  • Lykle,

    I have a theory (but it's unproven) that cartridge heaters "age" when you start pushing them to higher temperatures. I have one that used to do some testing on heat sink compound and which I pushed up to 400 deg C hot end temperature (yes I know it was extreme but had to be done in this case). Ever since then, that cartridge behaves completely different to any others (I have 10 of the things laying around). It still works but needs completely different PID settings to any others (and takes takes longer to reach the desired temperature). Maybe you had something similar happen and that was what you were seeing from one day to the next? Just a thought.
    Ian



  • @deckingman:

    Lykle,

    I have a theory (but it's unproven) that cartridge heaters "age" when you start pushing them to higher temperatures. I have one that used to do some testing on heat sink compound and which I pushed up to 400 deg C hot end temperature (yes I know it was extreme but had to be done in this case). Ever since then, that cartridge behaves completely different to any others (I have 10 of the things laying around). It still works but needs completely different PID settings to any others (and takes takes longer to reach the desired temperature). Maybe you had something similar happen and that was what you were seeing from one day to the next? Just a thought.
    Ian

    that makes total sense,because the compound the wires are packed into may have micro fissures form after a while due to different rates of expansion and contraction, allowing in air that causes oxidation and degradation of the wire.



  • @deckingman:

    Lykle,

    I have a theory (but it's unproven) that cartridge heaters "age" when you start pushing them to higher temperatures. I have one that used to do some testing on heat sink compound and which I pushed up to 400 deg C hot end temperature (yes I know it was extreme but had to be done in this case). Ever since then, that cartridge behaves completely different to any others (I have 10 of the things laying around). It still works but needs completely different PID settings to any others (and takes takes longer to reach the desired temperature). Maybe you had something similar happen and that was what you were seeing from one day to the next? Just a thought.
    Ian

    A resistance measurement between a good cartridge and an "aged" cartridge would go a long way to prove your theory. Short of some super thermal insulator forming inside the cartridge if the resistance stays the same it should work more or less the same, air gaps aside. Funny I found E3D's 30w heater to be 30 watts. I found some no name heaters I got off amazon which look good to instead of 40w be around 47w. Talk about too much heat.

    Jeff


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