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Solved Losing Temp

Discussion in 'Troubleshooting' started by Gage, Aug 1, 2016.

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  1. Gage

    Gage Member

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    Been printing for several months with my Robo after switching to the E3D V6 hotend, have loved the quality of the prints and playing with different filaments. However, I have run into a real snag now.

    Just the other day I purchased a roll of PETg filament. Printed a few smaller items just fine to get a feel for the filament. Having gotten the settings correct I set out to print something larger. First two layers are fine, then the hot end seems to continually lose temp.

    Printing at 245 by the 4th layer the temp readings are at 235 and then trips the failsafe to stop the print due to temperature of the hotend being too low.
    I replaced the heating element with another 12v 30amp element that I bought (same as the stock) that came with the E3D head.
    I also thought that maybe the thermistor could have been off and there was some plastic that had gotten around the bulb, so I replaced that. All seemed to run fine. Started the print again, and the same issue popped up, at roughly the same point, end of the third/start of the 4th layer.
    Please help!
     
    #1 Gage, Aug 1, 2016
  2. danzca6

    danzca6 Well-Known Member

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    What are you using for a part cooling fan? Is it hitting the nozzle too much and cooling it off? That sometimes has been the issue.
     
    #2 danzca6, Aug 2, 2016
  3. Gage

    Gage Member

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    I'm using the ducted fan holders from thingiverse. I have checked the parts fan to make sure it is not blowing on the nozzle but just below it. I even printed two other objects last night with no trouble. I lowered parts fan speed so maybe it was hitting the nozzle more than it looks. I am also wondering if perhaps the gCode was screwed up with the particular piece I was printing because I noticed it was happening at the EXACT same point in the print every time.
     
    #3 Gage, Aug 2, 2016
  4. danzca6

    danzca6 Well-Known Member

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    That is odd. Is this the first time you have used a filament requiring that kind of temperature? If so, maybe a PID tuning would help. Also, when you switched to the E3D, what type of thermistor are you using? Just making sure you adjusted the firmware accordingly if needed.
     
    #4 danzca6, Aug 2, 2016
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  5. Gage

    Gage Member

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    Yes first time using this filament. I'm going to load some of the PLA I have been using and run a print to see if I can replicate the problem.
    I am using the thermistor that comes with the E3D V6. Firmware has not changed at all.
     
    #5 Gage, Aug 2, 2016
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The stock thermistor is a marlin type 1 (EPCOS), the one E3D provides is a marlin type 5 (Semitec).
    The calibration curves are different so the temperature will read inaccurately.
    It should not come/go/bounce around, but it will not be correct unless you change the firmware.
     
    #6 mark tomlinson, Aug 2, 2016
  7. danzca6

    danzca6 Well-Known Member

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    Well if you are not using a stud thermistor then no firmware change is needed, but if you are using the stock thermistor that comes with the V6 then you needed to change the sensor type to 5 in the configuration file.

    #define TEMP_SENSOR_0 5
     
    #7 danzca6, Aug 2, 2016
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  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Honestly I am not convinced this is part of the issue he is seeing, but either way it is not going to be reading accurately without that change.

    @danzca6 is looking at the right things since this is usually a heater core not able to keep up the temp (due to cooling or the like) or a flaky thermistor problem although, as he also points out yours is a rather odd behavior in any case.
     
    #8 mark tomlinson, Aug 2, 2016
  9. Gage

    Gage Member

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    I have made sure the firmware was correct when I first installed the V6. Mark helped me solve a few firmware problems I was having.
    I read on another thread of someone having a similar issue and switched to a 40amp heater core.
    The thermistor temp stays relatively close to the set temp. It will bounce up and down as it always has but never more than a few degrees unless it starts to drop off and it's as though the heater cannot continue to hold the heat up.
     
    #9 Gage, Aug 2, 2016
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It is possible it is a weak heater core. It happens :(
    If you have a spare you would suggest it is worth the effort to swap it and see.
    Alternatively it could be an issue with the RAMPS not keeping up with the current demand.
    The two big loads on the RAMPS are the two heaters (extruder and bed) and if you are going to loose a part it is likely one of the two MOSFETs that driver those outputs.

    You might want to sanity check that there is nothing silly going one from the software side, but I would consider that unlikely. I assume at the point the temperature drops that the slicer is calling for the correct temperature.
     
    #10 mark tomlinson, Aug 2, 2016
  11. Gage

    Gage Member

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    What steps would I take to check the RAMPS. I have already put in a new 12v 30amp heater.
     
    #11 Gage, Aug 2, 2016
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The easiest way would be to swap in a spare and see if it misbehaves.
    The alternative is much more difficult (and time consuming) since you would need to check that the MOSFET is driving the correct output current... If you have an R1 I would just buy a spare (Amazon has them really cheap) and swap it in. If you have an R1+ it gets more complicated since Robo installed a custom RAMPS board on those. @Geof has a thread dedicated to showing you how to do the wiring change needed to swap an R1+ back to a generic RAMPS -- it is a little more effort (but a lot cheaper).
     
    #12 mark tomlinson, Aug 2, 2016
  13. Gage

    Gage Member

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    I was looking at that thread last night. I have an R1+
     
    #13 Gage, Aug 2, 2016
  14. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If you are up to it here is a thread on how to dig into the MSOFETs and test, the only slight issue is that it discusses the standard RAMPS, but the MOSFETS are the same regardless.

    http://forums.reprap.org/read.php?219,454992,455314
     
    #14 mark tomlinson, Aug 2, 2016
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  15. Gage

    Gage Member

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    Well it won't hurt I guess to check it out. Guess I should look at switching to the standard RAMPS too.
     
    #15 Gage, Aug 2, 2016
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  16. Gage

    Gage Member

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    Well, been home for about an hour now.
    Tested a print that I know worked previously and had the same outcome of it stopping due to temp drop error. While cleaning the nozzle I realized that the problem arose when I added the second fan duct.
    I removed one of the ducts, and ran the same print with 100% success. Temp set at 235 and remained near there, never bouncing more than 2.5 degrees +/- from that point. So I'm going to assume that my issue was that the nozzle was being cooled too much by the parts fans.
    These were the shrouds I have currently https://www.thingiverse.com/thing:1000756
    I like the design, but looking at the blower openings they are rather wide, and angled towards the nozzle in general. I may try to tweak the design to blow more downwards as opposed to straight on. I am open to suggestions of what others have used.
    Also curious if I tuning the PIDs would help with this temp fluctuation?
     
    #16 Gage, Aug 2, 2016
    Last edited: Aug 2, 2016
  17. Geof

    Geof Volunteer Moderator
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    Hi gage, I use the original version but did have to shim (tape works) to angle the dips the down some for my set up :)

    It's been working very well. Have you installed a 40 watt heater?
     
    #17 Geof, Aug 2, 2016
  18. Gage

    Gage Member

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    I have not installed a 40 watt heater. I am using the 30 that I had as a back up from when I first bought the E3D.
    Did installing the 40 watt help? And are you using two ducted fans or a single? Because It works fine with a single, but the additional seems to be cooling the heater too much unless I turn down the fan speed.
     
    #18 Gage, Aug 2, 2016
  19. Geof

    Geof Volunteer Moderator
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    I'm using a robo r1+ e3dv6 dual ducted parts cooling fans (40x10 deep) 40 watt heater.
     
    #19 Geof, Aug 2, 2016
  20. Gage

    Gage Member

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    The original ducted fan parts by MarquisJohnson?
    And what speeds do you run the fans at?
     
    #20 Gage, Aug 2, 2016
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