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  1. #1
    3D Printer Noob
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    Apr 2019
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    Problem reaching higher temperatures

    Good evening people,
    I'm new to the group, but have been 3d printing Commercially for several years with 4 FlashForge Dreamers, A nova-Pro 600x300, & a couple of Biqu Delta printers.
    I have just bought 4 customer returned CR10 300x300 machines, & I have to say, I'm very impressed with the print quality & speed.
    One of these arrived beaten & damaged, so I will expand it to 420x420 eventually.

    I have a couple of issues to share, & maybe some one here has the answers ?
    I'm wanting to print PETg, & need 250'C at the Nozzle & 85'C at the bed....
    The machine struggles to hit temperature at the nozzle... any one else have this issue. ?
    I know this is HOT for PETg, but this particular material brand seems to need the extra heat when using my other machines too..

    Printing PLA at 215 / 65 'C is not a problem though.
    I have made the board upgrade with the capacitor & this stabilized the temperature fluctuations nicely, but I still struggle getting the nozzle to 250 when also wanting the heat-bed at 85'C....

    Is the power supply just struggling ??
    maybe need a higher power heating element ??
    insulate the under side of the heat bed ??

    any suggestions welcomed.
    Grant B

  2. #2
    Super Moderator
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    Welcome to the forum, Grant.

    Not a CR10 owner but I think you're on the right track. That is a lot of power being drawn.
    You have sufficient experience to know you've weeded out the obvious likely suspects in your post.
    What I'd like to query is your ability around electronics (low level), wiring and basic measurement tools...

    I can only point you to a few references I've gleaned in my YouTube perusal over time...
    Something about yellow heated bed connectors being wrongly substituted with lesser quality... if I am not mistaken, that was a PRUSA problem but could have been CR10. These connectors would begin to show burning-brown spots due to excess resistance in the contacts. Easy one to confirm if they are present.
    Second is to qualify the power supply as providing enough oomph to drive the system. Is this a DC (24v?) heater under the bed or 120/240?
    This counts only if the power supply voltage and current has to be shared with both the hot end and the bed...
    You will want to monitor the DC supply as you crank up the power. These power supplies regulate the voltage to 12VDC or 24VDC as long as the current requirement is available. Basically, V*A=W - volts times amps equals watts. The system requires enough available watts to do as you ask it to do.
    I am not going to suggest a current meter to determine this as that is not always simply, but what you can try with a volt meter is to know if the power supply remains in regulation. This means that no matter what you throw at it, it always outputs your required voltage. If you see a dip in this voltage as you crank up the bed temp, then you know you've lost regulation... and the system typically tries to pull more current to make up the difference to equal the required watts (less volts more amps equals equivalent watts). Of course it is not quite that simple but it is an easy way to explain it and for the most part, it is true.

    However, I am surprised that PETG requires that much bed temperature as it is known not to curl as much... or at least, it is a very forgiving material.
    Not that this matters... 250*C at the hot-end is perfectly normal for PETG. I've been successful up to 260*C.

    Part of the calculation on the bed-side of the equation is ambient. You want to raise the bed to 85*C which is ...say 65*C above ambient (68 degree room). If the room is 75*F, then the power supply works a little less hard. and for the area we're talking, that may be significant. Haven't run the number to know... basically watts per degree C required to to heat the bed over ambient.

    If the power supply is marginal and you find that the output voltage is no longer regulating to it's nominal voltage, then an upgraded power supply may be called for... or there is impedance in the line at some connector or frayed wire. Impedance simply means resistance where heat is generated and electrons are converted to heat.

    I'll let you ponder this and in no way am I trying to undermine your knowledge or expertise. I am only trying to cover as many basis as I can so the story is complete.

  3. #3
    Administrator bolsoncerrado's Avatar
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    Nov 2014
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    Perhaps something like this helps?
    https://www.reprap.me/power-expander.html

  4. #4
    3D Printer Noob
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    Good afternoon Gents from the UK - and MANY thanks TommyDee for such a great response.
    There issue is strange.... and similar to one I had on all 4 of my FlashForge Dreamers.

    These & the CR10 get 99% the way to the desired temp, then never quite reach it...., I'm thinking the power supply is just about up to the job, because if im trying to reach 250'C & the machine won't quite get there, I can turn up the temp to 260 & it will immediately get to about 253....
    The solution for the Flash Forges was to insulate the hot blocks with multiple layers of insulation material. I have already done the same to the CR10..

    The thought i had was that the power to the hot end is reduced as the temp gets there so as not to over-shoot the temperature.... but does not quite get there..
    Baffling indeed.

  5. #5
    Super Moderator
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    ...or dial it to 249*C Power supplies are fairly cheap. The 99% thing is a different. It probably get to a point to trigger completion but the processor is waiting for a different trigger from a different sensor. There just isn't enough headroom between the two. So offsetting by 1 or 2 degrees may compensate for this "perfect storm".

  6. #6
    3D Printer Noob
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    Hi Tommy,
    the prob with setting a 2 degree compensation is that this becomes the temp the machine wants, so until it reaches the higher temperature threshold for 15 seconds, it wont begin the print !!

    I'm thinking it is a software issue whereby the power dribbles off near the desired temperature, so the temperature doesn't overshoot & becomes more stable.

    I will find out what the wattage of the heater cartridge is & maybe fit one 10 watts more powerfull.

  7. #7
    Super Moderator
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    Yea, I've become use to designing for my particular printer... bad way to deal with things.

 

 

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