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Optimal Heat Break Length

Discussion in 'General Questions' started by Lance Weston, Nov 21, 2022.

  1. Lance Weston

    Lance Weston Active Member

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    In the past I have had some brands of plastic that always seem to clog the print head at some point during the print. I have avoided those and have not had problems until recently. I use the E3D J6 short wade printheads. These are all dirt cheap and come from China, but the quality control of all the parts ( throats, heatsink and nozzle) are terrible. I got the same failure to complete with clog on a brand of filament I use a lot of. I replaced the print head and the problem was gone, so I decided to examine both printheads. What I found was the bad printhead had a too long throat and the Heat break was at least 50% longer than normal. The working printhead had a Heat Break that was about half as long.

    I am now in the process of making print heads with very short Heat Breaks to see if there is a minimum/optimal length. Wish I had saved the troublesome rolls.

    Does anyone already know the answer?
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

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    It depends on the design ad is (oddly enough) one of the most critical parts of the hotend to get correct.
    Even more so if the hotend is a smaller, all-metal unit. You can buy the official heat break for the E3D from either E3D or a vender like @PrintedSolid, that may sort it for you.
     
  3. Lance Weston

    Lance Weston Active Member

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    I can set the heat break to whatever I like. It does not follow that the heat break from E3D is the optimal for all filaments. The heat break was working fine for PETG but going to PLA+ required a shorter heat break.

    That being said, I have fooled myself so many times with assumptions that the change I observed is the change that mattered.

    I fooled myself. After changing the heat gap in stages from large to small I had no improvement. I then went to no cooling and not retraction and still would not complete. I then realized that I had forgotten to put an oiler on the filament. In my case a piece of gun cleaning linen dampened with canola oil, wrapped around the filament and held in place with a folder clip.

    I removed the print arm and put a 1.8mm rod down the hole and found it did insert as smoothly as I would like. I coated the rod with canola oil and rand it up and down the hole until it moved smoothly.

    Problem solved and printing nicely.
     
    #3 Lance Weston, Nov 22, 2022
    Last edited: Nov 27, 2022

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