Heater Block Tightness

Discussion in 'E3D-v6 and Lite6' started by Aienan, Apr 14, 2014.

  1. Aienan

    Aienan Member

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    Installing on a Robo 3D, no issues until I realized I'd installed the fan on the wrong side of the heatsink. As I slid it off I bumped the heater block and it twisted a little bit.

    I have not heated it up to do the required torquing.

    My understanding is that I want the brass nozzle to seal against the stainless steel rod inside the heating block. I don't think this would not require the block to be torqued in against the SS rod (which is supposed to be level with the top of the block) in order to make the seal.

    However, I'm concerned by the fact that the heating block can swivel a bit currently. Am I on the right track or should I adjust my threading of the pieces?
     
  2. Eaglezsoar

    Eaglezsoar Administrator

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    You need to get the pdf that shows the assembly process and follow it. If not done as per the instructions you can have filament
    leaking out and other problems. The heater block should not swivel as yours does, please set it up per the instructions as soon as
    possible.
     
  3. Aienan

    Aienan Member

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    I think I'm missing something in the instructions.

    The stainless-steel heat-break is installed until it is flush with the top of the block. The brass nozzle is inserted from the bottom and it should tighten up against the heat-break inside the heat block, with a gap between the brass and the block.

    The heat sink is then screwed on over the heat-break, but goes finger tight.

    Where is the mechanical piece that will keep the heater block from swiveling? The brass nozzle and the heat-break should be meeting in the threaded hole in the heat block. You hold the heat block steady to allow for the nozzle to be tightened down. There is no mechanical mention of how the heat block's movement is put in check, as it rotates around what is in practice(you hope), a continuous threaded piece through it.

    TL;DR: Why should it not swivel? The heat-block is a glorified nut on a threaded rod with nothing to prevent it moving.
     
  4. lukan

    lukan Member

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    TL;DR; Then you will destroy, well mess it up badly, your hotend. Please do take the time to read the instructions...

    With that said, you *don't* want the heater block to swivel, or any part that attaches to the heat sink fins, as it will allow filament to leak. The reason it won't swivel, if you assemble it correctly, is that all of the metal has formed a friction seal with each piece. This means there are no gaps in between say the nozzle and the heat-break for example. No gap means no path for the liquid filament to go but through the nozzle. This also means cleaner prints.
     
  5. Aienan

    Aienan Member

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    I think I wrote poorly which resulted in my tone being misunderstood. I agree, I don't think it should move either. I am genuinely asking what mechanical force(s) keep the block from moving before the final tightening.

    I erred in an earlier post, I was thinking of the nozzle + heat-break as a solid threaded rod and forgot that you can tighten them against each other using the heater block as the nut which will cause resistance to the block moving. However, the instructions say not to apply torque beyond finger tight until the very end, so the question is, do I worry about it moving before final tightening (Step 14). If so, then I can torque it up, easy fix. I greatly appreciate the patience and knowledge shown here.

    Let's go through all the entries that talk about the mechanical interaction between the heat-break, the heat-sink, the block, and the nozzle and see what I'm missing.

    Step 1. Screw the short end of the stainless-steel heat-break into the heater block until the start of the constriction is flush with the top of the heater-block.
    Screw the heat-break in until it's flush.

    Step 2. Screw the nozzle into the heater block until it butts up against the heat-break inside the block, just finger tight is fine for now. The hexagonal flat por-tion should not touch the block, there should be a tiny gap between the flat area and the block – the nozzle should tighten up against the end of the break inside the block to form a seal. It should not tighten up against the block.
    Finger tight between the nozzle and heat-break.

    Step 10. Screw the heatsink onto the long end of the heat-break, firmly finger tight is fine, using a spanner and over-torquing will snap the thermal break at the constriction.
    Firmly finger tight. We should now have a little bit (but not much) of pressure between the nozzle and the heat-break.

    Should this be enough to keep the block from moving before step 14? This is what I am unclear on.

    Step 14. Final step - DO NOT SKIP THIS STEP – using your elec-tronics/software heat the now complete hotend up to 290C, then once up to tem-perature you need to do a final tightening of the nozzle against the heatbreak to form a good seal that prevents any plastic leak-ing. Use an adjustable span-ner on the heater-block and another spanner or pliers to tighten the nozzle up.
    The amount of torque needed is very low, using a spanner you can apply all the need-ed torque with a single finger.


    This seems to be where the tension that keeps the block from moving comes from once the parts have been tightened (the thermal expansion helping to provide the required seal).
     
  6. Chavaquiah

    Chavaquiah Active Member

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    Eppur non si muove (pun intended).

    I suppose that's because the set heat-break plus nozzle does not behave as a continuous threaded rod. With two parts pressed together very tight, I imagine their threads exert some pressure against the heat block's threads, creating enough friction to prevent unwanted movement. Something like a star washer between a bolt's head and a regular washer.
     
  7. Aienan

    Aienan Member

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    Update: Took much of it apart, and I torqued everything down a bit more, looks like as I twisted it into the machine the first time I allowed the heat sink to spin back a half turn or so which loosened everything up but still looked like it was torqued.

    Thanks for the help!
     
  8. Eaglezsoar

    Eaglezsoar Administrator

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    Chavaquiah's response was spot on. Glad you got it working okay.
     
  9. lukan

    lukan Member

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    I am guilty of poor wording as well Aienan. I too am glad that you have the HotEnd working!

    :)
     
  10. Aienan

    Aienan Member

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    An update (For future people who are looking at a similar problem):

    I heated up the hotend in stages yesterday (190C then 220, 250, 265, 290), and two things occurred:
    1. At 190C ish, the nozzle began to unthread itself based on gravity alone, which meant the whole block could move. Pliers and a quick turn of a socket and everything tightened up again. Watch for this.

    2. Once I tightened it at 290, I noticed that the cartridge heater was loose. My first guess was that I had not tightened the set screw enough, but once it cooled down it was tight again.

    I reused the original heater (it was already wired in so nicely) as it looked to be the same size when I held them to each other. I don't think it was moving at 190C which is around PLA, but I think there could be movement in the 220 ABS realm. I should have taken calipers to it and checked it before install. I will do that tonight and see if there is a difference (and update here accordingly).
     
  11. Aienan

    Aienan Member

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    Reply to myself!
    The difference in size of the heaters is about .15mm (The original being smaller), which is probably where the movement came from. So, if you are planning on reusing the same heater, check the size first.

    I've been printing PLA at 215C starting, and nothing has moved around, but I suspect I will have to change it out or adjust my set screw a little for significantly higher temps.
     
  12. Eaglezsoar

    Eaglezsoar Administrator

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    A minor adjustment to the set screw may be necessary. That was a nice write up you did and it sure sounds like you have
    learned a lot on how to install the E3D. Good job and good writeup for people to read with similar problems.
     

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