Lubricating Kraken Heat Breaks

Discussion in 'Multi-Extrusion' started by Eaglezsoar, Mar 17, 2014.

  1. Eaglezsoar

    Eaglezsoar Administrator

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    I have read several reports that users have experienced seizure of the extruders to the Kraken body.
    What is the opinion of using a thin coating of high temp grease to prevent such seizures?
     
  2. kilodoublemike

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    Re: Lubrication on the Kraken

    So i received my Kraken yesterday and while assembling it i had the exact same thought. I applied a little High Temp anti seize. I've found that it actually (at least in my case) made it much harder due to the high precision in the milling. There isnt enough room to get any ammount of anti-seize in there and whatever DID get in there just made the joint tighter and thus harder to adjust. Having said that, i continued to use the grease on all of the grub screws to prevent seizure in all of those spots.
     
  3. Eaglezsoar

    Eaglezsoar Administrator

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    Re: Lubrication on the Kraken

    Interesting that the tolerance is that close. Perhaps Josh or Sanjay could offer up an opinion on how to prevent a possible
    seizure. I don't believe that a seizure is all that common but it has happened.
     
  4. Josh

    Josh Administrator
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    So..

    The Kraken Heat Breaks are machined to be 0.05mm smaller than the hole in the Cooler Block. Engineering drawings can be found on our documentation page if anyone is interested: http://e3d-online.com/Documentation#Kraken

    There are a number of reasons, but mainly:
    • The location of each nozzle in X & Y is known very accurately
    • There is great thermal conductivity to keep the break cool

    The disadvantage of this is that any surface scaring can result in the heat break being quite hard to remove. If this does happen to anyone, the technique is to press it out from the top. We used a pillar drill and an appropriately sized drill bit which worked just fine.

    Due to the factors outlined above, grease will not solve the problem - and will actually just be scraped off the surface as you push the heat break in.

    The recommended procedure is to put something in ahead of the grub screws that will stop them from spoiling the surface of the heat breaks. We just used some thin card (~150gsm). This padding will allow you to tighten up your grub screws, although still don't go tighter than necessary.


    For the next batch of Krakens (currently on order! :D ) we are going to increase the clearance to 0.1mm and supply with more appropriate grub screws. In hindsight supplying knurled-tip grub screws designed to tighten up against precision ground stainless was an oversight.. :?

    The problem is mentioned in our release video: https://www.youtube.com/watch?v=wEw4UDUUbIE
     
  5. Eaglezsoar

    Eaglezsoar Administrator

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    Thank you Josh for such an in depth reply.
     
  6. enggmaug

    enggmaug Member

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    Yep, I experienced that just yesterday.

    As I am installing heating cartridges and thermistors, I put the heat breaks in the main bloc. It was already hard to move them in their hole before tightening the screws, but now that I tightened them, I had a hard time removing them, as 2 were totally stuck in place.

    I finally managed pushing them out from the top, but I am now thinking I should scrub everything with triple zero steal wool.

    What do you guys reckon ?

    The heat breaks not moving freely, I am not sure I could adjust the nozzle height as easily as I thought it would be when I first saw introduction video of the Kraken.
    Anyway, I'm sure I'll managae to tame the beast in the end.
     
  7. Eaglezsoar

    Eaglezsoar Administrator

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    I am not an expert on the Kraken but if yours is that tight making it difficult to adjust, I cannot see how a using some fine steel
    wool would harm anything. My biggest concern with that method is making sure that no particles of steel remain from the wool.
    Good luck with your Kraken.
     
  8. enggmaug

    enggmaug Member

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    anyway, some particles remain from inserting/removing the heat break... I know, I cleaned the bloc with coton bud...

    But anyway, I'll run everything under water tap and dry thorougly after using the steel wool.
     
  9. enggmaug

    enggmaug Member

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    I have a problem here.

    I used steel wool, but apprently it was not enough. one of my heat break was stuck there.

    I tried to turn it using a bolt nut, while pushing from the top to take it out... and the heat break broke.

    I wanna change it, but it's not available on the website.
    Do you guys have an idea of what can I do? I don't even know how to take it out, now... maybe with a hammer... but I'm not really keen on using that kind of tool ...
     
  10. Josh

    Josh Administrator
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    OK, first thing to do is put the hammer down! :p

    We are expecting heat-breaks to come back into stock in the next 2 weeks. I will message you when they are back in stock.

    The technique for removing jammed heat-breaks is to use a pillar-drill as a press. Use a 5mm drill bit (<=5mm & >4mm) and it should easily press out. (Remove the plastic collet first.)





    Once you do get it out, you may want to smooth the surface using some emery paper.

    Let us know how you get on!
     

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  11. enggmaug

    enggmaug Member

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    Thanks for the tip.

    Well, I did not use neither a drill press nor a drill bit, but I have a 5mm rod here, that fits just fine. to push on the heat break.

    I did remove the plastic thingy, and only tried to push by hand. and it did not come.

    I will try the drill press tonight and let you know.
     
  12. enggmaug

    enggmaug Member

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    Ok, it came out.... but it was not all so smooth and easy.

    Do you guys think I could exchange my block, 'cause I really believe it's too tight. I don't wanna break all my heat breaks.
     
  13. enggmaug

    enggmaug Member

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    I finally took my 3 remaining heat breaks, one after the other, and set them up on my dremel in order to evenly reduce their diameter on 1000 grade emery paper.

    Now, they go in and out freely, smoothly, and without any play that you could feel by hand.

    So, I can proceed with my installation... and my protect the screws' tip in order to avoid damaging the heat breaks..
     

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