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better hobbed bolt

Discussion in 'Mods and Upgrades' started by CAMBO3D, Jul 6, 2013.

  1. Thamer Albahiti

    Thamer Albahiti Active Member

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    i'd like to repeat Fabrice's question, are the new Robo 3D printers going to have a grooved bolt ? or did you guys buy extra and wanna get rid of them? :)
     
  2. splk3

    splk3 New Member

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  3. tesseract

    tesseract Moderator
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    I do not know of anyone who bought extra I am not sure if the hobbed bolts will be part of the upgrades or not but as splk3 just found again that is the exact bolt got from the same person/store on ebay and the same price US$6.25 which I still thinks is a good deal if you are so inclined there are actually youtube vids on how to make one yourself very similar to the one on Ebay
     
  4. splk3

    splk3 New Member

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    When I get my printer, I will try to keep track of all of the mods I make while learning (this is my first printer), and if it makes sense, I can put together kits so people can get common parts more easily. I'm brand new to this, but I am trying to be an evangelist where I live for this type of disruptive technology, so hopefully more people will be jumping on board and needing help getting started.

    Thanks everybody on the forums for helping us new guys get organized while we wait for our printers!
     
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  5. tesseract

    tesseract Moderator
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    well there will be plenty of mods to go around the one problem I see is that some work and then become obsolete due to changes it will be tough but I wish you luck have any idea when you may be getting yours
     
  6. splk3

    splk3 New Member

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    I just ordered. They are currently saying 8-12 weeks, but unless they really catch up soon, I'm thinking more like 16-20 weeks. I'll be pleased if I get it by February sometime, and completely surprised if by Christmas.
     
  7. Matthias

    Matthias Member

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  8. splk3

    splk3 New Member

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    Might end up making another one after all - I got mine from ebay, and it looks good, but not sure if the "guide" is deep enough to really benefit.
     
  9. tesseract

    tesseract Moderator
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    send a pic I got mine from the same place you did I believe and it has worked just fine
     
  10. Matthias

    Matthias Member

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    [​IMG]

    As I was lacking a 8x50 screw, I added 5mm nuts to the spring screws to increase the pressure on the filament that's pushed against the hobbed bolt.
    Works perfectly, no more friction.
     
  11. CAMBO3D

    CAMBO3D New Member

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    ??????? something isn't right with yours, You should not have to compress your springs that much. If your using the correct springs they should do the job. It looks like you have it tightened all the way down so your springs aren't doing anything for you. Matter of fact theres no need to have the springs in there if you tightened it down to to point of crushing them because at this point its not the springs that is keeping the tension on the filament its just the bolt and nuts.

    to much tension here is acutally a bad thing. you should only have enough tension that a light pinch with your fingers will not stop the filament from feeding.

    If you have deep grooves in your filament your spring tension is too tight. In post Number 2 at the beginning of this thread theres is a picture of my extruder with the new hobb and example showing how much my springs are compressed.
     
  12. Matthias

    Matthias Member

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    To get a constant stream of filament, I always hat to be around for the whole print and push it into the extruder, maybe related to my make of filament. As I didn't have a bolt that I could use, I did this as a workaround, and it works perfectly. I admit that I could probably try and remove one nut to give it some more space.
    Though, frankly, I don't see much use of giving it much more. The filament is supposed to be transported in there, no matter what...
     
  13. CAMBO3D

    CAMBO3D New Member

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    highlighted in red above, its possible your filament is slipping on the stock robo hobb (not to mention other possibilities) (assuming you have the stock hobb) Which is why I replaced mine and why this thread is here. The stock hobb allows the filament to walk off the hobb, to where the filament is no longer on the hobb. Which in turn allows to filament to slip becuase the filament is now on the smooth part of the hobbed bolt. (as shown in my posts).

    yes its supposed to be transported in there no matter what but there is a correct way and a wrong way.
    The filament is supposed to be transported in the teeth of the hobb. There's more to it then just tightening and hoping that friction will push it through. Even if you tighten it more and the filament is not on the teeth of the hobb. You will eventually start slipping again.

    (other problems could be that you haven't calibrated your hotend temperatures. 230c in repetier doesn't mean 230c at the hotend)
     
  14. Deadly Z Driver

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    How would you go about calibrating the hot end?
     
  15. tesseract

    tesseract Moderator
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    there is no real calibrating the hot end other than to know the difference between what repetier shows versus what it really is. So if you know via some type of measurement (contact probe etc) that the nozzle temp is 218C and repetier show it at 210C then you must keep that in mind that if you have to have something print at exactly 215C you need to set your temp to 207C taking into account the positive 8C degree delta you found.

    There is a process to calibrate how fast and even it heats up but I do not think you are talking about that
     
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  16. CAMBO3D

    CAMBO3D New Member

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    In the firmware, thermistor values can be adjusted so your repetier host readings match your actual temperature. Repetier firmware allows you to do this, i'm not sure if marlin firmware allows you to do this.
     
  17. tonycstech

    tonycstech Active Member

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    Where do u get that bolt ? I want one too. I have exact same problem that developed after day of use.
    It slips every complete turn at about 2 or 3 teeth. Shaving off the filament, catching it by the following teeth and continues to extrude untill it makes complete turn again.
    I had to make some crazy tension to compensate. Not sure if its a good idea for the motor or the bearings.
     
  18. tonycstech

    tonycstech Active Member

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  19. Thamer Albahiti

    Thamer Albahiti Active Member

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    the whole idea of replacing your hobbed bolt is to get a grooved one, you get a larger surface for the bolt to drag the filament
    Untitled.jpg
     
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