1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

better hobbed bolt

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

  1. tonycstech

    tonycstech Active Member

    Joined:
    Dec 16, 2013
    Messages:
    587
    Likes Received:
    195
    [​IMG]
    Mine is a combination of both. Its does have a recess but its as wide as the one on the top.

    Perhaps my bolt was badly cut, because it slips every complete turn by 2-3 teeth.
     
  2. Thamer Albahiti

    Thamer Albahiti Active Member

    Joined:
    Feb 20, 2013
    Messages:
    195
    Likes Received:
    36
    can you visually confirm it skipping ? try looking at it while manually extruding without filament
    maybe there is something you're missing

    I'm out of solutions, i solved mine by cleaning out the hot end as it was partially clogged. it couldn't push the filament through fast enough so it grind ed through it
     
  3. tonycstech

    tonycstech Active Member

    Joined:
    Dec 16, 2013
    Messages:
    587
    Likes Received:
    195
    I can visual and by hand.
    Every full turn it skips at same spot. I have to clean same threads everytime. Cleaning doesnot help, it starts to shave the very next turn.
    Nothing helped but more tension.

    I have only 1 explanation. It must be warped.
     
  4. splk3

    splk3 New Member

    Joined:
    Oct 5, 2013
    Messages:
    91
    Likes Received:
    33
    Got my bolt swapped in and it is working better. I used a dremel to cut off the extra length so it didn't hinder x-movement towards home and get in the way of the hotend cable plugs. Works great!
     
  5. splk3

    splk3 New Member

    Joined:
    Oct 5, 2013
    Messages:
    91
    Likes Received:
    33
    Got my bolt swapped in and it is working better. I used a dremel to cut off the extra length so it didn't hinder x-movement towards home and get in the way of the hotend cable plugs. Works great!
     
    3 people like this.
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    22,638
    Likes Received:
    7,236
    Another success story :)
     
    2 people like this.
  7. tonycstech

    tonycstech Active Member

    Joined:
    Dec 16, 2013
    Messages:
    587
    Likes Received:
    195
    I need my hubbed bolt replaced. Cant find anything on ebay, all of them are hubbed too far away from the bolt head.
    I got around 12.5mm from the head to the cuts. I can cut the bolt if its too long but i cant find the right one :
    I tried contacting ROBO support many times asking to buy another bolt but no one replied in MONTHS !

    Here is my bolt.
    DSC06715.JPG
     
  8. CAMBO3D

    CAMBO3D New Member

    Joined:
    Feb 20, 2013
    Messages:
    642
    Likes Received:
    296
    Dan Olson likes this.
  9. tesseract

    tesseract Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    1,924
    Likes Received:
    533
    I actually reversed mine so the head of the bolt was in the large gear and used the washers to position it so the holw was aligned with the hobbed area. Yours may be able to do the same thing
     
  10. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    I'm have some similar issues with slippage and grinding, it's making me paranoid to leave 2 hr prints alone as i have saved a few from being wasted by catching the slip when it happens and then pausing the print to fix the hob-grip. I think it's exacerbated by the cheap pla i have being extremely hard, so the stock robo3dr1 wade extruder and hobbed bolt aren't up to it.

    I believe the bolt and extruder on the robo are a re-purposed 3mm filament design. the filament guide slot is way too big, and on my larger prints you can see the filament leaning either way back and forth in this slot all the time. This can't help the already handicapped 'flat' hobbed bolt.

    Ive seen some parts designed to better guide the thin 1.75mm filament parrallel into the extruder, so i'm going to try a combination of something like it, with the addition of a diy hobbed bolt to solve the problem.
    If it's good I'll share results.
     
  11. Thamer Albahiti

    Thamer Albahiti Active Member

    Joined:
    Feb 20, 2013
    Messages:
    195
    Likes Received:
    36
    i fixed my problem with better filament, the one i was using was 1.6 or 1.4 which was why it wasn't holding it properly
     
  12. Printed Solid

    Printed Solid Volunteer Admin
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    1,605
    Likes Received:
    1,002
    Peter, you can certainly do that (rebuilding everything is part of the fun, right?), but you'll probably find that switching over to a grooved hobbed bolt fixes things pretty handily if you don't want to go to all of the effort.
     
  13. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    Haha, thats probably true, but i can buy an 8mm bolt today and i 'have the technolgy' to 'hob' it tomorrow at work.
    This will cost me $5 to have 4 goes at it.
    Although, my print bed has cracked so i'm out of commision until the new smooth rod upgrade kit arrives anyway which I have asked jerry about but havent ordered yet, i think i'll be waiting a while....
     
    2 people like this.
  14. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    Ok, an update on this, the handmade hobbed bolt worked, but no better than the stock one in my case.

    If I could be bothered using the mill at work I could probably do a better job, but the stock robo hobbed bolt should work fine if it is installed the right way.

    I'm also finding that aggressive retraction is tightening the nut in the gear wheel on the hobbed bolt to the point that the gear stalls the stepper. Honestly, driving a bolt by a nut on it's arse end is truly, truly.. insert appropriate words.

    Tesseract said he reversed his, I'm going to do the same before I lose it bigtime.

    Why?
    If you have a close look at the stock hobbed bolt, the 'teeth' are indeed 'directional', they are cut using an offset end mill bit with an indexing head and if you look at the side profile of the teeth, just like a shark, the teeth are angled a certain way to provide higher grip in one rotational direction.
    Guess which way.
    You bet, the opposite way to the stock robo assembly.

    Reversing the hobbed bolt will achieve two things.

    1. The teeth will grip filament as intended, most probably better.
    2. The bolt will never again self-loosen or tighten.

    Gargh!
     
  15. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    ok, so that wont work obviously. Just tried, no spacers or washers are going to get the stock robo bolt reversed.

    I need to buy a hobbed bolt with the hob further out so that it can go in in the reversed direction.

    Tesseract, could you please advise what hobbed bolt you used to get the head inside the gear?
     
  16. CAMBO3D

    CAMBO3D New Member

    Joined:
    Feb 20, 2013
    Messages:
    642
    Likes Received:
    296
    4 people like this.
  17. Galaxius

    Galaxius Well-Known Member

    Joined:
    Jan 18, 2014
    Messages:
    632
    Likes Received:
    342
    I tried a bolt with the hob at 25mm but it was 1-2mm too short. 27 or 28 should be right though you will probably need a washer or 2 at the gear end.
     
    2 people like this.
  18. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    Despite the pic, this one is hobbed at 15mm so it is a direct replacement of the Robo3d and will require the nut to be in the gear.
     
  19. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    3 people like this.
  20. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    22,638
    Likes Received:
    7,236
    That looks a lot like the one we most commonly use. Nice hobbed section.
     

Share This Page