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Hobbed Bolts and feeling Good! (for newbys)

Discussion in 'Troubleshooting' started by tompeel1, Mar 5, 2014.

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  1. Kevyn Watkins

    Kevyn Watkins New Member

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    Darrell I'm in exactly the same position, I'm away at work and hoping to order it before I go home so it will get home before I go back to work. Looks like the 15mm one is the one we need. I'll be ordering it today. I'll also get the grooved bearing from him and see how that goes.

    Just ordered it and left him a message to specify that it's 15mm and for a Robo3D. I also pointed him to this thread. He deserve's to know that Tom was a happy enough customer to recommend his bolts :-D
     
    #21 Kevyn Watkins, Mar 21, 2014
  2. Darrell

    Darrell Member

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    I know this is a couple days late but I thought some pictures of my bolt being measured with Digital Calipers would help others that aren't sure of their bolt measurements.
     

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    #22 Darrell, Mar 25, 2014
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  3. SoLongSidekick

    SoLongSidekick Active Member

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    Just ordered two so I would have a backup, always good to have backup parts. Didn't order the one with the bearing as it seems no one else needed one, hopefully I made the right call there. Anyone who has one already and using Matter Control, could you post instructions on how to re-calibrate?

    EDIT - Actually changed my mind and got the bearing as well. I don't have my printer in front of me right now but if my terrible memory serves me right (which it rarely does), the bearing that comes stock does not have a groove in it right? If that is the case this grooved bearing should be a real upgrade shouldn't it?
     
    #23 SoLongSidekick, Mar 25, 2014
  4. SteveC

    SteveC Well-Known Member

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    Yes the stock printer idler bearing has no groove. I do use a grooved bearing but I have no data to prove that it helps. It's possible that a deep groove in the bolt will keep the filament centered but I figured that the grooved bearing will definitely keep it centered. One thing to keep in mind is the the groove depth will take away from the idler spring tension and you should add washers to compensate. I ended up using 5 washers behind each spring and the one in front! That may be overkill but I never have filament feeding problems anymore and never get any plastic shavings in the bolt. This is over a couple brands of ABS and PLA.

    The dimensions for the stock bolt for my printer are the same as Darrell's but the funny thing is that the angle of the hobb is backwards. This meant that I probably got really good retraction but it would always slip for extrusion.
     
    #24 SteveC, Mar 25, 2014
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  5. AxisLab

    AxisLab Well-Known Member

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    Steve, can I ask what the purpose of the groove in the bearing is for? When I looked at the picture on ebay, somehow I'm not seeing it.
    Also of the two bearings, which one benefits from being "grooved"? The one closer to the bolt head or the one on the far side.
     
    #25 AxisLab, Mar 26, 2014
  6. tesseract

    tesseract Moderator
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    Ok Here is the item I got on ebay and sadly to say it appears he does not sell them anymore but it gives agood idea what to look for this hobbed bolt on my stock extruder was purchased within one month of me my receiving my ROBO and worked absolutely flawlessly up until I upgrade to dual bowdens. The key was I had several washers that I could place where I needed to to get the recess in the bolt to line up exactly with the hole. The recess sort of traps the filament in the area that allows it to go into the hole nicely that is its complete purpose, with a non recessed bolt the filament had a tendency to slide side to side and cause jams the recess simply guides it right in. The other key is that it must not be so deep that it allow the filament to NOT get extruded due to the gap between it and the pushdown bearing on the spring loaded latch cover being to large and not to make good contact with the filament. I know robo has changed alot of thing in this area so take these images as they are but again it worked perfectly on my system.

    hobbedbolt.jpg hobbedbolt1.jpg hobbedbolt2.jpg hobbedbolt3.jpg
    as you can see the actual recess is on the medium side not too deep thekey as I said was getting it to line up directly with the hole and that is where the washers came in
     
    #26 tesseract, Mar 26, 2014
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  7. SteveC

    SteveC Well-Known Member

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    That will work but the spacing to the hobb is quite long. The 26mm in the second photo from the base of the bolt head to the hobb will require quite a few washers to space it 11mm back to the proper 15mm value. The extra sticking out on the left side of the extruder could interfere with the wire harness depending on how you have it attached. I have found that many of the ebay vendors will ask you to specify the bolt head to hobb spacing in the ordering comments or in an email. If they don't have it on hand they will custom make it for the same price. If the overall length is excessive you can just hacksaw it off.
     
    #27 SteveC, Mar 26, 2014
  8. SteveC

    SteveC Well-Known Member

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    I got my grooved bearing so long ago I can't find the listing. Here is an example in this photo from the UK.
    http://www.ebay.co.uk/itm/RepRap-Ho...endel-Huxlel-3D-Printer-Extruder/310907954206

    The purpose of the groove is to keep the filament centered. I suspect that if you have a good groove in your bolt the grooved bearing is probably not necessary.

    FYI this is the bolt I have:
    http://www.ebay.com/itm/Hobbed-bolt...-Prusa-Mendel-Reprap-USA-Seller-/221355685972
    Just specify in a message to him 15mm from bottom of bolt head and it will work great.
     
    #28 SteveC, Mar 26, 2014
  9. tesseract

    tesseract Moderator
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    No cutting no interference at all in my stock setup.

    I am just adding my two cents worth this scenario not only worked but in my opinion worked extremely well I was able to start loading filament directly through the top opening without ever opening the springloaded latch cover I simple retracted right out of the hole and started an extraction of say 50mm and fed the filament in through the top. That is how I was able to due my color/filament change on the fly so well.

    I guess the point is people are WAY over-thinking this it does not have to be rocket science to get this right. There are so many of us that did this over 9 months ago when the printers first came out and we found the issue and we just ordered the hobbed bolts and that was that very few of us had problems but today people are simply over thinking it. I would lay odds the many of the issues people are associating with the hobbed bolt is not a hobbed bolt issue and they just think getting "perfect hobbed bolt" will answer all the issues if that is so they will be sadly mistaken.

    Get a hobbed bolt that fits in teh hole that has a recess that is not extremely deep use washers to line it up.
    I think in my case I the parts went in this order head of the bolt larger gear 5 washers the extruder and two nuts one to tighten it up and one to lock the first one down.

    In that arrangement my hobbed area of the bolt aligned with the hole. END OF STORY. KISS is usually the answer.
     
    #29 tesseract, Mar 26, 2014
  10. AxisLab

    AxisLab Well-Known Member

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    I'm an idiot, I figured out my own question. I was focused on the two bearings the bolt goes through and wondering why the heck one would need a groove in it. Duh, its the middle one on the latch that you are talking about.
    My bad.
     
    #30 AxisLab, Mar 26, 2014
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  11. Ziggy

    Ziggy Moderator
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    I notice your hobbed bolt has 26mm between the inside of the bolt head and the hobb. Is it correct that on your setup the bolt HEAD is in the big gear?

    The reason I ask is that my Robo has the NUT in the big gear (and of course the distance between the inside of the bolt head and the hobb is different too - about 15mm).

    And I would add having the nut (which is smaller than the head) in the big gear is not as good because there is too much backlash.
     
    #31 Ziggy, Mar 26, 2014
  12. SteveC

    SteveC Well-Known Member

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    Jeff, It's all about aesthetics ;). Can't have an unsightly bolt head or end sticking out the side!

    I pointed the length out because I had one just like yours and the wire bundle was very close to being pinched between the bolt head and the carriage side and I just could not leave it alone. Probably just the OCD engineer in me.
     
    #32 SteveC, Mar 26, 2014
  13. SteveC

    SteveC Well-Known Member

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    Ziggy, Either way around that fits is fine. If the nut is in the gear just put some drops of Extra Strength Locktite on the corners of the nut to keep it from moving on retractions. Wait a day for it to dry.
     
    #33 SteveC, Mar 26, 2014
  14. tesseract

    tesseract Moderator
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    yes my bolt head was in the large gear like I said they have made many changes I think I was #5 to get mine in June of last yearso it could have been reversed with all the thing they were trying at that time
    Here are pics of my extruder with the hobbed bolt installed I added a third locking nut and a washer it seems
    2014-03-26 12.51.17.jpg 2014-03-26 12.51.26.jpg 2014-03-26 12.51.31.jpg 2014-03-26 12.52.06.jpg 2014-03-26 12.52.15.jpg 2014-03-26 12.53.03.jpg
     
    #34 tesseract, Mar 26, 2014
  15. Rick Collins

    Rick Collins Member

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    An update for those considering buying the replacement bolt. The eBay trader to get it from is "jaisol0"

    He has asked that I pass this on:
    Dear collinsricki
    Can you check if you need the bearing and I'll make a note for future orders. If you don't need the bearing can you tell folk on the forum that I sell the bolts cheaper without the bearing. It will save them £2

    JAmes

    - jaisol0


    Dear collinsricki,

    Hi

    Its a 15mm M8 x 60 bolt. It seems to have gone mad this weekend for those bolts...


    James

    - jaisol0




    Sent from my iPhone using Tapatalk
     
    #35 Rick Collins, Mar 26, 2014
  16. SteveC

    SteveC Well-Known Member

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    Jeff, Yes in the November shipment or earlier they flipped the bolt around and replaced all those washers behind the gear with another bearing. And of course the hobb on that bolt was a disaster for many of us.
     
    #36 SteveC, Mar 26, 2014
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  17. tesseract

    tesseract Moderator
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    The main thing is that if you look at the key factors which are a recessed area that is not too deep and positioning so the hobbed area is line with the hole should be the goal out side of those parameters many possibilities are available sometimes creativity comes into play as well. It can be done your self with a bit of creativity or the creativity of others can be purchased the result will be similar.

    As I stated the ONLY reason I took this out was due to my bowden upgrade with out that I would still be Extremely happy with this setup as it worked and probably would still work EXTREMELY well.

    Total cost was about $6.90 probably the best benefit for money on the printer
     
    #37 tesseract, Mar 26, 2014
  18. Ziggy

    Ziggy Moderator
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    Your configuration makes sense and is pretty much the standard 25mm hobbed bolt Wade set up.
     
    #38 Ziggy, Mar 26, 2014
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