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Prusa I3 issues

Discussion in '3D printers' started by Flash22, Jan 31, 2016.

  1. Flash22

    Flash22 Veteran
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    Hi all

    I purchased a Prusa i3 kit Aluminium Frame the end of last year, slowly but surely its started to lose calibration to the point its now unusable even after 2 full rebuilds, I have many hours of fault finding it seems the main frame is flexing even with the ooznest upgrades

    I have sunk £200-250 extra into the printer to get a half decent print but I'm still struggling

    Its seem that this is the norm for the i3 and I can see why people give up with these machines

    When do you get to the point to say no more and get something that works ?
     
    #1 Flash22, Jan 31, 2016
    Last edited: Jan 31, 2016
  2. dddman

    dddman Master
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    This is the kind of stuff I can print with my prusa i3 aluminum frame. Upload some pictures of your printer and prints and we will be able to help :) Also, what software chain are you using?
     

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  3. Flash22

    Flash22 Veteran
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    I have had all sorts of print fails from reduce height lower levels to top layers melting and even stringy prints, lost count of the amount of times I have calibrated the bed then realised every time the nozzle come in contact with the bed the extruder mount flex's and there is movement in the frame

    I have setup the printer many times over, set all the tolerances with a Vernier, The printer sits on 6 points, To me this seems there is not enough support also the threaded rod frame has a habit of twisting no matter how you align it.

    I have even gone to the extent of levelling the machine on a 2" thick steel engineering slab
     
  4. Flash22

    Flash22 Veteran
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    build chain wise

    SketchUp - slic3r

    Fusion 360 - stl - slic3r - pronterface or straight to sd

    Fusion 360 - Meshmixer - STL - slic3r - SD

    Fusion 360 - Meshmixer

    I have tried al sorts of combination of software and settings, I have even gone through marlin and made sure the config is correct for the ramps 1.4

    I know this works as I have printed on other machines I also use a similar setup for the gcode on my C-Beam
     
  5. dddman

    dddman Master
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    Take some pictures :)
     
  6. Flash22

    Flash22 Veteran
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    well its a standard prusa i3 (ooznest) with a bulldog lite and (upgraded) AO hexagon hotend, one issue I come across is the extruder mount is bolted to the X axis by 2 bolts it seem that this is a small area for all the weight
     
  7. Ryan Lock

    Ryan Lock Veteran
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    Hi,

    I am sorry you are having troubles with our machine. Did you buy our full kit or just the aluminium frame kit?

    One thing we have now changed on our kit is to not having the autobed leveling, we have found it is just easier to level it by hand once, and then it should be fine. Should only need doing again if you move it.

    Best Regards

    Ryan Lock
     
  8. Flash22

    Flash22 Veteran
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    Hi Ryan

    I purchased the full kit from your self - I have come to the same conclusion - the drive block on the left with the micro switch has so much slack in it now I have put nearly 2 rolls through it, Its is making the X axis 2mm out of square

    Also the frame braces sit flush with the bottom of the frame but these are 3mm in the air so it sorts of defeats the object of them, Is this a print error or just a design issue

    As you will find on thingiverse the top z axis mounts where the bearings sit are slack (like a **** in a bucket) - well the bearings don't have any effect - I have replaced these with my own design so the bearings are a tight engineering fit - again don't know if its a design problem or just a case of bearing specs being changed

    Its not unsurmountable but with a iffy fet on the bed circuit and a driver go bad its bloody frustrating (fet changed, I had spare driver in my box of bits)


    Do you have the frames and bed mount made or do you buy them in ?? can I suggest adding a 5th mounting point so 3 point levelling is possible
     
  9. Ryan Lock

    Ryan Lock Veteran
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    Hi,

    What do you mean by it has slack, that it can move up and down on the threaded rod? Or what i think you mean is that the right hand side can go up and down a few mil each way compared with the left side? What you need to do is adjust the right side so it is level with the left. Then level the print bed.

    This is how they are meant to be, they are designed to clamp to the threaded rods. We found if we made them flush with the bottom of the printer, any slight print errors could stop the aluminium itself from touching the table top, and the printer would just be sitting on the braces.

    For the bearings being too lose, that is most likely a printer error on our side. I will look into that tomorrow.

    Sorry about the iffy board, i would have replaced it free charge if you contacted me sooner.

    We get the frames made, they are mostly the same as the standard prusa design.

    Best Regards

    Ryan Lock
     
  10. Flash22

    Flash22 Veteran
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    The lift blocks move front/back the nuts have loosened with use, there is also back lash between the 2 nuts - this causes it to move in a ellipse - with the bolt pressing on the micro switch - in turn this puts pressure on the joints on the pcb - I will do away with the bed levelling as this seems to be a problem

    I have a new printer on the way, once I get that up and running I will make the parts needed for the prusa

    The ramps board not a issue as I had access to the mosfet's the hard bit was re wiring it all

    Thanks for the reply
     
  11. Ryan Lock

    Ryan Lock Veteran
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    Hi,

    Yes i would definitely turn off the bed levelling, as said earlier we now recommend always running without it. If you need anything please get in contact.

    Best Regards

    Ryan Lock
     

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