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Discussion in '3D printers' started by Carl Feniak, Sep 29, 2014.

  1. JCPhlux

    JCPhlux Well-Known
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    @Carl Feniak Also one thing I am wondering why do you have a front and back plate on some axis not not others. In the original you did not have the back plate. Was this added for a purpose?
     
  2. Carl Feniak

    Carl Feniak Journeyman
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    Yes, in the original H-Bot design I used all cantilevered V-wheels with the M5 bolts that come with the mini V-wheel kit (no back plates at all). I found that this setup had too much flex due to the flexibility of the plastic parts the wheels were mounted to and contributed to the "H-Bar Torsion / racking" issue people talk about. It tried pre-loading them a bit but found it produced a slight angle to the V-wheel contact area. Using metal plates would do the trick, but not facilitate the belt runs.

    Using a back and front plate the wheels are well constrained and kept square in the V-Slot as they are supported from both sides. This setup is much more rigid and might make my original design feasible...

    The Z axis the V-wheels are still cantilevered. I didn't switch this as I already compensated for the cantilevered forces by constraining more bolt length in the plastic support to make it more rigid. I also wanted to keep the far side of the extrusion open to mount the extruder to. It could be done though. If you do go with a 12"x12" bed and think there is an issue then this area could be converted as well.

    Aside: The plates in the current design are overkill- I can shave some plastic out of them and they will function just as well.
     
  3. Carl Feniak

    Carl Feniak Journeyman
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    I used 40% honeycomb infill, but with my forced perimeter count only a few areas had infill
     
  4. JCPhlux

    JCPhlux Well-Known
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    Do you think a 3 wheel plate work 2 top, 1 bottom middle?
     
  5. Carl Feniak

    Carl Feniak Journeyman
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    I've seen some setups that do this, but having had the issues with the H-Bot rigidity I didn't want to skimp. I think with some part redesign it would work fine and be rigid enough for the CoreXY setup.
     
  6. JCPhlux

    JCPhlux Well-Known
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    @Carl Feniak looking at the XYIdlers and the XY Motor Mounts you have a 10mm hex on the outside of the rail housing. What purpose does this serve?
     
  7. JCPhlux

    JCPhlux Well-Known
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    My first question was about the blue circles.
    What is the part in red for?
    WhatIsThis.jpg
     
  8. Carl Feniak

    Carl Feniak Journeyman
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    The blue circled hex holes serve no purpose, they are just holes so that less plastic is used during printing.
    The red ones are for bolts to the V-slot extrusion end holes, which I drilled out to 4.5mm before assembly. The hole is countersunk so the same hex head M5x10mm bolts used elsewhere will work.

    If you don't have a 4.5mm drill bit, a 3/16" might work but leave less material to bite.
     
    #38 Carl Feniak, Oct 11, 2014
    Last edited: Oct 11, 2014
  9. JCPhlux

    JCPhlux Well-Known
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    I have a m5 tap
     
  10. JCPhlux

    JCPhlux Well-Known
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    Is there that much of a savings? Do you thing it weakens the structure at all?

    Why do you not just print the hole?
     
  11. Carl Feniak

    Carl Feniak Journeyman
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    You're right, there really isn't much of a savings in plastic. It really isn't a critical stress area so I don't think there are any structural issues with these. Easy to remove though once I finally post the 123D files. ;)

    As for the red holes above, they are fully printed in the idlers. There is a 0.2mm membrane layer designed in to facilitate bridging over the countersunk hole, but otherwise no drilling needed. The hole that needs to be drilled/tapped is in the end of the aluminum extrusion itself. They are about 4mm when you get the V-slot and needs to be enlarged to fit a M5 bolt. It can be tapped to M5 size or if drilled close enough, the bolt can cut threads for itself.
     
  12. JCPhlux

    JCPhlux Well-Known
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    I have already remodeled allot of it. I have changed some of the design. I will post some images later.
     
  13. Bclough

    Bclough New
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    Where did you purchase the glass for your heated bed? Makerfarm?

    Interestingly enough, I'm designing a printer similar to this one. I'll post it here once building starts.
     
  14. JCPhlux

    JCPhlux Well-Known
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    I got the glass and a glass cutter for less than $10 at Lowes. The glass was super easy to cut.
     
  15. JCPhlux

    JCPhlux Well-Known
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    So here is my re-imagining of the XY Idlers.
    I have made the holes more generic so that the left and right are exact mirrors.
    1.jpg 2.jpg 3.jpg 4.jpg
     
  16. Carl Feniak

    Carl Feniak Journeyman
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    I got mine custom cut from Voxel factory. It is 3mm borosilicate, which is nice for it's low thermal expansion and thermal shock resistance but expensive. The biggest thing is getting a nice flat piece of glass. You can't level a curved plane of glass!
    My friend prints on 2mm thick picture pane glass and while he has broken 2-3 pieces of it, it is only $3-4 a piece.
     
  17. Carl Feniak

    Carl Feniak Journeyman
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    Looks good. I see you are going with a 20x20 on the vertical legs. I think this a good modification to enable the use of a two plate setup for the Z axis.
    I don't think the bolt holes you added where the hexagons once were will be usable as the belt needs to run through that section of extrusion. However, I think your version is printed most easily from the left hand side of your first picture being down on the bed, which would enable you to add a support on the inside of the extrusion if you wanted.

    How is the prusa build going? A coworker of mine just ordered a Prusa 10" i3v Kit from Maker Farm.

    Do you think think I should put a word document together detailing some assembly steps for the C-Bot or do you think it is unnecessary/obvious?
     
  18. JCPhlux

    JCPhlux Well-Known
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    Yeah the 20x20 felt like a good fit.

    I am planning on changing the back plate also I am going to play with the spots that have overhand and see if I can add a taper instead of corner so I don't have to worry about support. I will post the STL file once I finish so you can see all the inter changes. It is hard to see in the images.

    The prusa build is going good the kit I got was missing a thermister on the heated bed but a replacement should be in this week. I am not going to rush it because in the past that is how I have screwed things up. Hope to be calibrating buy this week end.

    I think a document would be good. I was planning on creating some 3d models showing the belt runs in greater detail once I finished.
     
  19. JCPhlux

    JCPhlux Well-Known
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    Here is the STL file for the corrected version and some more screen shots. I am a little worried about some of the overhangs still. Any suggestions would be great.
    1.jpg 2.jpg 3.jpg 4.jpg
     

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  20. DarkAlchemist

    DarkAlchemist Well-Known
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    I love it and was going to do this exact same thing but my funds are precious and I have one need (build a new computer as mine is almost 6 years old) and one want (something like an Routy but with the reinforcement of the OX) then I would revisit the 3d printer as I really hate mine (I3 Rework) as it has issues I cannot remove (inherent issues in the I3 design that even Josef admitted to) completely.

    How is the speed on this versus smooth rods? I know the Ultimaker is amazingly fast and accurate but it is built like a tank so how is the V-Rail for doing this 3d printer sort of thing?
     
  21. DarkAlchemist

    DarkAlchemist Well-Known
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    I feel your pain my friend. I am not the type to sell anything so I would keep it all but have no use for the 130 dollar 6.35mm frame. The smooth rods were free via a Mitsumi deal so not a terrible waste but right now I am trying to find the BOM to this thing.
     
  22. nexty

    nexty New
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    Hi guys,

    Winter is coming... time to build something in the workshop ... it will be another 3d Printer (I have my k8200 working so far)

    obivously I like the design of the c-bot, and I'm thinking to start building this one, some question, since there is "not much activity on the thread" is it safe to start building this one? (no offense, just didn't want to start building something if the project is "dead" if you know what I mean)

    - does the .stl is the latest version (for example the BOM has 2 version listed, I understand you wasn't able to remove the previous version?)? if yes I'll start printing some part as soon as my printing job is finish

    thanks again for your brilliant work,

    Quentin.
     
  23. Carl Feniak

    Carl Feniak Journeyman
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    It is under the "files" tab of the build
     
  24. Carl Feniak

    Carl Feniak Journeyman
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    None taken, though I am not sure what you mean, is that an openbuilds site discussion status? This thread is new as I've just posted the build on this site less than 2 weeks ago (and just last night on thingiverse).

    I'd consider it live and is producing excellent prints as is (it is printing right now actually and I am not home). I could change the build status to complete. I'd love if people were interested in building this printer and add their improvements/twists to the design like John is above. He is working on some modifications to accommodate a larger bed (12"x12" I think) and enhance the Z axis to a two plate setup instead of a cantilever.

    The BOM has two versions but they are identical. One is an xls and the other is a xlsx to enable folks with older versions of excel to open it.
     
  25. nexty

    nexty New
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    thanks Carl,

    make sense and I'm not questioning the fact that you just created your thread ;-)

    has I'm not able to see the date of the post/message, I was just looking to see if people where arround and building this one

    I've already start ordered some part on ebay, and will print the STL really soon, I might go with a 210mm (10inc) bed, even if I'm not sure yet

    would you mind me if I post picture of the printed object?

    thanks and keep it up!

    Quentin.
     
  26. Carl Feniak

    Carl Feniak Journeyman
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    I can't really make that comparison as I have never seen an Ultimaker in person.
    The V-slot is very smooth and vibration free in my experience. I haven't attempted to push this printer to it's limits. I have been up to 200+% default reprap speeds temporarily (10 sec) but haven't left it there for a full print. Proper tuning of the stepper drivers is of course important and at this point I am able to run all motor and my drivers with no active cooling. Motors only get warm. I suspect my direct drive filament feed motor will end up being a limiting factor at some point and either active cooling/increased nozzle temps or orifice size/switching to a geared setup would be required. Alternatively, at some point sharp changes in direction with high acceleration will create belt stretch and reduce the print quality.
    I am focusing more on quality over quantity at this point, but with larger bed sizes higher print rates do become important. Something to stress down the road.
     
  27. Carl Feniak

    Carl Feniak Journeyman
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    Excellent mod. You said you were using sketch up for them?
    Two things to note:
    -V-Slot has pretty sharp corners. You are going to have to greatly reduce or remove the corner rounds from the inner extrusion profiles.
    -regarding the second support web for the 20x20 extrusion, do you think it will bridge at an angle? I guess it depends on the intelligence of your slicing program!
     
  28. Carl Feniak

    Carl Feniak Journeyman
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    Here are some prints in black ABS.
    http://www.thingiverse.com/thing:482043

    The little guy figure below was printed with pillar support, unfortunately I broke the spear bottom off with the needle nose pliers. The spear top is intact and printed wasn't supported. 0.15mm layer height. Source:
    http://www.thingiverse.com/thing:182618

    You will notice some cracking in the tower. I am new to printing in ABS and am not sure what caused this. Just a large part? If anything it is my printing settings or a need for an enclosure. 0.2mm layer height. None-the-less you can see the layer alignment is excellent and the fill is balanced and parallel (maybe a touch overextruded, but that is just tuning).

    IMG_0852.JPG IMG_0853.JPG IMG_0854.JPG IMG_0857.JPG
     
  29. JCPhlux

    JCPhlux Well-Known
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    I am using Rhino 3d.

    Here is a shot of it with extrusion.
    1.jpg 2.jpg
     
  30. JCPhlux

    JCPhlux Well-Known
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    I redesigned the XYIdler. I think I have addressed most of the issues.
     

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