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Prusa i3 Bear Edition

Discussion in '3D printers' started by pek, Sep 21, 2017.

  1. thess

    thess New
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    WRT - Ooznest taping.. I requested 20mm depth on my order and they were still 1-2 mm short. I already re-tapped them OK - they did the heavy lifting. Maybe I should have asked for 25mm?

    I probably won't get started on the full build until after the weekend when I can get over to a friends house with a drill-press for the frame. (That is if the printer kit gets here in time.)
     
  2. pek

    pek Journeyman
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    No 20mm is enough. I recommend 25mm screws and the frame is a bit more than 6mm. Happy building then :)
     
  3. SteverJ

    SteverJ New
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    Hey Greg,

    I finally have all of the parts coming to start working on the v2-half-upgrade for my Prusa MK2. The only thing that is going to slow me down is waiting for my MK2.5 upgrade but I'll have everything else ready to go once it gets here.

    Thanks for all your work and improvements!
    --Steve
     
    #63 SteverJ, Feb 7, 2018
    Last edited: Feb 7, 2018
  4. pek

    pek Journeyman
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    I wish you a happy build :) . Yes I am in the same case as you, waiting for the MK2.5 upgrade...

    Good news for you, I will publish the V2.0 build today (on openbuilds at first first) ! :nailbite:
     
  5. SteverJ

    SteverJ New
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    Awesome! I'll be looking for it. :thumbsup:
     
  6. xequtor

    xequtor New
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    Greg,

    would be possible to do it with Misumi Alu extrusion? they don't have the V-Slot and the Misumi should have same dimensions
    5 Series/slot width 6/20x40mm by MISUMI | MISUMI online shop - Select, configure, order

    The advantage of Misumi is that I can order the extrusion already cut to my specs. (about 35 EUR for all 6 20x40)

    With MK2S frame and MK2.5 upgrade plus Einsy and some parts I already have, I will build MK3 for half the price :)
    I already have Original MK3 Kit
     
    #66 xequtor, Feb 12, 2018
    Last edited: Feb 12, 2018
    p.builds likes this.
  7. JustinTime

    JustinTime Journeyman
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    You could use the Misumi since there are no wheels used in this build that has to run in the V-slot.
     
  8. pek

    pek Journeyman
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    It is something requested by several users, so I decided to add in all parts of Version 2 two parameters (in Fusion 360 files) : "rail_profile_width" and rail_profile_height". You can play with these parameters to adjust them to your Misumi profile. However, you cannot change the angle for two reasons :
    1. Some parts are printed vertically which means you will need to add a support, which results in fairly low accuracy
    2. When you print angles, the plastic will take a small shortcut which results in a rounded angle. All my "v-slots ergots" have a special shape to avoid this (advantages : more precise fitting, avoid stressing plastic parts on a small surface (on the shortcut), avoid bad alignments when building). Making this shape in parameter is not that easy.
    By the way, V-Slot is 45° and as you could see it has some advantages over T-Slot even if you do not use wheels!
     
  9. pek

    pek Journeyman
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  10. xequtor

    xequtor New
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    Thanks for the work and info!
    excellent, even better. I like the full upgrade much better.

    I even may go crazy and install HiWin linear glides

    Full frame 20x40, black anodized cost bei Misumi 35 EUR

    All rods are original, corect?
     
    #70 xequtor, Feb 12, 2018
    Last edited: Feb 12, 2018
  11. pek

    pek Journeyman
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    I would love to see a HiWin linear rail on my upgrade, this is in my head since a long time :D

    Yes all rods are original!

    I am currently fixing several issues on full upgrade, so wait a bit. Should be good by end of the week.
     
  12. xequtor

    xequtor New
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    please think about the endstop on top of the Z axis for the Z calibration.
    Maybe the top horizontal extrusion bars will be better to extend to go over the vertical extrusions to make sure that end stops (original M3 screws ) are in same and perfect horizontal positions?
     
  13. pek

    pek Journeyman
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    Yes I am thinking about this (and much more) ;)

    Moving the horizontal vslot on top does not solve this problem. The vertical extrusion can be cut with a slightly different length (or not a perfect 90° angle) and depending how well the build is done you might have unequal small spaces on top and bottom of vertical vslots. The advantage of the small top vslot is that you can use it to set same distance in bottom than in top.
     
  14. xequtor

    xequtor New
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    but with precision cut from Misumi you get perfect cut for the vertical profiles, with end-stop screws for Z-axis on the top just hold by making it tight, they still may get lose and move upwards, then you have skewed X-axis.
     
    #74 xequtor, Feb 18, 2018
    Last edited: Feb 18, 2018
  15. pek

    pek Journeyman
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    Precise cut does not mean perfect assembly, it depends how good you will square your frame (which depends on lots of factors). You also have to take in account that t-nuts are not centered in a hole like the screws on the prusa frame, they have a bit of play to help you square your build.

    Something else that is not perfect with the Prusa method and screws is that the plastic part are going to be deformed by the screws. Plus, they slightly twisting the X axis (specially on the side of the X motor).

    What I am doing to make a good alignment :
    • Z motor mounts are touching the bottom vslots
    • There is a smaller diameter on top of Z top smooth rod holes, if you push the smooth rod correctly you will get the perfect dimension. There is a hole to view that the smooth rod is correctly inserted
    • Flat surface in bottom of Z stop to stop the X motor and X idler without twisting them
    What do you think?
     
  16. xequtor

    xequtor New
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    1. Z motor touching vslot/extrusion may (not sure yet) generate vibration, I would decuple it, also not touching metal
    2. I'm not sure if I understand what it is, is it the square through-hole as in the original X Axis carige ?
    3. Bottom can't be really used as stop for X axis alignment, only top

    I think this will be not easy task to make perfect X axis stop on top for extrusion/vslot frame.

    I'm definitely building this frame for MK3 "clone" as I already have in my basket in Prusa Shop the MK2.5 upgrade, Einsy, MK3 Power supply and few other parts. Just waiting for final version so I can order extrusions by Misumi
     
  17. xequtor

    xequtor New
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    noch was, in which CAD app you make the design and are they public?
     
  18. pek

    pek Journeyman
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    Sorry I was not clear, quite hard to explain without an image...

    z-tops.png

    1. For now printer is quieter than original and maybe a bit quieter than Half Upgrade. If you prefer, you can add a piece of 1mm under the Z motor mount during the build (remove it when finished) and 1mm longer vslot. Bonus, you should win 1mm in Z axis (never tested this)
    2. Corresponds to red arrow. During the build, the smooth rod has to be fully inserted until touching on top. Their is a little hole in center to see it is correctly inserted. Rod will then define the Z height precisely. (this will be explained in the manual)
    3. Corresponds to green lines. When X idler (or X motor mount) will go up, it will touch the parts marked in green. For me it is way better than "half" of two screws head (as explained in my previous post)

    Is it better explained now? Does it make sense?
     
  19. xequtor

    xequtor New
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    now I understand what you mean, ein Bild sagt mehr als 1000 worte :)

    The Z endstop where the green line ist, wont this bend if the X carriage will push/hit it?

    I see one problem with the 3D printed parts, as they are they wont work with Misumi extrusion, if you can send me the IGES/STEP file, I can design for missumi or you can send you the Misumi dimensions
     
  20. pek

    pek Journeyman
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    I use Autodesk Fusion 360, everything will be open source!

    Fusion 360 files are available on my GitHub here (dev branch for now) : prusa_i3_bear_upgrade/src at dev · gregsaun/prusa_i3_bear_upgrade · GitHub
    STEP and STL files are available for each version as well

    As explained before (or maybe in V2 thread), if you are using other extrusion, there are 2 parameters to set the rail width and height. Checkout this article if you do not know how to do this : Making Parametric Models in Fusion 360
     
  21. pek

    pek Journeyman
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    Even more with my bad english. Ich verstehe ein wenig Deutsch aber ich bin from French part of Schweiz (yep we are speaking 3 languages in Switzerland + one for advance speaker :-D )

    No it will not bend (hard to show you on this pic without the X idler), the x idler/motor mount will touch a L shape on the Z tops.

    I think I answered this point in my previous comment. Sorry for know I do not plan to make Misumi version (only the parameters in the Fusion 360 files) I have to maintain 4 versions for now and it is not a small job :-D
     
  22. pek

    pek Journeyman
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