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  1. #11
    Thats how i did it on the gantry, my first build. gantry was flipped 180 degree and i poured gantry sides and lower beam epoxy. Then flipped and did upper rail. No problem.

    But you will need a straight edge and 2 precision squares for later when mounting the rails and so...
    project 1 , 2, Dust Shoe ...

  2. #12
    Quote Originally Posted by Clive S View Post
    Yes I agree. Have you decided on one motor or two?

    Don't buy any electrics until you have it all drawn up in CAD AM882 or EM806 work well for the drives at 68V
    Dear Clive S,

    My design dictates at least 2 idler pullys per ballscrew if i want to go single x axis nema 34 stepper... and have the whole bed space.

    Or... i have to limit bed space and cross the bed...There is room in the design to do this though.
    And 1 side is up against a wall anyways.

    When going single stepper,
    i think i would buy a wide stepper pully,
    and shift the ballscrews a belt width and use 2 belts, 1 for every ballscrew.

    For now a 2 stepper x setup looks more convenient from a mechanical point of view.
    2 short belts.
    lots of bed space

    My Electronic pov is opposit.

    For inertia it seems, in my mind, better too.
    2 powerful 3+Nm steppers on high voltage digital drivers. Instead of a single bigger 8/12nm nema34. this is just a gut feeling , not based on any sound research.

    Not sure what makes a 3, 3,1 or 4 Nm nema 23 stepper best choice.
    Just high amps low inductance right?



    Any thoughts?

    Verstuurd vanaf mijn SM-A320FL met Tapatalk

  3. #13
    For now a 2 stepper x setup looks more convenient from a mechanical point of view.
    2 short belts.
    lots of bed space
    That's what I use you can run them 1.5:1 or 2:1 I used 3.1Nm but with 1610 screws motors from https://www.cnc4you.co.uk/Stepper-Mo...YGH301B-Nema23
    with am882 drives from China

    I do have a nema 23 4Nm on my mill but don't see a difference in them
    ..Clive
    The more you know, The better you know, How little you know

  4. #14
    I would always prefer the mechanical convenience over the electrical...
    project 1 , 2, Dust Shoe ...

  5. #15
    Quote Originally Posted by driftspin View Post
    Dear Zeeflyboy,

    I hope for a miracle by epoxy

    First one needs a zero reference for horizontal level.

    I think it was Boyan who explained on the forum he made a reference level surface for this on a concrete floor by pouring epoxy.

    I will try this way.
    I will spirit level and anker bolt my frame to the concrete floor before pourings so nothing can move and use the x poured epoxy rail mounting surface for this.


    Pouring the rail mounting surface for X will be done like the example from a forum member see picture.


    like the X axis the 4 mounting surfaces on the gantry will be epoxy levelled.

    In 2 steps...

    Step 1 I will do the 2 gantry X rail carriage mounting surfaces, and bottom Y rail mounting surface pouring, in 1 go. ( gantry upside down )
    There will be an epoxy levelling bridge between the 2 carriage mounting surfaces
    Similar to x rail pouring setup


    So now those 3 surfaces will be in the same plain.

    After curing..

    Step 2 The gantry can now be flipped to normal position and top Y axis rail mounting surface can be poured..

    Placing the gantry in the normal position on the mounting surface of the x rail should give the best possible reference for a level plain.

    After pouring Y bottom and top should be in the same plain..

    In theory this should work.


    I know this will be a critical process.
    When this method fails i will redesign and have the gantry (rail) mounting surfaces milled. nothing much changes only a few pounds of steel added.


    When milling is needed i will upgrade the gantry box section to 80x120x8 or 10 to have some meat to mill
    I do want to avoid **bolting** the gantry sides to the gantry Y-axis.
    I prefer welded solid for best rigidity.
    But welding solid must be avoided going that route, because of warping.

    I have no friends with a mill capable of box section 1200X120x80.

    Would a surface grinder work for this purpose?

    Any other thoughts?
    Sounds good! Will watch with interest. Good luck!
    Last edited by Zeeflyboy; 14-08-2017 at 12:33 PM.

  6. #16
    Quote Originally Posted by Boyan Silyavski View Post
    I would always prefer the mechanical convenience over the electrical...
    Dear Boyan,

    Not sure iam really clear what your preference is.

    Do you mean use a single motor on 2 belts solution?
    Mechanical advantage is :
    - Y axis can not get out of alignment easy?
    * disadvantage idler pullys

    or

    use 2 motors and solve alignment in the homing sequence by electronic controls...
    - Y axis can be aligned easily that way.
    * Some (cheaper) controls dont do gantry squaring sequence.






    Verstuurd vanaf mijn SM-A320FL met Tapatalk

  7. #17
    Ok some progress.

    In the summer months the build did not get a lot of attention.

    I did manage to get some of the steelwork done.


    Did any of you run wiring through the box section?



    Verstuurd vanaf mijn SM-A320FL met Tapatalk
    Last edited by driftspin; 09-09-2017 at 01:07 PM.

  8. #18
    Aren't you going to put brace at the bed, at the long axis?

  9. #19
    Quote Originally Posted by driftspin View Post
    Dear Boyan,

    Not sure iam really clear what your preference is.

    Do you mean use a single motor on 2 belts solution?
    Mechanical advantage is :
    - Y axis can not get out of alignment easy?
    * disadvantage idler pullys

    or

    use 2 motors and solve alignment in the homing sequence by electronic controls...
    - Y axis can be aligned easily that way.
    * Some (cheaper) controls dont do gantry squaring sequence.






    Verstuurd vanaf mijn SM-A320FL met Tapatalk


    if you are experienced with belts, know how to tighten properly long belt, know how to align all components then go with 1 motor and belt system. If you dont have the space, have a suitable controller board, go with motor each side. At the end is a question of convenience.
    project 1 , 2, Dust Shoe ...

  10. #20
    Quote Originally Posted by Nickhofen View Post
    Aren't you going to put brace at the bed, at the long axis?
    Frame bracing.

    Well no...well not yet.

    Span is 2x1650mm span 120x80x4 mm box section....

    plenty stiff one would think...

    In Theory,

    At 400 pounds of moving gantry weight 0.0027 inches vertical deflection would occure ... but the bed would move also. so. well.

    At a more realistic 100 pounds 0.00068 inches

    This would only be a problem if the workpiece was stiffer than the box section right?


    In my design there is no absolute movement between router bit and workpiece when vertical X axis flex would occure. So no accuracy problems there.


    By now total weight is 190 kg with no gantry...

    I do believe "ringing" might become a problem... the assembly has a +/- 1khz resonance frequency.

    I might fill her up with something like sand or epoxy mix concrete or something need to look in to that.


    For shaking appart there is something to be said though.

    Bracing at the bottom should solve x axis flex.. some of it anyway. It felt plenty stiff  those diagonals are out of the way great.



    Y/X direction flex / bracing... yes.. well.. erh there is going to be cabinets installed ..

    And maybe a few bits like: compressor airbrush type , vacuum cleaner, dust removal cyclone, cooling for spindle,
    electronics cabinet.






    X-direction flex bracing
    I cannot yet fill the under the bed space with diagonals... yet.

    There will be bolt on triangles when stuff like that is sorted.


    Y-direction flexbracing

    There is a 3mm thick plate 1000mm x 200mm with curved edges between the legs.. bolted with 4xm10 threaded rod to the legs.. plenty long m10 rod +/- 100 mm for building up tension.



    Diagonal cross frame flex.

    At this time i have prepared 4 m12 screws at the bottom of the legs to level the frame
    And help with aligning icw anker bolts to the concrete floor.


    When it is level and all legs (set screws) are in contact with the floor.
    It feels incredibly stiff.


    When now a set screw is set out of alignment by a 1/4 turn (M12) the table is wobbly ... proof of stiffness...

    Any thoughts?

    I have no good idea what the shaking forces are like in real life.

    Verstuurd vanaf mijn SM-A320FL met Tapatalk
    Last edited by driftspin; 09-09-2017 at 03:17 PM.

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