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OpenBuilds OX CNC Machine

Discussion in 'CNC Mills/Routers' started by Mark Carew, Dec 15, 2013.

  1. Chris Laidlaw

    Chris Laidlaw Well-Known
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    HI Wassim,

    I have a few gantry plate sets that are 2" taller. I think much taller than that compromises stability.

    They are listed here: stores.ebay.com/chrisclub1
     
  2. William O. Yates

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    Hello, I'm a newbie to the cnc scene, so please bear with me if I ask simpleton questions... :)

    I'm buying in with some parts a former builder has for sale based on the "routy", but am more interested in building the ox...

    As none of the rails are in the parts he has, I so no reason to not go forward with the ox...
    (he already has the pulley/belts, but not much to lose...)

    My question is: would using ball screws be feasible with out major redesign issues?

    I am not attempting to build a steel cutting machine, but would like to handle aluminum and copper
    (base plates, heat sinks, covers, etc...) and also be precise for pcb board work, and with a laser head,
    logo/print board and cover etching...

    The ox-metal went with acme threads instead of pulley/belts, would not ball screws work the same while giving more precision and being stiffer?

    Am I on the right track or not?

    thanx bunches...

    william...
     
  3. Philip UD

    Philip UD New
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    Good timing.
    Easy way to attach ball screws to an OX.
    Easy Ox Ball Screw 600.jpg

    • FK/FF-12 Bearing Blocks (They mount with 4ea M4 screws and nuts)
    • Open Builds NEMA 23 Motor Mount Plates (drill or file the four center hole tab-slots to fit the M4 bearing block screws) 2ea per ball screw.
    • SFU1605 Ball Screws and Nuts (Length depends on machine axis lengths)
    • 1605 Ball Nut Housing
    Not a lot to it, except for figuring out the ball screw lengths.

    With a little creativity you don’t even need to disassemble anything for a conversion.
    Example: Use a 4.2mm drill bit to extend the back two Ball Nut Housing mounting holes so that they pass all the way through the Housings, mount the ball screws and position the housings to where you want to mount them, use the 4.2 mm holes as guides to drill two 4.2mm holes through the axis plates, tap the holes for M5 screws, enlarge the back two 4.2mm Housing holes to ~13/64” and mount to plates with two long M5 screws, ~30 to 40mm depending on whether you counter sink the back of the Housing or just let them hang out all ugly on the slanted surface. Pretty much the same for the X/Z just a bit harder to drill the mounting holes without disassembling anything.

    Even though this works I’m only using the FK/FF Bearing Blocks and Open Builds Motor Mount Plates to mount the single X axis ball screw, and making my own mounts with less expensive BK/BF-12 bearing block for the two Y ball screws. I just mounted the one Y-axis to check/verify the measurements before starting on my mounts.

    Cheers
     
    #3213 Philip UD, Aug 9, 2016
    Last edited: Aug 9, 2016
    Joe Santarsiero and GrayUK like this.
  4. Philip UD

    Philip UD New
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    Here’s a photo of the BK/BF-12 ball screw mounts.

    750mm Ball Screw.jpg

    About the ball screw lengths, my long axis screws are 750mm total length, 684mm working (thread) length, mounted in the photo with BK/BF-12 mounts and 6mm standoffs on both ends. The 20x80 rails are 741mm long. I’ll probably end up using no standoffs on the floating ends and longer ones on the fixed ends so that I can use 35mm motor standoffs which I have instead of making 41mm+ standoffs to use with the large coupler in the photo.

    The short axis ball screw has a 564mm total length and 500mm working length, and is a good example of why you need to ask how your seller is listing their screw lengths, some use total length others working lengths.
     
  5. michael nilsson

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    PLEASE HELP ME GUYS.
    ON THE VANILLA OX (or ooznest.co.uk preferably) with 1000x1000mm makerslide what is the exterior dimensions of the ox? Im building an enclosure before the machine arrives but i need that info.

    Can anyone help me? Would be great.
     
  6. Mark Carew

    Mark Carew OpenBuilds Team
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    @michael nilsson you could ask Ryan Lock in a conversation and I am sure he would be glad to help you out with the overall outside dimensions of the Ooznest OX
     
  7. Lstj

    Lstj New
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    hello ..
    I have question
    I draw a circle like this result.
    where my mistake ???
    I use a gecko G540
    mach3 setting step per 33.37, vel 15000, acc 1000
    belt 3mm pitch, pulley 20T

    IMG_0774.jpg
     
  8. Philip UD

    Philip UD New
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    I have a similar problem with Mach4, an Ethernet Smooth Stepper and G540, it’s why I’m trying ball screws. I get the same sort of not quite backlash problem and suspect it might be caused by the relatively low belt drive resolution, in the Mach4 manual under Motor Tuning Steps Per Unit it says the following:
    “As a rule of thumb an inch machine should have the steps per unit greater than 5000 (200 for MM)”

    In Jog Step if you zero the DRO and make ten 0.1mm X+ steps then ten 0.1mm X- steps does the DRO return to 0000 or do you lose a fraction each cycle?
     
  9. vjgr

    vjgr New
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    Hello,
    I want to build a XZ linear motion system with X movement of around 6000 mm and Z movement of 700 mm. Additionally, can the X linear rail be adjustable in steps of 500 mm so that I can have a linear motion on the X-axis from 500 mm to 6000 mm.

    Please give me your views.
     
  10. Philip UD

    Philip UD New
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    So I’m guessing not and Open Builds Ox router table? 6 meters would be a big Ox! Building something just depends on how much weight you need it to support, you could make the glide rails out of anything from v-slot to angle iron and skateboard wheels. The hard question is the controlling software, although if you only want 50 centimeter increments you could probably just use a simple DIY Robotic Controller.

    Photo of the gantry with the FK/FF Bearing Blocks and Open Builds Motor Mount Plates, no redesign necessary.
    Ox Short Axis Ballscrew.jpg
     
  11. vjgr

    vjgr New
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    Thank you.
    By increments of 500 mm, I meant to ask if I can physically adjust the X-axis length between 500 mm and 6000 mm. In other words, if I want to change the X-axis travel to 4500 mm in future, I want to remove 1500 mm physically on the system. Maybe butt joints on the rail can help this. Please let me know.

    The payload will be approx. 3 kg.

    Also, will the belt tension be a problem on longer lengths (6000 mm in this case) assuming a belt-pulley mechanism is ideal for this application? Also what do I use for the Z-axis movement of 700 mm?
     
  12. Philip UD

    Philip UD New
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    Rack and pinion.
     
  13. vjgr

    vjgr New
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    Is there any ready system I can use?
     
  14. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    For the 6000mm length you will probably want to use a double belted system to help deal with stretch in the belts. For the 700mm length you can either go with belts or screws but screws run considerably slower than belts. As far as being able to remove lengths, its possible but you will just have to find a way to handle the excess belt. If you cut it there's no adding it back later.
     
  15. vjgr

    vjgr New
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    Thank you. I never even thought of bicycle chain and sprockets. It is a very interesting thought. I will go deeper into it.
    Meanwhile if any of you have any thoughts on the adjustable rail system, or have any examples that you can share on double belts/ chain sprockets, it will be really very very helpful. Since I have not dealt with a system like this before, any suggestion/ video/ image would be very beneficial.

    Thanks again.
     
  16. GrayUK

    GrayUK Openbuilds Team Elder
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    Philip UD. In that picture of your Water Cooled Spindle, what is the purpose of that glass or plastic receptacle immediately above the spindle, with the yellow fluid in it?
    Gray
     
  17. Philip UD

    Philip UD New
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    It’s a flow indicator and temperature sensor.
    Temp and Flow.jpg
     
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  18. GrayUK

    GrayUK Openbuilds Team Elder
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    Something else I'll need to get. Was it expensive?
     
  19. Philip UD

    Philip UD New
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    ~$15 if I remember right.
     
  20. GrayUK

    GrayUK Openbuilds Team Elder
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    Cool. I'll have one of those, when I get my new spindle. I can see the need. :thumbsup:
     
  21. Philip UD

    Philip UD New
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    Necessary might be stretching it, but it does look cool and was nice to see that it doesn’t take much to keep my spindle at room temp.
     
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  22. Piero87

    Piero87 New
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    Hi,
    I just finished my OX CNC! and first of all I wanna say thank you to Mark and the community to make this thing possible :)
    My first project is using a pen to test the configuration of the CNC, i have 4 Nema 23, a GT3 6mm Belt, GT3 1/4 20 teeth pulley and an Arduino Clone + a CNC Shield v3.50 with last version of GRBL.
    I have see the suggested config of the GRBL settings in the home page of the project, and i have use some of that configuration, this is my config now:

    $0=3 (step pulse, usec)
    $1=25 (step idle delay, msec)
    $2=0 (step port invert mask:00000000)
    $3=0 (dir port invert mask:00000000)
    $4=0 (step enable invert, bool)
    $5=0 (limit pins invert, bool)
    $6=0 (probe pin invert, bool)
    $10=3 (status report mask:00000011)
    $11=0.010 (junction deviation, mm)
    $12=0.002 (arc tolerance, mm)
    $13=0 (report inches, bool)
    $20=0 (soft limits, bool)
    $21=0 (hard limits, bool)
    $22=0 (homing cycle, bool)
    $23=0 (homing dir invert mask:00000000)
    $24=25.000 (homing feed, mm/min)
    $25=500.000 (homing seek, mm/min)
    $26=250 (homing debounce, msec)
    $27=1.000 (homing pull-off, mm)
    $100=26.670 (x, step/mm)
    $101=26.670 (y, step/mm)
    $102=200.000 (z, step/mm)
    $110=500.000 (x max rate, mm/min)
    $111=500.000 (y max rate, mm/min)
    $112=500.000 (z max rate, mm/min)
    $120=150.000 (x accel, mm/sec^2)
    $121=150.000 (y accel, mm/sec^2)
    $122=150.000 (z accel, mm/sec^2)
    $130=290.000 (x max travel, mm)
    $131=290.000 (y max travel, mm)
    $132=200.000 (z max travel, mm)

    I don't have inserted all the suggested configuration because I haven't understand the purpose of a lot of them. This is the Data sheet of my Nema 23:

    IMG_0765.JPG

    If anyone can suggest me some setting i will appreciate. Anyway i'm explain here my problem, this is the svg i tried to draw with Easel:

    Schermata 2016-08-26 alle 21.57.40.png

    This is the first result:

    IMG_0766.JPG

    As you can see when finished to draw the R of IRON it should go to the top to draw the tie, instead the Z axis go down instead of go up and draw a line until the Tie. I can't understand why.
    I have tried to draw it again, with the same setting and this is the result:

    IMG_0767.JPG

    as you can see it was a problem again in the written IRON MAN, this time doesn't go down with the Z axis but the letters are not the right shape. Someone can tell me what could be the problem?

    I hope someone can help me.

    Thank you very much!!!
     
  23. Giarc

    Giarc OpenBuilds Team
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    Try this simple g-code file. It was posted elsewhere on this forum, and I used it as one of my first files due to its simplicity. If using a pen, there are two negative Z heights that will need to be changed to Z0.0 . Open the file in Notepad and "find" Z, then change the negative values so your z axis doesn't try to drive the pen through the board, then save the file.
    star.jpg
     

    Attached Files:

    #3233 Giarc, Aug 28, 2016
    Last edited: Aug 28, 2016
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  24. Tomi Hautala

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    Need little help, ive tried several weeks to get my ox work. Proplem is that i get really rough/jerky movement in low speeds(10-15mm/sec) it sounds and feels like it is fullstepping in low speed, i have it 32th stepping and i am using cnc shield whit drv8825 drivers and estlcam.
    I have 24v 10A psu
    I did try a4988 drivers but no luck whit those, i also have old server psu that have 18A and up to 60v, i tried from 12v to 36volts but no change in low speeds.

    It runs really smooth in high speeds, so if anyone can give any tips to try would be much appreciated.

    -Tom
     
  25. dddman

    dddman Journeyman
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    Did you try 1/16th or 1/8th stepping?
     
  26. Tomi Hautala

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    Yes i did and i tried even 1/4th stepping, it gets more jerky at lower steps.
    It does that on the y-axis not so much on x-axis.
     
  27. dddman

    dddman Journeyman
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    We will need a video :) What motors are you using?
     
  28. David the swarfer

    David the swarfer OpenBuilds Team
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    I just found this today...
    Power Cabristor: DRV8825 missing microsteps
    looks like the 8825 struggles at low speeds, but adding some diodes fixes it.
     
  29. Tomi Hautala

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    Ill shoot video for you, i am usin 2.8a nema 23.
    I did set current limit usin the vref, i think ill try to solder a wire to the drivers to but them to fast decay mode and see if it helps
     
  30. Tomi Hautala

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    In pololu page it says this:
    • Intelligent chopping control that automatically selects the correct current decay mode (fast decay or slow decay)
    So that soldered wire wont do anything?
    Dont know why are some people soldering that decay wire if it switches automatically to fast decay?
     

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