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OpenBuilds OX CNC Machine

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

  1. GrayUK

    GrayUK Openbuilds Team Elder
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  2. hydroquads

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    I work at a Cnc shop and guess who runs the water jet hehehe going to cut these plates out soon I have the file ready to cut. I would be able to pump these plates out quick going to see how they come out
     
  3. Daryl

    Daryl Well-Known
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    Hi Guys, I need some help,

    The Machine Configuration

    X and Y Axis
    200 Steps/Rotation Stepper 1.8 degree - http://openbuildspartstore.com/nema-23-stepper-motor/
    20 Tooth Pulley - http://openbuildspartstore.com/gt3-aluminum-timing-pulley-20/
    3mm Belt Pitch - http://openbuildspartstore.com/gt3-timing-belt-by-the-foot/


    So Using the Calculator at - http://prusaprinters.org/calculator/
    I get the following results:
    Result Resolution Teeth Step angle Stepping Belt
    53.33 18.75micron 20 1.8° 1/16th 3mm

    Z Axis
    200 Steps/Rotation Stepper - http://openbuildspartstore.com/nema-17-stepper-motor/
    Direct Coupled to
    8mm/Rotation Acme Screw (TR8*8, 4 Start, 2mm Pitch, 8mm Lead) http://openbuildspartstore.com/8mm-metric-lead-screw-acme/


    Result Resolution Teeth Step angle Stepping Screw Lead
    400.00 2.5micron 1 1.8° 1/16th 8mm


    I am Using Grbl 0.9g

    I Enter the commands
    $100=53.333
    $101=53.333
    $102=400

    I Zero the Axis's

    then I Enter G0 X1 Y1 Z1

    I get Machine Position:
    X:0.994
    Y:0.994
    Z:1

    Instead of X:1
    Y:1
    Z:1

    What am I doing Wrong?

    Thanks for your help.
     
  4. Robert Hummel

    Robert Hummel Custom Builder
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    Nothing :)
    Adjust your 53.33 to 53.34 and so on till the numbers add up ;)
     
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  5. Miguel Castillo

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    I would like to know if the 3 axes driver board can do 3D carvings, and if yes it requires special software, I will like to know if you are planning to sell the special plates too, I inquire for doing the plates locally on a machine shop and is really expensive. There are a couple of items that it state there are out of stock, are you plan to have them soon. I added all the parts together and is around $700.00 I think if I can find somebody who can made the plates it can be a very affordable CNC machine.
     
  6. dougsnash

    dougsnash Journeyman
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    Miguel, I'm not sure where you are located but I got my plates from Chris Laidlaw in California through eBay. I seem to recall they were about $150 but I don't recall exactly how much they were. The plates Chris made are absolute pieces of CNC art and are well worth what I paid for them.
     
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  7. pierry

    pierry New
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    i have problem with my OX to do circle :-( . i also order new driver and controller card ..i was hoping that it should help but no..same problem...everything else work fine but circle is not good...other with OX with that problem ,,or any idea what can be wrong..
     
  8. Robert Hummel

    Robert Hummel Custom Builder
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    Is the circle the same every time?
    Cut the circle twice and compare
    If it is consistent the your problem lies in your software.
    If not something mechanical is the issue like belt slip or binding somewhere is my guess
     
  9. pierry

    pierry New
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    i think i found the problem...the x was to tight.......now with my new ontrollercard my stepper motor get really hot.....why,, i put the rate to 2,7A ..it is nema 23...should i lower the rate or is it ok if they get really hot ??c IMG_2723p2.jpg
     
  10. dougsnash

    dougsnash Journeyman
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    Pierry, I'm going to guess you are having an issue with belt tension. Make sure your belts are good and tight for the X-Axis and both Y-Axis belts. Slack in the belts can cause misshapen circles as the same number of steps will not equal the same physical movement. Failing a loose belt, I would guess the problem is one of the axis are electronically dropping steps. Check you driver configurations, provided the motors are the same, the configuration should be essentially the same for the X-Axis and one of the Y-Axis drivers (with the second Y-Axis set up to turn the opposite direction).

    Hope this information helps.

    Doug M
     
  11. Robert Hummel

    Robert Hummel Custom Builder
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    Burning hot is not good, warm but able to touch is normal.
    I would say be 100% your drivers are set right, I know not much documentation is provided in most cases.
    If I'm correct the drivers I'm seeing are capable of 3.5 amps so maybe your higher then you think.
    Try dialling it down to 2.5 and see how that works for you.
    The resistors used in the dip switch setting circuit will have a +/- of 5%
     
  12. Past

    Past New
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    Hi all,

    This is my first post here. I've been headscratching about building my first CNC. I have been considering a CNC Router Parts machine, or an OX.

    I'm wondering if the OX is capable of cutting aluminum?

    Is the design of the smaller v-slot rigid enough for consistently accurate cuts? (compared to the larger 80/20 extrusion)

    How does the belt drive mechanism compare to an ACME screw or rack/pinion drive system?

    Has anyone mounted a full size router on their OX?

    Thank you,
    Past
     
  13. Jeremy Young

    Jeremy Young Well-Known
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    Hi Past,

    I am also interested in cutting aluminium plate, mainly just profiling up to 10mm thick. I have heard it can be done but I am not sure on the accuracy. My build is currently in progress, so I haven't had a chance to test.

    J
     
  14. Jeremy Young

    Jeremy Young Well-Known
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    Hi All,

    My Ox seems to be running quite well, have installed homing limit switches and the homing cycle seems to run well.

    I have a couple of questions:

    Is it possible to speed up the feed rate for the homing cycle?

    Also, It seems that the "Reset Zero" button doesn't work in Universal Gcode Sender V1.07, I get "error: unsupported command".

    Although it works fine in V1.06, my workflow is as follows: Turn on machine, use $H to run the homing cycle, Jog to a desired work Co-ord position, Press Reset Zero button to set my Work Co-ord, Run Gcode program.

    Has anyone experienced this issue in V1.07??

    Cheers,
    J
     
  15. davidbrowne

    davidbrowne Journeyman
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    Finally finished my OX! I've powered it up and run a few small tests, and I'm not really happy with sounds the z axis makes, do other machines sound this buzzy? The x axis sounds very smooth, and the y axis not far behind. I have yet to tune parameters but I really have no idea where to start. And how do I know the maximum feed rate and acceleration settings? Is it just a matter of trial and error or are there general guidelines to follow? I would appreciate any advice given in this area.
     
  16. Tweakie

    Tweakie OpenBuilds Team
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    Hi David,

    The maximum Velocity and Acceleration settings are usually found by 'trial and error' (just as you thought). When you have found the maximum for each axis (when the motor occasionally stalls) then reduce the Velocity and Acceleration settings by approx. 30%. This will then give a 'reliable' maximum rapid speed for each axis.
    The 'Feed-Rate' (G01/Go2/G03 moves) used, for any particular job, will of course be much slower than your 'rapids' (G00 moves) and will vary dependent on material being cut etc. etc.

    With belt driven axis it is often prudent to set the Velocity and Acceleration settings lower than the method mentioned above to prevent the possibility of the belt slipping on the drive pulley. In general choose settings that you and your machine are happy to run with. :thumbsup:

    Hope this helps.

    Tweakie.
     
  17. John Meikrantz

    John Meikrantz Veteran
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    David, the GRBL wiki has some good info on testing for the best settings for speed and acceleration.
    https://github.com/grbl/grbl/wiki/Configuring-Grbl-v0.9

    I had similar "buzzy" z axis, which was cured with increased settings for speed/acceleration.

    My settings that seem to be working well:

    $0=10 (step pulse, usec)
    $110=7500.000 (x max rate, mm/min)
    $111=7500.000 (y max rate, mm/min)
    $112=2000.000 (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)

    More discussion of tuning is in the myOx build thread:
    http://www.openbuilds.com/threads/myox-a-4-x-2-ox-with-potential.530/page-8

    Also check out the discussions in the CNC xPro build:
    http://www.openbuilds.com/builds/cnc-xpro-driver.643/

    -- John
     
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  18. davidbrowne

    davidbrowne Journeyman
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    @Tweakie and John
    Thanks Guys, I have a few days off, so we will see what I can accomplish.
     
  19. Paruk

    Paruk Master
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    A true steam punk CNC

     
  20. Tweakie

    Tweakie OpenBuilds Team
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    Steam Punk indeed :)
    I must admit, I have never seen anything quite like that before - thanks for posting the video.

    Tweakie.
     
  21. Paruk

    Paruk Master
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    There's no end to human imagination…..;) Very unique this one.
     
  22. TMG

    TMG Well-Known
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    What in earth would someone use such a big CNC Router for? Is he going to mill his own V8 engine out of aircraft specified Aluminum?
     
  23. GrayUK

    GrayUK Openbuilds Team Elder
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    Probably!!!! :D:D:D:D
     
  24. KerryH

    KerryH Journeyman
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    Well, after a ton of research and dreaming I finally placed an order for most of the mechanical parts of the small ox. I was disappointed that some of the crucial items were out of stock, but hopefully they will come back in soon.

    Can someone shed some light on what their preference would be between TinyG and CNC xPRO? Functionally they seem very similar to me.
     
  25. SlyClockWerkz

    SlyClockWerkz Veteran
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    The machine is capable, although I wouldn't want to do it regularly or for production use. Its going to be different for everybody as well, depending on your electronics setup, spindle etc..
    My machine runs a hobbycnc pro driver @2.8A to my motors @36vdc (200oz-in motors) and a dewalt 611 router. The small amount of aluminum that I've milled has been at about .020" doc @ ~20imp. Using a single flute .125" endmill
    3/8" 6061
    [​IMG]

    Hope this helps
     
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  26. Jeremy Young

    Jeremy Young Well-Known
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    Thanks for your reply @SlyClockWerkz . I look forward to giving it a go!
     
  27. SlyClockWerkz

    SlyClockWerkz Veteran
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    Just a bit of oil here and there.
     
  28. David the swarfer

    David the swarfer OpenBuilds Team
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    please don't use 'oil', especially on aluminum.
    (and if you meant 'proper cutting compound that is oily' then please say that, newcomers cannot tell the difference unless we tell them properly!)

    common oils are way too good at the job of lubricating to be good for cutting, where you want the oil to break down early and allow cutting freely, yet prevent the chips sticking to the tool.
    on aluminum, you can use kerosene (or beeswax rubbed onto the cut area)
    on steels, you can use chicken fat, collected from the roasting dish.
    on most brass, don't bother, they are self lubricating.
    on copper, good luck, cutting toffee with a brick is mostly easier (-:

    those are the cheep options, you can of course buy dedicated cutting compounds for any given material, and they are amazing when correctly used.
     
  29. David the swarfer

    David the swarfer OpenBuilds Team
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    btw sly, is that my code/drawing you used for that dragknife holder? I remember helping you with the method of cutting that thing.
     
  30. Steve123

    Steve123 Journeyman
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    That's a Grunblau drag knife designed by Brian Oltrogge.

     

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