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OpenBuilds OX CNC Machine

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

  1. Rich C

    Rich C New
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    Rhinofart, I have no idea what the nan's were.

    I did a $defa=1 reset and it cleared out and defaulted correctly :)
    CoolTerm'ed in and set all of my settings
    Started tgfx, connected, and everything worked perfectly. Ran a test and ran perfect. Now to finish up my last calibrations....distance checks, etc.

    How does everyone validate their z travel? (max) ... from all the way up, to top of scrap, to bottom of scrap, (zero) up or down etc.


    Now to buy 3 more switches...
    Rich
     
  2. asb_79

    asb_79 Well-Known
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    Here are some conservative measurements from my machine for the cutting area lost due to the shape and size of the Gantry parts. This will vary a little depending on the type of spindle mount you use.

    You'll lose 85-90mm on each side of the X-Gantry and 230-250mm in the Y direction.
     
  3. Rich C

    Rich C New
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    To chime in with asb_79 above, My OX is X=750mm and Y=1500mm (frame build). My actual working area is 570 x 1220 point-to-point (and I am using a 5mm buffer from that in my settings - $xtm=565 and $ytm=1215)

    I am still trying to work on getting my Z how I want it....(adjust mount up/down, adjust spindle up/down in mount) to get my desired travel...could use some input on this from anyone...

    Rich
     
  4. asb_79

    asb_79 Well-Known
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    Just wanted to share what I've used for my OX table.

    I used the machine to drill the series of holes in a sheet of 17mm formply, then I pressed in M5 T nuts from the underside, I'll use offcuts and/or metal clamps to secure my work pieces to the table. I'll use a thin sacrificial layer between the workpiece and the table as I don't fancy replacing it.
     

    Attached Files:

  5. Robert Hummel

    Robert Hummel Custom Builder
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    Ideal spot for you spindle is achieved by making sure your collet and bottom of the Z are at the same level.
    So if you had a flat surface the collet and Z would sit flat
     
  6. Robert Hummel

    Robert Hummel Custom Builder
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    Wow nice job, 160 T nuts !
    Man that must have bin fun :)
     
  7. Robert Hummel

    Robert Hummel Custom Builder
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    I'm working on mine also, along with the power supply mount :)
    image.jpg
    It's 3/4" MDF
    Just test fit after cutting it.
    Sits inside the frame as my supports are 20x60 :D
     
  8. asb_79

    asb_79 Well-Known
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    The number of t nuts I used seemed like a good idea until I started hammering them into place! Hopefully I won't mess it up to soon.

    Where are you mounting your power supply? I'd be interested in some ideas. Mine is just sitting on a bench beside the table right now.

    In hindsight I should have used 20x60 for the central supports too. I didn't realise the clearance between the z-axis and table would be so little. I probably will do that mod in the coming weeks.
     
  9. Robert Hummel

    Robert Hummel Custom Builder
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    The power supply will be mounted under the bed in the open space underneath :)
    Also you can't see it "will take a pic tomorrow" but it's 2 x 20x60 and 2 x 20x20 mounted to the side 20x80 to support the ends of the bed
     
  10. asb_79

    asb_79 Well-Known
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    Did you run your table supports across the bed or length ways per the build vid?

    I used 2 20x80 rails length ways, but with this height there isn't much room between the table and z-axis (maybe 45mm, allows for ~20-25mm depth of cut), I want to change them out for 20x60 soon.

    Also, I noticed that the table wouldn't be well supported on the outer sides with only the central supports, they deflected a bit when I leaned on it. To solve this I fixed two lengths of 20x20 Aluminium angle to the 20x80 side rails at the same height as the centre supports, then screwed the table to these too.
     
    Robert Hummel likes this.
  11. Robert Hummel

    Robert Hummel Custom Builder
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    Like the video I just used 20x20 extrusion where you used the angle
     
  12. Paruk

    Paruk Journeyman
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    Are you still talking about the Z limit switch?

    Here's what I think about it. Lets assume I set the limit switch so it will trigger 3mm before my spindle (without cutting tool) reaches the table. Now, I load an end mill that sticks out under the spindle collar with 1.5". When that end mill starts to work its way into my table (wether it runs or not) the limit switch will not be triggered until the end mills is already through my table with 41.45mm ((1.75" x25.4mm)-3mm). If it runs the damage might be just a hole in the table, but if that happens with the spindle turned off, Ouch! That will definitely screw up my gantry beams and possibly more. One tends to start to rely on a device like that and there is where it goes wrong one day (you can wait for it!).

    By not having a limit switch for the maximum depth I can easily train my brain to be extremely careful with jogging the Z up and down. Creating a permanent awareness because there is nothing to help you protect from going through the table is in my opinion more effective and less risky than a limit switch that will fail to stop your Z downwards because your cutter is longer than the one you used for calibrating the limit switch.

    What I find a bit more effective, and I just installed it on my table, is a tool offset sensor. USB CNC Controller software works great with that and makes it possible to make a tool change in between the work, have the tool offset reset, the new tool length measured and the new tool length offset applied. That way the Z will stop going downwards when it reaches the zero with the tip of the tool. Check Planet CNC's videos for how that works.
     
  13. Rich C

    Rich C New
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    Is it normal to have different $_tr=_ _ numbers for X and Y?? I am using the same motors, pulleys, and belts on both axis, but X=59.4 and both Y's ($2tr_ _ and $4tr=_ _ ) are 59.62

    I measured these on 500mm runs and these are the numbers that put me there.

    I am using NEMA23's
    GT3 belts
    20 tooth pulleys
    (all from OpenBuilds)

    and from my settings:
    1.800 deg step angle
    8 microsteps

    I just want to make sure that this is possible, or do I need to look for some type of misalignment or something.....

    Rich
     
  14. David the swarfer

    David the swarfer OpenBuilds Team
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    seems reasonable to me given belt stretch.
    the theoretical number is
    3x20 = 60mm per rev
    3 (space between teeth on belt)
    X
    20 (number of teeth on pulley)

    you pull the belt tight and it stretches a little so a full rev would go too far, so you reduce the mm/rev number to compensate.

    just remember to recalibrate if you adjust the belt tension.
     
  15. Robert Hummel

    Robert Hummel Custom Builder
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    The Fiber OX is getting 6061 spacers
    Mounting the Z motor and wiring it now.
    image.jpg
    Then it's just a matter of the control wiring :)
    Waiting on the last drag chain and then the real test :D
     
    asb_79 likes this.
  16. alisdair.harden

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    Hey I am looking to build a CNC router and this by far the coolest one I have found so far. This might have been covered already but can you comment on the accuracy of this router machine. Would it be suitable for making plates out of perspex for a letterpress machine? fine detail and the such
     
  17. Robert Hummel

    Robert Hummel Custom Builder
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    We'll all together and now the waiting game lol

    image.jpg

    image.jpg

    Just need the power supply and drag chain :D
     
    #1607 Robert Hummel, Oct 14, 2014
    Last edited: Oct 14, 2014
  18. DiggerJ

    DiggerJ Journeyman
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    Ooooooh...Pretty! Great work as always. Your special touches make the builds super nice.
     
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  19. Paruk

    Paruk Journeyman
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    Little teaser of what I was up to, today. Building a dust shoe for The Buffalo. Screen Shot 2014-10-15 at 20.34.46.png

    Some tweaking yesterday evening and this morning gave me a maximum error on the X of 0.1mm on the Y no error. So did two test cuts for the acrylic plate of the dust shoe. The cutting was done in MDF and turned out exact enough to give it a shot on the acrylic. HELLO Mr. Murphy glad you're here too! The compressor kicked in, I pulled the plug and next thing was that The Buffalo started to follow an unknown path. Emergency button BANG! Did a system reset and tried again. Well that one went right until it came at the second pass of the profile cutout. Slowly but surely The Buffalo started to look around and as a drunk Thai followed the intended tool path. EB Bang again!

    So, today was finished with glueing a part of the spoiler board in the table. Tomorrow another try with the dust shoe. The parts in red are already printed and it all fits snug and perfect. (Were it not for a drunk Buffalo!).:banghead:
     
    #1609 Paruk, Oct 15, 2014
    Last edited: Oct 15, 2014
    asb_79 likes this.
  20. asb_79

    asb_79 Well-Known
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    Hi Prauk,

    One of my friends had a similar issue where part way through the job the movements started getting erratic. Turns out the drivers were going into thermal shut down. Once cooled adequately it was fine.
     
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  21. Paruk

    Paruk Journeyman
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    Thanks for the tip, asb_79! I just did a partial leveling of the spoiler board, this time with an extra fan blowing at the electric box. No issues, all went well. Lots of passes, but not a lot of stress on the system since the leveling is very shallow cutting.

    While on it and looking for a good solution to hold workpieces on the table I must have had some kind of divine inspiration about mounting a vacuum device under the table, between the two longitudinal support beams. Drill holes in the table and there you have a vacuum hold down. Any thoughts about this?

    It helps to give the machine more rigidity and more weight on a low gravity point. It can be made easily out of some MDF and the v-slot support beams are giving enough places to hold the vacuum device in place. Off to SU and see how that turns out. :)
     
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  22. Paruk

    Paruk Journeyman
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    There you have it! An Openbuild with an under build vacuum table facility (device, whatever).

    Screen Shot 2014-10-16 at 18.58.57.png Screen Shot 2014-10-16 at 18.59.51.png Screen Shot 2014-10-16 at 18.59.21.png

    What I forgot to draw is the supports within the vacuum box. This can be simple strips of MDF (18mm) glued in between the rows of holes. This prevents the box from being deformed by the vacuum.
     
    #1612 Paruk, Oct 16, 2014
    Last edited: Oct 16, 2014
    Mark Carew likes this.
  23. dddman

    dddman Journeyman
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    I have this vacuum pump waiting for me in my basement... I don't know what to do with it... maybe a vacuum bed would me a good idea :p Maybe a little bit overkill though ;)

    [​IMG]
     
  24. Rich C

    Rich C New
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    dddman, it's never overkill if you already have something that can be utilized and don't need to spend money on something else (unless, of course, what you already have is so powerful that it will cause damage) ;)

    Rich
     
  25. Rich C

    Rich C New
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    Prauk, I have thought about something similar, based on that same video that Rick 2.0 attached. But, I don't know if I want to try to mess with a bunch of vacuum switches set up for different areas for different size work pieces, etc. Might be more work than wiring a switch layout for an electric train. Probably worth it - and I do like the thought of one...maybe I will attempt building one... Good luck with yours, let us know how it turns out.

    Rich
     
  26. Rich C

    Rich C New
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    So now for my item. Can anyone post a primer of sorts on how to go from a CAD, to cutting with tgfx please? For example, after creating your item in, say, sketchup, save the file as xxxxx. Then convert it to xxxxx extension using this software. Then, open it in tgfx....etc. I will be using Sketchup and BOBcam/cad, and maybe Inkscape, to create my work. But I don't know the process to get it from there to tgfx. Nor the extension(s) that should be used between each. Unless I have missed something somewhere in this forum, I didn't see something like this for a beginner. I would greatly appreciate it as might others. :)

    Rich
     
  27. David the swarfer

    David the swarfer OpenBuilds Team
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    i might be biased on this, but.....
    I would just use Sketchup with the SketchUcam plugin. This generates Gcode directly from your Sketchup drawing.
    (watch the various instruction videos on using it, http://www.phlatforum.com)
    Then you open the Gcode file in tgfx , set zeros for the material you are using, and away you go, cutting.

    Gcode is a simple text format file using the simple language developed in the days of paper tapes for giving instructions to machines.
    It contains quit a lot of possible codes but SketchUcam uses only the basics so it can be used with any CNC controller:
    G codes are for movement:
    G0 - move rapidly, not cutting
    G1 - move at cutting speed
    G2 G3 - cut arcs
    G20 - cut in inches
    G21 - cut in metric
    G90 - use absolute co-odinates

    Then you get some M codes, which are machine control commands
    M3 - spindle motor on clockwise
    M5 - spindle off
    M30 - end of program

    so for example:
    G21
    G0 X30 Y50
    moves the cutter to 30mm from the 0 in X, and 50mm from the 0 in Y
    G1 z-1
    G1 X50
    that moves the cutter down into the work (Z = 0 at surface of material)
    and then cuts from 30 to 50 in X direction.

    Sketchucam normally outputs files with the extension '.cnc' but you can change it to whatever tgfx prefers, usually '.cnc. or '.nc'.
    (read about default options in the help)
    As above, just a plain text file with instructions for machine control and movement so the extension does not really define it.

    you should read this https://github.com/synthetos/tgFX/wiki
    before cutting.
     
    Chris Laidlaw and Mark Carew like this.
  28. Astropoy

    Astropoy New
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    Hi,
    I'm trying to inquire for the gantry plates. Having difficulty finding one in the U.S. any suggestion preferably Socal/long beach area.
     
  29. DiggerJ

    DiggerJ Journeyman
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    From the first page of the build:


    • Chris Laidlaw is in your neck of the woods. Robert is north of you in Canada. I have worked with both of them and you will not go wrong with either choice.

    • I believe Anthony is in Australia.
     
  30. Astropoy

    Astropoy New
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    I believe i pm'd all of them in the link, but Anthony was the only one who replied back. I'll try to contact the other 2 again
     

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