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Plasma cutting

Discussion in 'CAM' started by David Miner, Mar 1, 2019.

  1. David Miner

    David Miner Well-Known
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    When the head moves to the starting point the Z axes should go down to the material and at that point it starts cutting and stays on until it gets to the end of the cycle then stops cutting and raises up and moves to the next position and repeats the process. I have a relay connected to the motor connection on the board which has 5v and makes the contact to my plasma cutter.
     

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  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    So you declared what you want it to do... but what DOES it do on the machine, etc.

    If its from openBuilds CAM, please provide Workspace export (obc file)

    The more details you give the easier it gets for us to help you
     
  3. David Miner

    David Miner Well-Known
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    Using the Open Builds CAM (OB) in the first file (2) when running the machine it will go to the first hole then the Z axes will lower and send a signal or power to the relay for a split second then off and the machine will start moving around the hole without power to the relay which is my switch for the plasma when finished with that hole the Z axes will raise up and move to the.next hole and repeat the same. Once it get to the Center large diameter hole the relay will do the same but it will click off and on all around the circle. Now when it goes to the square it lowers and the relay turns on and will stay on until it gets to the corners then it will momentarily turn off and turn on the relay like a break in the corner.
    The square was made from the program square tool and not from lines. So no broken thread
    The Coyote program will just run around and not activate the relay at all. It's just like running the simulation. It does not raise and lower the Z axes at the start of each segment nor any power to the relay.
     

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  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Still don't see the OBC export... I really want to help you man, but can't without it :(

    So without it best I can throw your way is generic tips:

    In OpenBuilds CAM
    1. Use a drag head setup, with a Probe switch wired to trigger when the tip contacts the material
    2. Setup your IHS Gcode on the settings tab
    3. Enable Use IHS on the Plasma cutting toolpath (IHS = Initial Height Sensing)
    4. IHS uses the Probe+Zeroing between entities, it doesnt really show up as Z moves as its not. It just lifts up to Z-Safe height, and then probes+zeros as per your IHS gcode from the setup tab
     
  5. David Miner

    David Miner Well-Known
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    Now we are getting to the problem. I made an other program File 4 which is 4 holes 25 mm radius. the first hole has 32 segments the second 64 the third has 128 and the forth has 256. the first one did not turn on the relay but the other 3 did. They started for a split second turn off and then turned back on again. the rectangle is still turning off in the corners so I guess it has broken lines. the Z head is moving up and down correctly. I'll try the IHS.
     

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  6. David Miner

    David Miner Well-Known
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    When I run OB program with three circles the light on the solid state relay comes on when cutting and there is a solid 4v but no action to the other side which is 24v to make contact with my plasma. I don' t know why, as it is rated for 30v on the low side. when I run the BOBCAD/CAM nothing happens not even a signal to the board with CNCjs cam.
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Solid state relay wont work well to close the trigger on a plasma.

    Tell me a little about the wiring? Took the two pin plug of the hand torch cable, and trying to close it with a relay?

    In that case, you need a MECHANICAL relay. SSR wont work, as it expects AC, and most of the cheaper chinese plasmas have a 24vdc trigger circuit.

    As the light on the SSR comes on you know the controller output is perfect.

    Now just replace the SSR with a mechanical relay US$4.80 2Pcs 5V 1 Channel Level Trigger Optocoupler Relay Module For Arduino Module Board For Arduino from Electronics on banggood.com will do fine (i used it till I got my Blackbox)

    Or put the xpro aside for a CNC machine project, and get a BlackBox OpenBuilds BlackBox 4X Documentation when they get back in stock (2-3 weeks from now)

     
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    The board just does what the GCODE says.

    You need to add M3s before each cut path and M5 afterwards. Setup your post processors on BOBCAM to add tool on/off commands before each cut entity. Speak to BobCAM support how to do this, I dont know it, dont own it.
     
  9. David Miner

    David Miner Well-Known
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    I will talk to BOB/CAD about turning on m3 and m5 but thous are the same SSR that I purchased. I have one SSR connected and the ground is connected to the - side and the variable spindle to the + side of the SSR. On the other side I connected to the N/O and the other to com post. I be leave that is right I then disconnected the two wire to the plasma machine and when it touched the wires the plasma turns on.
     
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Thats not an SSR...

    They need a 5v supply too, to power the mechanical relay on the other side of the ootocoupler. You dont mention having the 5v supply wired in?
     
  11. David Miner

    David Miner Well-Known
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    yes I do, and it has 4 volts coming into the SSR from the spindle side of the board. the light turns on showing that it has current to the board but wont close the circuit on the other side. It came with two SSR so I will try the other one to see if it works
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Theres still some confusion.

    This> Is a SSR (Solid State Relay)
    ssr.PNG
    This> is a Mechanical Relay:

    relay.PNG

    So Question no 1: WHICH DO YOU HAVE?
    Referring to the wrong name adds confusion - can't help you with it if I dont know what you have?!

    Secondly: If its a mechanical relay, the 5V SUPPLY I refers to is NOT the 4v signal you refer to.

    The Mechanical relay board needs 3 wires off the controller:
    GND = GND on the XPRO (labelled DC- on the Mechanical relay image above)
    SIG = Signal from the Variable Spindle Output (Send M3 S1000 to turn it on) (labelled IN on the Mechanical relay image above)
    5V = Always on 5v DC supply to power the COIL in the relay. (labelled DC+ on the Mechanical relay image above) - The little transistor or optocoupler on the board pulls this 5v through the coil in the relay. Without this 5v supply going to the Mechanical Relay Board you'll get the LED (before the optocoupler/transistor) but nothing will happen on the other side of the board after the optocouler/transistor.

    the other side has the RELAY OUTPUTS: COM, NC and NO. Depending on the board your required action might be between COM and NO, or COM and NC - do not assume the labelling is correct, I had many where they soldered the mirror image relay onto the boards. Test with a Multimeter in continuity when you send M3 S1000 which pair closes.
     
    #12 Peter Van Der Walt, Mar 22, 2019
    Last edited: Mar 22, 2019
  13. David Miner

    David Miner Well-Known
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    Thank you, I am using the Mechanical Relay and I didn't have the 5v wire connected to the board, now I have three wires connected. I'm trying to get the CNCjsc panel set up.
    When I talked to BobCam this morning they want to compare the OB against there setup. They did make some changes as for the M3 and M5 but I have to show them the OB how it is.
    It was running early this morning and now I can't get it to run. I went into trouble shooting and made sure i had the controller to XPro 4 and I tried both the Grbl F and G versions and still nothing. It shows the drawing and the G Codes but I can not run the program or move the machine manually in the different axes so with out the OB working I can't try the relay to see if it is working OK.
     
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  14. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    did you set $4=1

    NB to do so.

    Also stay on Grbl 1.1f. The G-prerelease is for Acro laser users only! Has specific Z-Homing-disabled functions
     
    #14 Peter Van Der Walt, Mar 22, 2019
    Last edited: Mar 22, 2019
  15. David Miner

    David Miner Well-Known
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    Yes the $4=1 is correct. I do have the SSR working. with the Ohm buzzer it shows it turning on and off. .Once I connect it to the machine, it will make an arc and the board will shut down. Red lights came on at the XYZ next to pins. The SSR has a low and high jumper pin I tried it both ways and the same. your right when you put the jumper on say the low side NO is correct wnen you put it on the high side the NO becomes NC.
    Are we getting some kind of feed back?
     
  16. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Cheap plasma inverter? Or something decent like a Hypertherm. Two kinds of starting systems on the market. Sub $500 is usually HF (a 4000-10000v prearc). Decent plasma inverters doesnt use HF start. They use Blowback starters. HF puts out tonnes of EMI. If you have a HF model (High Frequency) you will have to add EMI protection :

    Put board in metal case 10 feet away from machine and 20feet from inverter if you can. Further is better. Ground the case to spike in floor. Add Ferrite cores on EVERY cable before it enters your box.
    Run pc off seperate mains circuit from inverter
    Use screened cable for everthing.
    Ground screens of all cables in a star formation near machine. Ground inverter chassis.
     
  17. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Mine runs great on similar hardware and a $200 chinese plasma it can be done. Juat spend some time eliminating EMI. Compressor kicking on also spikes the mains circuits...
     
  18. David Miner

    David Miner Well-Known
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    Well it might be a toss up. Yes I have a really good plasma cutter that I can cut up to 16 mm plate. I put the machine in a metal box made for circuit boards with the power pack and I have 15 ft of torch cable, I put the cutter outside and then I closed the metal garage door as to shield it and still the same problem. I just get a small arc and then everything shuts down and the program closes. I was looking at enclosures but could find some made of die cast aluminum but not sure if that will work. This will turn out to be costly so I might look at purchasing another plasma cutter for up to 3 or 4mm.
    Any suggestions?
     
  19. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Try getting some clip on ferrites and cover every wire going to the controller (as close to the controller). Each wire coming out acts like a couple feet of antenna.
    the little Ferrites do wonders for noise suppression, they are like magic!

    If that doesnt help, it might be time to rethink a couple components in the system :)
     
  20. David Miner

    David Miner Well-Known
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    The box has circulation vents on each end would that also cause a problem
     
  21. David Miner

    David Miner Well-Known
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    Will the new black box solve this problem. I sent back to Mike my V3 that i bought with my machine as i couldn't get it to work so could I up date to the black box and I'll pay the difference. I haven't heard anything back about the board I sent him.
     
  22. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Its would improve it (prewired relay etc will help make it easier too) . But i cannot guarantee it will make it all go away. I'd still get a bunch of ferrites to install on all cables plugging into the Blackbox as it looks like your setup has some heavy EMI.

    And of course good grounds everywhere...


     
  23. David Miner

    David Miner Well-Known
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    I have to get my Plasma operating. I will build a new case with through case plugs (like for audio plugs). I have purchased cable suppressors and I have everything grounded, the Plasma machine, the board housing and I also put aluminum tape over all holes except the vents and the CNC frame is grounded to the metal building. I still put the machine out side the garage and closed the door. .
    I tried to cut but still the same. What about my laptop, will this effect the my laptop?
     
  24. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Yip anything electronic has to be shielded. Ferrite cores on all cables going into PC - near it as possible. Laptops has plastic cases.... a good old metal cased desktop is whats in my shop
     
    Mark Carew likes this.
  25. Rob Taylor

    Rob Taylor Master
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    When you say the XYZ red lights came on, is that the HF spiking your limit lines? If they're not shielded and ferrited, that could be something, but it may also be something weird like it inducing an arc in your microswitches or something completely off the wall like that. I'd consider changing the type of limit to see if that does anything- if you have active high, try active low. Maybe even go to proximity sensors (capacitive, not magnetic, I would suspect in this case).

    Also, in your code you have "M4 dynamic laser power on"- this will reduce PWM power in the corners as the absolute velocity of the head slows down. This might be low enough to un-trigger your relays if you have grbl set to pay attention to this. Make sure $32=0.

    However, when $32=0, the machine will pause at every S command (because mill spindles have momentum). Make sure you strip out all of the "S1000"s where they're not needed or you're gonna blow holes at corners). Can you get your CAM to output true arcs instead of piles of lines? Grbl will split them up into much smaller lines (a few microns?) itself in motion planning, you don't need to do it for it. Something that looks like "G3 X25.866 Y21.637 I-1.866 J-0.714" instead of those massive paragraphs of tiny lines.

    It would probably be better to manually write some lines of code until you get the operation figured out and understand how you need to post-process the output. CAM does NOT output machine-ready code (sometimes even the post-processor doesn't either, depending on how specialized your machine setup is). For example, based on your OBC output code, with zero somewhere in the middle of the sheet and cutting height Z-2:

    G21 G54 G90 G17 G94

    G0 X0 Y0 Z0

    G1 F300 Z-2
    M3 S1000
    G1 F1000 X50
    G1 Y40
    G1 X0
    G1 Y0
    M5
    G0 Z20

    Should cut a hard-cornered 50x40mm rectangle and safe retract. As long as you don't change your feed mode- and there's no reason to on a plasma- you don't need a feedrate in every line unless it's changing.

    G21 G54 G90 G17 G94

    G0 X50 Y0 Z0

    G1 F300 Z-2
    M3 S1000
    G3 F1000 X0Y50 I-50J0
    G3 X-50Y0 I0J-50
    G3 X0Y-50 I50J0
    G3 X50Y0 I0J50
    M5
    G0 Z20

    Should do a 100mm diameter circle about your zero point.

    Do simple, short codes like this for testing until you figure out the systemic issues. You don't want CAM problems and machine problems simultaneously or you'll never solve either.
     
    SpringBob likes this.

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