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Visual X axis "outta level" Indicators via Z Limit Switches

Discussion in 'Mods and Upgrades' started by jim3Dbot, Jun 3, 2015.

  1. jim3Dbot

    jim3Dbot Active Member

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    Installation added 'cause someone asked..........

    Following the forum & note'in the importance of tweakin' the z lead screws, listening for the barely audible click of the microswitches...........inspired this mod..........​
    009.JPG 010.JPG 011.JPG 008.JPG

    See youtube video..........
     
    #1 jim3Dbot, Jun 3, 2015
    Last edited: Jun 13, 2015
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Hey @jim3Dbot did you need to use a dropping resistor or are the LEDs directly connected? I might need to do this mod myself to help me visualize when the Z-Axis has hit it's limit. More precisely, just how many tenths of a millimeter the actual offset is between extruder and limit switches. It would sure help with debugging the new Marlin firmware.
     
  3. jim3Dbot

    jim3Dbot Active Member

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  4. jim3Dbot

    jim3Dbot Active Member

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    Sir Waldo, The Robo3d R1 connects the Z limits in parallel, making it a challenge to have a visual indication when one switch 'trips' before the other since the other switch is shorted across the contacts of the other.

    Here's How you do it:

    Each switch has a common contact, NC (normally closed contact), & a NO (normally open contact). Robo uses the two end switch contacts, common & NC.

    Three things you may want to know;

    1. Common & NC contacts OPEN while off the bed.
    2. Common & NC contacts CLOSE while Home on the bed.
    3. Switches must deactivate at the same time to true the X axis, as the bright ones on this forum suggested.

    By using the non-wired N.O. contact of each switch allows for the addition of the LED indicators.

    This mod is not for the faint of heart, but is worth the hour or so installation. If you are still interested, I can walk you thru the install.

    I used two T1 Leds driven from the Robos 12volt supply. Use a 1K, 1/4watt resistor in series with each LED anode,.
    Solder the cathode, negative lead to the unused N.O. contact, form the anode lead towards the spiral wrap wire harness.
    Attach a short length, a few inches, of 24awg stranded wire to the anode, heat shrink if desired. Solder other end of wire to one end of the 1k resistor. Do this on both switches. Solder a 24awg stranded wire, a few feet in length, to the other side of each resistor. Bury the resistors near the end of the spiral wrap harness.

    Lay the Robo on its side, of coarse you already have the top enclosure removed, carefully remove the flat bottom cover. It is best to lay down on its right side, the small fan cooling the Ramps driver board closest to the work table. Careful it's attached with a short wire cable. I have realized once the bottom cover was opened the cable almost prevented laying the bottom flat on the table. In my case, removing the 4 screws from the fan and rotating 90 degrees lengthened the cable nicely. The fan has polarity, notice where the red is in case it pops off the board. Before you close up unit , it would be wise to plug in the 120vac and check proper fan operation.

    Snake the two wires from the 1K resistors, thru the spiral wrap. and towards the large connector, that supplies 12vdc from the power supply to the Ramp Shield/Arduino assembly. You can use a voltmeter to locate the two +12vdc terminals. The connector may be unplugged, and both wires twisted together, then tightened into the connector. The z limit switches provide the ground for the LEDs.

    Lastly, Concerning the stock limit switch wiring: the signal wire & the ground wire must be swapped on both switches. Please cut off the hokey loose crimp terminals & solder the wires right to the switch contacts. My Robo had Ground on the N.C. contact & the signal wire on Common contact. You will need the Signal wire on N.C. & Ground on Common. Use an ohmmeter to locate ground of the switches, remember to activate the switch to isolate reading . Buzz back to that terminal block ground to be certain you have the ground wire.

    Sounds harder than it actually is, but is worth it..............
     
    #4 jim3Dbot, Jun 12, 2015
    Last edited: Jun 12, 2015
  5. regor

    regor Member

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    Would it be possible to draw a schematic of this layout?
     
  6. jim3Dbot

    jim3Dbot Active Member

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    Regor, Sure.....Let me draw tomorrow & I will post..........Take Care...........Jimmy
     
  7. regor

    regor Member

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    Thanks Jimmy, I kinda do better with a schematic, it seems I get lost in reading about it, but between your explanation and the schematic I should be able to get on the right track.
     
  8. Robert Foreman

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    Well I see the next mod I will be doing. :)
     
  9. regor

    regor Member

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    If you beat me to it, let me know how you make out. I really like the idea of the IR sensors over the mechanical switches, as long as the electronics of the board hold out.
     
  10. jim3Dbot

    jim3Dbot Active Member

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    .BMP zipped schematic for wiring of Robos' R1 Limit Switches...........Hope this helps Bob & Regor
     

    Attached Files:

    Geof likes this.
  11. jim3Dbot

    jim3Dbot Active Member

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    PCB Boards hold up very well....many in use.........
     
  12. regor

    regor Member

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    Thanks for the schematic, it paints a good mental picture for me!
     
  13. jim3Dbot

    jim3Dbot Active Member

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    Glad it helps Sir Regor........
     

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