Wiring

These things still need to be wired.  See note #5 in the Additional Notes section of this project page if this is confusing.

    • limit switches
      interfacePCB
      — x, y, and z switches should be closed to ground when not at limit.
      — there is only one z limit connection on the connector ( J3-1 ) in the wiring diagram, while the frame and gantry schematic calls for two.  A top and bottom one have been installed. I think we should just wire the bottom one to it and change the corresponding code, or wiring if necessary.
      — The connector that the limit switches are wired to (connects to J3 on the interface PCB) has a pin ( J3-2 ) for Input 13 which is connected to a pin ( J1-13 ) on the J1 connector, I assume this should be left floating on the end the switches are wired to.
      — The cover switch is in series with the Emergency stop return ( J2-8 ) and the water monitor switch ( TB4-1 ).  This means the cover switch should be wired the opposite way of the x, y, and z switches.  It should be closed when it is at limit (pressed).  This is because the safety loop of Emergency stop, cover switch, and water monitor should be closed to ground when all safety features are in the position for the laser to fire (see Emergency stop switch section).
UPDATE – 9/4/2014
The x and y switches were wired wrong but I rewired them in the correct configuration and wired up the bottom z switch.  The wires coming from all the limit switches are longer than needed but I haven’t trimmed them and wired them to the J3 connector yet.The way the wires for the steppers and the x and y limit switches are set up at the moment is kind of funky.

xy_mech
If you look at the forum post linked above the picture, it is mentioned that although the y axis cable carrier goes to the front right corner of the work volume, the design is supposed to be reversible.  This would allow for the y axis carrier to instead go to the back right corner.  Considering the location of the back panel and how that connects to the interface PCB, I think we should reverse this so the wires are fed to the back right corner.  Then we can clip the wires to the limit switches to the correct length and connect them to the J3 connector.
Once this has been reversed, the interface PCB can be secured in a more (semi)permanent way and the steppers can be connected.  This still leaves a problem with the location of the HV power supply in relation to the tube and the interface PCB so I’m not 100% on this idea.
After looking around for a while on the buildlog forum I found that a couple of people mentioned using a metal shelf for the HV supply to have it at the same level as the tube and shielded from the electronics below it.  The post linked below has one such setup.
  • Emergency stop switch

    The Emergency stop switch should be wired in such a way that it is closed when it is not pressed and open when it is pressed.  Any part of the safety loop should be closed when allowing the laser to fire so that opening any one of the three connections interrupts the loop.  This would not work if all features were open to allow firing, and one was subsequently closed.
  • Front Panel
    — Emergency stop switch (see above.)
    — Potentiometer for laser power control.
    — Manual trigger
    — PWM control switch, I’m not sure what we have for this or if we are going to use it at first.  Default setting is that the laser power is controlled by the potentiometer.
    — Analog Ammeter ( see laser tube section )
  • Stepper Motors
    — According to one of Alan’s posts on the buildlog forum:

    “I got the wiring to work by using the wires in a Blue, Red, Green, Black sequence from left to right (when looking at the card edge with the TB1, TB2, and TB3 connectors.”

    — These just need to be screwed in to the terminals on the board, the wiring is already in place.

  • Fan
    — Once everything is connected to the interface PCB we still need to mount and connect the fan. The board has a terminal ( TB8 ) that will power either a 5V or 24V fan. The only error I noticed in the wiring diagram for the interface PCB was in the connections to this terminal.  We should just test the voltage at the terminal to determine which is 5V and 24V.
  • Power Supply
    — I wired the 24V power supply with a wall outlet connector for power in and a barrel jack for the 24V output.  This needs to be tested to ensure the supply is providing 24V before connecting the barrel jack to the interface PCB.
  • Additional wiring
    Wiring for the laser tube power supply, air compressor, water pump and monitor, and exhaust system are discussed in additional sections of this project page.

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