Silly question, how do I ground my machine

  • I've completely rebuilt my printer, replaced pretty much every part. The original manufacturer didn't ground anything on the printer. The only connections are red&black pairs. There was a lead in the cable chain that said "ground" but it was never connected anywhere, on ANYONE's printer who bought it.

    How do I ground it?

  • A lot of printers use Meanwell power supplies they have Live, Neutral and ground coming in (North American setup) and attaching to the supply terminals. The case of the supply is grounded when the ground is connected. You could run a line from the supply to the printer frame.
    Note that the ground is only a safety issue that relates to line voltage. If you don't have line voltage anywhere on your printer (for example a 120V heated bed) then ground isn't that critical. You certainly should have the power supply grounded though.

  • Moderator

    Not a silly question at all. It's often taken for granted, or ignored entirely, but it's definitely in your best interest to get grounding in place for your own safety. 120v is sometimes fatal and always painful. So if you have mains wiring that goes beyond an enclosed PSU, such as to a mains powered heated bed, then absolutely the printer should be grounded.

    How you do it depends a lot on the construction of your printer. Is the frame conductive? Is there continuity through the whole of it? If so, you can ground the frame to the power supply chassis, or better yet right to the ground terminal.

    If the frame isn't conductive, or at least no continuity through the joints, then you can use wire attached to the extrusions and either connect the joints so that it's all continuous, or do a star topology and run multiple ground wires back to a central grounding point.

    The hotend metal work should be grounded since that's a common place for wire fatigue and failure. The bed plate should be grounded and any frame connected to it. Even your motors should be grounded ideally.

    At the power supply, you can also connect the DC - terminal to the earth terminal, that way any shorts on the low voltage side to the high voltage side will be shunted to ground as well. If you do this you need to be a bit more careful about ground loops when connecting via USB.

  • Yeah, I have a nice Meanwell supply connected as you described. What about things like belt static and grounding the duet itself?

  • Moderator

    Belt static may or may not be a big deal, but grounding the motors should take care of it. In industrial applications they sometimes use whiskers that contact the belt, but in the short runs used in 3d printers that are usually going back and forth rather than continuously in one direction probably not worth it at all.

    Grounding the Duet would be taken care of by bridging the DC- terminal to the earth terminal. Some PSUs already do this internally.

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