CNC router - Short controller cable

General CNC CNC Routers
1

Hola amigos -

My CNC router’s cable bundle which connects to the power/controller box is very short - which limits where/how I can setup the router. I’d love to put the box under the router on a shelf, but can’t due to the length.

IMG_5526
IMG_55263024×4032 2.69 MB

IMG_5528
IMG_55283024×4032 1.73 MB

Additionally, since I found out the the length of the USB cable, connecting to from the router’s controller to the computer can introduce interference and cause connection issues - I’m currently quite limited in the physical layout. The computer’s gotta be near the controller, and then I’ve gotta figure out extenders for HDMI/keyboard/mouse.

Open questions/thoughts:

(1) Why is this cable bundle so short? Am I completely missing something here, in that every customer would find this impractical? The bundle connects to the front corner…

(2) Are cable extenders for these types of cables common? What’s the interference impact on extending those? Could someone help me describe them accurately, so I could look for these cables locally (@ Medellin, Colombia), or online.

(3) USB-C cable length - my current solution is to use a powered USB-A hub, attached to a USB extension cable, and then plug the router into that. Unwieldy, but it works… but it feels like the black and white informercials, “There’s got to be a better way!”.

Open to thoughts, ideas, suggestions…

Thank you!

// JRO

2

The length of the cable matters because the motors, especially the spindle, use high currents that can cause noise to be radiated and/or conducted back to the controller. The longer the wire, the more the inductive and capacitive coupling.

That said, most of the problems I encountered were due to poor grounding design and cable routing.

Don’t assume that the controller manufacturer pays attention to good grounding design. Most controller designs do not even use input optical coupling, which, in my experience, is asking for trouble.

Verify that all grounds are tied together and as short as possible. Grounds need to be treated like transmission lines. High-speed currents combined with poor grounding can “shift” digital grounds, creating impossible-to-identify noise.

Often, the source of noise is the endstop and/or the spindle wiring.

Most DIY setups do not pay attention to wire size, routing, and grounding.

Do not run the spindle wiring in bundles with other wires, especially sensors like endstops. My spindle driver is located on the spindle, so I can keep the drive connection short and out of sensor wiring bundles. In this setup, the DC source wiring [which is mostly static] can be run inside main wiring bundles.

All grounds should terminate at a single point, and that point should be tied to the frame using gas-tight connections.

The frame of the controller and CNC may need to be tied together.

Sensor wiring should use twisted pair (TP) or shielded wire. I prefer TP because shielded wires are more $$ and can sometimes allow currents in the shield, making noise problems worse. I use CAT5 cable [TP] to run sensors in a separate bundle. Use stranded, not solid core CAT5 [patch] cables.

Using the above wiring and grounding hints I have not had any problems with the length of practical cable runs.

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