Where should I put them at to ensure that there is no EMI that can happen?
Hey CrazieBird,
in the first one would place the ferrite cores on the Monitor’s HDMI cable, best at both ends, especially if you have the monitor intermittent issue. Other candidates are generally everything that emits or is susceptible to EMI, especially if it is high power and high frequency, so important would be spindle power cable too. Note that these cables are also always recommended to be fully shielded. For the router cable it would be good too, but the “dirt” that comes from commutated series-wound motors like the one in the trim router mainly comes from the sparks that are emitted by the commutators, which make heavy EMI which comes both through power line and directly through the air, and these motors are not encapsulated in a shielded housing because they are air-cooled and commutated motors have a high risk of overheating. But putting ferrite cores on the other cables of the CNC machine, especially on HDMI and also USB cables, prevents signals from being deteriorated by router’s sparks and other EMI sources. Note that spindles are Induction motors which have no commutators and therefore emit less EMI through air, but their the power lines do, since their power is of high current and it is switched by IGBTs inside the VFD at varying frequencies which can produce high-frequency harmonics. Ferrite cores help to prevent EMI by dissipating radiated electromagnetic waves both coming from or exerted on the cables.
Snap-on Ferrite cores for cables
– Source: Unconventional2, CC BY-SA 4.0, via Wikimedia Commons
Ferrite choke on spindle cable
– Source: Omron MX2 User’s Manual
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Thank you so very much. I will be putting the cores on after the weekend.