Spindle to VFD cable...

[ZeroReciprocity]

What are people using for cable to connect from the VFD to the Spindle?

I know they recommend shielded/screened cable but I've also read in some places that it should be double shielded/screened. I've also read that you need to ensure that the cable has been designed to support continuous flexing.

Is 1.5mm2 CY cable ok to use? Can it stand the constant flexing that it will be subject to, and will its single shielding/screening be enough.

Cheers

[Muzzer]

1.5mm CY (screened flexi cable) should be fine for up to 16-18A. Good to see you using screened cable - and there's really no need for two braids.

There's a lot of bollards talked about when it comes to how to connect the screen - one end or both. Neither is right or wrong but I usually ground both ends, as recommended by Yaskawa. Others recommend just one end, although even then they may differ which one.....

Moving on from that old chestnut, it's also important to fit an EMC filter on the mains side of your VFD. Most of the Chinese ones don't come with one and many DIY projects get in trouble with the resulting electrical noise. The benchmark brands would be something like Schaffner or TDK/EPCOS, which you can assume will actually achieve some degree of filtering. God alone knows what if anything you might find inside an Aliexpress special.

[ZeroReciprocity]

My OP took so long to get approved, I ended up going with LAPP ÖLFLEX® SERVO FD cable. Got it from Rapid online. Certainly not cheap, but at least I should never have to worry about it wearing out due to over flexing ;-)

Thanks for the tip about the EMI filter, I'm planning on using the one from my DIY CO2 Laser that I have now dis-assembled.

One final question... Do you use any ferrite cores on your cables at all? I came across this very old but interesting video on YT and using them seemed to make quite a difference...

https://www.youtube.com/watch?v=DJfiOqaeFDg

I know it's not about a CNC but it is about a VFD and motor, so seems relevant.

Cheers

[Muzzer]

Yes, that Lapp cable is the ultimate solution. There are lots of different styles, some with both power and signal connections bundled and screened separately and collectively. On top of that they are very flexible and oil proof. I wired up my Bridgeport conversion with this stuff and one cable can cover a servo motor, encoder feedback, power supply and limit switches.

Those ferrite clamps are very useful to have handy. If you have taken care with your wiring and filtering, it's less likely you will need them but they are very convenient and can be very effective if you still find noise getting where it shouldn't. There are lots of different types of ferrite that work best at different frequencies, so there's no universal solution, although recognised brands may be worth sticking with. You can pass the wires through several times to get better effect if the hole is big enough. They are "lossy" chokes, rather than being purely inductive but their self inductance adds to their effectiveness.