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Hi all
First post!!!
Just built a 5x4 cnc machine and close to getting it cutting...but
I am trying to source a VFD cable (8.5amps / 2.2kw), all i can find are 100ft reels.
Can anyone point me to a UK supply! I need around 15ft.
Also any real good details of the wiring, I have some instructions but not sure about the earthing on the spindle itself.
The fourth wire doesn't seem to be connected..!!?
Many thanks
Flamered
Here you go. CSE Cables Website Home
The 4th wire won't be connected. Personally don't bother with an earth onto spindle has the VFD and main machine frame are earthed and VFD will shut down protecting it's self if detects short or heavy load. Just make sure the shielding is taken back to main earth point.
Big tip is to make sure the VFD connector terminals are soldered securely and no stray strands wires floating about and all wires are isolated well. Also that the wire is supported well so there's no stress on the connector. If not and the wire comes loose and shorts then it WILL more than likely KILL the spindle and possibly the VFD.? . . I've done this my self killing both spindle and VFD and know of others.!!
The wiring is easy. Just connect U V W If it spins reverse when first started just swap any 2 wires and it will spin right way.
I thought the same until I got a shock off it. It's not good practice to rely on bearings to transmit the fault current to earth so I would always advise using 4-core cable to include an earth connection just by the spindle. The cost it's negligible - just one tapped hole in the Z-axis plate to screw the wire on to and you're done. It also adds a bit of redundancy to the system.Quote:
Originally Posted by JAZZCNC
Thanks for the help!Quote:
Originally Posted by Jonathan
I need a little clarification on some of your instructions. I have no clue about electrics apart from wiring up a plug!!
- earth connection just by the spindle -
Do you mean attaching the earth to the z-axis? Only mine is made of MDF, although it has a strip of angle iron which holds part of the carriage. Would it need to be attached to the angle iron.
-just one tapped hole in the Z-axis plate to screw the wire on to -
So the cable attaches to the spindle! How do i get the wire to do this, do i need to leave the earth out of the plug that attaches to the spindle.
Do you have any pictures that would make things 100% crystal clear for someone like me.
Appreciate your help, as its taken me 4 months to get to this point. Its all moving just need to work out the homing and start making splinters
Cheers
Stephen (Bristol)
Understand your thinking and would agree if this was a just a normal motor and not run near stepper wires but because it's high frequency not so simple has just using the spare wire and running back to VFD earth without potential for creating ground loops if not done correctly.Quote:
Originally Posted by Jonathan
Seen has often the spindle cable and Z & Y stepper cables often run in the same cable trunk then noise from the VFD could get introduced across to the stepper wires so If this is going to be done then make sure that earth goes to the main Star earth point in your control box other wise the potential for ground loops increase.
This then becomes a bit more awkward using the 4th wire has often the VFD is not in control box and that is why I prefer not to do this.!
I've never had a problem with shocks and even when my cable broke and dead shorted the spindle the fuse and trip worked, unfortunately the damage was done by then.!!
Not saying don't do it but make sure you do it correctly other wise you'll be pulling your hair out chasing ghost issues, like false E-stops or limit trips, missing steps etc which you won't automaticly realise are coming from this.?
Please don't think I'm scare mongering here but I suggest you seek help from some one who does other wise you have large potential to get this wrong.!Quote:
Originally Posted by Flamered
Apart from the obvious danger to yourself from burning the house down if you completely get it wrong.!! . . .It's very possible you can damage the spindle or VFD if not correctly wired or careful attention to detail with wire connections.
Like my previous post says if you feel compelled to have an earth wire then in your case just take a wire from the spindle clamp bolt or any place that makes contact with the spindle body. Then take this wire back to the main Star Earth point in your control box.
So Jazz, where do you connect the shield to?
This is how I'd do it... though there are other variations you could do...
Attachment 6652
I Always take shield back to the Star point like you have drawn for every shielded cable. And in the case of VFD's I take to the VFD sheild point BUT only if the VFD picks up it's earth from main star point. If not then I take separate wire back to star point.!Quote:
Originally Posted by irving2008
Actually On reflection now knowing Stephens using MDF for a frame then yes I probably would run an earth from spindle but back to the star point like you have drawn NOT the VFD unless VFD picks it's earth from the star point.