[kolias]

This was posted by mistake in the Electronics Section of this Forum.

Can someone give me a hand with the VFD programming please? The included users guide is not very user friendly

The VFD will be approx, 15 feet away from the Spindle. What size cable should I use? I was thinking 20AWG or perhaps 22AWG?

In addition, I have 4 Stepper Motors 420 oz. to wire so maybe I can get the same cable size for both?

Thanks
Attachment 506176
Attachment 506178

[RaderSidetrack]

The product page at Amazon says:

"Wire specification suggestion

13AWG "

https://www.amazon.com/Single-Variab..._source=1&th=1

In the USA and likely Canada, 13AWG is less commonly available than 12 AWG, and 12AWG also matches up with the suggested 20amp breaker. You could use that same wire to the steppers, but typical 420oz steppers draw considerably less amps, so 20AWG could be a reasonable choice.

[kolias]

Much appreciated for your help
Thank you

[peteeng]

Hi Kolias - The cable from the VFD to the motor should be shielded if it runs with other wires. So it would be over priced to use for the motors. I would use a 1mm2 wire for the motor ($7.50aud per metre here 9.5mm OD). This is a ~17awg wire. A 420ozin motor will have 20awg wires hanging out (0.5mm2) so a size or two above that is good. I typically use 18awg (0.8mm2) 4 core flexible speaker wire ($7.50aud per meter 7.5mm OD) which has worked very well. 4 core extension cable is cheaper then speaker wire. But its 1.5mm2 (15/16awg) but bigger is better I suppose. Control cable is available in 1mm 4 core which has a small outer dia if thats important. Or buy a spool of single wire 0.8mm and run bundles....The stepper motor wires do not need shielding if the spindle is shielded wire and correctly earthed... Peter

[kolias]

I appreciate your help Peter but now I'm confused. I have always used shielded wiring for the spindle and all stepper motors and ground the shield to the main ground in the control panel. I thought that was required. On my last cnc I did not ground the cable shield and during start up I had the Y&A (they are slaved) going at different speeds and luckily I stopped the cnc before my gantry was twisted. Then I post in another forum the question and asked which cable should be grounded and the answer is attached here. To my opinion grounding the shield of both spindle and stepper is a good practice but my experience on this field is limited.

Many thanks Peter

[peteeng]

Hi Nicolas - I have never used shielded cable on the stepper motor cables only on the spindle motor due to the high frequency that it operates at. I haven't had any issues this way related to high freq interference. In your case of the motors going at different speeds was this due to the driver settings or did you isolate the issue to interference? I have had a problem with incorrect unstable 5V voltage to the BOB playing havoc with the slaved axis... That was a nightmare to solve. The slave axis would occasionally go the opposite dirn to the Y axis and nearly broke the machine in two...

There is no harm in using shielded cable for the driver lines. I have used that 800W spindle and it was very impressive see it in image attached. In the machine imaged (Frankie) all the wires went down the same umbilical, the spindle wire was shielded the rest were plain wires. No interference issues at all... Peter

wiring image - showing all wires are plain except spindle drive cable. Both ends of shield are grounded to chassis at z axis and to VFD earth.

[kolias]

Very nice machine you got there Peter and neat, congrads. In addition I love your workshop, probably bigger than my house, lol. My "workshop" its just 6 feet by 9 feet but its at the end of my double garage so all work is done in my garage. Good thing about a shop like mine is when I sit in the center I can get any tool I want without getting off my chair!

The problem in my last cnc was noise because after I connected the steppers shield to the ground all went good. And actually as you mentioned I had the same problem like you, the Y/A axis were going at different directions and not the speed, quite scary.

BTW I'm not very good at soldering and have to connect the cable (4 conductors) to the plug at the top of the spindle. I was told to fill the 4 pins of the plug with solder and when the solder is liquid push each conductor into the pin. Is this a good way of doing it?

Many thanks Peter

[peteeng]

Hi Nic - Thks for compliments. Frankie now lives interstate and is making surfboard fins and signage.. Now I'm making a 4x8ft machine and a 5 axis router...

Soldering - I would place the wire into the lug, crimp slightly, then solder. You could solder the wire end (called tinning) let solidify, place that in the lug then crimp then complete the soldering as well. I would not solder the lug then push the wire into it, that sounds dodgy to me... I use forceps to hold wires but there are small clamps on arms available (helping hands) that make this easier... we should have evolved a third or fourth arm/hand by now.

https://youtu.be/Qps9woUGkvI I wouldn't use a cone end, I'd have a small flat to increase the contact area... Peter

[kolias]

4'x8' machine? that's nice project. Thanks for the tip and video Peter, I would do it the way you described, sounds much better.

Thanks

[kolias]

Is Mactec54 still around? He gave me good VFD programming info some time ago and I wonder.

Thanks

[joeavaerage]

Hi,
No Matec has not posted here for quite a while. He used to have some good info, but was also a bombastic p****k! I rather think he was excluded from the forum....with cause.

Craig

[kolias]

Hi, No Matec has not posted here for quite a while. He used to have some good info, but was also a bombastic p****k! I rather think he was excluded from the forum....with cause. Craig

Thanks Craig, I remember some heated discussions of him with others but he knew his business. I will manage with what I have and post back if I run into problems.