z axis moves when spindle turned on

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ericbowman
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z axis moves when spindle turned on

Post by ericbowman »

I am working on the Gerber AR600 from this post:

viewtopic.php?f=60&t=6434

I have the VFD wired into power but not into the controller yet. My thinking there is that for the simple projects I'm doing at first I should be able to turn the VFD on to the appropriate HZ and then leave it there while I cut. I'm trying to get the machine working in the simplest way possible and then dial it in as I use it.

I've got the X Y and Z axis motors configured pretty well. They move a little slow but not terribly slow, and they move the right distance.

I did a few practice runs above the first piece I'm planning to cut and was about to go ahead and do my actual cut and decided to do one last practice run with the spindle running. Well, when I turned the spindle on, I think the Y axis moved a little and the Z axis started moving and kept moving!!! I tried it a few times to check and Usually it will slowly move down, but sometimes it will slowly move up.

I have attached my report from the controller. I'm happy to post photos of how I have everything wired, but I haven't even wired the VFD into the acorn yet. I am very confused.
ShawnM
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Re: z axis moves when spindle turned on

Post by ShawnM »

Clearly you have an EMI noise problem from the VFD. Are you using all shielded cables and wires everywhere in the system? Are those shields grounded at your ground buss? (only one end of course) Are the VFD power and signal cables shielded cables? Do you have high voltage and low voltage wires/cables separated as much as possible?

More pics of the wiring and cables would be nice to see. I remember a pic you posted when you first wired up one axis and that wire you used for testing should not be used for the actual build. I'm assuming from your first posted pics that you gutted the control cabinet and threw all the old wiring in the trash.
Last edited by ShawnM on Tue Nov 30, 2021 11:37 pm, edited 1 time in total.
ericbowman
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Re: z axis moves when spindle turned on

Post by ericbowman »

I'll post pictures as soon as I have time to take them; probably tomorrow.

Should high and low voltage wires be shielded?

I do not know what a ground bus is.

I do have high and low voltage wires separated as much as possible.

What is wrong with the wire I used for testing? It is high quality stranded wire of an appropriate gauge. Should it be shielded?

I did not gut the control cabinet, I reused its power supply.
Gary Campbell
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Re: z axis moves when spindle turned on

Post by Gary Campbell »

Not always the cause, but often. VFD cable shield grounding. See examples below.

Also an EMI filter or line conditioner before the VFD.
VFD Cable Grounding.JPG
VFD Cable Grounding 2.JPG
GCnC Control
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ericbowman
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Re: z axis moves when spindle turned on

Post by ericbowman »

Ok, I’ll post some photos of my setup tomorrow as long as you guys promise not to make fun of me too bad :/ I was out of stranded wire so I used romex
ericbowman
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Re: z axis moves when spindle turned on

Post by ericbowman »

For 220v 20amp wiring what gauge do I need? Where would I buy 3 shielded wire in that size? The highest capacity stranded, shielded wire I see on Amazon is 16 awg which seems a little thin.
ShawnM
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Re: z axis moves when spindle turned on

Post by ShawnM »

ericbowman wrote: Tue Nov 30, 2021 9:09 pm I'll post pictures as soon as I have time to take them; probably tomorrow.

Should high and low voltage wires be shielded?

I do not know what a ground bus is.

I do have high and low voltage wires separated as much as possible.

What is wrong with the wire I used for testing? It is high quality stranded wire of an appropriate gauge. Should it be shielded?

I did not gut the control cabinet, I reused its power supply.
All wires should be shielded in my opinion. A ground buss is a a copper busbar where all earth grounds in the system come back to. It's where you ground the shields on your shielded wire. It's best practice to use shielded, multi-conductor wire for all connections. The wire you used might be good quality wire but it's not what you use to wire a CNC machine. Neither is Romex. I'd recommend you take a step back and get a better understanding of what's needed to tackle the job at hand. A little education and planning will save you a lot of headaches, time and money.

Oh, and noise.
ericbowman
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Re: z axis moves when spindle turned on

Post by ericbowman »

Is there a website or book you recommend where I can educate myself better on CNC machinery wiring?

I could also still use a recommendation on where to buy shielded multi-conductor wire that can handle 20 amps.

And that explains the noise :)

I believe that all of the wiring on the machine itself is shielded, but it's possible I didn't properly ground it. I'll look into that tomorrow too.

Thanks for your help!
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Re: z axis moves when spindle turned on

Post by tblough »

ericbowman wrote: Wed Dec 01, 2021 12:04 am I could also still use a recommendation on where to buy shielded multi-conductor wire that can handle 20 amps.
A quick Google search for "ampacity table" will show you what gauge wire you need for the amperage. Insulation ratings are based on voltage and most are good for at least 600V.

This is the cable I use for spindles and drive motors: https://www.mcmaster.com/cable/wire-and ... lex-cable/
Cheers,

Tom
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