Grounding Writeup

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msimpson99
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Grounding Writeup

Post by msimpson99 »

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Since I have been building CNC machines over the last 10 years, I have handled my grounding in many different ways with mixed success.

Hypertherm has a Field Service Bulletin #805400 "Recommended Grounding and Shielding Practices". This is a great publication and helped me considerably setting up my current grounding setup.

You can find my full write-up here:
http://www.kronosrobotics.com/cnccsgrounding

While this system may not be perfect, It has been working well for me. I use it not just for my plasma CNC machines, but my router and milling machines as well.

Let me finish by saying, I am not an electrical contractor, and just bringing up the "grounding " work can stir things up.

One example of an area open for debate is connecting to aluminum. It is not recommended. However, I have no choice as the frame in the machines I am using is made from aluminum. What I did was attach grounding bar with a steel mounting base to the aluminum frame.

As an experiment on two identical machines:
Both surfaces were cleaned.
On one machine I use some anti-oxidant compound, on the other just metal to metal. In time we will see what transpires.

Please, Your comments.

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asuratman
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Re: Grounding Writeup

Post by asuratman »

Hello,
How deep is your grounding rod ? Do you think they have to go to water source ?
msimpson99
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Re: Grounding Writeup

Post by msimpson99 »

You want your grounding rod as deep as possible. There are codes that regulate the depth and number of rods needed for your home or shop. While the outside grounding rod for the CNC are not bound by these codes, I try to stick as close as possible.

That said, the ground for my CNC machines is only about 6' deep. Due to rocks, I cant go any further. What I do know is that since I have added the grounding rod, some issues I have had in the past have gone away.
asuratman
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Re: Grounding Writeup

Post by asuratman »

I thought that you will make parallel connection between your cnc machine ground and the main ground to keep resistance low. Thanks for the info.
msimpson99
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Re: Grounding Writeup

Post by msimpson99 »

Main Ground? Are you talking about your mains ground? If so that is also connected via the 110V supply. Grounding on the CNC is for much more than for safety. Its more about eliminating those strange little glitches that can cause us to ruin a part.
asuratman
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Re: Grounding Writeup

Post by asuratman »

I mean mains ground. Thanks for the info.
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