[Degrom]

Hi.

I am the stage where I want to mount the HobbyCNCPro into its own enclosure.

My question is : When mounting the board,do I bolt it to the enclosure with metal bolts or do I use plastic spacers?

I am going to use the controller for a CNC plasma table and all of the components needs to be grounded properly.

In other words will it be save to ground the board to the enclosure and then connect to enclosure to a proper ground connection? (Not the normal earth)

Any info would be welcomed.
Thanks.
Bert.

[martinw]

Hi.

I am the stage where I want to mount the HobbyCNCPro into its own enclosure.

My question is : When mounting the board,do I bolt it to the enclosure with metal bolts or do I use plastic spacers?

I am going to use the controller for a CNC plasma table and all of the components needs to be grounded properly.

In other words will it be save to ground the board to the enclosure and then connect to enclosure to a proper ground connection? (Not the normal earth)

Any info would be welcomed.
Thanks.
Bert.

Dear Bert,

Presumably there are pre-drilled holes in the board??

If there are, and the enclosure is metal, I would always go for an insulating plastic spacer. The simple reason being that with an insulating spacer, you know , absolutely, that there is no electrical connection between the case and and any PCB tracking close to the fixing hole. This means that you do not need to check pillar-to track -spacing, and you can be sure of the true earthing (grounding) of the metal enclosure (or lack of it).

One word of warning... some plastic spacers have brass bushes at each end, or studding moulded in in such a way that there is still metal on the spacer of a larger diameter than the fixing holes on the PCB These can short out tracks on the PCB if the guy who laid out the board put the tracks too close to the hole.

"Translation: track=traces".

Best wishes,

Martin

[martinw]

Dear Bert,

The latest post I can see is mine #2, so we may cross-post.

That advice was to prevent shorting out tracks on the PCB, and to be absolutely sure that the enclosure has no electrical connection to the board.

If you need to ground the case, (almost certainly a good idea) do it by a proper connection. A while ago, I tried to use metal pillars to do this. Loads of ground plane on the PCB, but it was covered in etch-resist that is a pretty good insulator. Net result, a thoroughly intermittent connection. We wasted many hours tracking it down. Arggh!

Best wishes,

Martin

[Degrom]

Thanks Martin,

I will go with the plastic spacers then. I am going to use the kind they use in computers. It basically clips onto the circuit board and onto the enclosure.

With the enclosure I will drill a hole in the back side of it and tighten a nut and bolt through and connect the ground cable to it.

The ground will basically be an 6" solid steel rod hammered into the ground and lots of cables connected to it.(A cable for each device.)

Thanks again for the info.
Bert.

[martinw]

[QUOTE=Degrom;369494]Thanks Martin,

With the enclosure I will drill a hole in the back side of it and tighten a nut and bolt through and connect the ground cable to it.

QUOTE]

Dear Bert,

One last thing... to make a good connection to the enclosure, if it is painted metal, you have to get through the paint. Use one of those spikey anti-vibration washers that digs into the metal. It gets through the paint, and if seriously tightened, should be good.

Best wishes,

Martin

[Degrom]

Thanks Martin,

Always wondered what those spiky washers was for!!!

I am very excited about this project,just don't hope the plasma cutter burns everything out on the first run... LOL