Help please. Dip switches and mach 3 settings

[cropwell]

Hi,

Having typed a long and laborious answer to some of your points, I then lost it all because this forum software is crap.

Here we go again :-----

1. a: Pigtailing - no problem, just remember shields should only be earthed at one end or you may get earth currents to make your shield as the primary in a transformer with the secondaries as your signal wires.

1. b: Single earth point in control box, all earths and shields and mains earth to it. Topographically, earth connections are a star, however spur connection is allowed as long as it is a single line spur chain earthed at one end only at the star point.



2. Yes.

3. The VFD is usually the main culprit in creating electrical noise and it is common practice to keep it out of the main enclosure (which should be an earthed, shielded box I.E. not plastic).

4. DC voltage supply lines are normally no problem in a steady state, switching transients can be a nuisance, but these would only be when there is an inductive load, like a pump motor, so these are best shielded. Homes and limit switches are normally in a steady state, but it wouldn't hurt to shield them against stray EM crap.

5 and 6 - whatever !

7. I hate ferrites and their nasty little cousins - slugs. Design out the problem if you can.

8. Noise from the BoB, not usually (only when it gets drunk on a Saturday night) but seriously - I refer you back to 3 above.

You should test each earth connection by continuity checking from the central earth point to the earthed appliance. Disconnect the appliance earth and check that the continuity between the earth point and the appliance then disappears. If it doesn't - you had a loop.

Hope this helps !

[Clive S]

As Rob said. But I hate timber boxes and think of the fire hazard. If you can go with a metal box with the VFD external to it.

edit: something like this could help https://www.jaycar.com.au/iec-emi-po...6-amp/p/MS4003

[cropwell]

As Rod said.

Hi Clyde, who's Rod?

Cheers,

Rob

[Clive S]

Well spotted now edited.

[Radu_Andrei]

Thank you Rob for the detailed answer.

Got it. Metal box at least for the vfd, ideally for everything else.
By shielded box, do you mean just an earthed metal enclosure, or aluminium foil :P or like a faraday cage with chicken wire?

Out of curiosity, Clive, about the fire hazard, how hot do this components get?
I did it from particle board cause it.s easy and fast, and I put all components on a metal plate, actually on the side panels of the pc enclosure, as I dismanteled it. All panels beeing raised half an inch from the wood.s surface. I could not wait to have the cnc running, and was planning to upgrade after a few months of use, and yes, I.m aware it.s a crap and unprofessional design, but it seemed to me a resonable prop at the time.

And should I add an enclosure fan to the drivers as well, as I already have 2 for the vfd enclosure.

[cropwell]

Hi,

If you don't want to replace the control box with a metal one, you could line it with aluminium foil (https://en.wikipedia.org/wiki/Tin_foil_hat) but to be any use it would need to be earthed. I don't think the guy in the wiki is grounded (I apologise if you don't get that joke straight away, it is a little play on the vernacular - in this instance 'grounded' means connected to reality).

LIDL sells adhesive backed foil tape, when they have it.

[Radu_Andrei]

I just googled what vernacular means. .
Thank you for sharing the joke. Jokes actually, as the noisy bob was funny as well.
And for the extra description. :)

May I, in exchange, share a simple one with you. Did not hear it in english as yet, but I might be wrong.

John speaking to his son in an encouraging manner.
- Come one son, take a step, come one, another one, yeah... yeah, that it, like this, smaaall and slooow. MARRY!!!, bring the camera quick!!, our son has come from the prom.