Painted enclosures - faraday cage?

[Coach_McGuirk]

I'm a noob but am currently building some pedals and ordered some painted enclosures from Tayda. The enclosures are painted pretty thoroughly, so that paint covers all of the area between where the bottom plate meets the enclosure, as well as in the screw holes. As such (assuming the paint is dielectric), I don't think there is conductive continuity between both pieces of the enclosure. Should I be sanding a bit of the paint off in order to make metal-on-metal contact between the two pieces or is this unnecessary? It's my understanding that a proper faraday cage should be continuous and fully grounded through the sleeves of cables connecting the pedals on my pedalboard.

 

[mkstewartesq]

There may be paint in the screw holes but I think inserting the screws (maybe insert them, screw them all the way in a couple of times to make sure paint is gone out of the hole) is enough for that connection. However, I also always sand the paint off of the inside of the enclosure where the jacks will make contact to make sure that the jacks are contacting bare metal.

Even after a year, I still consider myself “fairly new “at this, so I’m sure someone else can chime in with even better advice.

Mike

 

[owlexifry]

I'm a noob but am currently building some pedals and ordered some painted enclosures from Tayda. The enclosures are painted pretty thoroughly, so that paint covers all of the area between where the bottom plate meets the enclosure, as well as in the screw holes. As such (assuming the paint is dielectric), I don't think there is conductive continuity between both pieces of the enclosure. Should I be sanding a bit of the paint off in order to make metal-on-metal contact between the two pieces or is this unnecessary? It's my understanding that a proper faraday cage should be continuous and fully grounded through the sleeves of cables connecting the pedals on my pedalboard.

unless your build makes excessive noise or is prone to heavy EMF sources nearby, this isn't something i would ever worry about.

for continuity to the enclosure (for shielding) - you only need to ensure x1 point of continuity, not every single part that makes contact with the enclosure needs to be grounded. the input jack (sleeve) is ideal for this.

 

[Erik S]

I’ve run some enclosures with pretty heavy powder coat inside and never bothered with any sanding.

you only need to ensure x1 point of continuity

That makes a lot of sense to me. Seems like at least one of the components poking through a drilled hole is likely making contact with the side of the hole.

 

[Barry]

The masking service Tayda now offers cuts way down on paint inside the enclosure, you still have to clean out the drill holes though.

 

[owlexifry]

Seems like at least one of the components poking through a drilled hole is likely making contact with the side of the hole.

unless the component isn't made of conductive material - i.e. plastic cliff jacks.

and while it's nice (and probably a good idea) to ground pot cases, the cases aren't part of the circuit, so you won't be gaining any real shielding benefit if they're the only parts that have continuity to the enclosure. that's why i suggest the input or output jack sleeve.

the one time i had a noise (tick) / shielding-related issue was with a mutron phasor ii build, i used plastic jacks.
had to sneak a ground wire from the input jack sleeve into the jack hole for shielding continuity - completely resolved the noise.

 

[chris.knudson]

I’ve run some enclosures with pretty heavy powder coat inside and never bothered with any sanding.


That makes a lot of sense to me. Seems like at least one of the components poking through a drilled hole is likely making contact with the side of the hole.

Yeah, I think there are two schools of thought on this. If you ever watch any of Mason Marangella's (aka the Rig Doctor), videos (and he builds the rigs for the pros), he'll tell you to strip the paint/powder coat from the inside of every mounting screw hole on the baseplate of the pedal to ensure that you get a true Faraday cage. However, I'm with @Erik S on this -- unless you have a noise issue with the pedal, this isn't usually necessary.

It does make sense to sand off some of the powder coat/paint on the insider of the pedal around at least one of your internal connections (i.e. the input/output jack, or the footswitch), just to make sure you have a good ground connection to the enclosure. Really anything more than that is not really necessary (unless of course you have a particularly noisy pedal -- and even in those cases, it likely won't be because you haven't created a nice Faraday cage around your device).

 

[Coach_McGuirk]

unless your build makes excessive noise or is prone to heavy EMF sources nearby, this isn't something i would ever worry about.

for continuity to the enclosure (for shielding) - you only need to ensure x1 point of continuity, not every single part that makes contact with the enclosure needs to be grounded. the input jack (sleeve) is ideal for this.

I get this, but I was more-so concerned that maybe the metal of the bottom plate wouldn't make contact with the top of the enclosure because of the paint. It's not that big of a deal to scrape away some of the paint to ensure there is contact, but I'm just wondering if this is wasted effort.

 

[Erik S]

I get this, but I was more-so concerned that maybe the metal of the bottom plate wouldn't make contact with the top of the enclosure because of the paint. It's not that big of a deal to scrape away some of the paint to ensure there is contact, but I'm just wondering if this is wasted effort.

I say skip it until you have a noisy pedal, then try it and let us know if it fixed your problem.

 

[chris.knudson]

I get this, but I was more-so concerned that maybe the metal of the bottom plate wouldn't make contact with the top of the enclosure because of the paint. It's not that big of a deal to scrape away some of the paint to ensure there is contact, but I'm just wondering if this is wasted effort.

No, it's not a wasted effort -- you just don't need to go overboard.

 

[giovanni]

If you had a gap of 1mm or less between the enclosure and the bottom plate, you would expect interference in the 300GHz or higher. These waves are highly attenuated by the atmosphere so in practice it’s highly unlikely that you can actually get interference from them. The narrower the gap, the higher the frequency, the less likely the interference. Sub millimeter waves are typically only used in astronomy so not a concern.

Basically, I think it’s highly unlikely that the incomplete faraday cage will lead to interference.

 

[Erik S]

If you had an enclosure that was drilled but not populated yet, you could put the back on as normal without any paint removal, poke a DMM probe through the footswitch hole to contact the inside of the cover, then check for continuity between the cover and the bare edge of one of the other drilled holes. My money is on the electrons finding a path.

 

[jwin615]

OP isn't wrong in their thoughts.

For faraday cages, long cracks are far worse than holes. A 1mm gap could actually mean a 100-140mm gap, on its long end. That will potentially happily let a 1/4 wavelength of radio freq in. Mariachi anyone?


RF is fun and weird.


But, there's also that little lip in the lid. RF doesn't like to bend. It goes in a straight line until it bounces or gets absorbed. All that being said, I don't worry about it. If you get one that's super think, where it doesn't close flush, that's a potential problem. Having a grounded connection is good but having a metal to metal one IS better. When we work onnRF rooms, especially copper ones, and we need to mate to the room, we'll clean it of oxidation first. Same thing when they're being built. Every inch is clean and mated metal to metal.



But a tight fit is good enough for rock and roll. How many plastic pedals have been made? A LOT

 

[Coach_McGuirk]

OP isn't wrong in their thoughts.

For faraday cages, long cracks are far worse than holes. A 1mm gap could actually mean a 100-140mm gap, on its long end. That will potentially happily let a 1/4 wavelength of radio freq in. Mariachi anyone?


RF is fun and weird.


But, there's also that little lip in the lid. RF doesn't like to bend. It goes in a straight line until it bounces or gets absorbed. All that being said, I don't worry about it. If you get one that's super think, where it doesn't close flush, that's a potential problem. Having a grounded connection is good but having a metal to metal one IS better. When we work onnRF rooms, especially copper ones, and we need to mate to the room, we'll clean it of oxidation first. Same thing when they're being built. Every inch is clean and mated metal to metal.



But a tight fit is good enough for rock and roll. How many plastic pedals have been made? A LOT

Brilliant. This is informative and allays most of my concerns. Good point about that lip.

I'm not too concerned about this in general, but just want to make sure I'm following best practices. Lots of good info shared by everyone in this thread. Thanks y'all.

 

[bronomo]

Catalinbread (maybe others this is just where I've noticed it) sands the paint off of the countersink in one of the holes on the cover so the screw will make the contact. I bet if you had a dremel with the bullet shaped bit it would only take a second or two.

 

[cdwillis]

Yeah, I think there are two schools of thought on this. If you ever watch any of Mason Marangella's (aka the Rig Doctor), videos (and he builds the rigs for the pros), he'll tell you to strip the paint/powder coat from the inside of every mounting screw hole on the baseplate of the pedal to ensure that you get a true Faraday cage. However, I'm with @Erik S on this -- unless you have a noise issue with the pedal, this isn't usually necessary.

It does make sense to sand off some of the powder coat/paint on the insider of the pedal around at least one of your internal connections (i.e. the input/output jack, or the footswitch), just to make sure you have a good ground connection to the enclosure. Really anything more than that is not really necessary (unless of course you have a particularly noisy pedal -- and even in those cases, it likely won't be because you haven't created a nice Faraday cage around your device).

Take anything Mason Marangella says with a grain of salt. That guy is a con artist and a clown. I can't believe he's still in the industry.

 

[chris.knudson]

Take anything Mason Marangella says with a grain of salt.

I take everything I see on the internet with a grain of salt.

 

[Coach_McGuirk]

Take anything Mason Marangella says with a grain of salt. That guy is a con artist and a clown. I can't believe he's still in the industry.

Curious what the story is here? I'm only vaguely familiar with the guy's channel.

 

[Giorfida]

Curious what the story is here? I'm only vaguely familiar with the guy's channel.

Take anything you read on the internet with a grain of salt… but do some google searches.
The big accusation is that his “original” pedals are all direct copies of other pedals (not unlike what most of us do here… but we don’t pass them off as our designs). There is also an alleged “open letter from Michael Landau” about this as well. But again.. innocent until proven guilty and take things on the internet with a grain of salt… but do your research, and form your own opinions. I know I have.