I have several Ideas for custom designed 3D printed brackets to mount boards in power amp and preamp designs.
This is especially nice for PS boards mounted above transformers is my dual mono and quad mono power amps - 4u and 5u empty space at the top can be utilized
Bambu lab has a flame retardant filament.
Any thoughts are welcome, thank you!
This is especially nice for PS boards mounted above transformers is my dual mono and quad mono power amps - 4u and 5u empty space at the top can be utilized
Bambu lab has a flame retardant filament.
Any thoughts are welcome, thank you!
Attachments
Would the plastic hold up for several decades? I think the main risk is not that the plastic catches fire when the electronics are already burning, but a short circuit caused by a mechanical failure. That can start a fire or put the case at mains voltage.
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Metal fixings are hard to beat for vibration resistance, ruggedness and lack of combustibility. FR4 is very strong being a glass-fibre composite, your plastic mounts will likely be the first point of mechanical failure in a drop-test or vibration test. But for a light-weight PCB it might be fine.
I've never heard about an amplifier catching fire.
I have used PLA filament for parts of housings of preamplifiers (also with tubes). I wouldn't use it in a hot running class A amplifiers though.
I have used PLA filament for parts of housings of preamplifiers (also with tubes). I wouldn't use it in a hot running class A amplifiers though.
You've clearly not watched enough videos of electronics repair... FR4 can burn, its just reluctant to at first. A good metal enclosure can prevent fire spreading outside in the worst scenario, but obviously with air-flow slots fire is not definitely contained. Often electronics fires self-extinguish when the power is removed or a fuse goes, as most (quality) components are fire-retardent (they are this way for good reason). However once a fire gets big-enough flame-retardent doesn't cut it any more, organic material will burn in air.
The available power is a big factor as that is what provides the energy to heat things up in the first place. Good circuit design ensures no single-component failure can cause a fire. Judicious use of fuses, fusible resistors, derating and protection circuitry can help ensure this.
Fortunately semiconductors usually fail without catching fire (just release the magic smoke!), but can then become short circuits that overheat nearby resistors. Those resistors can then be bad news (they limit the current enough to save the fuse, but not enough to stop themselves heating up to ignition). Ironically a massively overloaded resistor tends to simply pop and act as a fuse by vaporizing, its the moderate overload that is most dangerous - that's when a fusible resistor is a good choice (they fail open without flames).
One of the best defences against fire in electronics is to power it fully off when unattended. Humans can smell burning and do something about it only if they are there at the time... It is also a defence against lightning damage (which is another way fires can start). Be safe...
The available power is a big factor as that is what provides the energy to heat things up in the first place. Good circuit design ensures no single-component failure can cause a fire. Judicious use of fuses, fusible resistors, derating and protection circuitry can help ensure this.
Fortunately semiconductors usually fail without catching fire (just release the magic smoke!), but can then become short circuits that overheat nearby resistors. Those resistors can then be bad news (they limit the current enough to save the fuse, but not enough to stop themselves heating up to ignition). Ironically a massively overloaded resistor tends to simply pop and act as a fuse by vaporizing, its the moderate overload that is most dangerous - that's when a fusible resistor is a good choice (they fail open without flames).
One of the best defences against fire in electronics is to power it fully off when unattended. Humans can smell burning and do something about it only if they are there at the time... It is also a defence against lightning damage (which is another way fires can start). Be safe...
Thanks!
I'll likely use metal.
I am mildly curious about Mylar on transformers.. High heat resistance but its flammable, though not as readily as some other materials.
I'll likely use metal.
I am mildly curious about Mylar on transformers.. High heat resistance but its flammable, though not as readily as some other materials.
I 3D print a lot of stuff. I see people designing parts for 3D printing that look like they are copying designs made of metal without considering that 3D printed plastic isn't nearly as strong. I also see most people using PLA filament, even though it softens at very low temperatures.
Prints that need strength need to be made bulky, with thick walls. I see a lot of people using gyroid infill, which is painfully slow to print and offers no extra strength. I usually use triangular infill as it prints fast and is quite strong.
I can't guarantee that a print won't end up sitting in a parked car or truck at some point in its life, or be exposed to other sources of heat, so I never print with PLA. PETG offers the same strength but doesn't soften at low temperatures. ABS is even better if your printer is enclosed and heated (mine is).
I made replacement button caps for a preamp and capacitor spacers for a Soundcraftsmen amp I recapped. I'd be careful about printing anything that will be exposed to heat.
Prints that need strength need to be made bulky, with thick walls. I see a lot of people using gyroid infill, which is painfully slow to print and offers no extra strength. I usually use triangular infill as it prints fast and is quite strong.
I can't guarantee that a print won't end up sitting in a parked car or truck at some point in its life, or be exposed to other sources of heat, so I never print with PLA. PETG offers the same strength but doesn't soften at low temperatures. ABS is even better if your printer is enclosed and heated (mine is).
I made replacement button caps for a preamp and capacitor spacers for a Soundcraftsmen amp I recapped. I'd be careful about printing anything that will be exposed to heat.
Something else to add to the discussion regarding flame retardants. They can use chemicals that are not nice -- brominated HC's (hydrocarbons) come to mind. Fumes from burning plastic are one of the leading causes of smoke inhalation related harm in house fires. So while flame retardants (not preventers) are good in one way they can be bad in others.
Having dealt with reliability issues in packaged IC's that were encapsulated with a particular type of flame retardant, I'd look long and hard at that filament before using it. It could actually cause metal corrosion.....
I'd go with metal.
Having dealt with reliability issues in packaged IC's that were encapsulated with a particular type of flame retardant, I'd look long and hard at that filament before using it. It could actually cause metal corrosion.....
I'd go with metal.