Tips on how to create a chassis (sample image inside)

Thinking of something like this (see below)

But in my case
  • the front fascia is made of wood
  • the top, bottom and rear are made of aluminum plates
  • 2 heatsinks attached to an aluminum plate make up each of the side
  • L brackets to attach each piece to each other

Feedback? Perhaps you have a better idea?

thanks in advance

Screenshot_20220914-221830_AliExpress~2.jpg
 
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Front is usually metal to keep out interference. Also because most switches and pots are too short to go through a board. This metal can be dressed with wood, if you wish.
thanks for the tip. I think I can still have a wood fascia but behind it some metal plate.

easier for me to get wood looking good (wood varnish/oil/etc or getting some nice wood like something special teak/bubinga/etc) than milling a metal plate.
 
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Ive had wood without metal first no issues, so try wood first seen your keen on it, any problems you now no where interference could be coming from, also Ive never had any burn marks from heat sink with wood bolted to it and that was on a F5, however non of the above will work proper till you post a pick when finished. 😉
 
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Ive had wood without metal first no issues, so try wood first seen your keen on it, any problems you now no where interference could be coming from, also Ive never had any burn marks from heat sink with wood bolted to it and that was on a F5, however non of the above will work proper till you post a pick when finished. 😉
I'm keen on wood only because i feel is the easiest (including availability) to make "pretty". With metal, i feel i would need access to a cnc.
 
I'm keen on wood only because i feel is the easiest (including availability) to make "pretty". With metal, i feel i would need access to a cnc.

Some things to consider:
  • you can do quality work on a thick Al plate with careful marking out, a drill press and some small files. Sand the front when you're done to make it look clean, maybe give it a light squirt with clear satin lacquer. You can even polish it if you want to spend the time working through a bunch of fine grits like you would with wood.
  • you can send your hand-drilled Al plate out to be sandblasted and anodised, or powder-coated - all pretty affordable.
  • you can subcontract CNC work for a fairly low price these days. I think some of the online PCB houses in China do cheap CNC work, or you might find a bored neighbour with a CNC router.

If you're dressing a metal panel with wood, you can also bore out the parts of the wood where the knobs etc go, partially recessing them into the panel, which can look good. Long-shaft pots are totally a thing, and can reach through a fairly thick slab of wood.

Make sure the metal/wood interface is well-filled at the edges or hidden so you can't see a hairline crack.

L brackets may consume an annoying amount of heatsink space, and internal fasteners can be really hard to get to, especially that last panel 🙂 Consider doing blind tapped holes in the heatsinks for attaching at least the back and bottom, where screws entering from the outside will be invisible. L-brackets only for the front (and top? unless this goes in a rack/stack), keeping those surfaces pristine.

You can put threaded steel (not the crap zinc ones) inserts into a thick wood panel which allows you to bolt into it from the rear and have the wood be the structural front member. Then glue/screw a thin Al sheet to cover most of the back of the wood panel, and connect it via short flying ground leads to each heatsink. If you keep the gaps between that shield panel and the sides down to a couple of mm, it will be totally fine.

Learning from my mistakes: if the box is going to be really full, it helps to have a lightweight lift-out internal chassis supporting all the electronics. That's harder with the heatsinks being the sides, but it can be a good approach in a rack case where you may have a fan-tunnel heatsink. Debug and maintenance access is something you will not regret. Make sure you can reach all your fuses and debug/test points with one panel removed - often that is the top, but might be the bottom if you have a pristine top fastened from the inside.
 
Some things to consider:
  • you can do quality work on a thick Al plate with careful marking out, a drill press and some small files. Sand the front when you're done to make it look clean, maybe give it a light squirt with clear satin lacquer. You can even polish it if you want to spend the time working through a bunch of fine grits like you would with wood.
  • you can send your hand-drilled Al plate out to be sandblasted and anodised, or powder-coated - all pretty affordable.
  • you can subcontract CNC work for a fairly low price these days. I think some of the online PCB houses in China do cheap CNC work, or you might find a bored neighbour with a CNC router.
snip

I am thinking of following (using this case as inspiration which I came across earlier today: https://www.diyaudio.com/community/...d-a-stripped-down-version-compact3886.345511/)


Screenshot 2022-09-15 204306.jpg
 


Thinking of something like this (see below)

But in my case
  • the front fascia is made of wood
  • the top, bottom and rear are made of aluminum plates
  • 2 heatsinks attached to an aluminum plate make up each of the side
  • L brackets to attach each piece to each other's

My dual MoFos are almost done like that. MDF base; each heatsink mounted with aluminum L channel pieces; wood front salvaged from an old pallet, and mounted with same L brackets.
IMG_20220918_113708394.jpg

IMG_20220918_113736898.jpg


Kind regards,
Drew
 
can you please tell me what's the dimensions (approximately) of the chassis? Thanks again
  • Front piece is 360mm x 125mm
  • Base is 280mm x 215mm
The MoFo power amplifier: https://www.diyaudio.com/community/threads/build-this-mofo.313649/

I created 2 bases from MDF after "laying out" the PCB and the transformer, giving myself a lot of room.
After a while, I decided I wanted to co-house both L&R channels, and it turned out that my oversized monoblock bases were big enough to hold both MoFos if I mounted the MOSFET so that the PCB was flat against the heatsinks.

After mounting the heatsinks, I cut the front board to fit, again, with a bit more overhang than needed.

I haven't figured out how I'm going to cover it. Or if I will. 😉

Kind regards,
Drew
 
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Sometimes, I've left a gap between the heatsinks and the chassis base and top cover using a simple spacer, nut, etc to allow extra air flow around the heatsink and reduce internal temperatures - you do miss out on the extra metal of the base to dissipate heat so it's not always a benefit

Another thing that fallen out of favour is using a fan to 'force cool' smaller internal heatsinks - many fans these days are very quiet indeed particularly for low velocity, low turbulence air flow.
 
Seriously, Smokey says prevent house fires, and build it from metal if there’s line potential inside. Aluminum is practically like a hard wood anyways.
Point well taken. My M2x with its own PSU will be in a metal box. The basic MoFo uses 19V laptop power supplies; in my case a pair of new supplies for ASUS laptops.
...using a fan to 'force cool' smaller internal heatsinks - many fans these days are very quiet indeed particularly for low velocity, low turbulence air flow.
Several builders of Big MoFos did so using Noctua fans.

Kind regards,
Drew