SqueezeAMP boxes

[chill]

I'm reasonably confident now that the various holes are all in the right place, and that the pieces might all snap together and hold the PCB in place.



So I've made a DXF with the outlines, and I've found a local place that can laser cut acrylic from a DXF. Just waiting on a price from him. My plan is to make sure the design works as intended, and then either just post the DXF for others to use or have a batch made by this local place (or both!). I also want to make a version without the battery side connector but with a chamber below the PCB to take a cell pack. Not sure what to do about a fan mount. With the PCB this way up the fan would have to be on the underside. Maybe I should flip the PCB over again (like the 3D printed boxes) and mount the fan on top, but then we'd lose access to the speaker terminal screws and the IO pins for the battery chamber version.

[chill]

By adding extra 'feet' to the end pieces, the box could go either way up.



I could make a new top piece (was the bottom piece) to take a fan, rather than the simple rectangular vent. That would solve the fan issue for the basic box. But for the battery box, to have the choice of putting the PCB either way up above the batteries would require two sets of side and front pieces.

These are really small pieces though, so it would be feasible to make a complete set that has all these options, and it would probably still fit easily onto one sheet of A4 acrylic. I'll see what the laser cutting place says about prices.

Basic Box:
- Front
- Back
- Left (with battery connector side entry)
- Right
- Top x2 (with and without access to speaker terminals and IO pins)
- Bottom x2 (vent and fan)

Battery Box (uses same Top and Bottom pieces):
- Front x2
- Back
- Left x2 (without battery connector side entry)
- Right x2

Total = 15 pieces, to give options for:
- Basic box or battery box (space for 2x18500 or 3x18350 cell pack)
- PCB either way up
- with or without fan

[philippe_44]

By adding extra 'feet' to the end pieces, the box could go either way up.



I could make a new top piece (was the bottom piece) to take a fan, rather than the simple rectangular vent. That would solve the fan issue for the basic box. But for the battery box, to have the choice of putting the PCB either way up above the batteries would require two sets of side and front pieces.

These are really small pieces though, so it would be feasible to make a complete set that has all these options, and it would probably still fit easily onto one sheet of A4 acrylic. I'll see what the laser cutting place says about prices.

Basic Box:
- Front
- Back
- Left (with battery connector side entry)
- Right
- Top x2 (with and without access to speaker terminals and IO pins)
- Bottom x2 (vent and fan)

Battery Box (uses same Top and Bottom pieces):
- Front x2
- Back
- Left x2 (without battery connector side entry)
- Right x2

Total = 15 pieces, to give options for:
- Basic box or battery box (space for 2x18500 or 3x18350 cell pack)
- PCB either way up
- with or without fan

This looks excellent. I’m not sure now that we really need the fan option. Let’s see what people say with the first batch, but the heat sink (or even nothing) might be good enough

[chill]

This looks excellent. I’m not sure now that we really need the fan option. Let’s see what people say with the first batch, but the heat sink (or even nothing) might be good enough

Understood - that would be good. But it would only save one piece, so 14 instead of 15 pieces. I've done a quick layout showing an A4 sheet with the 14 pieces placed very roughly. It shows that they'd easily fit. For bigger sheets I'd take care to pack them as efficiently as possible.



Acrylic doesn't seem to come in the standard 'A' sheets, but 300mm x 200mm seems standard, and is very close to A4.

I've found a place at work that will do a test cut for me free of charge provided I can supply the material. And I've found a local plastic supplier who have given me some offcuts, again free of charge. So early next week I'll try and get the above sheet cut out to test the fitment.

[chill]

I had a go at 'virtually' assembling the various options for the battery box, just to make sure I've got all the options covered. I'd missed an option for one piece (a plain top/base), and I've now also added a top to suit a 30mm fan. There's still a bit of space left on an A4 sheet.



The battery box versions won't hold the cells in place, or provide wired terminals, but should have room for a pre-assembled pack of 2x18500 or 3x18350 cells.

[chill]

I took my test file and my free acrylic samples along to our lab where they have a really nice laser cutter. I learned a few things about the file format requirements, but after we sorted those out the job took about 10 mins to complete - fascinating to watch.

My sample acrylic was the wrong sort (extruded, rather than cast), so there are a few scorch marks on some of the cuts, but the cuts themselves are nice and clean.

Amazingly, most of the pieces fit together well. The PCB is held in place very securely, and the assembled box is completely rigid despite there being a bit of play in some of the interlocking slots. I learned that some parts are a bit too delicate (such as one of the flexi-arms, which has snapped off in the first image below), but that's easily fixed for the next version. And I need a bit more wiggle room to assemble the basic small box. But otherwise I'm encouraged at the way they've turned out. A few more tweaks and it should be ready.

[philippe_44]

It looks perfect. You’re really good at designing these, thanks again!

Would that make sense on such casing to have room for a small switch for the on/off we discussed?

[chill]

Would that make sense on such casing to have room for a small switch for the on/off we discussed?

Yes, I think it would. I did start looking for a suitable switch, but a lot that I found were a bit ambiguous with their dimensions. I'll look again, but if you have a suggestion please point me to it. I believe a tiny little slide switch will be best. If the switch is narrow enough then it can mount in the side with the back extended over the PCB, but if not then it could, for example, fit in the space next to the WROVER antenna, e.g. mounted in the lid so that the switch is on the top face.

[chill]

Would that make sense on such casing to have room for a small switch for the on/off we discussed?

I've tweaked the design a little so that the flexi-arms will be a bit stronger. I've also found a nice compact little slide switch (this one) which includes an accurate drawing of the required cutout. I've ordered a few of them, and have added a suitable cutout to the lid. The switch should fit neatly into the gap next to the WROVER antenna.



My DXF file is ready to cut, so I'll see if I can find an excuse to visit the lab again!

@Philippe: Can you tell me the dimensions of the heatsink that you've been using, so that I can make sure the cutout in the lid is big enough? And does it sit centred on the amplifier chip? I recall seeing an image that had a second heatsink on the silver square next to the amplifier chip - should I allow a cutout for that too?

[philippe_44]

SqueezeAMP boxes

I've tweaked the design a little so that the flexi-arms will be a bit stronger. I've also found a nice compact little slide switch (this one) which includes an accurate drawing of the required cutout. I've ordered a few of them, and have added a suitable cutout to the lid. The switch should fit neatly into the gap next to the WROVER antenna.



My DXF file is ready to cut, so I'll see if I can find an excuse to visit the lab again!

@Philippe: Can you tell me the dimensions of the heatsink that you've been using, so that I can make sure the cutout in the lid is big enough? And does it sit centred on the amplifier chip? I recall seeing an image that had a second heatsink on the silver square next to the amplifier chip - should I allow a cutout for that too?

You don't prefer something round like that https://www.digikey.ca/product-detai...DA-ND/4511431?

Heatsink for the amplifier:
https://canada.newark.com/fischer-el...anada%2Fsearch (I’m sure there are other more elegant choices, I just took this first one)

Heatsink for the exposed copper:

https://canada.newark.com/fischer-elektronik/ick-smd-a-8-sa/heat-sink-dip-ssop-tssop/dp/34M6428?ost=ICK+SMD+A+8+SA&ddkey=https%3Aen-CA%2FElement14_Canada%2Fsearch

PS: I'm really impatient to see these casing, they look really good, I think we should propose them with the first batch. That gives a much better finishing look

[chill]

You don't prefer something round like that https://www.digikey.ca/product-detai...DA-ND/4511431?

Thanks Philippe - yes I did consider a push-button switch like that, but I couldn't find a suitable space for it. On the basic small box (no batteries) there's very little space to work with. The battery boxes do appear to give more options, but in fact the space will mostly be filled with batteries, and the extra space would be on one of the sides, which doesn't seem ideal for a switch. I preferred the little slide switch because it can fit into the only gap in the PCB footprint and it will end up on the top face of the box, whichever way up the PCB goes.

I've now adjusted the opening over the amplifier chip to take those two heatsinks, and I've left a bit of a gap to allow for other heatsink options.



I'm quite hopeful for the next test run, but of course there are often unexpected little 'gotchas'. But another iteration would hopefully fix any last issues. I agree that it makes sense to ship the SqueezeAMPs with a case. Have you considered how you would go about doing this? At the moment I've got a layout that would make parts for any configuration (with or without batteries, PCB either way up), and these all fit onto both an A4 sheet and a 200mm x 300mm sheet. The company I approached for a quote hasn't got back to me, but here are plenty of others, and they don't have to be local - online services would be fine. But if an A4 sheet is cheap enough (when done in quantity) then it would be nice to provide all the configurations. If an A4 sheet is too pricey then I could make a layout that squeezes as many of the basic boxes onto a single sheet as possible, to keep the cost down - the other boxes could be customer options.

I could have these made and ship them to you, or you could use the DXF file to have them made locally to save on shipping costs.

[paul-]

Now you need to Laser etch “SqueezeAMP” on the box.

[chill]

Now you need to Laser etch “SqueezeAMP” on the box.

I've included a couple of end pieces with some lettering, just as a trial to see whether cutting the letters out completely would work.



I tried to find a font that matches the 'SQUEEZE AUDIO DEVICE' font used in pCP, but I had to slightly modify the Q, A and P so that the islands in the middle of those letters won't fall out. Obviously etching would not need those modifications, and I think that would be preferable. I think it would be for Philippe to state a preference for the look of the logo - e.g. all upper case (SQUEEZEAMP) or mixed (SqueezeAMP), cut through or etched, AMP in bold (like DEVICE in pCP) or plain etc.

When I have this test file cut (hopefully tomorrow) I'll find out about laser etching. He did mention it the other day, but I want to find out if it would be a separate process (which would probably mean extra cost for a commercial run) or whether it's all part of one job.

EDIT: @Paul - do you know the name of the font used for the pCP banner? I'm sure I've seen the pCP banner style elsewhere (i.e the SQUEEZE AUDIO DEVICE), but I can't recall where. I thought it appropriate here because it would link SqueezeAMP to the ecosystem, but what are the origins of that banner?

[chill]

...what are the origins of that banner?

D'Oh - of course - it's based on the original Slim Devices logo.

So perhaps 'SQUEEZE AMP', with the lines above and below?

[chill]

@Paul - do you know the name of the font used for the pCP banner?

Found it: https://forums.slimdevices.com/archi...hp/t-5969.html

Eurostyle Extended 2 and Eurostyle Bold Extended 2