Your choice of enclosure might likely affect some of your build choices. LCD mounting and control placement, for example, might dictate how you connect those components to the board.
Although you could use a non-metalic enclosure, it's generally not recommended. A metal enclosure shields the circuitry from spurious noise. Without that shielding, you are almost guaranteed to experience increased noise in the output. And if it'll be a “stomp” box on the floor, you'll likely appreciate the robustness of metal.
Aluminum is the most common material used for music pedals. It's generally much easier to machine than steel and available in a number of different of styles.
Diecast enclosures like the 1590 series from Hammond Manufacturing are very common, relatively cheap and available in a wide variety of sizes.
Yup, size matters. Obviously, the enclosure needs to be large enough in each dimension to house the guts, but you'll probably find that too big is usually not ideal either. Personally, I don't like pedals much taller than 2“, but often, going taller is required to get the other required dimensions since the 3 dimensions tend to scale together.
A completed pi-Stomp Core measures approximately 4.2” x 2.75“ x 1.4” (105mm x 71mm x 36mm). Keep in mind, that's the minimal required interior dimension, most enclosures are listed by their exterior dimensions. Also, many enclosures include screw “bosses” in the corners which reduce the effective interior. So, looking at the menu of Hammond 1590 enclosures
… the following should be able to accommodate pi-Stomp Core:
I've installed a pi-Stomp Core into a 1590BBS and can attest that 1.66” is the minimum height for a diecast enclosure. In fact, I'll have to insulate the back panel to assure it doesn't short out the bottom of the raspberry pi. For this reason, I don't recommend it. Go with the “C” if you want the smallest footprint.
The “J” size seems the best small but roomier enclosure. It can accommodate 3 footswitches, at least 2 additional tweak knobs and probably an extra a jack or two (expression pedal, MIDI, etc.)
The “D” size is probably best for a larger form factor with lots of controls (up to 4 footswitches, 4+ additional tweak knobs) and/or lots of extra jacks, or additional circuitry. However, the Hammond version has 6 screws with two screw “bosses” along the center of the length. Those will get in the way of the pi-Stomp guts being mounted along the North edge of the enclosure. You'd either need to cut away that North boss (dremel, file, etc.) or find a Chinese knock-off 1590D 4-screw version. They do exist. I used them for the original pi-Stomp but sourcing them was too unpredictable to base a new design around.
For longer enclosures that will accommodate 4+ footswitches, you'll likely need to use an extruded aluminum enclosure. Something like: 1455N2201
Or a folded aluminum enclosure like: 563-AC-403
One of the most critical decisions you'll need to make is where and how to attach and mount the LCD. Here are a few possibilities:
|Mount||Enclosure manufacturing||Electrical connection to board||Board Header|
|Top mount||Slot on enclosure face (~0.15“ x 1”)||Tall header thru slot||Tall (11mm)|
|Under mount||Rectangular cutout (~1.9“ x 1.4”)||Solder directly to board||None|
|Top or Under||Slot or rectangular cutout||Ribbon jumper to board||None or 90 Degree|
pi-Stomp Core has 3 expansion headers along the South edge of the board for debounced switch inputs, MIDI I/O, and Analog (control) inputs. If your chosen enclosure is not very wide, connections to those headers could be made difficult. For example, a 3+ footswitch configuration, would likely place a footswitch very close to that South edge not leaving much or any room for a jumper to plug into the board. In that case, your options would be to use a straight header (mounted at an angle) in place of the right-angled headers for Debounce and/or MIDI, or to solder the cabling directly to the board without a header. If in doubt, you might defer soldering of those headers until you've confirmed (dry fit, etc.) your enclosure layout.
Same footprint as a 1590C which is taller and thus recommended over the 1590BBS. For either, the LCD is not well protected and extends past the left edge. This enclosure is very small and not recommended but shown to demonstrate how the display can be mounted on top with just a slot if you are unable to cut a rectangular cutout for the LCD to mount under the face of the enclosure.
Although one could use just a hand drill for the enclosure, a drillpress will yield much better results. A CNC machine would be even better, especially for the rectangular cutouts.
With a drill and some patience, decent rectangular holes can me made in aluminum by drilling a bunch of adjacent holes, 4mm (5/32“) or smaller, then filing the material between working outwards towards the final cutout size/shape. You can find youtube vids on this technique.
“Stepped” drill bits (aka Unibit) are highly recommended for holes. All the holes shown in the template below can be drilled with a single #1, 1/8" to 1/2" Unibit
Also highly recommended that you center-punch your holes before drilling and draw crosshair lines so that you can compensate if the hole starts to drift as you increase its diameter. Although you can start a hole with a unibit, I prefer starting all holes with a 1/8” drill bit or better yet, a #4 Center drill.
The main part to get right is the relationship of the Top Face cutouts (Volume pot, encoder and LCD) to the North Face cutouts (I/O, power, USB). You could measure your build pi-Stomp core with a caliper and create your own CAD drawings, or assume yours will end up much like ours and use the one we used for our 1590J prototype seen elsewhere in this wiki.
The 3 footswitch and two knob cutouts on the right are optional, the other cutouts will be required for most builds. It is generalized with all measurements relative to the edge between the Top and North faces so that it can be used with larger or smaller enclosures.
The PDF of the template pi-stomp-core-drill-template_v1.0.pdf can be printed at full scale, folded along the “Enclosure edge” line, then attached (ie. taped) to a blank enclosure for marking. Make sure you have any printer scaling options (“fit”, etc.) disabled so that it is printed 1:1. Might be good to double check with a caliper or ruler before drilling (eg. make sure the LCD cutout measures as shown).
All measurements are shown in mm. Holes also have the equivalent size in inches since many drill indexes will be sized that way. As long as your cuts are within about +/- 1mm, your pi-Stomp Core guts should mount nicely. If you do run into mounting issues, you can usually oversize a hole a bit until it works.
All vertical measurements are relative to the “Enclosure edge”. All horizontal measurements are relative to the centerline defined by the Volume pot and encoder shafts. For this reason, it would generally be best to drill those holes first since that will define the positioning of your pi-stomp Core, then mark the other cuts relative to those.
Understand that this drawing assumes the wall thickness of a typical diecast enclosure (~2.4mm). If you're using something much thinner like folded aluminum, the distance of components to the enclosure edge will be greater than depicted here.
If you do powdercoat, paint or otherwise coat/seal a metal enclosure, make sure that you mask the inside of the enclosure around the volume knob. The body and shaft of the Volume knob connect to signal ground and are used to then ground the enclosure. This connection is important to keep the analog circuits shielded from noise. If you do experience extra noise, check with an ohm meter to assure the enclosure is within 1 ohm of ground (ie. ring conductor of I/O jacks).