The scad file contains lots of comments that may be handy for assembly.
Hi John,
What a sweet enclosure!
What printer did you use to make this?
The parametric-ness of OpenSCAD is really something - I’ve really got to dip my toes in, but Fusion for work and OnShape for hobby projects is just such an easy combo.
I wanted to see and appreciate the programmatic → 3D goodness so had a look at the file (and thought it would be kind to share).
Johns work not mine…
/*
OpenSCAD design to produce enclosures for Pi and 1 to 8 Sequent
8 channel relay boards.
There is a base for attaching to the Pi after the relay boards
have been attached to the Pi. This base can be screwed to a bench.
There are 2 side boards that slot into the Pi base (under and over)
and a lid that screws to the side boards
To use set num_relay_boards then go to the end and enable each of
the commented out calls in turn to produce the four STL files.
*/
$fn=120;
// Change this parameter to a value between 1 and 8 according to the number
// of relay boards used
num_relay_boards = 2;
// Pi 4 dimensions. Should be the same for Pi 5
pi_width = 85 + 4;
pi_lng = 56;
hole2hole_y = 58;
hole_y_1_offset = 3.5;
hole2hole_x = 49;
// Measurements for a base
part_thick = 2;
hole_dia = 3.2;
screwhead_dia = 5;
standoff_dia = 7;
// The base needs to be extended to suit relay connectors and allow
// screwdriver access to screw holes to fasten base to a bench
sd_card_end_extra = 35 + 12;
usb_end_extra = 20 + 12;
screwdown_dia = 4.5;
// Stand-offs are supplied with the relay boards. However 4 12 mm
// 2 mm female to female stand-offs are also required. These screw on
// under the Pi to the male ends of the bottom relay board stand-offs.
// The underside of the base has stand-offs that allow 2 mm dia screws
// to connect the 12 mm stand-offs with the screw head recessed.
pi_stand_off = 12;
pi_base_thick = 1.5;
relay_base_thick = 1.65;
relay_standoff = 19;
clrc = 0.75;
sidewidth = pi_width + sd_card_end_extra + usb_end_extra;
// There are 2 side plates that fit over the base plate and are held in
// place by a lid that is fastened to stand-offs by self tapper screws.
// The side height depends on the number of relay boards
sidehgt = 2*part_thick + pi_stand_off + pi_base_thick
+ (num_relay_boards + 1) * (relay_base_thick + relay_standoff)
+ 5; // Extra clearance //85;
// Provide clearance between Pi and side for ventilation and a 90 degree
// USB power cable
side_clrc = 20;
// Set the width that suits slotting the side to the base
overlap = 32;
// Connect top to sides using M4 self tapper screws
screw_dia = 3.5;
screw_column_dia = 8.5; // Stand-offs to fasten lid
module pirelayboxbase(){
difference(){
union(){
// Pi footprint
translate([-pi_lng/2, 0, 0]){
cube([pi_lng, pi_width, part_thick]);
}
// Add overlaps for relay hats and securing holes
translate([-pi_lng/2, -sd_card_end_extra, 0]){
cube([pi_lng, sd_card_end_extra, part_thick]);
}
translate([-pi_lng/2, pi_width, 0]){
cube([pi_lng, usb_end_extra, part_thick]);
}
// Base to bench screw down offsets
translate([-hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([-hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
// Pi Standoffs
translate([-hole2hole_x/2, hole_y_1_offset, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([hole2hole_x/2, hole_y_1_offset, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([-hole2hole_x/2, hole_y_1_offset + hole2hole_y, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
translate([hole2hole_x/2, hole_y_1_offset + hole2hole_y, 0]){
cylinder(h=2*part_thick, d=standoff_dia);
}
} // Union
// Screw holes to connect Pi base to a bench
translate([-hole2hole_x/2, hole_y_1_offset, 0]){
cylinder(h=20, d=hole_dia);
}
translate([hole2hole_x/2, hole_y_1_offset, 0]){
cylinder(h=20, d=hole_dia);
}
translate([-hole2hole_x/2, hole_y_1_offset + hole2hole_y, 0]){
cylinder(h=20, d=hole_dia);
}
translate([hole2hole_x/2, hole_y_1_offset + hole2hole_y, 0]){
cylinder(h=20, d=hole_dia);
}
// Screw head holes to connect Pi base with heads recessed
translate([-hole2hole_x/2, hole_y_1_offset, part_thick]){
cylinder(h=20, d=screwhead_dia);
}
translate([hole2hole_x/2, hole_y_1_offset, part_thick]){
cylinder(h=20, d=screwhead_dia);
}
translate([-hole2hole_x/2, hole_y_1_offset + hole2hole_y, part_thick]){
cylinder(h=20, d=screwhead_dia);
}
translate([hole2hole_x/2, hole_y_1_offset + hole2hole_y, part_thick]){
cylinder(h=20, d=screwhead_dia);
}
// Screw holes to attach to bench
translate([-hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, 0]){
cylinder(h=20, d=screwdown_dia);
}
translate([hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, 0]){
cylinder(h=20, d=screwdown_dia);
}
translate([-hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, 0]){
cylinder(h=20, d=screwdown_dia);
}
translate([hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, 0]){
cylinder(h=20, d=screwdown_dia);
}
} // Difference
}
module pirelayboxside(){
difference(){
union(){
// Under base
translate([pi_lng/2 - overlap + side_clrc, -sd_card_end_extra, part_thick]){
cube([overlap, sidewidth, part_thick]);
}
// Over base
translate([pi_lng/2 - overlap + side_clrc, -sd_card_end_extra, - part_thick - 0.17]){
cube([overlap, sidewidth, part_thick]);
}
// Side
translate([pi_lng/2 + side_clrc, -sd_card_end_extra, 2*part_thick - sidehgt]){
cube([part_thick, sidewidth, sidehgt]);
}
// Lid screws supports
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, 0, 2*part_thick - sidehgt]){
cylinder(h=sidehgt, d=screw_column_dia);
}
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, pi_width, 2*part_thick - sidehgt]){
cylinder(h=sidehgt, d=screw_column_dia);
}
} // Union
// Cut-outs for stand-offset
hull(){
translate([-hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
translate([hole2hole_x/2, -sd_card_end_extra + standoff_dia/2, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
}
hull(){
translate([-hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
translate([hole2hole_x/2, pi_width + usb_end_extra - standoff_dia/2, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
}
// Pi Standoffs
hull(){
translate([-hole2hole_x/2, hole_y_1_offset, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
translate([hole2hole_x/2, hole_y_1_offset, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
}
hull(){
translate([-hole2hole_x/2, hole_y_1_offset + hole2hole_y, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
translate([hole2hole_x/2, hole_y_1_offset + hole2hole_y, -10]){
cylinder(h=20, d=standoff_dia + clrc);
}
}
// Top screw holes
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, 0, 2*part_thick - sidehgt]){
cylinder(h=30, d=screw_dia);
}
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, pi_width, 2*part_thick - sidehgt]){
cylinder(h=30, d=screw_dia);
}
} // Difference
}
module pirelayboxsidemirrored(){
mirror([1,0,0]){
pirelayboxside();
}
}
module pirelayboxtop(){
difference(){
union(){
// Main top part
translate([-pi_lng/2 - side_clrc - 2*part_thick, -screw_column_dia/2, part_thick - sidehgt]){
cube([pi_lng + 2* side_clrc + 4*part_thick, pi_width + screw_column_dia, part_thick]);
}
// Outer sides
translate([-pi_lng/2 - side_clrc - 2*part_thick, -screw_column_dia/2, part_thick - sidehgt]){
cube([part_thick, pi_width + screw_column_dia, 4*part_thick]);
}
translate([pi_lng/2 + side_clrc + part_thick, -screw_column_dia/2, part_thick - sidehgt]){
cube([part_thick, pi_width + screw_column_dia, 4*part_thick]);
}
// Inner sides
translate([-pi_lng/2 - side_clrc + 0.2, (1.5*screw_column_dia)/2, part_thick - sidehgt]){
cube([part_thick, pi_width - 1.5 * screw_column_dia - 2, 4*part_thick]);
}
translate([pi_lng/2 + side_clrc - 0.2 - part_thick, (1.5*screw_column_dia)/2, part_thick - sidehgt]){
cube([part_thick, pi_width - 1.5 * screw_column_dia - 2, 4*part_thick]);
}
} // Union
// Screw holes
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, 0, 0]){
cylinder(h=300, d=screw_dia, center=true);
}
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, pi_width, 0]){
cylinder(h=300, d=screw_dia, center=true);
}
mirror([1,0,0]){
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, 0, 0]){
cylinder(h=300, d=screw_dia, center=true);
}
translate([pi_lng/2 + side_clrc - screw_column_dia/2 + part_thick, pi_width, 0]){
cylinder(h=300, d=screw_dia, center=true);
}
}
} // Difference
}
// Enable each of the following in turn to create the 4 STL files required.
//pirelayboxbase();
//pirelayboxside();
//pirelayboxsidemirrored();
//pirelayboxtop();
Liam
I’m a mining engineer that went into software development. I’m long retired but have lots of accumulated knowledge. I’ve used the internet to deal with heaps of problems and figure I need to do some payback.
I’ve been into 3D printing for about 5 years now. I love working with OpenSCAD as I have the engineering skills to do some creative designs. I use threaded rod, couplers etc to achieve high strength modules. I’m also aware of the fact that 3D printed parts are very weak across layers. If you look closely you will see that the Pi relay enclosure sides are printed so that the sides are really strong because they are printed flat. Printing the sides vertically may work for 2 relay boards but not for 8 as the sides will probably snap.
Regards
John
Oops. Didn’t answer all of your questions.
Printing was done on a Prusa MK4S 3D printer using PCTG filament. It is a bit stronger than PETG. I reckon most 3D printers using PLA will provide a good result because the sections that need to be strong are printed on the bed. Printing sides vertically would be hopeless with 8 relay boards but they will be very strong with the sides flat.
Think about a karate hit to a timber board. It is is always done with the grain but never across the grain. The same principle applies to 3D prints.
Regards
John
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