Tag: MK4

Prusa Mk 4 3D printer with MMU3 feeder

Prusa MK4 + MMU3 Test Piece

The slanted layers mean this simple block requires something like 180 filament changes while verifying the Prusa MK4 + MMU3 / filament buffer setup:

Prusa MK4 MMU test piece – finished

Because of all the color changes, the Wipe Tower holding the extruder waste is much much larger than the block:

Prusa MK4 MMU test piece – on platform

The first attempt taught me, once again, the value of cleanliness:

Prusa MK4 MMU test piece – birds nest as found

The extruder head required tedious cleaning:

Prusa MK4 MMU test piece – extruder tangle

Scrubbing the steel plate with dish detergent and wiping it with isopropyl alcohol improved the outcome, but one corner of the Wipe Tower still lifted:

Prusa MK4 MMU test piece – wipe tower corner lifting

All’s well that ends well, but perhaps glue stick / hair spray under future Wipe Towers will ensure they don’t wander off.

2024-08-28

Cutting Board Shim

The kitchen counter has only two useful places for the cutting board and the spot Mary favors puts a distinct swale under one corner. A bit of measuring and solid modeling produced a simple shim to make the answer come out right:

The basic shape is union() of a trio of hull() operations forming the three sides, with the text label as a separate object to verify I understood how to build a multi-material object.

Export it as a 3mf file, open it in PrusaSlicer, slice, print:

Cutting Board shim - label — Cutting Board shim – label

Putting the label on the bottom surface takes advantage of the nubbly finish on the Textured Steel Sheet to make it look like it just grew in there.

The label is just barely visible from the top, despite extending only 1/4 of the way through the 1.6 mm bottom slab:

Cutting Board shim - top — Cutting Board shim – top

So white PETG needs more than 1.2 mm of thickness to hid a black feature. Today I Learned, etc.

Multi-material printing produces a Wipe Tower to hold all the extruded junk during color changes:

Cutting Board shim - wipe tower — Cutting Board shim – wipe tower

The curl under the nozzle comes from the final ramming used to shape the end of the filament into a point for reliable material / color changing.

Although a shim is something of a nuisance, it works perfectly:

Cutting Board shim - in use — Cutting Board shim – in use

Much easier than installing an L-shaped Corian slab with a sink cutout!

The faded engraving dates back to the early days of the laser …

The OpenSCAD source code as a GitHub Gist:

	// Cutting Board alignment shim
	// Ed Nisley KE4ZNU – 2024-08-20

	//—–
	// Dimensions

	ShimThick = 1.6; // thickness of shim under board

	/* [Hidden] */

	ShimOA = [25.0,25.0,15.0]; // overall size of shim

	WallThick = 4.0;

	ShimRadius = WallThick/2;

	LabelThick = ShimThick/4;

	NumSides = 3*4;

	//—–
	// Build it

	union() {
	hull()
	for (i=[0,1])
	translate([i*(ShimOA.x – ShimRadius),0,0])
	cylinder(r=ShimRadius,h=ShimOA.z,$fn=NumSides);
	hull()
	for (j=[0,1])
	translate([0,j*(ShimOA.y – ShimRadius),0])
	cylinder(r=ShimRadius,h=ShimOA.z,$fn=NumSides);

	hull() {
	for (i=[0,1])
	translate([i*(ShimOA.x – ShimRadius),0,0])
	cylinder(r=ShimRadius,h=ShimThick,$fn=NumSides);
	translate([0,1*(ShimOA.y – ShimRadius),0])
	cylinder(r=ShimRadius,h=ShimThick,$fn=NumSides);
	}

	}

	color("Black")
	translate([ShimOA.x/3,ShimOA.y/3,LabelThick])
	rotate([180,0,90 + 45])
	linear_extrude(height=LabelThick,convexity=20)
	text(text=str(ShimThick),size=6,spacing=1.00,
	font="Arial:style:Bold",halign="center",valign="center");

view raw Cutting Board shim.scad hosted with ❤ by GitHub

2024-08-27

Under-cabinet LED Light Brick Mounts

Descending directly from the holders for the MPCNC power brick, slightly smaller brackets for the power bricks attached to the under-cabinet LED strip light in the kitchen:

Kitchen Under-cabinet light power brick mounts - slicer view — Kitchen Under-cabinet light power brick mounts – slicer view

Made from black PETG (because they’re in the kitchen) they fit fine:

Under-cabinet light - brick B — Under-cabinet light – brick B

Although the elegance depends on which way the brick points:

Under-cabinet light - brick A — Under-cabinet light – brick A

They have the distinction of being the first “real” objects from the Prusa MK4. All my hard-won knowledge of forcing solid models into reality through a 3D printer is obsolete: the default slicer settings on a new printer work perfectly, with no fiddling required.

The OpenSCAD source code as a GitHub Gist:

	// Power Supply Brick brackets
	// Ed Nisley KE4ZNU 2024-08-19

	Layout = "Show"; // [Show,Build]

	//– Extrusion parameters

	/* [Hidden] */

	ThreadThick = 0.20;
	ThreadWidth = 0.45;

	HoleWindage = 0.3; // enlarge hole dia by this amount

	function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

	Protrusion = 0.1; // make holes look good and joints intersect properly

	//– Useful sizes

	ID = 0;
	OD = 1;
	LENGTH = 2;

	//– Bracket Dimensions

	Brick = [115.0,51.0,32.0]; // overall size, add details in module

	Socket = [20.0,10.0]; // binocular power socket
	Cable = [5.0,12.0]; // DC output cable ID=wire OD=strain relief

	//Socket = [30.0,24.0]; // IEC power socket
	//Cable = [6.0,15.0]; // DC output cable ID=wire OD=strain relief

	WallThick = 3.0; // default wall thickness
	BaseThick = 4.0;

	Screw = [5.1,10.0,3.0]; // screw size, more-or-less 10-32, OD & LENGTH for head

	NumSides = 3*4;

	//———————-
	// Useful routines

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes

	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

	FixDia = Dia / cos(180/Sides);

	cylinder(r=(FixDia + HoleWindage)/2,
	h=Height,
	$fn=Sides);
	}

	//———————-
	// Models

	module BrickMount(End="Both") {

	difference() {
	union() {
	hull() // main block
	for (i=[-1,1], j=[-1,1], k=[0,1])
	translate([i*(Brick.x/2 + WallThick – WallThick),
	j*(Brick.y/2 + WallThick – WallThick),
	k*(Brick.z + WallThick – WallThick)])
	sphere(r=WallThick,$fn=NumSides);
	hull() // screw flanges
	for (i=[-1,1], j=[-1,1])
	translate([i*(Brick.x/2 + WallThick – BaseThick),
	j(Brick.y/2 + WallThick + 2Screw[OD] – BaseThick),
	0])
	sphere(r=BaseThick,$fn=NumSides);
	}
	for (i=[-1,1], j=[-1,1]) // remove screw holes
	translate([i*(Brick.x/2 + WallThick – Screw[OD]),
	j*(Brick.y/2 + WallThick + Screw[OD]),
	-Protrusion])
	rotate(180/6)
	PolyCyl(Screw[ID],2*WallThick,6);

	translate([0,0,Brick.z/2]) // remove center part to leave ends
	cube([(Brick.x + 2WallThick – 4Screw[OD]),2Brick.y,2Brick.z],center=true);

	if (End == "Socket")
	translate([Brick.x/2,0,Brick.z/2]) // remove cable end to leave socket
	cube([(Brick.x + 2WallThick – 4Screw[OD]),2Brick.y,2Brick.z],center=true);

	if (End == "Cable")
	translate([-Brick.x/2,0,Brick.z/2]) // remove socket end to leave cable
	cube([(Brick.x + 2WallThick – 4Screw[OD]),2Brick.y,2Brick.z],center=true);

	translate([0,0,Brick.z/2 – Protrusion/2]) // remove power supply brick from interior
	cube(Brick + [0,0,Protrusion],center=true);

	translate([0,0,-Brick.z]) // remove below XY plane
	cube(2*Brick,center=true);

	translate([0,0,Brick.z/2]) // remove AC socket
	rotate([0,-90,0])
	rotate(90)
	linear_extrude(height=Brick.x,convexity=2)
	square(Socket,center=true);

	translate([0,0,Brick.z/2]) // remove DC cable
	rotate([0,90,0])
	rotate(180/8)
	PolyCyl(Cable[OD],Brick.x,8);

	translate([Brick.x/2,0,Brick.z/4 – Protrusion/2]) // … and wire slot
	cube([Brick.x,Cable[ID],Brick.z/2 + Protrusion],center=true);
	}

	}

	//———————-
	// Build it

	if (Layout == "Show")
	BrickMount("Both");

	if (Layout == "Build") {
	translate([5,0,Brick.x/2 + WallThick])
	rotate([0,90,0])
	BrickMount("Cable");
	translate([-5,0,Brick.x/2 + WallThick])
	rotate([0,-90,0])
	BrickMount("Socket");
	}

view raw Power Supply Brick Mount.scad hosted with ❤ by GitHub

2024-08-26

Prusa MK4 Y Motor Shim
Having been viciously nerd-sniped by The Great Dragorn of Kismet, I’m in the process of building a Prusa MK4 3D printer with an MMU3. This has been a generally pleasant experience, although I am beginning to loathe Genuine Haribo Goldbären.

Anyhow, the Y axis motor position puts the belt too close to one side of the pulley, with no further adjustment possible:

Prusa MK4 Y axis motor mount – as-built

The stepper motor stator laminations are the striped gray area on the far left, the 3D printed motor mount is the striped black area on the right, and the belt pulley is snugged up against the motor as far as it can go on the shaft.

Pushing the motor a little more to the left requires a shim:

Prusa MK4 Y axis motor mount – shim

Rather than fiddle with scanning the motor mount, I imported its STL model from the Prusa MK4 files:

Prusa MK4 Y Axis Motor mount – solid model

Importing the STL into OpenSCAD and converting the motor face into an SVG file is basically a one-liner:
```
projection(cut=true)
translate([0,0,-5.0])
import("/mnt/bulkdata/Project Files/Prusa Mk4/Calibration/y_motor_holder_R3.stl");
```
Import the SVG into LightBurn, round the corners a little, set it up for 1.5 mm Trocraft Eco, Fire. The. Laser. and it fits perfectly and stands out nicely:

Prusa MK4 Y axis motor mount – shimmed

Having the right tools for a job makes it easy …
2024-08-21

Tag: MK4

Prusa MK4 + MMU3 Test Piece

Cutting Board Shim

Under-cabinet LED Light Brick Mounts

Prusa MK4 Y Motor Shim