The New Hotness

The smaller and more rigid CNC 3018-Pro should be able to engrave text faster than the larger and rather springy MPCNC, which could engrave text at about 50 mm/min. This test pattern pushes both cutting depth and engraving speed to absurd values:

Engraving Test Pattern - 2019-09-18 — Engraving Test Pattern – 2019-09-18

Compile the GCMC source to generate G-Code, lash a CD / DVD to the platform (masking tape works fine), touch off the XY coordinates in the center, touch off Z=0 on the surface, then see what happens:

CNC 3018-Pro - Engraving test pattern - curved text — CNC 3018-Pro – Engraving test pattern – curved text

The “engraving depth” translates directly into the force applied to the diamond point, because the spring converts displacement into force. Knowing the Z depth, you can calculate or guesstimate the force.

Early results from the 3018 suggest it can engrave good-looking text about 20 times faster than the MPCNC:

CNC 3018-Pro - Engraving - speeds — CNC 3018-Pro – Engraving – speeds

You must trade off speed with accuracy on your very own machine, as your mileage will certainly differ!

The GCMC source code as a GitHub Gist:

	// Engraving test piece
	// Ed Nisley KE4ZNU – 2019-09

	//—–
	// Command line parameters

	// -D OuterDia=number

	if (!isdefined("OuterDia")) {
	OuterDia = 120mm – 2mm; // CD = 120, 3.5 inch drive = 95
	}

	OuterRad = OuterDia / 2.0;
	comment("Outer Diameter: ",OuterDia);
	comment(" Radius: ",OuterRad);

	//—–
	// Library routines

	include("tracepath.inc.gcmc");
	include("engrave.inc.gcmc");

	//—–
	// Bend text around an arc

	function ArcText(TextPath,Center,Radius,BaseAngle,Align) {

	PathLength = TextPath[-1].x;
	Circumf = 2pi()Radius;
	TextAngle = to_deg(360 * PathLength / Circumf);

	AlignAngle = BaseAngle + (Align == "Left" ? 0 :
	Align == "Center" ? -TextAngle / 2 :
	Align == "Right" ? -TextAngle :
	0);

	ArcPath = {};

	foreach(TextPath; pt) {
	if (!isundef(pt.x) && !isundef(pt.y) && isundef(pt.z)) { // XY motion, no Z
	r = Radius – pt.y;
	a = 360deg * (pt.x / Circumf) + AlignAngle;
	ArcPath += {[rcos(a) + Center.x, rsin(a) + Center.y,-]};
	}
	elif (isundef(pt.x) && isundef(pt.y) && !isundef(pt.z)) { // no XY, Z up/down
	ArcPath += {pt};
	}
	else {
	error("Point is not pure XY or pure Z: " + to_string(pt));
	}
	}

	return ArcPath;

	}

	//—–
	// Set up for drawing

	SafeZ = 10.0mm; // above clamps and screws
	TravelZ = 1.0mm; // above workpiece
	PlotZ = -0.5mm; // tune for best results

	TextSpeed = 1000mm; // intricate detail
	DrawSpeed = 2000mm; // smooth curves

	TextFont = FONT_HSANS_1_RS;
	TextSize = [2.0mm,2.0mm];
	TextLeading = 2*TextSize.y; // line spacing

	DiskCenter = [0mm,0mm]; // middle of the platter

	InnerDia = 40mm;
	InnerRad = InnerDia / 2.0;
	comment("Inner Diameter: ",InnerDia);
	comment(" Radius: ",InnerRad);

	NumRings = ceil((OuterRad – (InnerRad + TextLeading))/TextLeading); // number of rings to draw
	comment("Numer of rings: ",NumRings);

	if (1) {
	comment("Text Size begins");

	feedrate(TextSpeed);
	ts = "Text size: " + to_string(TextSize);
	tp = scale(typeset(ts,TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,OuterRad,90deg,"Left");
	engrave(tpa,TravelZ,PlotZ);
	}

	if (1) {
	comment("Depth variations begin");

	TextRadius = OuterRad;

	pz = 0.0mm;
	repeat(NumRings ; i) {
	comment(" depth: " + to_string(pz));

	feedrate(TextSpeed);
	ts = "Depth: " + to_string(pz) + " at " + to_string(TextSpeed) + "/min";
	tp = scale(typeset(ts,TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,TextRadius,-5deg,"Right");
	engrave(tpa,TravelZ,pz);

	feedrate(DrawSpeed);
	goto([0,-TextRadius,-]);
	move([-,-,pz]);
	arc_ccw([-TextRadius,0,-],-TextRadius);
	goto([-,-,TravelZ]);

	feedrate(TextSpeed);
	tp = scale(typeset("Rad: " + to_string(TextRadius),TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,TextRadius,180deg,"Right");
	engrave(tpa,TravelZ,PlotZ);

	TextRadius -= TextLeading;
	pz -= 0.10mm;
	}
	}

	if (1) {
	comment("Feedrate variations begin");

	TextRadius = OuterRad;

	ps = 250mm;
	repeat(NumRings ; i) {
	comment(" speed: " + to_string(ps) + "/min");

	feedrate(ps);
	ts = "Speed: " + to_string(ps) + "/min at " + to_string(PlotZ);
	tp = scale(typeset(ts,TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,TextRadius,5deg,"Left");
	engrave(tpa,TravelZ,PlotZ);

	TextRadius -= TextLeading;
	ps += 250mm;
	}
	}

	if (1) {
	comment("Off-center text arcs begin");

	feedrate(TextSpeed);
	tc = [-40mm/sqrt(2),-40mm/sqrt(2)]; // center point

	r = 3mm;
	s = [0.5mm,0.5mm];
	ts = "Radius: " + to_string(r) + " Size: " + to_string(s);
	tp = scale(typeset(ts,TextFont),s);
	tpa = ArcText(tp,tc,r,0deg,"Center");
	engrave(tpa,TravelZ,PlotZ);

	r = 5mm;
	s = [1.0mm,1.0mm];
	ts = "Radius: " + to_string(r) + " Size: " + to_string(s);
	tp = scale(typeset(ts,TextFont),s);
	tpa = ArcText(tp,tc,r,0deg,"Center");
	engrave(tpa,TravelZ,PlotZ);

	r = 8mm;
	s = [1.5mm,1.5mm];
	ts = "Radius: " + to_string(r) + " Size: " + to_string(s);
	tp = scale(typeset(ts,TextFont),s);
	tpa = ArcText(tp,tc,r,0deg,"Center");
	engrave(tpa,TravelZ,PlotZ);

	r = 15mm;
	s = [3.0mm,3.0mm];
	ts = "Radius: " + to_string(r) + " Size: " + to_string(s);
	tp = scale(typeset(ts,FONT_HSCRIPT_2),s);
	tpa = ArcText(tp,tc,r,0deg,"Center");
	engrave(tpa,TravelZ,PlotZ);
	}

	if (1) {
	comment("Attribution begins");

	feedrate(TextSpeed);
	tp = scale(typeset("Ed Nisley – KE4ZNU – softsolder.com",TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,15mm,0deg,"Center");
	engrave(tpa,TravelZ,PlotZ);

	tp = scale(typeset("Engraving Test Disc",TextFont),TextSize);
	tpa = ArcText(tp,DiskCenter,15mm,180deg,"Center");
	engrave(tpa,TravelZ,PlotZ);
	}

	goto([-,-,SafeZ]);
	goto([0mm,0mm,-]);

	comment("Done!");

view raw Engraving Test.gcmc hosted with ❤ by GitHub

	#!/bin/bash
	# Engraving test pattern generator
	# Ed Nisley KE4ZNU – 2019-08

	Diameter='OuterDia=116mm'

	Flags='-P 3 –pedantic'

	# Set these to match your file layout
	LibPath='/opt/gcmc/library'
	Prolog='/mnt/bulkdata/Project Files/CNC 3018-Pro Router/Patterns/gcmc/prolog.gcmc'
	Epilog='/mnt/bulkdata/Project Files/CNC 3018-Pro Router/Patterns/gcmc/epilog.gcmc'

	Script='/mnt/bulkdata/Project Files/CNC 3018-Pro Router/Patterns/Engraving Test.gcmc'

	ts=$(date +%Y%m%d-%H%M%S)

	fn='TestPattern_'${ts}'.ngc'
	echo Output: $fn

	rm -f $fn
	echo "(File: "$fn")" > $fn

	/opt/gcmc/src/gcmc -D $Diameter $Flags \
	–include "$LibPath" –prologue "$Prolog" –epilogue "$Epilog" \
	"$Script" >> $fn

view raw Engraving Test.sh hosted with ❤ by GitHub

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