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Although the OMTech laser controls the laser power supply with a key-lock switch, there’s little visible difference between the OFF and ON positions. Having occasionally mistaken it in both directions, this seemed like a useful addition:

Laser Power Lock Indicator - installed — Laser Power Lock Indicator – installed

The strip of black duct tape below the lock muffles the rattle of the triangle hatch key against the metal cabinet.

Two snippets of foam tape hold the knob to the lock cylinder, making an admittedly tenuous connection, but the knob fits around the outside of the switch housing with minimal clearance and ~~doesn’t~~ shouldn’t suffer any torque or pulling, so it might work.

The solid model looks about like you’d expect:

Laser Power Lock Indicator - solid model — Laser Power Lock Indicator – solid model

Unfortunately, it has no good orientation for printing, so I let PrusaSlicer generate support material inside the knob:

Laser Power Lock Indicator - Support structures — Laser Power Lock Indicator – Support structures

Suffice it to say: removing all that plastic did not go well.

I eventually grabbed the knob in the lathe and bored the interior out to its more-or-less proper dimensions, figuring nobody would ever notice the carnage, and it worked reasonably well. In the unlikely event I need another pointer, I’ll add a support spider to hold up the interior with minimal contact and less plastic.

Yeah, the laser really needs a stack light showing its condition and safety status …

The OpenSCAD source code as a GitHub Gist:

	// Indicator for OMTech laser power lock
	// Ed Nisley KE4ZNU 2022-04-09

	KnobOD = 35.0;
	KnobHeight = 22.0;
	KnobTaper = 4.0;

	PointerLength = 45.0;
	PointerThick = 3.0;

	TipOD = 2.0;

	/* [Hidden] */

	//——

	Protrusion = 0.1; // make holes end cleanly
	HoleWindage = 0.2;

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes
	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
	FixDia = Dia / cos(180/Sides);
	cylinder(d=(FixDia + HoleWindage),h=Height,$fn=Sides);
	}



	//———-
	// Create part
	// Plenty of magic numbers from actual measurements

	module Pointer() {

	difference() {
	union() {
	linear_extrude(height=PointerThick)
	hull() {
	circle(d=KnobOD,$fn=24);
	translate([PointerLength – TipOD/2,0])
	circle(d=TipOD,$fn=12);
	}

	cylinder(d=KnobOD,h=KnobHeight – KnobTaper,$fn=24);
	translate([0,0,KnobHeight – KnobTaper – Protrusion])
	cylinder(d1=KnobOD,d2=KnobOD – 3.0,h=KnobTaper + Protrusion,$fn=24);
	}

	translate([0,0,-Protrusion]) {
	PolyCyl(29.0,14.0 + Protrusion,24);
	PolyCyl(24.0,14.0 + 5.0 + Protrusion,24); // leaves clearance under pointer
	}

	translate([0,0,KnobHeight])
	cube([12.0,2.0,2*KnobHeight],center=true);

	}
	}

	//———-
	// Build it

	Pointer();

view raw Laser Power Lock Indicator.scad hosted with ❤ by GitHub

And doodles giving the dimensions of the key lock, not all of which can be true at the same time:

The New Hotness

OMTech 60 W Laser: Laser Power Indicator