The New Hotness

Mary wanted a rigid cap for a Clover seam ripper that came with a small plastic sheath, so I called one from the vasty digital deep:

Clover Seam Ripper - new cap — Clover Seam Ripper – new cap

The solid model looks about like you’d expect, with a brim around the bottom to paste it on the platform:

Clover Seam Ripper Cap - Slic3r preview — Clover Seam Ripper Cap – Slic3r preview

I added a slightly tapered entry to work around the usual tolerance problems:

Clover Seam Ripper Cap - bottom view — Clover Seam Ripper Cap – bottom view

The taper comes from a hull wrapped around eight small spheres:

Clover Seam Ripper Cap - Entry Pyramid — Clover Seam Ripper Cap – Entry Pyramid

That’s surprisingly easy to accomplish, at least after you get used to this sort of thing:

hull() {																		// entry taper
	for (i=[-1,1] , j=[-1,1])
		translate([i*(HandleEntry[0]/2 - StemRadius),j*(HandleEntry[1]/2 - StemRadius),0])
			sphere(r=StemRadius,$fn=4*4);
	for (i=[-1,1] , j=[-1,1])
		translate([i*(HandleStem[0]/2 - StemRadius),j*(HandleStem[1]/2 - StemRadius),HandleEntry[2] - StemRadius])
			sphere(r=StemRadius,$fn=4*4);	
}

The side walls are two threads thick and, at least in PETG, entirely too rigid to slide on easily. I think a single-thread wall with a narrow ridge would provide more spring; if this one gets too annoying, I’ll try that.

The OpenSCAD source code as a GitHub gist:

	// Clover seam ripper cap
	// Ed Nisley KE4ZNU – April 2016

	//- Extrusion parameters – must match reality!
	// Build with a 5 mm brim to keep it glued to the platform

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	Protrusion = 0.1;

	//——
	// Dimensions

	StemRadius = 0.50; // corner radius

	HandleStem = [6.1, 7.1, 9.0];

	HandleEntry = HandleStem + [1.0,1.0,-4.0]; // Z is -(straight part of stem)

	Cap = [8.5,11.0,45.0]; // XY exterior, Z interior


	//———————-
	//- Build it

	difference() {
	union() {
	translate([0,0,Cap[2]/2]) // main body column
	cube(Cap,center=true);

	translate([-Cap[0]/2,0,Cap[2]]) // rounded cap
	rotate([0,90,0])
	cylinder(d=Cap[1],h=Cap[0],$fn=8*4);

	translate([Cap[0]/2 – Protrusion,0,(Cap[2] + Cap[1]/2)/2]) // text
	rotate([0,90,0])
	linear_extrude(height=ThreadWidth,convexity=10)
	text("Mary Nisley",halign="center",valign="center",size=0.5*Cap[1],font="Arial");
	}

	hull() // stem + blade clearance
	for (i=[-1,1] , j=[-1,1])
	translate([i(HandleStem[0]/2 – StemRadius),j(HandleStem[1]/2 – StemRadius),-Protrusion])
	cylinder(r=StemRadius,h=Cap[2] + Protrusion,$fn=4*4);

	hull() { // entry taper
	for (i=[-1,1] , j=[-1,1])
	translate([i(HandleEntry[0]/2 – StemRadius),j(HandleEntry[1]/2 – StemRadius),0])
	sphere(r=StemRadius,$fn=4*4);
	for (i=[-1,1] , j=[-1,1])
	translate([i(HandleStem[0]/2 – StemRadius),j(HandleStem[1]/2 – StemRadius),HandleEntry[2] – StemRadius])
	sphere(r=StemRadius,$fn=4*4);

	}
	}

view raw Clover Seam Ripper Cap.scad hosted with ❤ by GitHub