Tailor’s Clapper: 3D Printed Finger Grips

With the pockets milled into the oak blocks, the next step is to insert a pair of comfy 3D printed finger grips:

Ironing weight – prototype grip

Getting comfy required a bank shot off the familiar chord equation to find the radius of a much larger circle producing the proper depth between the known width. The recess then comes from subtracting a hotdog from a lozenge exactly filling the wood pocket.

Ironing Weight Finger Grip – recess chord

A pair of grips takes just under two hours to print while requiring no attention, which I vastly prefer to tending the Sherline.

The wood pocket is 7 mm deep and the grips stand 6.5 mm tall, leaving just enough room for three blobs of acrylic adhesive to hold them together. After squishing the grips into their pockets, a pair of right angles aligned everything while the adhesive cured:

Ironing weight – grip adhesive curing

Mary asked for a longer weight for a place mat project, with a slightly narrower block to compensate for the additional length:

Ironing weight – seam ironing B

The grip and pocket were the same size, so it was just a matter of tweaking the block size and cutting more wood.

All in all, a quick project with satisfying results!

The OpenSCAD source code as a GitHub Gist:

	// Oak ironing weight finger grips
	// Ed Nisley KE4ZNU 2023-01

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

	//- Extrusion parameters must match reality!

	/* [Hidden] */

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

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

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

	//———-
	// Dimensions
	// Length along X axis

	Block = [250.0,50.0,39.0]; // overall wood block
	BlockRadius = 10.0;

	CornerRadius = 10.0;
	Kerf = 0.2;

	Socket = [160.0,25.0,6.5]; // raw recess into block
	SocketRadius = Socket.y/2;
	echo(Socket=Socket,SocketRadius=SocketRadius);

	WallThick = ThreadWidth; // Thinnest printed wall
	Clearance = 0.5; // between grip and recess

	GripBlock = Socket – [2Clearance,2Clearance,Clearance];
	GripBlockRadius = SocketRadius – Clearance;
	echo(GripBlock=GripBlock);

	GripDepth = 5.0; // finger grip recess

	GripRecess = [GripBlock.x – 2WallThick,GripBlock.y – 2WallThick,GripDepth];
	GripRecessRadius = GripBlockRadius – WallThick;
	echo(GripRecess=GripRecess,GripRecessRadius=GripRecessRadius);

	GripChordRadius = (pow(GripDepth,2) + pow(GripRecess.y,2)/4) / (2*GripDepth);
	echo(GripChordRadius=GripChordRadius);

	NumSides = 4*8;

	//———-
	// Shapes

	module WoodBlock() {

	difference() {
	hull()
	for (i=[-1,1], j=[-1,1]) // rounded block
	translate([i(Block.x/2 – BlockRadius),j(Block.y/2 – BlockRadius),-Block.z/2])
	cylinder(r=BlockRadius,h=Block.z,$fn=NumSides);

	for (j=[-1,1]) // grip socket
	translate([0,j*(Block.y/2 + Protrusion),0])
	rotate([j*90,0,0])
	hull() {
	for (i=[-1,1])
	translate([i*(Socket.x/2 – SocketRadius),(Socket.y/2 – SocketRadius),0])
	cylinder(r=SocketRadius,h=Socket.z + Protrusion,$fn=NumSides);
	}

	cube([2Block.x,2Block.y,Kerf],center=true);
	}
	}


	module Grip() {

	difference() {
	hull()
	for (i=[-1,1]) // overall grip block
	translate([i*(GripBlock.x/2 – GripBlockRadius),0,0])
	cylinder(r=GripBlockRadius,h=GripBlock.z,$fn=NumSides);

	hull() {
	for (i=[-1,1]) // grip recess
	translate([i*(GripBlock.x/2 – GripRecessRadius – WallThick),
	0,
	GripChordRadius + GripBlock.z – GripDepth])
	sphere(r=GripChordRadius,$fn=NumSides);
	}
	}

	}

	//———-
	// Build them

	if (Layout == "Block")
	WoodBlock();

	if (Layout == "Grip")
	Grip();

	if (Layout == "Show") {
	color("Brown")
	WoodBlock();
	color("Silver")
	for (j=[-1,1])
	translate([0,j*(Block.y/2 – GripBlock.z),0])
	rotate([j*-90,0,0])
	Grip();
	}

	if (Layout == "Build") {
	for (i=[-1,1])
	translate([i*(Block.y/2 – GripBlock.z),0,0])
	rotate([0,0,90])
	Grip();

	}