Garden Hose Valve Knobs: One Wrench To Rule Them

A sampling of the various Y connectors and manifolds that water Mary’s gardens:

Those little handles don’t turn nearly as easily as they should and some require far more finger pressure than Mary can exert. Lubrication being unavailing, the solution is to apply torque through a wrench, rather than fingertips, but fiddling around to match the proper wrench with the valve in hand isn’t acceptable.

The first pass at a Universal Wrench:

Hose Valve Knob - with measurements
Hose Valve Knob – with measurements

The embossed sheet (the back of my Geek Scratch Paper) carried the knob shapes & dimensions from the garden to the desk, where I measured & laid out the wrench:

Hose Connector Knob - Build layout
Hose Connector Knob – Build layout

I filched the knob design from the OXO Can Opener Handle, made it somewhat taller, and applied a scale() operation to mash it into an ellipse aligned with the wrench slot. That huge hexagonal socket in the middle bridged just fine, even though the threads came out as distinct cylinders:

Hose Connector Knob - bridge layer - Slic3r preview
Hose Connector Knob – bridge layer – Slic3r preview

Adding one thread width of clearance around the stem to form the socket produced a slip fit, with a dollop of fast-cure epoxy holding the pieces together.

The wrench fits the largest valve knob with enough clearance to eliminate fiddling. A cylinder punched into the middle of the slot accommodates those teardrop handles:

Hose Connector Knob - Show layout - bottom view
Hose Connector Knob – Show layout – bottom view

It’s oversized for the smallest “knob”, a vicious triangular stalk that’s murder on the fingers (and not shown here), but fits well enough that, should we deploy any of those, she’ll be ready.

The stem diameter can’t be any larger, because the knobs on Valve 1 don’t allow any clearance. It could be more circular, but I doubt that buys anything. The open ends of the slot won’t let mulch pack into the recesses.

I expect a wrench jaw will eventually snap off as the layers delaminate. In that case I’ll either sink a pair of steel pins into each jaw or, more likely, combine the handle & stem into one object, split the whole affair across the jaws, print the two halves, and glue them together so that the threads run in the proper direction to meet the stress.

Be that as it may, as of right now this is The Best Thing I’ve Ever Built

The OpenSCAD source code:

// Hose connector knob
// Ed Nisley KE4ZNU - June 2015

Layout = "Build";				// Show Build Knob Stem

//- Extrusion parameters - must match reality!

ThreadThick = 0.25;
ThreadWidth = 0.40;

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

Protrusion = 0.1;

HoleWindage = 0.2;

// Dimensions

StemOD = 30.0;					// max OD for valve-to-valve clearance

BossOD = 16.0;					// single-ended handle boss

SlotWidth = 13.0;
SlotHeight = 10.0;

StemInset = 10.0;
StemLength = StemInset + SlotHeight + 25.0;
StemSides = 2*4;

KnobOD1 = 70;						// maximum dia without chamfer
KnobOD2 = 60;						// top dia

KnobSides = 4*4;

DomeHeight = 12;					// dome shape above lobes

KnobHeight = DomeHeight + 2*SlotHeight;

DomeOD = KnobOD2 + (KnobOD1 - KnobOD2)*(DomeHeight/KnobHeight);

DomeArcRad = (pow(KnobHeight,2) + pow(DomeOD,2)/4) / (2*DomeHeight);

//- Adjust hole diameter to make the size come out right

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);

//-- Stem for valve handles

module Stem() {

	difference() {
		translate([0,0,SlotHeight/2 - Protrusion/2])
			cube([2*StemOD,SlotWidth,(SlotHeight + Protrusion)],center=true);


//-- Hand-friendly knob

module KnobCap() {
	difference() {
		intersection() {
				cylinder(d=(StemOD + 2*ThreadWidth),h=(StemInset + Protrusion),$fn=StemSides);

//- Build it

if (Layout == "Knob")

if (Layout == "Stem")

if (Layout == "Build") {

if (Layout == "Show") {
	translate([0,0,StemLength - StemInset])

7 thoughts on “Garden Hose Valve Knobs: One Wrench To Rule Them

  1. The non-standard standardizer, I like it. We have a few of those hose manifolds as well, really prefer the Gilmores. My wife has the same trouble with the little handles too. Maybe I’ll crank something similar out in aluminum or brass. Nice work Ed.

  2. I’d like to recommend 1mm dia carbon fiber rod for increasing strength. Just subtract long 1mm dia holes from your object, ream them out after printing with a 1mm drill bit and use gap-filling crazy glue to glue them in place. Carbon fiber rod is cheap and available at your local hobby store. You can be strategic about where you put the holes for strength. It’s especially good for helping to bind the layers together better.

    1. Sounds good to me; I should lay in a stock of that stuff just to have it around…

  3. Haven’t been fond of the plastic ball valves, especially after one of the high-flow types froze and broke the handle. I did a very-high-flow manifold with 3/4″ NPT stainless ball valves, and another with some 1/2″ valves from the stash. The big one means I can keep a 3/4″ hose set up at all times for small fires–the joy of thunderstorm season.

    1. broke the handle

      I fully expect that Mary can now apply enough torque to snap the flimsier handles, but they’re significantly less difficult to replace than her fingertips…

Comments are closed.