Dripworks Mainline Pipe Clamp

This is laid in against a need I hope never occurs:

Dripworks 0.75 inch pipe clamp
Dripworks 0.75 inch pipe clamp

It’s intended to clamp around one of the Dripworks mainline pipes carrying water from the pressure regulator to the driplines in the raised beds, should an errant shovel or fork find the pipe.

It descends from a long line of soaker hose clamps, with a 25 mm ID allowing for a silicone tape wrap as a water barrier.

The solid model has no surprises:

Dripworks Mainline Clamp - build view
Dripworks Mainline Clamp – build view

The OpenSCAD source code as a GitHub Gist:

// Dripworks 3/4 inch mainline clamp
// Ed Nisley KE4ZNU 2021-06
Layout = "Build"; // [Hose,Block,Show,Build]
HoseOD = 25.0;
TestFit = false; // true to build test fit slice from center
//- 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;
// Dimensions
// Hose lies along X axis
Hose = [200,HoseOD,HoseOD]; // X = longer than anything else
NumScrews = 2; // screws along each side of cable
WallThick = 3.0; // Thinnest printed wall
PlateThick = 1.5; // Stiffening plate thickness
// 8-32 stainless screws
Screw = [4.1,8.0,50.0]; // OD = head LENGTH = thread length
Washer = [4.4,9.5,1.0];
Nut = [4.1,9.7,3.3];
Block = [30.0,Hose.y + 2*Washer[OD],HoseOD + 2*WallThick]; // overall splice block size
echo(str("Block: ",Block));
ScrewMinLength = Block.z + 2*PlateThick + 2*Washer.z + Nut.z; // minimum screw length
echo(str("Screw min length: ",ScrewMinLength));
Kerf = 1.0; // cut through middle to apply compression
CornerRadius = Washer[OD]/2;
ScrewOC = [(Block.x - 2*CornerRadius) / (NumScrews - 1),
Block.y - 2*CornerRadius,
2*Block.z // ensure complete holes
echo(str("Screw OC: x=",ScrewOC.x," y=",ScrewOC.y));
// Useful routines
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);
// Hose shape
// This includes magic numbers measured from reality
module HoseProfile() {
NumSides = 12*4;
// Outside shape of splice Block
// Z centered on hose rim circles, not overall thickness through center ridge
module SpliceBlock() {
difference() {
for (i=[-1,1], j=[-1,1]) // rounded block
translate([i*(Block.x/2 - CornerRadius),j*(Block.y/2 - CornerRadius),-Block.z/2])
for (i = [0:NumScrews - 1], j=[-1,1]) // screw holes
translate([-(Block.x/2 - CornerRadius) + i*ScrewOC.x,
-(Block.z/2 + Protrusion)])
PolyCyl(Screw[ID],Block.z + 2*Protrusion,6);
cube([2*Block.x,2*Block.y,Kerf],center=true); // slice through center
// Splice block less hose
module ShapedBlock() {
difference() {
// Build them
if (Layout == "Hose")
if (Layout == "Block")
if (Layout == "Show") {
difference() {
if (Layout == "Build") {
SliceOffset = TestFit && !(NumScrews % 2) ? ScrewOC.x/2 : 0;
intersection() {
if (TestFit)
union() {

A New Rabbit Appears

Mary chased a small rabbit out of her garden a few days ago, whereupon we up-armored a few vulnerable parts of the fence. The culprit turns out to be insufferably cute:

Young Rabbit - at the gate
Young Rabbit – at the gate

You cannot be annoyed with something like this:

Young Rabbit - alert
Young Rabbit – alert

Oh, yes, you can. Rabbits are basically eating machines:

Young Rabbit - grazing
Young Rabbit – grazing

They’re welcome to all the greenery in the yard, just nothing in the garden:

Young Rabbit - overcompressed A
Young Rabbit – overcompressed A

It’s known as a 2×2 Bunny, because it can fit through that size opening in a chain link fence while traveling at a dead run.

This one has yet to learn about being wary around the Big People:

Young Rabbit - overcompressed B
Young Rabbit – overcompressed B

The alert reader will have noted the crappy quality of the last three pictures, at least in comparison with the first two. It’s the difference between digital zoom on my Pixel 3a phone applied to a zoomed-all-the-way image and optical zoom on a “real” camera (admittedly, an old Sony DSC-H5). On the other paw, I had the phone in my pocket when Mary spotted the bunny on the driveway, which counts for everything in similar situations.

JPG compression doesn’t handle hair particularly well, so the low-res bunny wears a rather artistic brush-stroke coat; it’s OK if you like that sort of thing.

Dripworks Micro-Flow Valves: QC FAIL

We recently installed a Dripworks drip irrigation system for Mary’s garden and, of course, pre-assembled the emitter / dripline tubing, fittings, and supply / filter / plumbing for each of the beds in the Basement Shop. A few days after burying the main lines, plumbing the filter + pressure regulator, and plugging in half a dozen bed assemblies, Mary noticed some emitter tubes weren’t delivering any water and other beds seemed too dry.

N.B.: We bought everything directly from Dripworks. This is not counterfeit crap from a sketchy Amazon seller.

I cut the dripline just downstream of the Micro-Flow valve on a completely dry bed, whereupon no water emerged. Cutting the supply tube just upstream of the valve produced a jet squirting halfway along the bed. I tried and failed to blow air through the valve: it was completely blocked despite being in the “open” position. I installed another valve and the emitter tube started working properly.

I sat down at the kitchen table with a bag of unused valves and peered through them (the pix are through the microscope):

Dripworks valve - mostly open lumen
Dripworks valve – mostly open lumen

That’s one of the better-looking valves, with only a little mold flash in the lumen.

Partially occluded lumens were more typical:

Dripworks valve - partially occluded lumen
Dripworks valve – partially occluded lumen

Quite a few were almost completely obstructed:

Dripworks valve - mostly occluded lumen
Dripworks valve – mostly occluded lumen

For lack of better instrumentation, I blew through the valves and sorted them by effort:

Dripworks valve - sorted by blockage
Dripworks valve – sorted by blockage

Two of the valves in the group on the left are completely blocked, with the others mostly blocked.

The middle group has enough mold flash to produce noticeable resistance to the air flow. I think water would have more trouble getting through, but the emitters would at least look like they’re delivering water.

The group on the right has mostly unblocked valves, with visible mold flash but little restriction.

I have no way to measure the actual water flow, so it’s entirely possible the QC spec allows considerable blockage while still delivering enough water to the emitters. More likely, the spec assumes a clear lumen and the mold flash is a total QC faceplant; it’s obviously not a controlled quantity.

Well, I can fix that:

Dripworks valve - drilling
Dripworks valve – drilling

That’s a 2.3 mm drill going straight through the valve body. I drilled the valves from both ends and blew out the swarf:

Dripworks valve - drill swarf
Dripworks valve – drill swarf

That produced twenty valves with clear lumens. Of course, the drill leaves a slightly rough interior surface, but it’s now much easier to blow air through them.

We hadn’t installed the driplines in two beds with three emitter tubes per bed. I cut out those six unused valves and sorted them by resistance:

Dripworks valve - six samples
Dripworks valve – six samples

Both of the valves on the left are blocked, the three on the right are mostly OK, and the one in the middle is partially blocked.

With two dozen repaired valves in hand, we returned to the garden, I cut 22 valves out of the installed driplines and replaced them under field conditions. Returning to the Basement Laboratory, I blew the water out (*), sorted them by resistance, and produced a similar distribution, albeit with no pictorial evidence. Although we have no immediate need for the used valves, they’re drilled out and ready for use.

In very round numbers, you should expect:

  • A third of Dripworks valves will pass (close to) the expected flow
  • A third will have a minor flow restriction
  • A quarter will have a severe flow restriction
  • One valve in ten will be completely blocked

Plan to drill out all the Micro-Flow valves before you assemble your driplines.

AFAICT, none of the other ¼ inch fittings we used have any interior flash, so it’s only a problem with the valves.

We are, as the saying goes, not amused.

(*) If you will eat a peck of dirt before you die, I’m well on my way.

Sticky Trap Screen Frames

The objective being to reduce the number of onion maggots in Mary’s Vassar Farm plot without chemical agents, I conjured sticky trap screen frames from the vasty digital deep:

Sticky Trap - first production run
Sticky Trap – first production run

Each one contains half a sheet of yellow sticky plastic, which is easy enough to cut before peeling off the protective covering sheets. The cage is half-inch galvanized hardware cloth snipped with hardened diagonal cutters. A bead of acrylic adhesive around the base holds the cage in place

Although you can deploy sticky sheets without cages, they tend to attract and affix beneficial critters: butterflies, small birds, furry critters, toads, gardeners, and the like. We don’t know how effective the cages will be, but they seemed better than nothing.

They mount on ski poles cut in half:

Sticky Trap - ski pole installed
Sticky Trap – ski pole installed

And on fence posts around the perimeter:

Sticky Trap - angle bracket installed
Sticky Trap – angle bracket installed

To my untrained eye, some of those doomed critters are, indeed, onion maggot flies. The rest seem to be gnats and other nuisances, so IMO we’re applying population pressure in the right direction.

Each base-and-cap frame takes about three hours to print, so I did them one at a time over the course of a few days while applying continuous product improvement.

The sheets rest on small V blocks intended to keep them centered within the cage:

Sticky Sheet Cage - angle bracket - solid model
Sticky Sheet Cage – angle bracket – solid model

The ski pole attachment must build with the cap on top, but it bridges well enough for the purpose:

Sticky Sheet Cage - ski pole - solid model
Sticky Sheet Cage – ski pole – solid model

The overhanging hooks on the blocks (just barely) engage the grid to keep the lid in place, while remaining short enough to not droop too badly. You could probably delete the hooks from the bottom plate, but they align the cage while the adhesive cures.

The sheets tend to bend in the middle, so I’ll stick a thin slat or two vertically to keep them straight.

Deer Fence Hangers

For what should be obvious reasons, we armored Mary’s “kitchen garden” with buried concrete blocks and deer fence. I secured the fence to 7 foot plastic-coated steel-core posts strapped to shorter stakes supporting the lower wire fence, using cable ties we both knew wouldn’t survive exposure to the sun.

As part of the spring garden prep, I summoned proper supports from the vasty digital deep:

Deer Fence Hanger - Build view
Deer Fence Hanger – Build view

The general idea is to plunk one atop each post and tangle wrap the netting through the hooks, thusly:

Deer Fence Hanger - installed
Deer Fence Hanger – installed

The garden looks like we killed an entire chess set and impaled their carcasses as a warning to others of their kind, but the fence now hangs neatly from the top of the posts rather than drooping sadly.

Each one of those things takes nigh onto two hours to emerge from the M2, so I printed them one by one over the course of a few days while making continuous product improvements.

The “natural” PETG isn’t UV stabilized, either, but it ought to last longer than those little bitty nylon cable ties. We shall see.

The OpenSCAD source code as a GitHub Gist:

// Deer Fence Hangers
// Ed Nisley KE4ZNU May 2021
Layout = "Show"; // [Build, Show, Cap, Hook]
// net grid spacing
NetOC = 55.0; // [40.0:5.0:70.0]
// stake OD
PoleDia = 23.0; // [20.0:30.0]
//- 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;
ID = 0;
OD = 1;
function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
// Dimensions
Notch = 5.0; // hook engagement
WallThick = 3.0; // min wall and end thickness
Shell = [PoleDia,PoleDia + 2*WallThick,NetOC + 2*Notch];
HookBlock = [10.0,Shell.y/4,2*Notch]; // hanger inside length
LegendBlock = [0.7*Shell.z,Shell.y/2,2*ThreadThick]; // legend size
// Useful routines
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,
// Pieces
module Hook() {
translate([Shell[OD]/2 - Protrusion,HookBlock.y/2,0])
difference() {
intersection() {
module Cap() {
difference() {
translate([-(Shell[OD]/2 - LegendBlock.z/2),0,Shell[LENGTH]/2])
text(text=str(NetOC," ",PoleDia),
size=6,spacing=1.00,font="Bitstream Vera Sans:style=Bold",
module Hanger() {
for (k=[0,1])
for (a=[-1:1])
// Build it
if (Layout == "Cap")
if (Layout == "Hook")
if (Layout == "Show")
if (Layout == "Build")

Bypass Lopper Bumper

I used the long-handled bypass lopper to harvest the 3D printed soaker hose splices and clamps, which made the sad state of the lopper’s bumper painfully obvious:

Bypass Lopper - OEM bumper
Bypass Lopper – OEM bumper

Contrary to what you might think, those rivets never had a head on this side and the bumper seems to be held in place by an interference fit with the plastic handle cover.

A bit of cutoff wheel work removed the crimped end on the 5 mm stud holding the bumper to the pot-metal dingus:

Bypass Lopper - shaft cut
Bypass Lopper – shaft cut

Whacking it with a punch separated all the parts:

Bypass Lopper - bumper parts
Bypass Lopper – bumper parts

The gray thing is a silicone rubber vibration isolator that’s a bit too large in all dimensions, but surely Close Enough™ for present purposes.

A length of 5 mm shaft became the new stud, with M3×0.5 threads tapped into both ends and a pair of random screws held in place with red Loctite:

Bypass Lopper - epoxy curing
Bypass Lopper – epoxy curing

There are no pix of the drilling and threading, as it was accomplished after a shiny-new 2.7 mm “titanium” metric drill from a not-dirt-cheap set shattered in the shaft:

Shattered metric drill
Shattered metric drill

The blue color on the flutes is Sharpie to remind me it’s defunct. I completed the mission using a #36 drill with no further excitement.

The dingus is now held to the lopper with JB Weld and, should that fail, I’ll drill-n-tap the rivets and be done with it.

Soaker Hose Splices: End Of Life

The soaker hoses from Mary’s garden all came from someone else and have now reached their second end of life:

Soaker Hose Splices - end of life
Soaker Hose Splices – end of life

Those orange lumps kept them alive for a few more seasons:

Soaker Hose Splices - harvested
Soaker Hose Splices – harvested

In the unlikely event I ever give another in-person presentation about 3D printing and what it’s good for, I’ll have some interesting show-n-tell samples. Might have to soak the dirt off, though.