Software – Page 49 – The Smell of Molten Projects in the Morning

MPCNC Diamond Engraver: LM3UU Bearings, Second Pass

Having a single spring and a fixed upper plate works much better than the first version:

Diamond Scribe - LM3UU Rev 2 - overview — Diamond Scribe – LM3UU Rev 2 – overview

The (lubricated!) nyloc nuts under the plate provide a little friction and stabilize the whole affair.

The solid model has the same stylin’ tapered snout as the LM12UU drag knife mount:

Diamond Scribe - LM3UU bearings — Diamond Scribe – LM3UU bearings

The spring seats in the plate recess, with the 3 mm shank passing through the hole as the tool holder presses the tip against the workpiece.

I diamond-filed a broken carbide end mill to make a slotting tool:

Diamond Scribe - LM3UU - Rev 2 - carbide notch tool — Diamond Scribe – LM3UU – Rev 2 – carbide notch tool

Lacking any better method (“a tiny clip spreader tool”), I rammed the Jesus clip the length of the shank with a (loose-fitting) chuck in the tailstock:

Diamond Scribe - LM3UU - Rev 2 - clip installation — Diamond Scribe – LM3UU – Rev 2 – clip installation

Even without nyloc nuts, the first test worked fine:

Diamond Scribe - LM3UU - Rev 2 - first light — Diamond Scribe – LM3UU – Rev 2 – first light

The 53 g/mm spring rate may be too low for serious engraving, but it suffices for subtle Guilloché patterns on scrap platters.

The OpenSCAD source code as a GitHub Gist:

	// Drag Knife Holder using LM12UU linear bearing
	// Ed Nisley KE4ZNU – 2019-04-26
	// 2019-05-09 LM3UU for diamond scribe
	// 2019-05-28 taper end, single spring around shaft

	Layout = "Build"; // [Build, Show, Puck, Mount, Plate]

	/* [Extrusion] */

	ThreadThick = 0.25; // [0.20, 0.25]
	ThreadWidth = 0.40; // [0.40, 0.40]

	/* [Hidden] */

	Protrusion = 0.1; // [0.01, 0.1]

	HoleWindage = 0.2;

	inch = 25.4;

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

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

	//- 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);
	}

	//- Dimensions

	// Knife holder & suchlike

	KnifeBody = [3.0,9.0,2.0]; // washer epoxied to diamond shaft, with epoxy fillet

	Spring = [9.5,10.0,3*ThreadThick]; // compression spring around shaft, LENGTH = socket depth

	WallThick = 4.0; // minimum thickness / width

	Screw = [4.0,8.5,8.0]; // holding it all together, OD = washer

	Insert = [4.0,6.0,10.0]; // brass insert

	Bearing = [3.0,7.0,2*10.0 + WallThick]; // linear bearing body (pair + small gap)

	// Basic shape of DW660 snout fitting into the holder
	// Lip goes upward to lock into MPCNC mount

	Snout = [44.6,50.0,9.6]; // LENGTH = ID height
	Lip = 4.0; // height of lip at end of snout

	Plate = [KnifeBody[ID],Snout[OD] – WallThick,WallThick]; // spring reaction plate

	PuckOAL = max(Bearing[LENGTH],(Snout[LENGTH] + Lip)); // total height of DW660 fitting
	echo(str("PuckOAL: ",PuckOAL));
	Key = [Snout[ID],25.7,(Snout[LENGTH] + Lip)]; // rectangular key

	NumScrews = 3;

	ScrewBCD = 2.5*(Bearing[OD]/2 + Insert[OD]/2 + WallThick);

	NumSides = 9*4; // cylinder facets (multiple of 3 for lathe trimming)

	module DW660Puck() {

	translate([0,0,PuckOAL])
	rotate([180,0,0]) {
	cylinder(d=Snout[OD],h=Lip/2,$fn=NumSides);
	translate([0,0,Lip/2])
	cylinder(d1=Snout[OD],d2=Snout[ID],h=Lip/2,$fn=NumSides);
	cylinder(d=Snout[ID],h=(Snout[LENGTH] + Lip),$fn=NumSides);
	translate([0,0,(Snout[LENGTH] + Lip) – Protrusion])
	cylinder(d1=Snout[ID],d2=2*WallThick + Bearing[OD],h=PuckOAL – (Snout[LENGTH] + Lip),$fn=NumSides);
	intersection() {
	translate([0,0,0*Lip + Key.z/2])
	cube(Key,center=true);
	cylinder(d=Snout[OD],h=Lip + Key.z,$fn=NumSides);
	}
	}
	}

	module MountBase() {

	difference() {
	DW660Puck();

	translate([0,0,-Protrusion]) // bearing
	PolyCyl(Bearing[OD],2*PuckOAL,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Insert[OD],2*PuckOAL,8);
	}
	}

	module SpringPlate() {
	difference() {
	cylinder(d=Plate[OD],h=Plate[LENGTH],$fn=NumSides);

	translate([0,0,-Protrusion]) // ample shaft clearance
	PolyCyl(1.5KnifeBody[ID],2PuckOAL,NumSides);

	// translate([0,0,Plate[LENGTH] – KnifeBody[LENGTH]]) // flange, snug fit
	// PolyCyl(KnifeBody[OD],KnifeBody[LENGTH] + Protrusion,NumSides);

	translate([0,0,Plate[LENGTH] – Spring[LENGTH]]) // spring retainer
	PolyCyl(Spring[OD],Spring[LENGTH] + Protrusion,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Screw[ID],2*PuckOAL,8);
	}
	}

	//—–
	// Build it

	if (Layout == "Puck")
	DW660Puck();

	if (Layout == "Plate")
	SpringPlate();

	if (Layout == "Mount")
	MountBase();

	if (Layout == "Show") {
	MountBase();
	translate([0,0,1.5*PuckOAL])
	rotate([180,0,0])
	SpringPlate();
	}

	if (Layout == "Build") {
	translate([0,Snout[OD]/2,PuckOAL])
	rotate([180,0,0])
	MountBase();
	translate([0,-Snout[OD]/2,0])
	SpringPlate();
	}

view raw Diamond Scribe – LM3UU bearings.scad hosted with ❤ by GitHub

2019-06-28

Garden Soaker Hose Connector Repair

Two of Mary’s garden soaker hoses failed their pre-installation checks with leaks from around their connectors. The problem seemed to be a break in the hose inside the connector, with water spewing out of the connector around the hose. Having previously fixed a gash in another hose, I figured I might have some success at fixing these leaks.

The general idea is to squish enough silicone rubber inside the connector to seal around the hose, then clamp the hose and connector snugly enough to hold the rubber in place:

Soaker Hose Connector Clamp - Show view — Soaker Hose Connector Clamp – Show view

The enlarged recess fits around the brass connector shell, which is squashed loosely around the hose and from which the leaking water emerges. Of course, because this is a different hose, the previous model didn’t quite fit and I had to doodle up new geometry:

Soaker Hose Connector repair - Dimension doodle — Soaker Hose Connector repair – Dimension doodle

As before, I bandsawed aluminum backing plates to ensure the plastic didn’t get all bendy in the middle:

The hose clamp (!) around the connector on the far right ensures a split in the brass shell doesn’t get any larger.

They’ll spend the rest of their lives under the garden mulch, where nobody will ever see those bulky lumps. Life is good!

The OpenSCAD source code as a GitHub Gist:

	// Rubber Soaker Hose End Connector Clamp
	// Helps hold silicone rubber in connector
	// Ed Nisley KE4ZNU June 2019

	Layout = "Build"; // [Hose,Connector,Block,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);

	//———-
	// Dimensions
	// Hose lies along X axis

	Hose = [200,26.5,11.6]; // X=very long, Y=width, Z=overall height

	RimThick = 10.3; // outer sections
	RimOD = RimThick;
	RimFlatRecess = 1.0; // recess to front flat surface

	OuterOC = Hose.y – RimOD; // outer tube centers

	RecessM = 0.8; // back recess chord
	RecessC = OuterOC;
	RecessR = (pow(RecessM,2) + pow(RecessC,2)/4) / (2*RecessM);

	RidgeM = 1.6; // front ridge chord
	RidgeC = 7.5;
	RidgeR = (pow(RidgeM,2) + pow(RidgeC,2)/4) / (2*RidgeM);

	HoseSides = 12*4;

	Connector = [5.0,33.0,13.0]; // oval brass: X=snout Y=width Z=dia

	Block = [20.0,50.0,4.0 + Hose.z]; // overall splice block size
	echo(str("Block: ",Block));

	Kerf = 0.5; // cut through middle to apply compression

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

	// 8-32 stainless screws
	Screw = [4.1,8.0,3.0]; // OD = head LENGTH = head thickness
	Washer = [4.4,9.5,1.0];
	Nut = [4.1,9.7,6.0];

	CornerRadius = Washer[OD]/2;

	ScrewOC = Block.y – 2*CornerRadius;

	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() {

	rotate([0,-90,0])
	translate([0,0,-Hose.x/2])
	linear_extrude(height=Hose.x,convexity=4)
	difference() {
	union() {
	for (j=[-1,1]) // outer channels
	translate([0,j*OuterOC/2])
	circle(d=RimOD,$fn=HoseSides);
	translate([-RimOD/4,0]) // rear flat fill
	square([RimOD/2,OuterOC],center=true);
	translate([(RimOD/4 – RimFlatRecess),0]) // front flat fill
	square([RimOD/2,OuterOC],center=true);
	intersection() {
	translate([Hose.z/2,0])
	square([Hose.z,OuterOC],center=true);
	translate([-RidgeR + RimOD/2 – RimFlatRecess + RidgeM,0])
	circle(r=RidgeR,$fn=HoseSides);
	}
	}
	translate([-(RecessR + RimOD/2 – RecessM),0])
	circle(r=RecessR,$fn=2*HoseSides);
	}
	}

	// Outside shape of splice Block
	// Z centered on hose rim circles, not overall thickness through center ridge

	module SpliceBlock() {
	difference() {
	hull()
	for (i=[-1,1], j=[-1,1]) // rounded block
	translate([i(Block.x/2 – CornerRadius),j(Block.y/2 – CornerRadius),-Block.z/2])
	cylinder(r=CornerRadius,h=Block.z,$fn=4*8);
	for (j=[-1,1]) // screw holes
	translate([0,
	j*ScrewOC/2,
	-(Block.z/2 + Protrusion)])
	PolyCyl(Screw[ID],Block.z + 2*Protrusion,6);
	cube([2Block.x,2Block.y,Kerf],center=true); // slice through center
	}
	}

	// Splice block less hose

	module ShapedBlock() {
	difference() {
	SpliceBlock();
	HoseProfile();
	Connector();
	}
	}

	// Brass connector end

	module Connector() {
	translate([-(Block.x/2 + Protrusion),0,0])
	rotate([0,90,0])
	linear_extrude(height=Connector.x + Protrusion)
	hull()
	for (i = [-1,1])
	translate([0,i*(Connector.y – Connector.z)/2])
	circle(d=Connector.z);
	}


	//———-
	// Build them

	if (Layout == "Hose")
	HoseProfile();

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

	if (Layout == "Connector")
	Connector();

	if (Layout == "Show") {
	ShapedBlock();
	color("Green",0.25)
	HoseProfile();
	}

	if (Layout == "Build") {
	SliceOffset = 0;
	intersection() {
	translate([SliceOffset,0,Block.z/4])
	cube([4Block.x,4Block.y,Block.z/2],center=true);
	union() {
	translate([0,0.6*Block.y,Block.z/2])
	ShapedBlock();
	translate([0,-0.6*Block.y,Block.z/2])
	rotate([0,180,0])
	ShapedBlock();
	}
	}
	}

view raw Soaker Hose Connector Clamp.scad hosted with ❤ by GitHub

2019-06-27

Kitchen Blender Base Spacer

We don’t use the blender much, so the most recent bearing replacement continues to work. I never got around to re-making the overly long shaft spacer from the first bearing replacement, which I compensated for with a spacer kludge cut from a random chunk of bendy plastic sheet.

Which we put up with For. Eleven. Years.

The blender recently emerged from hiding and, with my solid modeling-fu cranked up to a dangerous chattering whine, I conjured a real spacer:

Blender base spacer - Slic3r preview — Blender base spacer – Slic3r preview

It pretty much disappears into the blender base, which is the whole point of the operation:

Blender base spacer - installed — Blender base spacer – installed

When the bearings fail again, I promise to make a proper shaft spacer and toss this bodge.

The OpenSCAD code as a GitHub Gist:

	// Kitchen blender base adapter
	// Ed Nisley KE4ZNU June 2019

	//- 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;

	//———-
	// Just build it

	Spacer = [48.0,66.0,1.8]; // LENGTH raises blade holder
	Aligner = [Spacer[ID],52.0,Spacer[LENGTH] + 3.0]; // LENGTH locks into base ring

	NumSides = 434;

	//———-
	// Just build it

	difference() {
	union() {
	cylinder(d=Spacer[OD],h=IntegerMultiple(Spacer[LENGTH],ThreadThick),$fn=NumSides);
	cylinder(d=Aligner[OD],h=Aligner[LENGTH],$fn=NumSides);
	}
	translate([0,0,-Protrusion])
	cylinder(d=Spacer[ID],h=10*Aligner[LENGTH],$fn=NumSides);
	}

view raw Blender base spacer.scad hosted with ❤ by GitHub

Not that it really deserves so much attention …

2019-06-21

MPCNC Drag Knife: Ground Shaft in LM12UU Bearing

The 12 mm drag knife holder on the left slides nicely in an LM12UU bearing:

Drag Knife holders - detail — Drag Knife holders – detail

However, its aluminum body isn’t really intended as a bearing surface and it extends only halfway through the LM12UU, so I finally got around to modifying the 11.5 mm body on the right to fit into a section of 12 mm ground shaft:

Drag Knife - turning 11.5 mm body to 10 mm — Drag Knife – turning 11.5 mm body to 10 mm

The general idea is to turn the body down to 10 mm OD; the picture shows the first pass over the nose after turning the far end down and removing the flange in the process. Exact concentricity of both ends isn’t important (it gets epoxied into a 10 mm hole through the 12 mm ground shaft), but it came out rather pretty:

Drag Knife - 11.5 mm body - turned to 10 mm — Drag Knife – 11.5 mm body – turned to 10 mm

The ground shaft started as a pen holder:

DW660 Pen Holder - ground shaft — DW660 Pen Holder – ground shaft

I knocked off the ring and bored the interior to fit the 10 mm knife body. The large end of the existing bore came from a 25/64 inch = 9.92 mm drill, so it was just shy of 10.0 mm, and I drilled the small end upward from 0.33 inch = 8.4 mm.

The smallest trio of a new set of cheap carbide boring bars allegedly went into a 5/16 inch = 7.9 mm bore, but I had to file the bar body down and diamond-file more end relief into the carbide for clearance inside the drilled hole:

I blued the bit, kissed it against the drilled bore, filed off whatever wasn’t blued, and iterated until the carbide edge started cutting. Sissy cuts all the way, with no pix to show for all the flailing around.

Epoxying the turned-down drag knife body into the shaft: anticlimactic.

The solid model features a stylin’ tapered snout:

Drag Knife LM12UU holder - tapered end — Drag Knife LM12UU holder – tapered end

Which gets an LM12UU bearing rammed into place:

Drag Knife - LM12UU holder - inserting bearing — Drag Knife – LM12UU holder – inserting bearing

The steel block leaves the bearing flush with the plastic surface, rather than having it continue onward and indent itself into the wood; I can learn from my mistakes.

The new idea: a single spring pressing the knife holder downward, reacting against a fixed plastic plate:

Drag Knife - LM12UU ground shaft - assembled — Drag Knife – LM12UU ground shaft – assembled

Unlike the previous design, the upper plate doesn’t move, so there’s no problem caused by sliding along the screw threads. I should run nylock nuts up against the plate to keep it in place, stiffen the structure, and provide some friction to keep the screws from loosening.

The top of the knife holder now has a boss anchoring the spring:

Drag Knife - turning spring recess — Drag Knife – turning spring recess

As you’d expect, the ground shaft slides wonderfully in the bearing, because that’s what it’s designed to do, and the knife has essentially zero stiction and friction at any point along the bearing, which is exactly what I wanted.

The spring, from the same assortment as all the others, has a 48 g/mm rate.

The OpenSCAD source code as a GitHub Gist:

	// Drag Knife Holder using LM12UU linear bearing
	// Ed Nisley KE4ZNU – 2019-04-26
	// 2019-06-01 Taper the nose

	Layout = "Build"; // [Build, Show, Puck, Mount, Plate]

	/* [Extrusion] */

	ThreadThick = 0.25; // [0.20, 0.25]
	ThreadWidth = 0.40; // [0.40]

	/* [Hidden] */

	Protrusion = 0.1; // [0.01, 0.1]

	HoleWindage = 0.2;

	inch = 25.4;

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

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

	//- 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);
	}

	//- Dimensions

	// Basic shape of DW660 snout fitting into the holder
	// Lip goes upward to lock into MPCNC mount

	Snout = [44.6,50.0,9.6]; // LENGTH = ID height
	Lip = 4.0; // height of lip at end of snout

	// Knife holder & suchlike

	KnifeBody = [12.0,18.0,2.0]; // body OD, flange OD, flange thickness

	Spring = [9.5,10.0,3*ThreadThick]; // compression spring loading knife blade

	PinAccess = 4.0; // hole to reach knife ejection pin

	WallThick = 4.0; // minimum thickness / width

	Screw = [4.0,8.5,25.0]; // thread ID, washer OD, length

	Insert = [4.0,6.0,10.0]; // brass insert

	Bearing = [12.0,21.0,30.0]; // linear bearing body

	Plate = [PinAccess,Snout[OD] – WallThick,WallThick]; // spring reaction plate

	echo(str("Plate: ",Plate));

	SpringSeat = [0.56,7.2,2*ThreadThick]; // wire = ID, coil = OD, seat depth = length

	PuckOAL = max(Bearing[LENGTH],(Snout[LENGTH] + Lip)); // total height of DW660 fitting
	echo(str("PuckOAL: ",PuckOAL));
	Key = [Snout[ID],25.7,(Snout[LENGTH] + Lip)]; // rectangular key

	NumScrews = 3;

	//ScrewBCD = 2.0*(Bearing[OD]/2 + Insert[OD]/2 + WallThick);
	ScrewBCD = (Snout[ID] + Bearing[OD])/2;

	NumSides = 9*4; // cylinder facets (multiple of 3 for lathe trimming)

	module DW660Puck() {

	translate([0,0,PuckOAL])
	rotate([180,0,0]) {
	cylinder(d=Snout[OD],h=Lip/2,$fn=NumSides);
	translate([0,0,Lip/2])
	cylinder(d1=Snout[OD],d2=Snout[ID],h=Lip/2,$fn=NumSides);
	cylinder(d=Snout[ID],h=(Snout[LENGTH] + Lip),$fn=NumSides);
	translate([0,0,(Snout[LENGTH] + Lip) – Protrusion])
	cylinder(d1=Snout[ID],d2=2*WallThick + Bearing[OD],h=PuckOAL – (Snout[LENGTH] + Lip),$fn=NumSides);
	intersection() {
	translate([0,0,0*Lip + Key.z/2])
	cube(Key,center=true);
	cylinder(d=Snout[OD],h=Lip + Key.z,$fn=NumSides);
	}
	}
	}

	module MountBase() {

	difference() {
	DW660Puck();

	translate([0,0,-Protrusion]) // bearing
	PolyCyl(Bearing[OD],2*PuckOAL,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Insert[OD],2*PuckOAL,8);
	}
	}

	module SpringPlate() {
	difference() {
	cylinder(d=Plate[OD],h=Plate[LENGTH],$fn=NumSides);

	translate([0,0,-Protrusion]) // ejection pin hole
	PolyCyl(PinAccess,2*Plate[LENGTH],NumSides);

	translate([0,0,Plate[LENGTH] – Spring[LENGTH]]) // spring retaining recess
	PolyCyl(Spring[OD],Spring[LENGTH] + Protrusion,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Screw[ID],2*PuckOAL,8);

	if (false)
	for (i=[0:NumScrews – 1]) // coil positioning recess
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(SpringSeat[OD],SpringSeat[LENGTH] + Protrusion,8);

	}
	}

	//—–
	// Build it

	if (Layout == "Puck")
	DW660Puck();

	if (Layout == "Plate")
	SpringPlate();

	if (Layout == "Mount")
	MountBase();

	if (Layout == "Show") {
	MountBase();
	translate([0,0,1.6*PuckOAL])
	rotate([180,0,0])
	SpringPlate();
	}

	if (Layout == "Build") {
	translate([0,Snout[OD]/2,PuckOAL])
	rotate([180,0,0])
	MountBase();
	translate([0,-Snout[OD]/2,0])
	SpringPlate();
	}

view raw Drag Knife LM12UU holder.scad hosted with ❤ by GitHub

2019-06-18

MPCNC Drag Knife: LM12UU Linear Bearing

The anodized body of the drag knife on the left measures exactly 12.0 mm OD:

Which happy fact suggested I might be able to use a standard LM12UU linear bearing, despite the obvious stupidity of running an aluminum “shaft” in a steel-ball bearing race:

Drag Knife - LM12UU holder - solid model — Drag Knife – LM12UU holder – solid model

The 12 mm section extends about halfway through the bearing, with barely 3 mm extending out the far end:

Drag Knife - LM12UU - knife blade detail — Drag Knife – LM12UU – knife blade detail

Because the knife body isn’t touching the bearing for the lower half of its length, it’ll probably deflect too much in the XY plane, but it’s simple enough to try out.

As before, the knife body’s flange is a snug fit in the hole bored in the upper disk:

Drag Knife - spring plate test fit — Drag Knife – spring plate test fit

This time, I tried faking stripper bolts by filling the threads of ordinary socket head cap screws with epoxy:

Ersatz stripper bolts - epoxy fill — Ersatz stripper bolts – epoxy fill

Turning the filled section to match the thread OD showed this just wasn’t going to work at all, so I turned the gunked section of the threads down to about 3.5 mm and continued the mission:

Drag Knife - LM12UU holder - assembled — Drag Knife – LM12UU holder – assembled

Next time, I’ll try mounting the disk on telescoping brass tubing nested around the screws. The motivation for the epoxy nonsense came from the discovery that real stainless steel stripper bolts run five bucks each, which means I’m just not stocking up on the things.

It slide surprisingly well on the cut-down screws, though:

Drag Knife - applique templates — Drag Knife – applique templates

Those appliqué templates came from patterns for a block in one of Mary’s current quilting projects, so perhaps I can be of some use whenever she next needs intricate cutouts.

The OpenSCAD source code as a GitHub Gist:

	// Drag Knife Holder using LM12UU linear bearing
	// Ed Nisley KE4ZNU – 2019-04-26

	Layout = "Show"; // [Build, Show, Puck, Mount, Plate]

	/* [Extrusion] */

	ThreadThick = 0.25; // [0.20, 0.25]
	ThreadWidth = 0.40; // [0.40]

	/* [Hidden] */

	Protrusion = 0.1; // [0.01, 0.1]

	HoleWindage = 0.2;

	inch = 25.4;

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

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

	//- 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);
	}

	//- Dimensions

	// Basic shape of DW660 snout fitting into the holder
	// Lip goes upward to lock into MPCNC mount

	Snout = [44.6,50.0,9.6]; // LENGTH = ID height
	Lip = 4.0; // height of lip at end of snout

	// Knife holder & suchlike

	KnifeBody = [12.0,15.9,2.0]; // flange epoxied to top of diamond shaft, with epoxy fillet

	WallThick = 4.0; // minimum thickness / width

	Screw = [4.0,8.5,8.0]; // holding it all together, OD = washer

	Insert = [4.0,6.0,10.0]; // brass insert

	Bearing = [12.0,21.0,30.0]; // linear bearing body

	Plate = [KnifeBody[ID],Snout[OD] – WallThick,KnifeBody[LENGTH] + WallThick]; // spring reaction plate
	PlateGuide = [4.0,4.8,Plate[LENGTH]]; // … guide tubes

	PuckOAL = max(Bearing[LENGTH],(Snout[LENGTH] + Lip)); // total height of DW660 fitting
	echo(str("PuckOAL: ",PuckOAL));
	Key = [Snout[ID],25.7,(Snout[LENGTH] + Lip)]; // rectangular key

	NumScrews = 3;

	ScrewBCD = 2.0*(Bearing[OD]/2 + Insert[OD]/2 + WallThick);

	NumSides = 9*4; // cylinder facets (multiple of 3 for lathe trimming)

	module DW660Puck() {

	translate([0,0,PuckOAL])
	rotate([180,0,0]) {
	cylinder(d=Snout[OD],h=Lip/2,$fn=NumSides);
	translate([0,0,Lip/2])
	cylinder(d1=Snout[OD],d2=Snout[ID],h=Lip/2,$fn=NumSides);
	cylinder(d=Snout[ID],h=PuckOAL,$fn=NumSides);
	intersection() {
	translate([0,0,0*Lip + Key.z/2])
	cube(Key,center=true);
	cylinder(d=Snout[OD],h=Lip + Key.z,$fn=NumSides);
	}
	}
	}

	module MountBase() {

	difference() {
	DW660Puck();

	translate([0,0,-Protrusion]) // bearing
	PolyCyl(Bearing[OD],2*PuckOAL,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Insert[OD],2*PuckOAL,8);
	}
	}

	module SpringPlate() {
	difference() {
	cylinder(d=Plate[OD],h=Plate[LENGTH],$fn=NumSides);

	translate([0,0,-Protrusion]) // knife holder body
	PolyCyl(KnifeBody[ID],2*PuckOAL,NumSides);

	translate([0,0,Plate[LENGTH] – KnifeBody[LENGTH]]) // flange, snug fit
	PolyCyl(KnifeBody[OD],KnifeBody[LENGTH] + Protrusion,NumSides);

	for (i=[0:NumScrews – 1]) // clamp screws
	rotate(i*360/NumScrews)
	translate([ScrewBCD/2,0,-Protrusion])
	rotate(180/8)
	PolyCyl(PlateGuide[OD],2*PuckOAL,8);
	}
	}

	//—–
	// Build it

	if (Layout == "Puck")
	DW660Puck();

	if (Layout == "Plate")
	SpringPlate();

	if (Layout == "Mount")
	MountBase();

	if (Layout == "Show") {
	MountBase();
	translate([0,0,1.6*PuckOAL])
	rotate([180,0,0])
	SpringPlate();
	}

	if (Layout == "Build") {
	translate([0,Snout[OD]/2,PuckOAL])
	rotate([180,0,0])
	MountBase();
	translate([0,-Snout[OD]/2,0])
	SpringPlate();
	}

view raw Drag Knife LM12UU holder.scad hosted with ❤ by GitHub

2019-05-29

Epson R380 Printer: Waste Ink Counter Reset

Following the same drill as before, the Epson R380 printer once again thinks I’ve changed its diaper before resetting its waste ink counter. Instead, I’ve poured what would be a moderate fortune of waste ink down the drain from the external tank, had I not grafted a continuous flow ink supply onto the thing.

To judge from how often I must reset the counters, I’m expected to buy a new printer every three years. For sure, it’s uneconomical to have anybody else (the nearest Epson Authorized Customer Care Centers is 68 miles away on Long Island) do the deed. As Epson delicately puts it “replacement of ink pads may not be a good investment for lower-cost printers”.

Epson now provides a utility allowing you to reset the counters exactly one time. Having a scrap Windows PC ready to go, I didn’t bother capturing the partition before firing off the previous Sketchy Utility™, nor did I restore it, so the whole process took about half an hour.

The hard drive platters will eventually become nightlights.

2019-05-07

Xiaomi Dafang Hacks: Hostname for OSD and Filename

The config/hostname.conf file (found under /system/sdcard/when the camera is running) file defines the camera’s name:

Cam4

That file overrides the contents of the usual etc/hostname.conf file, somewhat to my surprise, which remains the default Ingenic-uc1_1.

The bin/hostname utility returns the hostname:

[root@Cam4 ~]# which hostname
/bin/hostname
[root@Cam4 ~]# hostname
Cam4

You can automagically get the hostname in the on-screen display by modifying the OSD formatting variable in config/osd.conf:

OSD="$(/bin/hostname) %Y-%m-%d %H:%M:%S"

Which works because the main OSD script sources the config file to set the variable:

Xiaomi Dafang - 15-04-2019_13.26.18 — Xiaomi Dafang – 15-04-2019_13.26.18

It’s also helpful (at least for my purposes) to add the hostname to the image filenames. A one-line tweak in the scripts/detectionOn.sh script does the trick:

snapshot_filename=$(/bin/hostname)_$(date "$snapshot_pattern")

Which produces names along these lines:

-rwxr-xr-x  1 ed   root 246K Apr 23  2019 Cam4_2019-04-23_17.51.02.jpg*

Having source code makes simple changes like this … simple!

2019-04-24

Category: Software

MPCNC Diamond Engraver: LM3UU Bearings, Second Pass

Garden Soaker Hose Connector Repair

Kitchen Blender Base Spacer

MPCNC Drag Knife: Ground Shaft in LM12UU Bearing

MPCNC Drag Knife: LM12UU Linear Bearing

Epson R380 Printer: Waste Ink Counter Reset

Xiaomi Dafang Hacks: Hostname for OSD and Filename