Posts Tagged M2

Search Engine Optimization: Replacement Shelf Bracket Whirlpool Freezer

If I were selling those brackets, I’d be rich:

Search Engine Optimization - Freezer Shelf Bracket

Search Engine Optimization – Freezer Shelf Bracket

Now, that looks like Search Engine Optimization it is to die for! Google will give you a different set of pictures, but I own that all-important top row.

Alas, anybody can just print their own…

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Kenmore 158: LED Strip Light Cable Clips

Commercial LED strip lights for sewing machines mount their cables with little stick-on anchors and cable ties. I wasn’t happy with the cable tie thing and finally figured this out:

Kenmore 158 - LED strip light cable clips

Kenmore 158 – LED strip light cable clips

The clips have that size & shape because they fit exactly atop some pre-cut foam squares from the Tape Lookaside Buffer:

LED strip light cable clips

LED strip light cable clips

You can see the shape better in the solid model:

LED Cable Clips

LED Cable Clips

The central bollard has a slight taper to retain the cable, the quarter-posts are straight, and they’re both twice the cable diameter tall. The clearance between the center and corner posts at the top matches the cable diameter, so there’s a bit of bending room at the bottom, and, with the cable bent around the center, it won’t fall out on its own.

The cute coaxial cable I’m misusing for the LED strips measures just shy of 2 mm, making these into little bitty things. The corner posts seem surprisingly strong, despite 3D printing’s reputation for crappy quality; I haven’t been able to break one off with more effort than seemed warranted.

The OpenSCAD source code:

// LED Cable Clips
// Ed Nisley - KE4ZNU - October 2014

//- Extrusion parameters must match reality!

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

AlignPinOD = 1.70;			// assembly alignment pins: filament dia

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

//----------------------
// Dimensions

Base = [12.0,12.0,IntegerMultiple(2.0,ThreadThick)];	// base over sticky square

CableOD = 2.0;

BendRadius = 3.0;

Bollard = [BendRadius,(sqrt(2)*Base[0]/2 - CableOD - BendRadius),2*CableOD];
B_BOT = 0;
B_TOP = 1;
B_LEN = 2;

NumSides = 5*4;

//----------------------
// 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,
           h=Height,
           $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

//----------------------
// Build it

ShowPegGrid();

intersection() {
	translate([0,0,(Base[2] + Bollard[2])/2])			// overall XYZ outline
		cube(Base + [0,0,Bollard[2]],center=true);
	
	union() {
		translate([0,0,Base[2]/2])						// oversize mount base
			scale([2,2,1])
				cube(Base,center=true);
				
		for (i=[-1,1] , j=[-1,1]) {						// corner bollards
			translate([i*Base[0]/2,j*Base[1]/2,(Base[2] - Protrusion)])
				rotate(180/NumSides)
				cylinder(r=Bollard[B_BOT],h=(Bollard[B_LEN] + Protrusion),center=false,$fn=NumSides);

		translate([0,0,(Base[2] - Protrusion)])			// center tapered bollard
			cylinder(r1=Bollard[B_BOT],r2=Bollard[B_TOP],h=(Bollard[B_LEN] + Protrusion),center=false,$fn=NumSides);
		}
	}
}

Now that I think of it, maybe a round clip would look nicer. The central bollard would stay, but the circular outside rim could have three cutouts. When these fall off, I’ll give that a try.

They may be square and clunky, but they look much better than Gorilla Tape…

 

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ATX Power Supply: System Board Connector Bracket

The GX270 case contains a perfectly serviceable ATX power supply that can power all the bits & pieces that don’t run directly from the AC power line. I torched the connector off the system board, but there’s no practical way to mount it standing up through the prototyping board I’m using for the low voltage electronics. This bracket surrounds that connector and holds it at right angles to the board, with a pair of screws clamping it in place:

ATX Connector Bracket - front

ATX Connector Bracket – front

I invoked the shade of Willy McCoy, slashed the outside of the connector with a razor knife, buttered it up with epoxy, and shoved it flush inside the adapter. That messy epoxy bead around the joint should prevent it from pulling out to the front:

ATX Connector Bracket - rear

ATX Connector Bracket – rear

The solid model looks like you’d expect:

ATX Connector Mount

ATX Connector Mount

In the unlikely event you need one, make sure the slot clears the locking clip on your ATX connector, as they differ between (at least) the 20 and 24 pin versions. This is actually a split 20/24 connector, with the smaller connector terminating elsewhere to power the LED strips.

The OpenSCAD source code:

// ATX power supply connector mounting bracket
// Ed Nisley - KE4ZNU - September 2014

//- Extrusion parameters must match reality!

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

AlignPinOD = 1.70;			// assembly alignment pins: filament dia

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

//----------------------
// Dimensions

Screw = [3.5,7.0];						// mounting screws
OD = 0;
HEAD_OD = 1;

Wall = 3.0;

ATX = [43.5,9.75,12.0];					// connector outline

Shell = ATX + [2*(2*Wall + Screw[OD]),2*Wall,0.0];	// mount outline

Latch = [5.0,5.0,7.0];							// latch overlay

ScrewOC = ATX[0] + Screw[OD] + 2*Wall;

echo(str("Screw OC: ",ScrewOC," mm"));

//----------------------
// 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,
           h=Height,
           $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

ShowPegGrid();

difference() {
	translate([0,0,Shell[2]/2])						// mount shell
		cube(Shell,center=true);
	translate([0,0,ATX[2]/2])					// connector shell
		cube(ATX + [0,0,2*Protrusion],center=true);

	translate([0,(Latch[1]/2 + ATX[1]/2 - Protrusion),(-Latch[2]/2 + Shell[2])])
		cube(Latch + [0,Protrusion,Protrusion],center=true);

	for (i=[-1,1])
		translate([i*ScrewOC/2,(Shell[1]/2 + Protrusion),Shell[2]/2])
			rotate([90,0,0])
				PolyCyl(Screw[OD],(Shell[1] + 2*Protrusion));

}

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ET227 Transistor: Monster Heatsink Mounting

Back in the day, heatsinks like this sat atop Moah Powah Pentium CPUs:

ET227 transistor on heatsink

ET227 transistor on heatsink

I picked it because the hulking ET227 transistor fit neatly on its backside, it seemed capable of handling 30 to 50 W of power, and I have several of them in the Big Box o’ Heatsinks. No careful thermal analysis was involved…

Mounting it on the polycarbonate sheet inside the repurposed GX270 case involved drilling & tapping a pair of 6-32 holes in one side:

ET227 Heatsink - tapping

ET227 Heatsink – tapping

That’s not rigid tapping on a Sherline, it’s aligning a hand-turned tap in the spindle bore. Sorry.

And, yeah, you’re not supposed to leave the semiconductors mounted when you’re drilling the heatsink. I figure there’s nothing I can possibly do without using a hammer that will bother that transistor in the slightest. What, me worry?

The transistor collector runs at line voltage, which means the entire heatsink will pose a lethal shock hazard. I thought about isolating the collector and failed to come up with anything I’d trust to be both thermally conductive and electrically insulating over the long term; the screw heads must be isolated from the collector plate, too.

The screws stick out below the polycarbonate sheet, just above the grounded EMI shell lining the case, so I flattened them a bit:

ET227 Heatsink - mounting screws

ET227 Heatsink – mounting screws

The simple rectangular strip to the rear of the chassis mounting clips is just slightly thicker than the screw heads, so they can’t possibly contact the case:

Chassis Clips

Chassis Clips

It gets glued to the underside of the nearly invisible sheet:

ET227 heatsink - gluing screw shield

ET227 heatsink – gluing screw shield

With Kapton tape over the heads, Just In Case:

ET227 Heatsink - mounted

ET227 Heatsink – mounted

It makes a nice linear counterpoint to the jumble of AC interface wiring:

AC Interface Chassis

AC Interface Chassis

The insulating sheet on the case lid came from the bottom of the original GX270 system board, where I think it served much the same purpose. It’s surely not rated for AC line voltages, but the thought must count for something:

AC Interface Chassis

AC Interface Chassis

More of the parts are flying in formation…

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AC Interface Chassis Mounting Clips

The Dell GX270 system board mounts on a tray, latching into small tabs, with a single screw locking it in place. The tray then slides into the metal EMI shield / case, latching onto more tabs, with a spring-loaded pair of tabs snapping into a slot under the green latch:

Optiplex GX270 - system board tray

Optiplex GX270 – system board tray

All that is well and good for a mass-production PC system board, but poses a problem for mounting anything else: there’s no room for screw heads below the tray, adhesives really don’t bond to slightly flexible aluminum sheets, and I definitely can’t do large-scale precision metal bending.

So a cheat seems in order. The general idea is to support a 6 mm polycarbonate sheet on clips that slide under the small tabs along the front, support the sheet on the rear tabs, and secure it with the screw. That’s thick enough to allow tapping holes for mounting screws, so everything else can mount to the sheet.

The sheet fits around the power supply on the right, protrudes over the rear of the tray to the back of the case (with a recess around the green latch), and clears the hinge assembly on the left. There are no dimensions, as it’s all done by eye with the Joggy Thing.

AC Chassis Shaping

AC Chassis Shaping

A drive bay EMI plug from a long-discarded PC provided some nice springy steel strips that slide neatly under those tray tabs:

Drive EMI shield

Drive EMI shield

That actually took a bit of trial-and-error:

AC Chassis mounting brackets - practice makes perfect

AC Chassis mounting brackets – practice makes perfect

My first attempts used slightly thicker steel that didn’t fit nearly as well, plus I wasn’t quite sure how wide they should be.

As with nearly all plastic doodads around here, the white plastic mounting clips / brackets come from the M2:

Chassis Clips

Chassis Clips

The two brackets in the middle of the solid model slide around the tabs at the rear corners of the tray and capture the bent-over top section below the polycarbonate sheet.

The strip in the rear goes around the screws holding the heatsink to the sheet; more on that later.

The PLA brackets get themselves glued to the sheet with IPS #4 solvent adhesive, a hellish mixture of chlorinated hydrocarbons that attacks most plastics with gleeful enthusiasm. I positioned the brackets on the tray, slobbered adhesive on their tops, slapped the polycarbonate sheet in place, and applied clamps:

AC Chassis - gluing bracket blocks

AC Chassis – gluing bracket blocks

The final bonds weren’t as uniform as I’d like, but they seem rugged enough. The lip along the rear of the tray was slightly higher on the left edge, which may have interfered with the clamping pressure; it’s obviously not a controlled dimension.

The tapped holes in the sheet accommodate screws for various bits & pieces.

All in all, that worked out pretty well…

The OpenSCAD source code:

// AC Interface sheet mounting brackets
// Ed Nisley - KE4ZNU - August 2014

Layout = "Build";		// FrontClip RearClip HeatSink Build

Gap = 5.0;					// between Build objects

//- Extrusion parameters must match reality!

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

AlignPinOD = 1.70;			// assembly alignment pins: filament dia

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

//----------------------
// Dimensions

FC_Block = [45.0,30.0,IntegerMultiple(5.6,ThreadThick)];
FC_Retainer = [15.5,9.0,3.0,15.0];					// central section: L,W,H, inset from front

RC_Block = [30.0,25.0,IntegerMultiple(5.6,ThreadThick)];
RC_RecessOffset = [9.0,5.0,IntegerMultiple(4.8,ThreadThick)];	// X,Y,thickness
RC_SlotWidth = 2.5;

HS_Insulation = [80.0,16.0,2.5];
HS_Hole = [8.0,40.0];					// screw clearance dia,on-center

//----------------------
// 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,
           h=Height,
           $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

//----------------------
// Front clips

module FrontClip() {

	difference() {
		translate([0,0,FC_Block[2]/2])
			cube(FC_Block,center=true);

		translate([0,(FC_Retainer[3] - FC_Block[1]/2),(FC_Retainer[2] + FC_Block[2]/2)])
			cube([(FC_Block[0] - 12*ThreadWidth),FC_Retainer[1],FC_Block[2]],center=true);

		translate([0,FC_Retainer[3] - FC_Retainer[1]/2,FC_Block[2]/2])
			cube([FC_Retainer[0],FC_Block[1],2*FC_Block[2]],center=true);
	}

}

//----------------------
// Rear clips

module RearClip(Hand="Left") {

HandSign = (Hand == "Left") ? -1 : 1;

	difference() {
		translate([0,0,RC_Block[2]/2])
			cube(RC_Block,center=true);

		translate([0,RC_RecessOffset[1],RC_RecessOffset[2] + RC_Block[2]/2])
			cube([RC_Block[0] - 2*RC_RecessOffset[0],
				  RC_Block[1],
				  RC_Block[2]],center=true);

		translate([HandSign*(RC_Block[0]/2 - RC_RecessOffset[0]),
				   RC_RecessOffset[1],
				   0])
			cube([RC_SlotWidth,RC_Block[1],3*RC_Block[2]],center=true);

	}

}

//----------------------
// Heatsink bumper

module HeatSink() {

	difference() {
		translate([0,0,HS_Insulation[2]/2])
			cube(HS_Insulation,center=true);

	for (x=[-1,1])
		translate([x*HS_Hole[1]/2,0,-HS_Insulation[2]])
			PolyCyl(HS_Hole[0],3*HS_Insulation[2],8);
	}

}

ShowPegGrid();

if (Layout == "FrontClip") {
	FrontClip();
}

if (Layout == "RearClip") {
	RearClip("Left");
}

if (Layout == "HeatSink") {
	HeatSink();
}

if (Layout == "Build") {
	for (x=[-1,1]) {
		translate([x*(Gap + FC_Block[0])/2,(Gap + FC_Block[1])/2,0])
			FrontClip();
		translate([x*(Gap + RC_Block[0])/2,-(Gap + RC_Block[1])/2,0])
			RearClip((x == -1) ? "Left" : "Right");
	}
	translate([0,-(RC_Block[1] + HS_Insulation[1]/2 + 3*Gap/2),0])
		HeatSink();
}

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Panel-mount Fuseholder Holder

Under ordinary circumstances, a fuseholder mounts in a square-ish panel cutout, but there’s no convenient panel to be found in the repurposed GX270 case. So now there’s a holder for the fuseholder stuck to the side of the power supply inside the case:

Fuseholder - installed

Fuseholder – installed

The square tube covers the entire fuseholder, with the quick-connect tabs protruding from the back, to provide enough surface area for the double-stick foam tape.

Looking down into the solid model, you can see the reduced width near the back end:

Fuseholder Holder

Fuseholder Holder

The black fuseholder contains a 5 A fast blow fuse, which should be entirely adequate for normal operation. In the event that a wire breaks loose and contacts the metal shell surrounding the whole chassis, it will pop instantly. That won’t disable the power supply, but it will remove line voltage from the entire motor controller chassis.

Remember that the source power line goes to the center QC tab, thus burying the always-hot contact deep in the fuseholder.

The OpenSCAD source code:

// Fuseholder mount
// Ed Nisley - KE4ZNU - August 2014

//- Extrusion parameters must match reality!

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

AlignPinOD = 1.70;			// assembly alignment pins: filament dia

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

//----------------------
// Dimensions

Shell = [25.0,25];						// outside = bezel size + some stiffening

Mount = [17.3,15.7,21.0];					// mount section = slight compression in X
Base = [13.5,15.7,17.0];					// clearance over crimped contact

OAL = Mount[2] + Base[2];

//----------------------
// 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,
           h=Height,
           $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

//----------------------
// Build it

ShowPegGrid();

difference() {
	translate([0,0,OAL/2])
		cube([Shell[0],Shell[1],OAL],center=true);
	translate([0,0,Base[2] + Mount[2]/2])
		cube(Mount + [0,0,2*Protrusion],center=true);
	translate([0,0,Base[2]/2])
		cube(Base + [0,0,2*Protrusion],center=true);
}

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ET227 Transistor Heatsink: Angled Blower Mount

This angled ring fits under a repurposed CPU cooler:

Blower Mount - solid model

Blower Mount – solid model

Viewed perpendicular to the angled surface, it’s a circle, so what looks like a vertical cylinder is actually slightly oval to make the top come out right. That way, the walls are vertical, not angled, and it doesn’t stand crooked on the base plate.

Such a shape is trivially easy for a 3D printer:

Blower mount - on build platform

Blower mount – on build platform

And looks about like you’d expect on the blower, which is why that surface must be a circle:

Blower Mount - bottom view

Blower Mount – bottom view

A trial fit in the case, along with a bunch of parts I haven’t written up yet:

Blower Mount - installed

Blower Mount – installed

Under normal circumstances, you’d want the blower a bit higher and level, but there just wasn’t anywhere else to fit the fuseholder. Besides, this way the airflow goes slightly upward toward the clearance over the top of that monster heatsink. Some air flows along the side of the heatsink to cool the isolated power supply you can’t quite see in the far corner of the chassis beyond that tangle of wires.

The angle seems pretty close to right, although I must get the rest of the circuitry running to know if the airflow can actually transfer the heat from the heatsink out of the case.

It doesn’t take much OpenSCAD source code to define the shape:

// Blower mount
// Ed Nisley - KE4ZNU - August 2014

//- Extrusion parameters must match reality!

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

AlignPinOD = 1.70;			// assembly alignment pins: filament dia

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

//----------------------
// Dimensions

MountOD = 85.0;						// a bit smaller than the housing OD

MountID = 60.0;						// carve out to reduce printing time

Base = 5.0;							// minimum thickness (allowing for some overhang)

ElevationAngle = atan(20/90);		// net tilt across fan base

ElevationDelta = MountOD * tan(ElevationAngle);

echo(str("Elevation angle: ",ElevationAngle," delta: ",ElevationDelta));

//----------------------
// 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,
           h=Height,
           $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

//----------------------
// Build it

ShowPegGrid();

difference() {
	scale([1,cos(ElevationAngle),1])
		cylinder(d=MountOD,h=Base + ElevationDelta);
	translate([-MountOD,-MountOD/2,Base])
		rotate([ElevationAngle,0,0])
			cube([2*MountOD,2*MountOD,ElevationDelta],center=false);
	translate([0,0,-Protrusion])
		cylinder(d=MountID,h=Base + 3*ElevationDelta);
}

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