Category: Machine Shop

Mechanical widgetry

Improved Lip Balm / Lipstick Holder

Mary asked for a less angular version of the Lip Balm Holder, which gave me a chance to practice my list comprehension:

You hand the OpenSCAD program a list of desired tube diameters in the order you want them, the program plunks the first one (ideally, the largest diameter) in the middle, arranges the others around it counterclockwise from left to right, then slips a lilypad under each tube.

As long as you don’t ask for anything egregiously stupid, the results look reasonably good:

Improved Lipstick and Balm Holder - 8 tubes — Improved Lipstick and Balm Holder – 8 tubes

As before, each tube length is 1.5 times its diameter; the lipsticks / balms fit loosely and don’t flop around.

Given the tube diameters and the wall thickness, list comprehensions simplify creating lists of the radii from the center tube to each surrounding tube, the center-to-center distances between each of the outer tubes, and the angles between successive tubes:

// per-tube info, first element forced to 0 to make entries match RawDia vector indexes

Radius = [0, for (i=[1:NumTubes-1]) (TubeRad[0] + TubeRad[i] + Wall)];			// Tube[i] distance to center pointRadius = [0, for (i=[1:NumTubes-1]) (TubeRad[0] + TubeRad[i] + Wall)];			// Tube[i] distance to center point
echo(str("Radius: ",Radius));

CtrToCtr = [0, for (i=[1:NumTubes-2]) (TubeRad[i] + TubeRad[i+1] + Wall)];		// Tube[i] distance to Tube[i+1]
echo(str("CtrToCtr: ",CtrToCtr));

Angle = [0, for (i=[1:NumTubes-2]) acos((pow(Radius[i],2) + pow(Radius[i+1],2) - pow(CtrToCtr[i],2)) / (2 * Radius[i] * Radius[i+1]))];
echo(str("Angle: ",Angle));

TotalAngle = sumv(Angle,len(Angle)-1);
echo(str("TotalAngle: ",TotalAngle));

The angles come from the oblique triangle solution when you know all three sides (abc) and want the angle (C) between a and b:

C = arccos( (a² + b² - c²) / (2ab) )

Peering down inside, the Slic3r preview shows the lily pads are the tops of squashed spheres:

Improved Lipstick and Balm Holder - Slic3r preview — Improved Lipstick and Balm Holder – Slic3r preview

The pads are 2.0 times the tube diameter, which seemed most pleasing to the eye. They top out at 2.0 mm thick, which might make the edges too thin for comfort.

Update: Here’s what it looks like with a convex hull wrapped around all the lilypads:

Improved Lipstick and Balm Holder - hulled base — Improved Lipstick and Balm Holder – hulled base

I’m awaiting reports from My Spies concerning the typical diameter(s) of lipstick tubes, then I’ll run off a prototype and see about the lily pad edges.

The OpenSCAD source code as a GitHub gist:

	// Lipstick and Balm Tube Holder
	// Ed Nisley KE4ZNU – February 2016

	//- 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

	RawDia = [26,21,19,17,19,21]; // actual tube diameters in desired order, center = largest first
	NumTubes = len(RawDia);

	Clearance = 2.0;

	TubeDia = [for (i=[0:NumTubes-1]) (RawDia[i] + Clearance)]; // actual tube diameters
	TubeRad = TubeDia / 2;

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

	Wall = 2.0;

	BaseThick = 2.0;
	BaseFactor = 2.0;

	NumSides = 8*4;

	// per-tube info, first element forced to 0 to make entries match RawDia vector indexes

	Radius = [0, for (i=[1:NumTubes-1]) (TubeRad[0] + TubeRad[i] + Wall)]; // Tube[i] distance to center point
	echo(str("Radius: ",Radius));

	CtrToCtr = [0, for (i=[1:NumTubes-2]) (TubeRad[i] + TubeRad[i+1] + Wall)]; // Tube[i] distance to Tube[i+1]
	echo(str("CtrToCtr: ",CtrToCtr));

	Angle = [0, for (i=[1:NumTubes-2]) acos((pow(Radius[i],2) + pow(Radius[i+1],2) – pow(CtrToCtr[i],2)) / (2 * Radius[i] * Radius[i+1]))];
	echo(str("Angle: ",Angle));

	TotalAngle = sumv(Angle,len(Angle)-1);
	echo(str("TotalAngle: ",TotalAngle));


	//———————-
	// Useful routines

	// vector sum cribbed from doc

	function sumv(v,i,s=0) = (i==s ? v[i] : v[i] + sumv(v,i-1,s));

	//———————-
	//- Build it

	for (i=[0:NumTubes-1])
	rotate(90 – TotalAngle/2 + sumv(Angle, (i>0) ? (i-1) : 0))
	translate([Radius[i],0,0]) {
	resize([0,0,2*BaseThick]) // bases
	difference() {
	sphere(r=BaseFactor*TubeRad[i],$fn=NumSides);
	translate([0,0,-BaseFactor*TubeDia[i]])
	cube(2BaseFactorTubeDia[i],center=true);
	}
	difference() { // tubes
	cylinder(r=TubeRad[i] + Wall,h=1.5*TubeDia[i] + BaseThick,$fn=NumSides);
	cylinder(d=TubeDia[i],h=1.5*TubeDia[i] + BaseThick + Protrusion,$fn=NumSides);
	}
	}

view raw Improved Lipstick and Balm Holder.scad hosted with ❤ by GitHub

2016-02-23

Knurled Inch Inserts
Tagging along behind the metric inserts, a sack of knurled brass inch-size screw inserts arrived:

Threaded Inserts – metric and inch

The nice stainless steel screws on the right range from 4-40 to 10-32, which suffice for nearly everything I build around here.

Unlike the splined metric inserts on the left, these inserts have actual knurls and ridges that should hold them firmly in place. The specs give hard-inch dimensions, of course, that (seem to) correspond to the root diameter of the knurls. You can find nice engineering drawings of precise tapered holes (by drilling down into the Heat-Set Inserts for Plastics item on that page), but a few metric measurements of the actual parts on hand should suffice for my simple needs.

Thread: overall length x small rim OD x (knurl length x larger knurl OD)
- 4-40: 5.8 x 3.9 x (4.0 x 4.6)
- 6-32: 7.1 x 4.7 x (4.6 x 5.5)
- 8-32: 8.1 x 5.5 x (5.9 x 6.3)
- 10-32: 9.5 x 6.3 x (7.0 x 7.1)
Rather than fussing with a tapered hole, just punch a cylinder with the small rim OD (to clear the screw) through the part and put a cylinder with the knurl OD x length at the surface.

Using cylinders without diameter correction will make them slightly undersized for heat bonding. The usual 3D printing tolerances don’t justify anything fussier than that.

Using PolyCyl diameter correction will make the holes nearly spot on for epoxy bonding: butter ’em up, ram ’em in, pause for curing, done.

That’s the plan, anyhow…
2016-02-16

Vacuum Tube LEDs: Ersatz Heat Sink Plate Cap

I wanted a slightly larger “plate cap” to fit a big incandescent bulb and it seemed a fake heatsink might add gravitas to the proceedings:

Vacuum Tube LEDs - large incandescent bulb — Vacuum Tube LEDs – large incandescent bulb

Yeah, that antique ceramic socket holds the bulb at a rakish angle. Worse, even though I painstakingly laid out the position of the heatsink atop the bulb, it’s visibly off-center. Which wouldn’t be so bad, had I not epoxied the damn thing in place.

After reaming out the M2’s filament drive, the entire blue base printed without incident.

A closer look at the cap:

Vacuum Tube LEDs - ersatz heatsink plate cap — Vacuum Tube LEDs – ersatz heatsink plate cap

Memo to Self: Next time, line it up with the vertical glass support inside the bulb and ignore the external evidence.

The boss has a hole for the braid-enclosed cable to the knockoff Neopixel:

Vacuum Tube Lights - finned cap - Slic3r preview — Vacuum Tube Lights – finned cap – Slic3r preview

The cupped surface perfectly fits the bulb’s 3.75 inch diameter. While you wouldn’t mill out a real heatsink, it definitely looks better this way and (alas) gives the epoxy more footprint for a better grip.

I built the fins with a 1/8 inch cutter in mind, so the fin root radius allows for a G3/G3 arc without gouging. I doubt machining a fake heatsink from aluminum makes any sense, but the cheap extruded heatsinks on eBay don’t look very good. Plus, they sport completely unnecessary tapped holes for LED mounts and suchlike.

A cross-section shows the wiring channel and cable entry:

Vacuum Tube Lights - fin cap solid model - section — Vacuum Tube Lights – fin cap solid model – section

I epoxied the Neopixel in place, applied double-sided carpet tape to the whole thing, then painstakingly trimmed around the fins with an Xacto knife:

Vacuum Tube LEDs - Ersatz Heatsink plate cap - tape — Vacuum Tube LEDs – Ersatz Heatsink plate cap – tape

That looked better from the top side (where it was completely hidden) and came heartbreakingly close to working, but after about a day the cable + braid put enough torque on the cap to peel it off the bulb. Obviously, the tape holds much less enthusiastically after that.

Part of the problem came from the cable’s rather sharp angle just outside the cap:

Vacuum Tube LEDs - Ersatz Heatink plate cap - detail — Vacuum Tube LEDs – Ersatz Heatink plate cap – detail

Rakish angle, indeed. Two of ’em, in fact.

Unlike the smaller cap on the halogen bulb, this time I didn’t bother with a brass tube ferrule, mostly to see how it looks. I think it came out OK and the black braid looks striking in person. Conversely, a touch of brass never detracts from the appearance.

Obviously, the cable wasn’t long enough, either. Part of that problem came from underestimating the braid length: it shortens dramatically when slipped over the cable, even when you expect shortening. Somehow I managed to overlook that, despite cutting the cable quite long enough, thankyouverymuch. There’s a tradeoff between gentle angles and having the cable stick out too far for comfort.

Memo to Self: Use a cable at least four inches longer than necessary, measure the combined cable + braid assembly after screwing the bulb in the socket, and don’t epoxy anything before all the parts are ready for assembly.

That’s why it’s a prototype made out of blue PETG…

Protip: running old ceramic sockets through the dishwasher greatly simplifies their subsequent cleanup.

All in all, I like it.

The OpenSCAD source code as a GitHub gist:

	// Vacuum Tube LED Lights
	// Ed Nisley KE4ZNU January 2016

	Layout = "FinCap"; // Cap LampBase USBPort Socket(s) (Build)FinCap

	Section = true; // cross-section the object

	Support = true;

	//- Extrusion parameters must match reality!

	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
	// https://en.wikipedia.org/wiki/Tube_socket#Summary_of_Base_Details

	T_NAME = 0; // common name
	T_NUMPINS = 1; // total, with no allowance for keying
	T_PINBCD = 2; // tube pin circle diameter
	T_PINOD = 3; // … diameter
	T_PINLEN = 4; // … length (overestimate)
	T_HOLEOD = 5; // nominal panel hole from various sources
	T_PUNCHOD = 6; // panel hole optimized for inch-size Greenlee punches
	T_TUBEOD = 7; // envelope or base diameter
	T_PIPEOD = 8; // light pipe from LED to tube base
	T_SCREWOC = 9; // mounting screw holes

	// Name pins BCD dia length hole punch env pipe screw
	TubeData = [
	["Mini7", 8, 9.53, 1.016, 7.0, 16.0, 11/16 * inch, 18.0, 5.0, 22.5],
	["Octal", 8, 17.45, 2.36, 10.0, 36.2, (8 + 1)/8 * inch, 32.0, 11.5, 39.0],
	["Noval", 10, 11.89, 1.1016, 7.0, 22.0, 7/8 * inch, 21.0, 5.0, 28.0],
	["Duodecar", 13, 19.10, 1.05, 9.0, 32.0, 1.25 * inch, 38.0, 12.5, 39.0],
	];

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

	Pixel = [7.0,10.0,3.0]; // ID = contact patch, OD = PCB dia, LENGTH = overall thickness

	Nut = [3.5,8.0,3.0]; // socket mounting nut recess

	BaseShim = 2*ThreadThick; // between pin holes and pixel top
	SocketFlange = 2.0; // rim around socket below punchout
	PanelThick = 2.0; // socket extension through punchout

	//———————-
	// 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);
	}

	//———————-
	// Tube cap

	CapTube = [4.0,3/16 * inch,10.0]; // brass tube for flying lead to cap LED

	CapSize = [Pixel[ID],(Pixel[OD] + 3.0),(CapTube[OD] + 2*Pixel[LENGTH])];

	CapSides = 6*4;

	module Cap() {

	difference() {
	union() {
	cylinder(d=CapSize[OD],h=(CapSize[LENGTH]),$fn=CapSides); // main cap body
	translate([0,0,CapSize[LENGTH]]) // rounded top
	scale([1.0,1.0,0.65])
	sphere(d=CapSize[OD]/cos(180/CapSides),$fn=CapSides); // cos() fixes slight undersize vs cylinder
	cylinder(d1=(CapSize[OD] + 23ThreadWidth),d2=CapSize[OD],h=1.5*Pixel[LENGTH],$fn=CapSides); // skirt
	}

	translate([0,0,-Protrusion]) // bore for wiring to LED
	PolyCyl(CapSize[ID],(CapSize[LENGTH] + 3*ThreadThick + Protrusion),CapSides);

	translate([0,0,-Protrusion]) // PCB recess with clearance for tube dome
	PolyCyl(Pixel[OD],(1.5*Pixel[LENGTH] + Protrusion),CapSides);

	translate([0,0,(1.5*Pixel[LENGTH] – Protrusion)]) // small step + cone to retain PCB
	cylinder(d1=(Pixel[OD]/cos(180/CapSides)),d2=Pixel[ID],h=(Pixel[LENGTH] + Protrusion),$fn=CapSides);

	translate([0,0,(CapSize[LENGTH] – CapTube[OD]/(2*cos(180/8)))]) // hole for brass tube holding wire loom
	rotate([90,0,0]) rotate(180/8)
	PolyCyl(CapTube[OD],CapSize[OD],8);
	}

	}

	//———————-
	// Heatsink tube cap

	CableOD = 3.5; // cable + braid diameter
	BulbOD = 3.75 * inch; // bulb OD; use 10 inches for flat

	FinCutterOD = 1/8 * inch;
	echo(str("Fin Cutter: ",FinCutterOD));
	FinSides = 2*4;

	FinCapSize = [(Pixel[OD] + 2FinCutterOD),30.0,(10.0 + 2Pixel[LENGTH])];

	BulbRadius = BulbOD / 2;
	BulbDepth = BulbRadius – sqrt(pow(BulbRadius,2) – pow(FinCapSize[OD],2)/4);
	echo(str("Bulb OD: ",BulbOD," recess: ",BulbDepth));

	module FinCap() {

	NumFins = floor(PIFinCapSize[ID] / (2FinCutterOD));
	FinAngle = 360 / NumFins;
	echo(str("NumFins: ",NumFins," angle: ",FinAngle," deg"));

	difference() {
	union() {
	cylinder(d=FinCapSize[ID],h=FinCapSize[LENGTH],$fn=2*NumFins); // main body

	for (i = [0:NumFins – 1]) // fins
	rotate(i * FinAngle)
	hull() {
	translate([FinCapSize[ID]/2,0,0])
	rotate(180/FinSides)
	cylinder(d=FinCutterOD,h=FinCapSize[LENGTH],$fn=FinSides);
	translate([(FinCapSize[OD] – FinCutterOD)/2,0,0])
	rotate(180/FinSides)
	cylinder(d=FinCutterOD,h=FinCapSize[LENGTH],$fn=FinSides);
	}

	rotate(FinAngle/2) // cable entry boss
	translate([FinCapSize[ID]/2,0,FinCapSize[LENGTH]/2])
	cube([FinCapSize[OD]/4,FinCapSize[OD]/4,FinCapSize[LENGTH]],center=true);
	}

	for (i = [1:NumFins – 1]) // fin inner gullets, omit cable entry side
	rotate(i * FinAngle + FinAngle/2) // joint isn't quite perfect, but OK
	translate([FinCapSize[ID]/2,0,-Protrusion])
	rotate(0*180/FinSides)
	cylinder(d=FinCutterOD/cos(180/FinSides),h=(FinCapSize[LENGTH] + 2*Protrusion),$fn=FinSides);

	translate([0,0,-Protrusion]) // PCB recess
	PolyCyl(Pixel[OD],(1.5*Pixel[LENGTH] + Protrusion),FinSides);

	PolyCyl(Pixel[ID],(FinCapSize[LENGTH] – 3*ThreadThick),FinSides); // bore for LED wiring

	translate([0,0,(FinCapSize[LENGTH] – 3ThreadThick – 2CableOD/(2*cos(180/8)))]) // cable inlet
	rotate(FinAngle/2) rotate([0,90,0]) rotate(180/8)
	PolyCyl(CableOD,FinCapSize[OD],8);

	if (BulbOD <= 10.0 * inch) // curve for top of bulb
	translate([0,0,-(BulbRadius – BulbDepth + 2*ThreadThick)]) // … slightly flatten tips
	sphere(d=BulbOD,$fn=16*FinSides);
	}

	}


	//———————-
	// Aperture for USB-to-serial adapter snout
	// These are all magic numbers, of course

	module USBPort() {

	translate([0,28.0])
	rotate([90,0,0])
	linear_extrude(height=28.0)
	polygon(points=[
	[0,0],
	[8.0,0],
	[8.0,4.0],
	// [4.0,4.0],
	[4.0,6.5],
	[-4.0,6.5],
	// [-4.0,4.0],
	[-8.0,4.0],
	[-8.0,0],
	]);
	}


	//———————-
	// Box for Leviton ceramic lamp base

	module LampBase() {

	Bottom = 3.0;
	Base = [4.0inch,4.5inch,20.0 + Bottom];
	Sides = 12*4;

	Retainer = [3.5,11.0,1.0]; // flat fiber washer holding lamp base screws in place

	StudSides = 8;
	StudOC = 3.5 * inch;
	Stud = [0.107 * inch, // 6-32 mounting screws
	min(15.0,1.5*(Base[ID] – StudOC)/cos(180/StudSides)), // OD = big enough to merge with walls
	(Base[LENGTH] – Retainer[LENGTH])]; // leave room for retainer


	union() {
	difference() {
	rotate(180/Sides)
	cylinder(d=Base[OD],h=Base[LENGTH],$fn=Sides);
	rotate(180/Sides)
	translate([0,0,Bottom])
	cylinder(d=Base[ID],h=Base[LENGTH],$fn=Sides);
	translate([0,-Base[OD]/2,Bottom + 1.2]) // mount on double-sided foam tape
	rotate(0)
	USBPort();
	}
	for (i = [-1,1])
	translate([i*StudOC/2,0,0])
	rotate(180/StudSides)
	difference() {
	# cylinder(d=Stud[OD],h=Stud[LENGTH],$fn=StudSides);
	translate([0,0,Bottom])
	PolyCyl(Stud[ID],(Stud[LENGTH] – (Bottom – Protrusion)),6);
	}
	}
	}

	//———————-
	// Tube Socket

	module Socket(Name = "Mini7") {

	NumSides = 6*4;

	Tube = search([Name],TubeData,1,0)[0];
	echo(str("Building ",TubeData[Tube][0]," socket"));
	echo(str(" Punch: ",TubeData[ID][T_PUNCHOD]," mm = ",TubeData[ID][T_PUNCHOD]/inch," inch"));
	echo(str(" Screws: ",TubeData[ID][T_SCREWOC]," mm =",TubeData[ID][T_SCREWOC]/inch," inch OC"));

	OAH = Pixel[LENGTH] + BaseShim + TubeData[Tube][T_PINLEN];
	BaseHeight = OAH – PanelThick;

	difference() {
	union() {
	linear_extrude(height=BaseHeight)
	hull() {
	circle(d=(TubeData[Tube][T_PUNCHOD] + 2*SocketFlange),$fn=NumSides);
	for (i=[-1,1])
	translate([i*TubeData[Tube][T_SCREWOC]/2,0])
	circle(d=2*Nut[OD],$fn=NumSides);
	}
	cylinder(d=TubeData[Tube][T_PUNCHOD],h=OAH,$fn=NumSides);
	}

	for (i=[0:(TubeData[Tube][T_NUMPINS] – 1)]) // tube pins
	rotate(i*360/TubeData[Tube][T_NUMPINS])
	translate([TubeData[Tube][T_PINBCD]/2,0,(OAH – TubeData[Tube][T_PINLEN])])
	rotate(180/4)
	PolyCyl(TubeData[Tube][T_PINOD],(TubeData[Tube][T_PINLEN] + Protrusion),4);

	for (i=[-1,1]) // mounting screw holes & nut traps
	translate([i*TubeData[Tube][T_SCREWOC]/2,0,-Protrusion]) {
	PolyCyl(Nut[OD],(Nut[LENGTH] + Protrusion),6);
	PolyCyl(Nut[ID],(OAH + 2*Protrusion),6);
	}

	translate([0,0,-Protrusion]) { // LED recess
	PolyCyl(Pixel[OD],(Pixel[LENGTH] + Protrusion),8);
	}

	translate([0,0,(Pixel[LENGTH] – Protrusion)]) { // light pipe
	rotate(180/TubeData[Tube][T_NUMPINS])
	PolyCyl(TubeData[Tube][T_PIPEOD],(OAH + 2*Protrusion),TubeData[Tube][T_NUMPINS]);
	}
	}

	// Totally ad-hoc support structures …

	if (Support) {
	color("Yellow") {
	for (i=[-1,1]) // nut traps
	translate([i*TubeData[Tube][T_SCREWOC]/2,0,(Nut[LENGTH] – ThreadThick)/2])
	for (a=[0:5])
	rotate(a*30 + 15)
	cube([2ThreadWidth,0.9Nut[OD],(Nut[LENGTH] – ThreadThick)],center=true);

	if (Pixel[OD] > TubeData[Tube][T_PIPEOD]) // support pipe only if needed
	translate([0,0,(Pixel[LENGTH] – ThreadThick)/2])
	for (a=[0:7])
	rotate(a*22.5)
	cube([2ThreadWidth,0.9Pixel[OD],(Pixel[LENGTH] – ThreadThick)],center=true);

	}
	}

	}

	//———————-
	// Build it

	if (Layout == "Cap") {
	if (Section)
	difference() {
	Cap();
	translate([-CapSize[OD],0,CapSize[LENGTH]])
	cube([2CapSize[OD],2CapSize[OD],3*CapSize[LENGTH]],center=true);
	}
	else
	Cap();
	}

	if (Layout == "FinCap") {
	if (Section) render(convexity=5)
	difference() {
	FinCap();
	// translate([0,-FinCapSize[OD],FinCapSize[LENGTH]])
	// cube([2FinCapSize[OD],2FinCapSize[OD],3*FinCapSize[LENGTH]],center=true);
	translate([-FinCapSize[OD],0,FinCapSize[LENGTH]])
	cube([2FinCapSize[OD],2FinCapSize[OD],3*FinCapSize[LENGTH]],center=true);
	}
	else
	FinCap();
	}

	if (Layout == "BuildFinCap")
	translate([0,0,FinCapSize[LENGTH]])
	rotate([180,0,0])
	FinCap();

	if (Layout == "LampBase")
	LampBase();

	if (Layout == "USBPort")
	USBPort();

	if (Layout == "Socket")
	if (Section) {
	difference() {
	Socket();
	translate([-100/2,0,-Protrusion])
	cube([100,50,50],center=false);
	}
	}
	else
	Socket();

	if (Layout == "Sockets") {
	translate([0,50,0])
	Socket("Mini7");
	translate([0,20,0])
	Socket("Octal");
	translate([0,-15,0])
	Socket("Duodecar");
	translate([0,-50,0])
	Socket("Noval");
	}

view raw Vacuum Tube Lights.scad hosted with ❤ by GitHub

2016-02-12

Vacuum Tube LEDs: First Light!

A test lashup to see how it all works, with an ersatz plate cap atop the IBM 21HB5A Beam Power tube on the far right end:

Vacuum Tube LEDs - test lashup — Vacuum Tube LEDs – test lashup

Those sockets must mount in a chassis, not flop around loose on the cable.

I hacked the code out of the Hard Drive Platter Mood Light; there’s a lot to not like about what’s left and I must rethink the overall structure. The colors now run an order of magnitude faster than the Platter Mood Light, with a 90° phase angle between successive Neopixels.

The mica spacers in the 12AT7 Dual Triode tube (second in the sequence, Noval socket) look cool & crystalline:

Vacuum Tube LEDs - Noval tube - blue phase — Vacuum Tube LEDs – Noval tube – blue phase

When the red phase comes around, it becomes a firebottle:

Vacuum Tube LEDs - Noval tube - red phase — Vacuum Tube LEDs – Noval tube – red phase

With a touch of fire in its hole, the IBM 21HB5A Beam Power tube looks just flat-out gorgeous, despite that translucent blue plate cap:

Vacuum Tube LEDs - IBM 21HB5A Beam Power Tube - violet amber phase — Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – violet amber phase

Cool green works pretty well:

Vacuum Tube LEDs - IBM 21HB5A Beam Power Tube - green violet phase — Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – green violet phase

If you wait long enough, it’ll probably turn True IBM Blue.

This worked out even better than I expected!

The Arduino source code as a GitHub gist:

	// Neopixel lighting for multiple vacuum tubes
	// Ed Nisley – KE4ANU – January 2015

	#include <Adafruit_NeoPixel.h>

	//———-
	// Pin assignments

	const byte PIN_NEO = A3; // DO – data out to first Neopixel

	const byte PIN_HEARTBEAT = 13; // DO – Arduino LED

	//———-
	// Constants

	#define UPDATEINTERVAL 25ul
	const unsigned long UpdateMS = UPDATEINTERVAL – 1ul; // update LEDs only this many ms apart minus loop() overhead

	// number of steps per cycle, before applying prime factors
	#define RESOLUTION 100

	// phase difference between tubes for slowest color
	#define BASEPHASE (PI/4.0)

	// number of LED strips around each tube
	#define LEDSTRIPCOUNT 1

	// number of LEDs per strip
	#define LEDSTRINGCOUNT 5

	// want to randomize the startup a little?
	#define RANDOMIZE true

	//———-
	// Globals

	// instantiate the Neopixel buffer array

	Adafruit_NeoPixel strip = Adafruit_NeoPixel(LEDSTRIPCOUNT * LEDSTRINGCOUNT, PIN_NEO, NEO_GRB + NEO_KHZ800);

	uint32_t FullWhite = strip.Color(255,255,255);
	uint32_t FullOff = strip.Color(0,0,0);

	struct pixcolor_t {
	byte Prime;
	unsigned int NumSteps;
	unsigned int Step;
	float StepSize;
	float TubePhase;
	byte MaxPWM;
	};

	// colors in each LED
	enum pixcolors {RED, GREEN, BLUE, PIXELSIZE};

	struct pixcolor_t Pixels[PIXELSIZE]; // all the data for each pixel color intensity

	byte Map[LEDSTRINGCOUNT][LEDSTRIPCOUNT] = {{0},{1},{2},{3},{4}}; // pixel IDs around each tube, bottom to top.

	unsigned long MillisNow;
	unsigned long MillisThen;

	//– Figure PWM based on current state

	byte StepColor(byte Color, float Phi) {

	byte Value;

	Value = (Pixels[Color].MaxPWM / 2.0) * (1.0 + sin(Pixels[Color].Step * Pixels[Color].StepSize + Phi));

	// Value = (Value) ? Value : Pixels[Color].MaxPWM; // flash at dimmest points
	// printf("C: %d Phi: %d Value: %d\r\n",Color,(int)(Phi*180.0/PI),Value);

	return Value;
	}


	//– Helper routine for printf()

	int s_putc(char c, FILE *t) {
	Serial.write(c);
	}

	//——————
	// Set the mood

	void setup() {

	pinMode(PIN_HEARTBEAT,OUTPUT);
	digitalWrite(PIN_HEARTBEAT,LOW); // show we arrived

	Serial.begin(57600);
	fdevopen(&s_putc,0); // set up serial output for printf()

	printf("Multiple Vacuum Tube Mood Light with Neopixels\r\nEd Nisley – KE4ZNU – January 2016\r\n");

	/// set up Neopixels

	strip.begin();
	strip.show();

	// lamp test: run a brilliant white dot along the length of the strip

	printf("Lamp test: walking white\r\n");

	strip.setPixelColor(0,FullWhite);
	strip.show();
	delay(500);

	for (int i=1; i<strip.numPixels(); i++) {
	digitalWrite(PIN_HEARTBEAT,HIGH);
	strip.setPixelColor(i-1,FullOff);
	strip.setPixelColor(i,FullWhite);
	strip.show();
	digitalWrite(PIN_HEARTBEAT,LOW);
	delay(500);
	}

	strip.setPixelColor(strip.numPixels() – 1,FullOff);
	strip.show();
	delay(500);

	// fill the layers

	printf(" … fill using Map array\r\n");

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	digitalWrite(PIN_HEARTBEAT,HIGH);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // spread color around the layer
	strip.setPixelColor(Map[i][j],FullWhite);
	strip.show();
	delay(250);
	}
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	// clear to black

	printf(" … clear\r\n");

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	digitalWrite(PIN_HEARTBEAT,HIGH);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // spread color around the layer
	strip.setPixelColor(Map[i][j],FullOff);
	strip.show();
	delay(250);
	}
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	delay(1000);

	// set up the color generators

	MillisNow = MillisThen = millis();
	if (RANDOMIZE)
	randomSeed(MillisNow + analogRead(7));
	else
	printf("Start not randomized\r\n");
	printf("First random number: %ld\r\n",random(10));

	Pixels[RED].Prime = 7;
	Pixels[GREEN].Prime = 5;
	Pixels[BLUE].Prime = 3;
	printf("Primes: (%d,%d,%d)\r\n",Pixels[RED].Prime,Pixels[GREEN].Prime,Pixels[BLUE].Prime);

	unsigned int TubeSteps = (unsigned int) ((BASEPHASE / TWO_PI) *
	RESOLUTION * (unsigned int) max(max(Pixels[RED].Prime,Pixels[GREEN].Prime),Pixels[BLUE].Prime));
	printf("Tube phase offset: %d deg = %d steps\r\n",(int)(BASEPHASE*(360.0/TWO_PI)),TubeSteps);

	Pixels[RED].MaxPWM = 255;
	Pixels[GREEN].MaxPWM = 128;
	Pixels[BLUE].MaxPWM = 255;

	for (byte c=0; c < PIXELSIZE; c++) {
	Pixels[c].NumSteps = RESOLUTION * (unsigned int) Pixels[c].Prime;
	Pixels[c].Step = (RANDOMIZE) ? random(Pixels[c].NumSteps) : (3*Pixels[c].NumSteps)/4;
	Pixels[c].StepSize = TWO_PI / Pixels[c].NumSteps; // in radians per step
	Pixels[c].TubePhase = TubeSteps * Pixels[c].StepSize; // radians per tube

	printf("c: %d Steps: %d Init: %d",c,Pixels[c].NumSteps,Pixels[c].Step);
	printf(" PWM: %d Phi %d deg\r\n",Pixels[c].MaxPWM,(int)(Pixels[c].TubePhase*(360.0/TWO_PI)));
	}


	}

	//——————
	// Run the mood

	void loop() {

	MillisNow = millis();
	if ((MillisNow – MillisThen) > UpdateMS) {
	digitalWrite(PIN_HEARTBEAT,HIGH);

	for (byte c=0; c < PIXELSIZE; c++) { // step to next increment in each color
	if (++Pixels[c].Step >= Pixels[c].NumSteps) {
	Pixels[c].Step = 0;
	printf("Cycle %d steps %d at %8ld delta %ld ms\r\n",c,Pixels[c].NumSteps,MillisNow,(MillisNow – MillisThen));
	}
	}

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	byte Value[PIXELSIZE];
	for (byte c=0; c < PIXELSIZE; c++) { // … for each color
	Value[c] = StepColor(c,-i*Pixels[c].TubePhase); // figure new PWM value
	// Value[c] = (c == RED && Value[c] == 0) ? Pixels[c].MaxPWM : Value[c]; // flash highlight for tracking
	}
	uint32_t UniColor = strip.Color(Value[RED],Value[GREEN],Value[BLUE]);
	if (false && (i == 0))
	printf("L: %d C: %08lx\r\n",i,UniColor);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // fill layer with color
	strip.setPixelColor(Map[i][j],UniColor);
	}
	}
	strip.show();

	MillisThen = MillisNow;
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	}

view raw MultiTube.ino hosted with ❤ by GitHub

2016-02-11

Vacuum Tube LEDs: Ersatz Tube Sockets

Even vacuum tubes destined to be decorations need sockets:

Vacuum Tube Bases - solid models — Vacuum Tube Bases – solid models

They’re entirely plastic, of course, but they match the dimensions of “real” tube sockets pretty closely. The bosses around the pins have hard-inch dimensions, so you (well, I) can unleash Genuine Greenlee Radio Chassis Punches on sheet metal.

All the key dimensions come from a table, so you can build whatever sockets you need. These four seem to cover the most common relics of the Hollow State Empire:

T_NAME = 0;                                             // common name
T_NUMPINS = 1;                                          // total, with no allowance for keying
T_PINBCD = 2;                                           // tube pin circle diameter
T_PINOD = 3;                                            //  ... diameter
T_PINLEN = 4;                                           //  ... length (overestimate)
T_HOLEOD = 5;                                           // nominal panel hole from various sources
T_PUNCHOD = 6;                                          // panel hole optimized for inch-size Greenlee punches
T_TUBEOD = 7;                                           // envelope or base diameter
T_PIPEOD = 8;                                           // light pipe from LED to tube base
T_SCREWOC = 9;                                          // mounting screw holes

//    Name      pins     BCD   dia  length   hole            punch       env  pipe screw
TubeData = [
    ["Mini7",     8,    9.53, 1.016,   7.0,  16.0,        11/16 * inch,  18.0,  5.0, 22.5],
    ["Octal",     8,   17.45, 2.36,   10.0,  36.2,    (8 + 1)/8 * inch,  32.0, 11.5, 39.0],
    ["Noval",    10,   11.89, 1.1016,  7.0,  22.0,          7/8 * inch,  21.0,  5.0, 28.0],
    ["Duodecar", 13,   19.10, 1.05,    9.0,  32.0,         1.25 * inch,  38.0, 12.5, 39.0],
];

Given that the tubes lack electrical connections, I omitted the base keying: plug them in for best visual effect.

The hole through the middle passes light from a knockoff Neopixel on a 10 mm OD PCB:

Vacuum Tube LEDs - Octal base - top — Vacuum Tube LEDs – Octal base – top

Seen from the bottom, each base traps a pair of 6-32 nuts for chassis mounting and has a Neopixel press-fit in the middle:

Vacuum Tube LEDs - Duodecar base - bottom — Vacuum Tube LEDs – Duodecar base – bottom

Those recesses require support structures:

Vacuum Tube Bases - solid models - support — Vacuum Tube Bases – solid models – support

The Miniature 7-pin socket has the least space for the 10 mm OD Neopixel PCB and shows the thin layer between the bottom of the pin holes and the top of the openings.

Vacuum Tube Base - Mini7 - solid model section — Vacuum Tube Base – Mini7 – solid model section

You see half of the eight holes in the “7 pin” socket, because it has the eighth hole where a standard socket has a gap between pins 1 and 7.

Somewhat to my surprise, punching the support spiders out with a 6-32 stud (grabbed in the drill press) worked perfectly:

Vacuum Tube Base - nut trap overhang - detail — Vacuum Tube Base – nut trap overhang – detail

They look like I intended to build tiny decorations:

Vacuum Tube Base - support structure - detail — Vacuum Tube Base – support structure – detail

The cookies held on tenuously, then released with a loud bang! as I gradually increased the pressure. A PETG support structure in a blind recess wouldn’t pop out nearly so well.

The OpenSCAD source code as a GitHub gist:

	// Vacuum Tube LED Lights
	// Ed Nisley KE4ZNU January 2016

	Layout = "Sockets"; // Cap LampBase USBPort Socket(s)

	Section = true; // cross-section the object

	Support = true;

	//- Extrusion parameters must match reality!

	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
	// https://en.wikipedia.org/wiki/Tube_socket#Summary_of_Base_Details

	T_NAME = 0; // common name
	T_NUMPINS = 1; // total, with no allowance for keying
	T_PINBCD = 2; // tube pin circle diameter
	T_PINOD = 3; // … diameter
	T_PINLEN = 4; // … length (overestimate)
	T_HOLEOD = 5; // nominal panel hole from various sources
	T_PUNCHOD = 6; // panel hole optimized for inch-size Greenlee punches
	T_TUBEOD = 7; // envelope or base diameter
	T_PIPEOD = 8; // light pipe from LED to tube base
	T_SCREWOC = 9; // mounting screw holes

	// Name pins BCD dia length hole punch env pipe screw
	TubeData = [
	["Mini7", 8, 9.53, 1.016, 7.0, 16.0, 11/16 * inch, 18.0, 5.0, 22.5],
	["Octal", 8, 17.45, 2.36, 10.0, 36.2, (8 + 1)/8 * inch, 32.0, 11.5, 39.0],
	["Noval", 10, 11.89, 1.1016, 7.0, 22.0, 7/8 * inch, 21.0, 5.0, 28.0],
	["Duodecar", 13, 19.10, 1.05, 9.0, 32.0, 1.25 * inch, 38.0, 12.5, 39.0],
	];

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

	Pixel = [7.0,10.0,3.0]; // ID = contact patch, OD = PCB dia, LENGTH = overall thickness

	Nut = [3.5,8.0,3.0]; // socket mounting nut recess

	BaseShim = 2*ThreadThick; // between pin holes and pixel top
	SocketFlange = 2.0; // rim around socket below punchout
	PanelThick = 2.0; // socket extension through punchout

	//———————-
	// 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);
	}

	//———————-
	// Tube cap

	CapTube = [4.0,3/16 * inch,10.0]; // brass tube for flying lead to cap LED

	CapSize = [Pixel[ID],(Pixel[OD] + 3.0),(CapTube[OD] + 2*Pixel[LENGTH])];

	CapSides = 6*4;

	module Cap() {

	difference() {
	union() {
	cylinder(d=CapSize[OD],h=(CapSize[LENGTH]),$fn=CapSides); // main cap body
	translate([0,0,CapSize[LENGTH]]) // rounded top
	scale([1.0,1.0,0.65])
	sphere(d=CapSize[OD]/cos(180/CapSides),$fn=CapSides); // cos() fixes slight undersize vs cylinder
	cylinder(d1=(CapSize[OD] + 23ThreadWidth),d2=CapSize[OD],h=1.5*Pixel[LENGTH],$fn=CapSides); // skirt
	}

	translate([0,0,-Protrusion]) // bore for wiring to LED
	PolyCyl(CapSize[ID],(CapSize[LENGTH] + 3*ThreadThick + Protrusion),CapSides);

	translate([0,0,-Protrusion]) // PCB recess with clearance for tube dome
	PolyCyl(Pixel[OD],(1.5*Pixel[LENGTH] + Protrusion),CapSides);

	translate([0,0,(1.5*Pixel[LENGTH] – Protrusion)]) // small step + cone to retain PCB
	cylinder(d1=(Pixel[OD]/cos(180/CapSides)),d2=Pixel[ID],h=(Pixel[LENGTH] + Protrusion),$fn=CapSides);

	translate([0,0,(CapSize[LENGTH] – CapTube[OD]/(2*cos(180/8)))]) // hole for brass tube holding wire loom
	rotate([90,0,0]) rotate(180/8)
	PolyCyl(CapTube[OD],CapSize[OD],8);
	}

	}

	//———————-
	// Aperture for USB-to-serial adapter snout
	// These are all magic numbers, of course

	module USBPort() {

	translate([0,28.0])
	rotate([90,0,0])
	linear_extrude(height=28.0)
	polygon(points=[
	[0,0],
	[8.0,0],
	[8.0,4.0],
	// [4.0,4.0],
	[4.0,6.5],
	[-4.0,6.5],
	// [-4.0,4.0],
	[-8.0,4.0],
	[-8.0,0],
	]);
	}


	//———————-
	// Box for Leviton ceramic lamp base

	module LampBase() {

	Bottom = 3.0;
	Base = [4.0inch,4.5inch,20.0 + Bottom];
	Sides = 12*4;

	Retainer = [3.5,11.0,1.0]; // flat fiber washer holding lamp base screws in place

	StudSides = 8;
	StudOC = 3.5 * inch;
	Stud = [0.107 * inch, // 6-32 mounting screws
	min(15.0,1.5*(Base[ID] – StudOC)/cos(180/StudSides)), // OD = big enough to merge with walls
	(Base[LENGTH] – Retainer[LENGTH])]; // leave room for retainer


	union() {
	difference() {
	rotate(180/Sides)
	cylinder(d=Base[OD],h=Base[LENGTH],$fn=Sides);
	rotate(180/Sides)
	translate([0,0,Bottom])
	cylinder(d=Base[ID],h=Base[LENGTH],$fn=Sides);
	translate([0,-Base[OD]/2,Bottom + 1.2]) // mount on double-sided foam tape
	rotate(0)
	USBPort();
	}
	for (i = [-1,1])
	translate([i*StudOC/2,0,0])
	rotate(180/StudSides)
	difference() {
	# cylinder(d=Stud[OD],h=Stud[LENGTH],$fn=StudSides);
	translate([0,0,Bottom])
	PolyCyl(Stud[ID],(Stud[LENGTH] – (Bottom – Protrusion)),6);
	}
	}
	}

	//———————-
	// Tube Socket

	module Socket(Name = "Mini7") {

	NumSides = 6*4;

	Tube = search([Name],TubeData,1,0)[0];
	echo(str("Building ",TubeData[Tube][0]," socket"));
	echo(str(" Punch: ",TubeData[ID][T_PUNCHOD]," mm = ",TubeData[ID][T_PUNCHOD]/inch," inch"));
	echo(str(" Screws: ",TubeData[ID][T_SCREWOC]," mm =",TubeData[ID][T_SCREWOC]/inch," inch OC"));

	OAH = Pixel[LENGTH] + BaseShim + TubeData[Tube][T_PINLEN];
	BaseHeight = OAH – PanelThick;

	difference() {
	union() {
	linear_extrude(height=BaseHeight)
	hull() {
	circle(d=(TubeData[Tube][T_PUNCHOD] + 2*SocketFlange),$fn=NumSides);
	for (i=[-1,1])
	translate([i*TubeData[Tube][T_SCREWOC]/2,0])
	circle(d=2*Nut[OD],$fn=NumSides);
	}
	cylinder(d=TubeData[Tube][T_PUNCHOD],h=OAH,$fn=NumSides);
	}

	for (i=[0:(TubeData[Tube][T_NUMPINS] – 1)]) // tube pins
	rotate(i*360/TubeData[Tube][T_NUMPINS])
	translate([TubeData[Tube][T_PINBCD]/2,0,(OAH – TubeData[Tube][T_PINLEN])])
	rotate(180/4)
	PolyCyl(TubeData[Tube][T_PINOD],(TubeData[Tube][T_PINLEN] + Protrusion),4);

	for (i=[-1,1]) // mounting screw holes & nut traps
	translate([i*TubeData[Tube][T_SCREWOC]/2,0,-Protrusion]) {
	PolyCyl(Nut[OD],(Nut[LENGTH] + Protrusion),6);
	PolyCyl(Nut[ID],(OAH + 2*Protrusion),6);
	}

	translate([0,0,-Protrusion]) { // LED recess
	PolyCyl(Pixel[OD],(Pixel[LENGTH] + Protrusion),8);
	}

	translate([0,0,(Pixel[LENGTH] – Protrusion)]) { // light pipe
	rotate(180/TubeData[Tube][T_NUMPINS])
	PolyCyl(TubeData[Tube][T_PIPEOD],(OAH + 2*Protrusion),TubeData[Tube][T_NUMPINS]);
	}
	}

	// Totally ad-hoc support structures …

	if (Support) {
	color("Yellow") {
	for (i=[-1,1]) // nut traps
	translate([i*TubeData[Tube][T_SCREWOC]/2,0,(Nut[LENGTH] – ThreadThick)/2])
	for (a=[0:5])
	rotate(a*30 + 15)
	cube([2ThreadWidth,0.9Nut[OD],(Nut[LENGTH] – ThreadThick)],center=true);

	if (Pixel[OD] > TubeData[Tube][T_PIPEOD]) // support pipe only if needed
	translate([0,0,(Pixel[LENGTH] – ThreadThick)/2])
	for (a=[0:7])
	rotate(a*22.5)
	cube([2ThreadWidth,0.9Pixel[OD],(Pixel[LENGTH] – ThreadThick)],center=true);

	}
	}

	}

	//———————-
	// Build it

	if (Layout == "Cap") {
	if (Section)
	difference() {
	Cap();
	translate([-CapSize[OD],0,CapSize[LENGTH]])
	cube([2CapSize[OD],2CapSize[OD],3*CapSize[LENGTH]],center=true);
	}
	else
	Cap();
	}

	if (Layout == "LampBase")
	LampBase();

	if (Layout == "USBPort")
	USBPort();

	if (Layout == "Socket")
	if (Section) {
	difference() {
	Socket();
	translate([-100/2,0,-Protrusion])
	cube([100,50,50],center=false);
	}
	}
	else
	Socket();

	if (Layout == "Sockets") {
	translate([0,50,0])
	Socket("Mini7");
	translate([0,20,0])
	Socket("Octal");
	translate([0,-15,0])
	Socket("Duodecar");
	translate([0,-50,0])
	Socket("Noval");
	}

view raw Vacuum Tube Lights.scad hosted with ❤ by GitHub

2016-02-10

Sears Sewing Table Hinge Covers

The extension surfaces on the Sears sewing table in the Basement Sewing Room unfold from the top, leaving the hinges exposed:

Alas, quilts snag on the squared-off ends of the hinges, a situation that is not to be tolerated…

This protective cap isn’t as small as we’d like, but it must be that thick to cover the hinge, that long to cover the squared-off ends, and that wide for symmetry:

Sears Sewing Table Hinge Cover - solid model — Sears Sewing Table Hinge Cover – solid model

Two neodymium magnets fit in the holes and secure the cover to the all-steel “bronzed” hinges:

Sears Sewing Table - hinge covers — Sears Sewing Table – hinge covers

We’re not sure how well that will work in the long term, but early returns seem promising.

It could be slightly narrower left-to-right and maybe fewer vertices should be oriented differently.

The OpenSCAD source code as a GitHub gist:

	// Vacuum Tube LED Lights
	// Ed Nisley KE4ZNU January 2016

	//- Extrusion parameters must match reality!

	ThreadThick = 0.20;
	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

	Hinge = [7.0,52.0,6.0];

	TopThick = 3*ThreadThick;
	PlateThick = Hinge[2] + TopThick;

	NumSides = 8*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);
	}

	//———————-
	// Build it

	difference() {
	hull()
	for (a=[0:7])
	rotate(a*360/8)
	translate([Hinge[1]/2,0,0])
	scale([1.5,1.5,1])
	sphere(r=PlateThick,$fn=NumSides);
	hull()
	for (k=[-1,1])
	translate([0,Hinge[1]/2,k*(Hinge[2] – Hinge[0]/2)])
	rotate([90,0,0]) rotate(180/8)
	PolyCyl(Hinge[0],Hinge[1],8);

	for (i=[-1,1])
	translate([i*Hinge[1]/2,0,-Protrusion])
	PolyCyl(4.8,2.5 + Protrusion,8);

	translate([0,0,-PlateThick])
	cube(2*[Hinge[1],Hinge[1],PlateThick],center=true);
	}

view raw Sewing Table Hinge Covers.scad hosted with ❤ by GitHub

2016-02-09

Hollow State Electronics: Desk Decorations

I did a lightning talk / show-n-tell last Tuesday at the MHV LUG meeting and covered one end of a table with the Neopixel-lit bulbs & vacuum tubes & hard drive platters I’ve been playing with:

MHVLUG – Hollow State Decorations – Lightning Talk

Some of the posts won’t go live for a week, but here’s a peek into the future:

Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – violet amber phase

Dang, that came out well…

2016-02-06

Category: Machine Shop

Improved Lip Balm / Lipstick Holder

Knurled Inch Inserts

Vacuum Tube LEDs: Ersatz Heat Sink Plate Cap

Vacuum Tube LEDs: First Light!

Vacuum Tube LEDs: Ersatz Tube Sockets

Sears Sewing Table Hinge Covers

Hollow State Electronics: Desk Decorations