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Octal Tube Base Clamp
One of the octal tubes in my collection has a broken spigot / key post that lets some light in through the bottom of the normally opaque Bakelite base:

Octal socket in CD – LED diffraction Perhaps drilling out the base would let more light pass around the evacuation tip, but that requires a shell drill to clear the tip. Some doodling suggested a drill with 12 mm OD and 8 mm ID, which was close enough to one of the smaller homebrew drills in my collection that I decided to see how it worked:

Shell drill assortment You (well, I) can’t freehand such a hole, particularly with a glass tip in the middle, so I needed a way to clamp the tube in either the drill press or the Sherline. A pad for the clamp screw in a V-block seemed appropriate:

Vacuum Tube Lights – Octal base clamp – Slic3r preview The screw hole sits at the 1/3 point to put more pressure near the pin end of the base. Maybe that matters.
The setup looks like this, with a small red laser dot near the front of the base:

Octal tube clamped on Sherline mill The tube rests on a random scrap of plastic, with the hope that the drill won’t apply enough pressure to break the glass envelope.
In normal use, the V-block would be oriented the other way to let you cross-drill the cylinder. In this end-on orientation, drilling torque can rotate the tube; compliant padding for more traction may be in order.
The OpenSCAD source code as a GitHub Gist now includes a module that spits out the clamp:
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters// Vacuum Tube LED Lights // Ed Nisley KE4ZNU February … September 2016 Layout = "TubeClamp"; // Cap LampBase USBPort Bushings // Socket(s) Cap (Build)FinCap Platter[Base|Fixture] // TubeClamp DefaultSocket = "Mini7"; Section = false; // 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 // punch & screw OC modified for drive platter chassis plate // platter = 25 mm ID // CD = 15 mm ID with raised ring at 37 mm, needs screw head clearance 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 (must also clear evacuation tip / spigot) 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 (clear evac tip / spigot) T_SCREWOC = 9; // mounting screw holes // Name pins BCD dia length hole punch tube pipe screw TubeData = [ ["Mini7", 8, 9.53, 1.016, 7.0, 16.0, 25.0, 18.0, 5.0, 35.0], // punch 11/16, screw 22.5 OC // ["Octal", 8, 17.45, 2.36, 11.0, 36.2, (8 + 1)/8 * inch, 32.0, 11.5, 47.0], // screw 39.0 OC ["Octal", 8, 17.45, 2.36, 11.0, 36.2, 25.0, 32.0, 11.5, 42.0], // platter + 4 mm screws ["Noval", 10, 11.89, 1.1016, 7.0, 22.0, 25.0, 21.0, 7.5, 35.0], // punch 7/8, screw 28.0 OC ["Magnoval", 10, 17.45, 1.27, 9.0, 29.7, (4 + 1)/4 * inch, 46.0, 12.4, 38.2], // similar to Novar // ["Duodecar", 13, 19.10, 1.05, 9.0, 32.0, (4 + 1)/4 * inch, 38.0, 12.5, 47.0], // screw was 39.0 OC ["Duodecar", 13, 19.10, 1.05, 9.0, 25.0, 25.0, 38.0, 12.5, 42.0], // fit un-punched drive platter ]; ID = 0; OD = 1; LENGTH = 2; Pixel = [7.0,10.0,3.0]; // ID = contact patch, OD = PCB dia, LENGTH = overall thickness SocketNut = // socket mounting: threaded insert or nut recess // [3.5,5.2,7.2] // 6-32 insert [4.0,6.0,5.9] // 4 mm short insert ; NutSides = 8; SocketShim = 2*ThreadThick; // between pin holes and pixel top SocketFlange = 1.5; // rim around socket below punchout PanelThick = 1.5; // socket extension through punchout FinCutterOD = 1/8 * inch; FinCapSize = [(Pixel[OD] + 2*FinCutterOD),30.0,(10.0 + 2*Pixel[LENGTH])]; USBPCB = // [28,16,6.5] // small Sparkfun knockoff [36,18 + 1,5.8 + 0.4] // Deek-Robot fake FTDI with ISP header ; Platter = [25.0,95.0,1.26]; // hard drive platter dimensions //———————- // 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,$fn=Sides); } //———————- // Tube cap CapTube = [4.0,3/16 * inch,10.0]; // brass tube for flying lead to cap LED CapSize = [Pixel[ID],(Pixel[OD] + 2.0),(CapTube[OD] + 2*Pixel[LENGTH])]; CapSides = 8*4; module Cap() { difference() { union() { cylinder(d=CapSize[OD],h=(CapSize[LENGTH]),$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),$fn=CapSides); // cos() fixes slight undersize vs cylinder cylinder(d1=(CapSize[OD] + 2*3*ThreadWidth),d2=CapSize[OD],h=1.5*Pixel[LENGTH],$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) + HoleWindage),d2=Pixel[ID],h=(Pixel[LENGTH] + Protrusion),$fn=CapSides); translate([0,0,(CapSize[LENGTH] – CapTube[OD]/(2*cos(180/8)))]) // hole for brass tube holding wire loom rotate([90,0,0]) rotate(180/8) PolyCyl(CapTube[OD],CapSize[OD],8); } } //———————- // Heatsink tube cap module FinCap() { CableOD = 3.5; // cable + braid diameter BulbOD = 3.75 * inch; // bulb OD; use 10 inches for flat echo(str("Fin Cutter: ",FinCutterOD)); FinSides = 2*4; BulbRadius = BulbOD / 2; BulbDepth = BulbRadius – sqrt(pow(BulbRadius,2) – pow(FinCapSize[OD],2)/4); echo(str("Bulb OD: ",BulbOD," recess: ",BulbDepth)); NumFins = floor(PI*FinCapSize[ID] / (2*FinCutterOD)); FinAngle = 360 / NumFins; echo(str("NumFins: ",NumFins," angle: ",FinAngle," deg")); difference() { union() { cylinder(d=FinCapSize[ID],h=FinCapSize[LENGTH],$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),$fn=FinSides); translate([0,0,-Protrusion]) // PCB recess PolyCyl(Pixel[OD],(1.5*Pixel[LENGTH] + Protrusion),FinSides); PolyCyl(Pixel[ID],(FinCapSize[LENGTH] – 3*ThreadThick),FinSides); // bore for LED wiring translate([0,0,(FinCapSize[LENGTH] – 3*ThreadThick – 2*CableOD/(2*cos(180/8)))]) // cable inlet rotate(FinAngle/2) rotate([0,90,0]) rotate(180/8) PolyCyl(CableOD,FinCapSize[OD],8); if (BulbOD <= 10.0 * inch) // curve for top of bulb translate([0,0,-(BulbRadius – BulbDepth + 2*ThreadThick)]) // … slightly flatten tips sphere(d=BulbOD,$fn=16*FinSides); } } //———————- // Aperture for USB-to-serial adapter snout // These are all magic numbers, of course module USBPort() { translate([0,USBPCB[0]]) rotate([90,0,0]) linear_extrude(height=USBPCB[0]) polygon(points=[ [0,0], [USBPCB[1]/2,0], [USBPCB[1]/2,0.5*USBPCB[2]], [USBPCB[1]/3,USBPCB[2]], [-USBPCB[1]/3,USBPCB[2]], [-USBPCB[1]/2,0.5*USBPCB[2]], [-USBPCB[1]/2,0], ]); } //———————- // Box for Leviton ceramic lamp base module LampBase() { Insert = [3.5,5.2,7.2]; // 6-32 brass insert to match standard electrical screws Bottom = 3.0; Base = [4.0*inch,4.5*inch,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 = [Insert[OD], // insert for socket 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],$fn=StudSides); translate([0,0,Bottom]) PolyCyl(Stud[ID],(Stud[LENGTH] – (Bottom – Protrusion)),6); } } } //———————- // Base for hard drive platters module PlatterBase(TubeName = DefaultSocket) { PCB = [36,18,3] // Arduino Pro Mini ; Tube = search([TubeName],TubeData,1,0)[0]; SocketHeight = Pixel[LENGTH] + SocketShim + TubeData[Tube][T_PINLEN] – PanelThick; echo(str("Base for ",TubeData[Tube][0]," socket")); Overhang = 5.5; // platter overhangs base by this much Bottom = 4*ThreadThick; Base = [(Platter[OD] – 3*Overhang), // smaller than 3.5 inch Sch 40 PVC pipe… (Platter[OD] – 2*Overhang), 2.0 + max(PCB[1],(2.0 + SocketHeight + USBPCB[2])) + Bottom]; Sides = 24*4; echo(str(" Height: ",Base[2]," mm")); Insert = // platter mounting: threaded insert or nut recess // [3.5,5.2,7.2] // 6-32 insert [3.9,5.0,8.0] // 3 mm – long insert ; NumStuds = 4; StudSides = 8; Stud = [Insert[OD], // insert for socket screws 2*Insert[OD], // OD = big enough to merge with walls Base[LENGTH]]; // leave room for retainer StudBCD = floor(Base[ID] – Stud[OD] + (Stud[OD] – Stud[ID])/2); echo(str("Platter screw BCD: ",StudBCD," mm")); PCBInset = Base[ID]/2 – sqrt(pow(Base[ID]/2,2) – pow(PCB[0],2)/4); union() { difference() { rotate(180/Sides) cylinder(d=Base[OD],h=Base[LENGTH],$fn=Sides); rotate(180/Sides) translate([0,0,Bottom]) cylinder(d=Base[ID],h=Base[LENGTH],$fn=Sides); translate([0,-Base[OD]/2,Bottom + 1.2]) // mount PCB on foam tape rotate(0) USBPort(); } for (a = [0:(NumStuds – 1)]) // platter mounting studs rotate(180/NumStuds + a*360/(NumStuds)) translate([StudBCD/2,0,0]) rotate(180/StudSides) difference() { cylinder(d=Stud[OD],h=Stud[LENGTH],$fn=2*StudSides); translate([0,0,Bottom]) PolyCyl(Stud[ID],(Stud[LENGTH] – (Bottom – Protrusion)),StudSides); } intersection() { // microcontroller PCB mounting plate rotate(180/Sides) cylinder(d=Base[OD],h=Base[LENGTH],$fn=Sides); translate([-PCB[0]/2,(Base[ID]/2 – PCBInset),0]) cube([PCB[0],Base[OD]/2,Base[LENGTH]],center=false); } difference() { intersection() { // totally ad-hoc bridge around USB opening rotate(180/Sides) cylinder(d=Base[OD],h=Base[LENGTH],$fn=Sides); translate([-1.25*USBPCB[1]/2,-(Base[ID]/2),0]) cube([1.25*USBPCB[1],2.0,Base[LENGTH]],center=false); } translate([0,-Base[OD]/2,Bottom + 1.2]) // mount PCB on foam tape rotate(0) USBPort(); translate([0,-(Base[ID]/2 – 2.0 + 1*ThreadWidth),Bottom – 3*ThreadThick]) // legend rotate([90,0,180]) linear_extrude(height=1*ThreadWidth + Protrusion) { translate([0,(Base[LENGTH] – 5.5),0]) text(text=TubeName,size=4,font="Arial:style=Bold",halign="center"); // translate([0,(Base[LENGTH] – 8.5),0]) // text(text=str("BCD ",StudBCD),size=2,font="Arial",halign="center"); translate([0,(Base[LENGTH] – 11),0]) text(text="KE4ZNU",size=3,font="Arial",halign="center"); } } } } //———————- // Drilling fixture for disk platters module PlatterFixture() { StudOC = [1.16*inch,1.16*inch]; // Sherline tooling plate screw spacing StudClear = 5.0; BasePlate = [(20 + StudOC[0]*ceil(Platter[OD] / StudOC[0])),(Platter[OD] + 10),7.0]; PlateRound = 10.0; // corner radius difference() { hull() // basic block for (i=[-1,1], j=[-1,1]) translate([i*(BasePlate[0]/2 – PlateRound),j*(BasePlate[1]/2 – PlateRound),0]) cylinder(r=PlateRound,h=BasePlate[2],$fn=4*4); for (i=[-1:1], j=[-1:1]) // index marks translate([i*100/2,j*100/2,BasePlate[2] – 2*ThreadThick]) cylinder(d=1.5,h=1,$fn=6); for (i=[-1,1], j=[-1,0,1]) // holes for tooling plate studs translate([i*StudOC[0]*ceil(Platter[OD] / StudOC[0])/2,j*StudOC[0],-Protrusion]) PolyCyl(StudClear,BasePlate[2] + 2*Protrusion,6); translate([0,0,-Protrusion]) // center clamp hole PolyCyl(StudClear,BasePlate[2] + 2*Protrusion,6); translate([0,0,BasePlate[2] – Platter[LENGTH]]) // disk locating recess linear_extrude(height=(Platter[LENGTH] + Protrusion),convexity=2) difference() { circle(d=(Platter[OD] + 1),$fn=8*4); circle(d=Platter[ID],$fn=8*4); } translate([0,0,BasePlate[2] – 4.0]) // drilling recess linear_extrude(height=(4.0 + Protrusion),convexity=2) difference() { circle(d=(Platter[OD] – 10),$fn=8*4); circle(d=(Platter[ID] + 10),$fn=8*4); } } } //———————- // Tube Socket module Socket(Name = DefaultSocket) { NumSides = 6*4; Tube = search([Name],TubeData,1,0)[0]; echo(str("Building ",TubeData[Tube][0]," socket")); echo(str(" Punch: ",TubeData[Tube][T_PUNCHOD]," mm = ",TubeData[Tube][T_PUNCHOD]/inch," inch")); echo(str(" Screws: ",TubeData[Tube][T_SCREWOC]," mm =",TubeData[Tube][T_SCREWOC]/inch," inch OC")); OAH = Pixel[LENGTH] + SocketShim + TubeData[Tube][T_PINLEN]; BaseHeight = OAH – PanelThick; difference() { union() { linear_extrude(height=BaseHeight) // base outline hull() { circle(d=(TubeData[Tube][T_PUNCHOD] + 2*SocketFlange),$fn=NumSides); for (i=[-1,1]) translate([i*TubeData[Tube][T_SCREWOC]/2,0]) circle(d=2.0*SocketNut[OD],$fn=NumSides); } cylinder(d=TubeData[Tube][T_PUNCHOD],h=OAH,$fn=NumSides); // boss in chassis punch hole } for (i=[0:(TubeData[Tube][T_NUMPINS] – 1)]) // tube pins rotate(i*360/TubeData[Tube][T_NUMPINS]) translate([TubeData[Tube][T_PINBCD]/2,0,(OAH – TubeData[Tube][T_PINLEN])]) rotate(180/4) PolyCyl(TubeData[Tube][T_PINOD],(TubeData[Tube][T_PINLEN] + Protrusion),4); for (i=[-1,1]) // mounting screw holes & nut traps / threaded inserts translate([i*TubeData[Tube][T_SCREWOC]/2,0,-Protrusion]) { PolyCyl(SocketNut[OD],(SocketNut[LENGTH] + Protrusion),NutSides); PolyCyl(SocketNut[ID],(OAH + 2*Protrusion),NutSides); } translate([0,0,-Protrusion]) { // LED recess PolyCyl(Pixel[OD],(Pixel[LENGTH] + Protrusion),8); } translate([0,0,(Pixel[LENGTH] – Protrusion)]) { // light pipe rotate(180/TubeData[Tube][T_NUMPINS]) PolyCyl(TubeData[Tube][T_PIPEOD],(OAH + 2*Protrusion),TubeData[Tube][T_NUMPINS]); } for (i=[-1,1]) // cable retaining slots translate([i*(Pixel[OD] + TubeData[Tube][T_SCREWOC])/4,0,(Pixel[LENGTH] – Protrusion)/2]) cube([Pixel[LENGTH],TubeData[Tube][T_SCREWOC],(Pixel[LENGTH] + Protrusion)],center=true); } // Totally ad-hoc support structures … if (Support) { color("Yellow") { for (i=[-1,1]) // nut traps translate([i*TubeData[Tube][T_SCREWOC]/2,0,(SocketNut[LENGTH] – ThreadThick)/2]) for (a=[0:5]) rotate(a*30 + 15) cube([2*ThreadWidth,0.9*SocketNut[OD],(SocketNut[LENGTH] – ThreadThick)],center=true); if (Pixel[OD] > TubeData[Tube][T_PIPEOD]) // support pipe only if needed translate([0,0,(Pixel[LENGTH] – ThreadThick)/2]) for (a=[0:7]) rotate(a*22.5) cube([2*ThreadWidth,0.9*Pixel[OD],(Pixel[LENGTH] – ThreadThick)],center=true); } } } //———————- // Greenlee punch bushings module PunchBushing(Name = DefaultSocket) { PunchScrew = 9.5; BushingThick = 3.0; Tube = search([Name],TubeData,1,0)[0]; echo(str("Building ",TubeData[Tube][0]," bushing")); NumSides = 6*4; difference() { union() { cylinder(d=Platter[ID],h=BushingThick,$fn=NumSides); cylinder(d=TubeData[Tube][T_PUNCHOD],h=(BushingThick – Platter[LENGTH]),$fn=NumSides); } translate([0,0,-Protrusion]) PolyCyl(PunchScrew,5.0,8); } } //———————- // Tube clamp module TubeClamp(Name = DefaultSocket) { Tube = search([Name],TubeData,1,0)[0]; echo(str("Building ",TubeData[Tube][0]," clamp")); ClampWidth = 37.0; // inside of clamp arch ClampLength = 20; // along tube base ClampScrew = [6.0,7.8,6.0]; // nose of clamp screw ClampArc = 3*45; // angle subtended by block bottom ClampChordWidth = 2 * (TubeData[Tube][T_TUBEOD]/2) * sin(ClampArc/2); ClampChordDepth = (ClampChordWidth / 2) * tan(ClampArc/4); echo(str("Chord width: ",ClampChordWidth," depth: ",ClampChordDepth)); ClampBlock = [ClampWidth,(ClampChordDepth + 2*ClampScrew[LENGTH]),ClampLength]; difference() { translate([0,(ClampBlock[1]/2 + TubeData[Tube][T_TUBEOD]/2 – ClampChordDepth),0]) intersection() { translate([0,0,ClampLength/2]) cube(ClampBlock,center=true); translate([0,(ClampBlock[1]/2 – ClampWidth/2),0]) cylinder(d=ClampWidth,h=ClampLength); } translate([0,0,-Protrusion]) // remove tube base (remains centered) cylinder(d=TubeData[Tube][T_TUBEOD],h=(ClampLength + 2*Protrusion)); translate([0,(TubeData[Tube][T_TUBEOD]/2 + ClampScrew[LENGTH]),ClampBlock[LENGTH]/3]) rotate([-90,0,0]) PolyCyl(ClampScrew[ID],2*ClampScrew[LENGTH],6); } } //———————- // Build it if (Layout == "Cap") { if (Section) difference() { Cap(); translate([-CapSize[OD],0,CapSize[LENGTH]]) cube([2*CapSize[OD],2*CapSize[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([2*FinCapSize[OD],2*FinCapSize[OD],3*FinCapSize[LENGTH]],center=true); translate([-FinCapSize[OD],0,FinCapSize[LENGTH]]) cube([2*FinCapSize[OD],2*FinCapSize[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 == "PlatterBase") PlatterBase(); if (Layout == "PlatterFixture") PlatterFixture(); if (Layout == "USBPort") USBPort(); if (Layout == "TubeClamp") TubeClamp("Octal"); if (Layout == "Bushings") PunchBushing(); 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"); translate([0,-85,0]) Socket("Magnoval");}