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Archive for November 5th, 2011

Logitech Ball Camera Tripod Adapter

The Logitech notebook webcam that peers into the Thing-O-Matic has terrible dynamic range compensation; turning on the LED ring light washes out the image something awful. An old Logitech ball camera seems better, but it sits atop a rubbery dingus adapted to grip huge old laptops. So I built an adapter with a standard 1/4-20 tripod screw thread in the bottom that ought to make it more useful.

The old & new mounts compared:

Logitech ball camera mounts

Logitech ball camera mounts

The color change comes from switching to yellow filament for an upcoming larger object.

The solid model shows those tiny little notches will require a bit of riffler file work:

Logitech camera tripod adapter - solid model

Logitech camera tripod adapter - solid model

The bottom has a blind 1/4-20 tapped hole. Lacking a bottoming tap, not having any broken 1/4-20 taps, and being unwilling to grind the end off a perfectly good taper tap, I filed three notches along a bolt. Ran the taper tap in until it hit bottom, ran the bolt in likewise, and defined the result to be Good Enough:

Homebrew bottoming tap

Homebrew bottoming tap

On the other end, the most probable failure will leave that delicate little post jammed firmly inside the camera’s socket. There’s not enough post to allow printing a small guide hole, but there’s no real need for one; I drilled a #50 hole right down the middle, ran a 2-56 screw into it without tapping the hole, and filed the screw head flat:

Camera mount with filed screw

Camera mount with filed screw

After cleaning up those notches, it snapped solidly into place:

Logitech ball camera with mount

Logitech ball camera with mount

And then the camera sits neatly atop a cheap Gorillapod knockoff:

Logitech ball camera on tripod

Logitech ball camera on tripod

That tiny reddish dot in the middle of the imposing set of rings marks the actual lens, so it’s more of a pinhole camera than anything else. The fixed focus kicks in beyond a meter, but a bit of rummaging in the Box o’ Lenses produced a random meniscus lens that pulled the focus in to maybe 100 mm. Alas, that means the camera must float in mid-air about 15 mm inside the Thing-O-Matic’s box. If I can conjure up a mount that holds the ball inside the box, above-and-forward of the stage, that’d work great. VLC can allegedly rotate the image upside-down, so maybe I can mount it bottom-up.

Here’s everything I know about those two cameras, with the ball camera on top and the webcam on the bottom:

Logitech ball and notebook webcam data

Logitech ball and notebook webcam data

Apparently it’s easier to put that information on a tag than provide a good old data plate on the camera body.

The OpenSCAD source code:

// Tripod mount for Logitech ball camera
// Ed Nisley KE4ZNU - Oct 2011

include </home/ed/Thing-O-Matic/lib/MCAD/units.scad>
include </home/ed/Thing-O-Matic/Useful Sizes.scad>
include </home/ed/Thing-O-Matic/lib/visibone_colors.scad>

//-------
//- Extrusion parameters must match reality!
//  Print with +0 shells and 3 solid layers

ThreadThick = 0.33;
ThreadWidth = 2.0 * ThreadThick;

HoleFinagle = 0.2;
HoleFudge = 1.02;

function HoleAdjust(Diameter) = HoleFudge*Diameter + HoleFinagle;

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

Protrusion = 0.1;			// make holes end cleanly

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

BallDia = 60.0;				// camera ball
BallRad = BallDia/2;

BaseDia = 16.0;				// interface at tripod surface
BaseRad = BaseDia/2;

BaseLength = 10.0;			// to base of ball

BoltDia = Tap025_20;		// standard 1/4-20 thread
BoltLength = 7.0;

StemLength = 8.5;
StemDia = 4.7;
StemRad = StemDia/2;

FlangeWidth = 6.6;
FlangeThick = 2.6;

NotchSectionDia = 1.4;		// toroid cross-section diameter
NotchSectionRad = NotchSectionDia/2;
NotchOffset = 2.3;			// from top of stem

//-------

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=HoleAdjust(FixDia)/2,h=Height,$fn=Sides);
}

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

  Range = floor(50 / Space);

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

}

//-------
//

ShowPegGrid();

translate([0,0,BaseLength])
  union() {
	difference() {
	  translate([0,0,-BaseLength])
		cylinder(r=BaseRad,h=2*BaseLength);
	  translate([0,0,BallRad])
		sphere(r=BallRad);
	  translate([0,0,-(BaseLength + Protrusion)])
		PolyCyl(BoltDia,(BoltLength + Protrusion));
	}
	rotate(180/16)
	  cylinder(r=StemRad,h=StemLength,$fn=16);
	difference() {
	  translate([0,0,StemLength/2])
		cube([FlangeWidth,FlangeThick,StemLength],center=true);
	  translate([0,0,(StemLength - NotchOffset)])
		rotate_extrude(convexity=3,$fn=64)
		  translate([FlangeWidth/2,0,0])
			circle(r=NotchSectionRad,$fn=16);
	  translate([0,-FlangeWidth/2,StemLength + sqrt(FlangeWidth)])
		rotate([0,45,0])
		  cube(FlangeWidth + 2*Protrusion);
	  translate([0,FlangeWidth/2,StemLength + sqrt(FlangeWidth)])
		rotate([0,45,180])
		  cube(FlangeWidth + 2*Protrusion);
	}
  }
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