Tag: Improvements

Making the world a better place, one piece at a time

MPCNC: USB Camera Alignment

Adding a lock screw to the camera mount stabilized the camera-to-spindle offset enough to make calibration meaningful. Mark the spot directly under the camera:

bCNC – Camera – hot glue align

Then mark the spot directly under the spindle, perhaps by poking a small cutter into the tape, measure the XY distances between the two center points, and use bCNC’s camera registration process to set the camera offset.

With those numbers in place, switching to the tool view (the green button with the end mill to the right in the ribbon bar) puts the camera at the spindle location:

bCNC – Spindle – hot glue align

The view from outside shows the relation between those two pieces of tape:

MPCNC – USB camera-to-spindle alignment

Now I can align the camera view to a fixture position and be (reasonably) sure the spindle will automagically align to the same XY coordinate when I switch to the “tool” view. Seems to work well in preliminary tests, anyhow.

2018-03-29

MPCNC: USB Camera Mount With Lock Screw

It turned out the previous version of the USB camera mount lacked sufficient griptivity to hold the ball’s position against even moderate bumps, so the upper “half” is now tall enough to hold a lock screw directly over the ball:

MPCNC - USB Camera mount - lock screw - Slic3r — MPCNC – USB Camera mount – lock screw – Slic3r

It doesn’t look much different:

MPCNC - USB Camera Mount - lock screw — MPCNC – USB Camera Mount – lock screw

A view from the other side:

USB Camera - lock screw mount — USB Camera – lock screw mount

The previous iterations used Genuine 3M foam tape, which seemed too flexy for comfort. This one sits on a bed of hot melt glue and is absolutely rigid. We’ll see how long it survives.

Tightening the cap screw requires needle-nose pliers, because the whole affair has no room for a hex key.

The OpenSCAD source code as a GitHub Gist:

	// MPCNC USB Camera Mount
	// Ed Nisley KE4ZNU – 2018-02-22

	Layout = "Build"; // Build, Show

	/* [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

	WallThick = 3.0; // minimum thickness / width

	CameraStalk = [6.0 + 1.0,10.0 + HoleWindage,4.0]; // stalk OD, ball OD, stalk length
	CameraAngle = -5; // stalk tilt, negative = downward

	Screw = [3.0,7.0,25.0]; // holding it all together, OD = washer

	Insert = [3.0,4.4,4.5]; // brass insert
	Pusher = Insert[LENGTH] / 2; // plastic locking snippet

	UpperThick = IntegerMultiple(CameraStalk[OD]/2 + Insert[LENGTH] + Pusher + WallThick,ThreadThick);
	LowerThick = Screw[LENGTH] – UpperThick;

	MountBlock = [24.0,20.0,LowerThick + UpperThick];

	echo(str("Block: ",MountBlock));

	NumSides = 6*4;

	//—–
	// Define shapes

	// Camera mount, enlongated for E-Z differencing
	// Origin at center of ball, stalk along +X

	module Camera() {

	union() {
	sphere(d=CameraStalk[OD],$fn=NumSides);
	rotate([0,90 – CameraAngle,0])
	PolyCyl(CameraStalk[ID],3*CameraStalk[LENGTH],NumSides);
	}
	}

	// Mount block with all the cutouts
	// Ball centerline on XY plane = block split line

	module Mount(Half="All") {

	Rounding = 2.0; // corner radius

	ZShift = // block shift to remove unwanted half
	(Half == "Upper") ? -MountBlock.z/2 – 0*UpperThick :
	(Half == "Lower") ? MountBlock.z/2 + 0*LowerThick :
	2*MountBlock.z; // … want both halves, remove none

	difference() {
	hull()
	for (i=[-1,1], j=[-1,1]) {
	translate([i(MountBlock.x/2 – Rounding),j(MountBlock.y/2 – Rounding),(UpperThick – Rounding)])
	sphere(r=Rounding,$fn=3*4);
	translate([i(MountBlock.x/2 – Rounding),j(MountBlock.y/2 – Rounding),-(LowerThick – Rounding)])
	sphere(r=Rounding,$fn=3*4);
	}

	for (j=[-1,1])
	translate([-MountBlock.x/4,j*MountBlock.y/4,-(LowerThick + Protrusion)]) {
	PolyCyl(Insert[OD],Insert[LENGTH] + Protrusion,6);
	PolyCyl(Insert[ID],2*MountBlock.z,6);
	}

	translate([MountBlock.x/2 – (CameraStalk[OD]/2 + CameraStalk[LENGTH]),0,0]) {
	Camera();
	translate([0,0,UpperThick – (Insert[LENGTH] + WallThick)])
	PolyCyl(Insert[OD],Insert[LENGTH] + WallThick,6);
	PolyCyl(Insert[ID],2*UpperThick,6);
	}

	translate([0,0,ZShift])
	cube([2MountBlock.x,2MountBlock.y,MountBlock.z],center=true);
	}

	}

	//—–
	// Build it

	if (Layout == "Show")
	Mount("All");

	if (Layout == "Build") {
	translate([0,0.75*MountBlock.y,UpperThick])
	rotate([180,0,0])
	Mount("Upper");
	translate([0,-0.75*MountBlock.y,LowerThick])
	rotate([0,0,0])
	Mount("Lower");}

view raw USB Camera Mount.scad hosted with ❤ by GitHub

2018-03-28

Baofeng BL-5 Pack Rebuild

The 18650 cell protection PCBs with 8205 ICs arrived and seemed small enough to simply tuck into the gap between the rounded cells in the second Baofeng BL-5 pack:

Baofeng BL-5 – new protection PCB – wiring 1

For whatever it might be worth, you’re looking at the only Baofeng battery pack containing an actual 10 kΩ thermistor, harvested from the benchtop Tray of Doom:

Baofeng BL-5 pack – thermistor

Unfortunately, the components on the PCB stuck up a bit too far from the cell surface and held the lid just slightly proud of the case. Applying pressure to lithium cells being a Bad Idea, I rearranged the layout by flipping the cells over, tucking the PCB components between the cells, and connecting everything with nickel tape instead of insulated wires:

Baofeng BL-5 – new protection PCB – wiring 2

The snippets of manila paper and Kapton tape hold things apart and together, as needed. Looks ugly, fits better.

Pop it in the charger to reset the protection PCB lockout and it’s all good again.

2018-03-26
Sena PS410 Serial Server: Configuration
Although I cannot explain why those ferrite beads lit up, it seems connecting the DE-9 shell to the serial device ground is an Extremely Bad Idea. I removed that wire from the HP 8591 spectrum analyzer cable and everything seems to work, so I’ll declare victory:

Sena PS410 Serial Server – in action

Not shown: the tangle of cables tucked behind that tidy box. You can plug a serial terminal into the DE-9 connector, but it’s much easier to use the PS410’s web interface.

It needs a static IP address to make it findable, although I also told the router to force the same address should it start up in DHCP mode:

IP Configuration

Yeah, Google DNS, if all else fails.

The serial port overview:

Serial port overview

I’ll go into more detail in a while about individual device setups and the scripts slurping screen shots out of them, but giving each one a useful name is a Good Idea, even though it doesn’t appear anywhere else. I changed the default Inactivity Timeout for each port from the default 100 seconds to zero, thereby preventing the PS410 from closing the connection due to inactivity:

Serial Port 2 – host params

The DTR and DSR defaults work out well; the other choices solve problems I don’t have. Indeed, the PS410 has a myriad configuration options best left in their Disabled state.

The serial parameters for each port need tweaking to suit the hardware gadget on the other end of the cable:

Serial Port 2 – serial params

Flow Control applies between the PS410 and the gadget. You can choose:
- Disabled
- XON/XOFF – in-band characters
- RTS/CTS – RS-232 hardware signals
Somewhat to my surprise, It Just Worked despite my blundering.
2018-03-23
Bottle Cap Rehabilitation

Mary acquired this bottle a long time ago and has used it forever, so it has Historic Connotations and cannot be discarded. Alas, the cardboard-and-plastic seal in the cap finally disintegrated; I replaced it with various plastic foams and sheets, none of which worked.

Finally, I found the cork sheet stash while looking for something else and cut out a disk:

Rehabilitated bottle cap

It works perfectly, of course, because cork.

That was easy.

2018-03-17
SJCAM M20 Camera: Dimensions
The SJCAM M20 action camera came with a whole bunch of doodads:

SJCAM M20 Accessories – Manual pg 25

Including a waterproof case, some right-angle connectors, and a pipe clamp:

M20 in waterproof case – Tour Easy seat

The stack turns out to be about as flexy as one might imagine, definitely a Bad Thing for a bike-mounted camera, and a somewhat more rugged mount seems in order.

A diagram from the M20 manual shows the parts:

SJCAM M20 Overview – Manual pg 5

Some camera dimensions:
- 40.2 mm wide + 0.5 mm for the Up/Down buttons
- 21.8 mm thick + 1.0 mm cylindrical front curve + 1.0 mm rear screen
- 50.0 mm tall + 4.0 mm cylindrical top curve + buttons
- 21.7 mm OD × 6.0 mm long lens housing, 1.3 mm down from top center
All the edges have neat chamfers or radius rounding on the order of a few millimeters.

Applying the chord equation to the spans inside the rounding:
- Front radius: 162.5 mm
- Top radius: 42.5 mm
The new batteries survive for a bit over an hour, not quite enough for our usual rides. Rather than conjure a fake battery pack connected to an external 18650 cell with a wire chewed through the case, the least awful way to go may involve a relatively small battery pack (with internal 18650 cells, of course) plugged into the USB port with a right-angle cable and a rigid mount holding both the camera and the pack to the seat frame.

More pondering is in order.
2018-03-14
Paper Airplanes

Milo showed how to construct his realistic-looking paper airplane design at Squidwrench, so I had to fold an airplane pattern I learned in fifth grade:

Paper Airplanes – front view

Side views:

Paper Airplanes – side view

Bottom views:

Paper Airplanes – bottom view

His plane flies fine, but “my” airplane has the virtue of simplicity. He had a snippet left over for a fourth engine, so I cut it in half and rolled a pair; the original pattern has none.

It flies best when made from a sheet of 8-½×11 inch (Letter) paper, but anything will suffice. Here’s how to fold one from a Geek Scratch Pad half-Letter sheet.

Start with two diagonal folds:

Best Paper Airplane Ever – 1

Push the sides in and flatten:

Best Paper Airplane Ever – 2

Fold the side tips forward, then again to form pockets:

Best Paper Airplane Ever – 3

I’ve always made those folds to leave a few millimeters of clearance along the centerline, but it probably doesn’t matter.

Tear the fuselage rearward from the nose, along the center line, back to the pockets:

Best Paper Airplane Ever – 4

Tuck the nose pieces into the pockets, flatten firmly, then fold in half lengthwise:

Best Paper Airplane Ever – 5

Fold each wing downward from the pocket, upward to put the edge along the bottom of the fuselage, then fold downward to align the edge at the previous fold:

Best Paper Airplane Ever – 6

Which is harder to describe than to do. The end result should look like this:

Best Paper Airplane Ever – 7

Crisp the folds, tear a square-ish vertical-ish stabilizer, fold a triangle into the fuselage, then un-flatten the airplane into shape:

Best Paper Airplane Ever – 8

Grab just behind the pockets, toss gently upward, and it’ll fly fine the first time. Slightly bend the rear edges of the wing and stabilizer to trim the flight path until it sails gently across the room.

It’s a glider, not a dart!

Enjoy …

2018-03-13