The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Machine Shop

Mechanical widgetry

Heavy Hauling

A recent road trip presented this spectacle in the first Pennsylvania rest step on northbound I-83 (clicky for many more dots, then scroll to see it all):

Heavy Hauling – panorama mid

It’s a 150 Ton Flat and Depressed Well 19 Axle Trailer, including four axles on the front truck:

Heavy Hauling – front

Another truck on the rear pushes uphill and provides lateral control downhill:

Heavy Hauling – panorama rear

The weight block on the rear truck provides more traction, because friction depends on normal force.

The PA transportation folks were verifying the overall weight and per-axle distribution by weighing three axles at a time:

Heavy Hauling – weight check

Each scale has a 20 k pound range:

Heavy Hauling – weight check – detail

The ones I saw reported 10-14 k pounds, so figure 24 k pounds per axle, then multiply by 19 to get 456 k pounds overall.

The driver of the lead escort vehicle said the tarp covers a machined steel assembly weighing around 200 k pounds, with a total “vehicle” weight a bit under 500 k pounds. This is the second of four similar loads going from the Port of Baltimore to somewhere in Ohio where they’re assembling a huge press. It seems American manufacturing is still a thing.

They’ll be driving for four or five days from Port o’ Baltimore to Ohio, following a route described in excruciating detail on four pages of notes, plus another 16 pages of permits for the series of bridges rated to carry however many axles will be on them simultaneously.

Some searching produced a video of a similar load in transit, perhaps on the same trailer. Another video shows a different trailer jockeying into position beside a ferry (!).

For the folks involved, it was just another day at the office.

2018-05-03
Mis-Punched Scope Probe Hook

Back in the day, HP scope probes had a rugged music-wire hook on the tip:

HP scope probe tip

These days, scope probe tips use ordinary sheet steel punched into a hook shape:

Siglent scope probe – good tip

By sheer bad luck, the first probe out of the bag had a mis-punched end with no griptivity:

Siglent scope probe – mis-cut tip

Dunno what happened, but it was definitely sheared off in the factory.

After I finally recognized the problem, I shaped a crude hook with a safe-edge needle file and continued the mission:

Siglent scope probe – filed tip

A quick note to Siglent put a replacement probe tip in the mail, so it’s all good.

2018-04-24
Magnetic Field Visualization

Thinking about springs to apply downforce on plotting pen holders suggested magnets, so I extricated some neodymium bars from my collection of power toothbrush heads:

Magnets – single

A snippet of magnetic field visualization film shows a dipole pattern:

Magnets – single – field visualization

Snapping two of them together in line:

Magnets – in line

… produces a quadrupole:

Magnets – in line – field visualization

Now, if only I had some magnetic monopoles, this whole thing would be easier!

2018-04-21
MPCNC: Ground Shaft Pen Holder

Drilling a pair of holes into a length of ground steel shaft turned it into a holder for a Sakura Micron pen:

DW660 Pen Holder – printed plastic vs ground steel

The aluminum ring epoxied to the top keeps it from falling completely through the linear bearing.

The hole sizes are the nearest inch drills matching the pen’s hard metric sizes:

Ground 12 mm rod – Sakura pen drill diameters

While I was at the lathe, I turned another layer of epoxy on the printed holder down to a consistent 11.95+ OD. It fits the bearing nearly as well as the steel shaft, although it’s not quite as smooth.

The steel version weighs about 20 g with the pen, so it applies about the same downforce on the pen nib as the HP 7475A plotter. The force varies from about 19 g as the Z axis moves upward to 23 g as it move downward, so the stiction amounts to less than 10% of the weight:

DW660 Pen Holder – ground shaft

However, the more I ponder this setup, the less I like it.

When the Z-axis moves downward and the nib hits the paper, it must decelerate the weight of the pen + holder + ballast within a fraction of a millimeter, without crushing the nib. If the pen moves downward at 3000 mm/min = 50 mm/s, stopping in 0.3 mm requires an acceleration of 4.2 m/s² and a 20 g = 2/3 oz mass will apply 0.08 N = 0.3 oz to the nib. Seems survivable, but smashing the tip a few hundred times while drawing the legends can’t possibly be good for it.

Also, the tool length probe switch trips at 60 (-ish) g, which means the pen can’t activate the switch. Adding a manual latch seems absurd, but you can get used to anything if you do it enough.

2018-04-18

Propane Tank QD Fitting Adapter, PETG Edition

Smoking bacon during the winter months brought the third tank into play, requiring the POL-to-QD adapter I’d had in the drawer for just such an occasion. Not much to my surprise, the old PLA fitting adapter snapped along the layers near the outside end of the triangular snout:

So I ran off the two orange ones in PETG with six perimeter layers and 50% infill density:

Propane QD Adapter Tool - Slic3r — Propane QD Adapter Tool – Slic3r

Those should last roughly forever …

The OpenSCAD source code as a GitHub Gist:

	// Propane tank QD connector adapter tool
	// Ed Nisley KE4ZNU November 2012
	// 2018-04-08 toss MCAD includes overboard

	//- Extrusion parameters must match reality!
	// Print with about half a dozen perimeter threads and 50% infill

	ThreadThick = 0.25;
	ThreadWidth = 2.0 * ThreadThick;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

	//———————-
	// Dimensions

	WrenchSize = (5/8) * inch; // across the flats
	WrenchThick = 10;

	NoseDia = 8.6;
	NoseLength = 9.0;

	LockDia = 12.5;
	LockRingLength = 1.0;
	LockTaperLength = 1.5;

	TriDia = 15.1;
	TriWide = 12.2; // from OD across center to triangle side
	TriOffset = TriWide – TriDia/2; // from center to triangle side
	TriLength = 9.8;

	NeckDia = TriDia;
	NeckLength = 4.0;

	//———————-
	// 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) {

	Range = floor(50 / Space);

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

	//——————-
	// Build it…

	$fn = 4*6;

	//ShowPegGrid();

	union() {

	translate([0,0,(WrenchThick + NeckLength + TriLength – LockTaperLength – LockRingLength + Protrusion)])
	cylinder(r1=NoseDia/2,r2=LockDia/2,h=LockTaperLength);

	translate([0,0,(WrenchThick + NeckLength + TriLength – LockRingLength)])
	cylinder(r=LockDia/2,h=LockRingLength);



	difference() {
	union() {

	translate([0,0,WrenchThick/2])
	cube([WrenchSize,WrenchSize,WrenchThick],center=true);

	cylinder(r=TriDia/2,h=(WrenchThick + NeckLength +TriLength));

	cylinder(r=NoseDia/2,h=(WrenchThick + NeckLength + TriLength + NoseLength));
	}

	for (a=[-1:1]) {
	rotate(a*120)
	translate([(TriOffset + WrenchSize/2),0,(WrenchThick + NeckLength + TriLength/2 + Protrusion/2)])
	cube([WrenchSize,WrenchSize,(TriLength + Protrusion)],center=true);
	}
	}
	}

view raw Propane QD Adapter Tool.scad hosted with ❤ by GitHub

2018-04-17

Monthly Image: Amazon Packing

I have often kvetched about Amazon’s casual approach to packaging, so this took me completely by surprise:

Amazon packaging – 16 mm linear motion rod

There’s a 500 mm length of 16 mm round linear motion rod / shaft inside the small blue-and-white box. Previous shipments of similar rod have arrived in a lightly padded envelope or rattling loose in a box of other stuff.

The small blue-and-white corrugated cardboard box contains a bag protecting the well-oiled shaft, with padded end caps preventing the shaft from escaping or whacking against anything.

The middle box is made from two U-shaped sheets of molded (not corrugated) fiberboard, with one rigid U stapled into those wood end caps, the other U fitting over the assembly, and plenty of packing tape securing the two. Enough bubble wrap fills the cavity to surround and completely immobilize the inner box.

FedEx carried the armored box from Thomson to an Amazon warehouse in February, so it wasn’t packed specifically for me.

The upper box is a standard Amazon corrugated carton, with slightly more than a token amount of paper packed around the fiberboard box. The paper didn’t completely immobilize the middle box, but did serve to keep it from rattling loose.

I paid twenty bucks for the rod, with “free” Amazon Prime shipping, and UPS delivered it in the usual two days.

The whole affair weighs 7 pounds. If I were to reship it to somebody using UPS 2nd Day, they’d charge me $39 just for the shipping.

I felt unworthy …

On the other paw, Amazon recently sent a dozen LED lights with a casual disregard for protection:

Amazon packaging – shredded LED lamp carton

Both ends of the carton were shredded, although all of the cardboard tubes and LED lamps remained still inside. Not all the tube end caps completed the journey, however.

The carton didn’t sport the usual Box Certificate mark found on all Amazon cartons and was made of brittle Chinese cardboard, so it was intended for protected shipping, perhaps inside a freight container, not as a business-to-consumer shipping box.

Somewhat to my surprise, all the LED lights worked, including several that shrugged off their tube caps, as in the upper right, or broke their white cardboard end plates, as in the rest. The plastic protectors on the LED pins served their purpose!

Amazon provided a partial refund when I filed Package Feedback, so they’re paying attention to damages.

Five pounds of granular erythritol fared better, with a token air pillow contributing nothing:

Amazon packaging – 5 lb bag

It makes ya wonder, it does …

2018-04-15
Brother BAS-311 Control Head Salvage

A control head from an ancient Brother BAS-311 sewing machine emerged from a recent Squidwrench clearing-out session:

Brother BAS-311 Control Head

The sturdy metal enclosure ought to be good for something, I thought, so I rescued it from the trash.

One of the ten button-head screws galled in place and resisted a few days of penetrating oil, so I drilled it out:

Drilled-out button screw head

The PCB has no ICs! It simply routes all the LED and button pins through the pillar into the sewing machine controller:

Brother BAS-311 Control Head – interior

The ribbon cable alternates the usual flat strip with sections of split conductors:

Segmented ribbon cable

The split segments let it roll up into the pillar, with enough flexibility to allow rotating the head. I’ve seen segmented twisted-pair ribbon cable, but never just flat conductors.

Maybe the control head can become Art in its next life?

2018-04-13