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.

Tag: Repairs

If it used to work, it can work again

Refrigerator Coil Wand Adapter Rebuild
After five years, the adapter between the Kenmore Progressive vacuum cleaner and the long wand required to reach inside the refrigerator evaporator coils broke at the latch opening:

$Kenmore Vacuum - refrigerator coil adapter - fracture$
Kenmore Vacuum – refrigerator coil adapter – fracture

A quick fix let me continue the mission:

Kenmore Vacuum – refrigerator coil adapter – temporary fix

A better fix required a few minutes of OpenSCAD tweakage and a few hours of hands-off build time:

Refrigerator Coil Wand Adapter – Slic3r preview

The fitting ID is now 2 mm smaller, the 3D honeycomb infill is 25%, and (contrary to the picture) it now has 4 perimeter threads. It’s a two-line change from the last time:
```
OEMTube = [35.0 - 2.0,35.0,41.7,40.5,30.0];           // main fitting tube
… then, inside MaleFitting() …
cylinder(d1=OEMTube[ID2],d2=OEMTube[ID1],h=2*OEMTube[LENGTH] + 2*Protrusion);
```
Those will propagate to anything I build from now on, although this is the first latch fracture.

Gotta love it when 3D printing lives up to the hype!
2020-02-25
HON Lateral File Cabinet Foot Repair

We bought the best-looking (pronounced “least bashed”) pair of hulking five-drawer industrial-strength HON Brigade Lateral File Cabinets from the local ReStore outlet’s assortment for Mary’s quilting fabric stash. They came with a steep discount, barely fit inside the Forester, caused minor interior trim damage, and should organize her entire stash.

One cabinet lost a foot nut at some point in its 16 year history:

HON Lateral File – foot hole – weld nugget filed

The surviving foot nuts sported two weld nuggets apiece:

HON Lateral File – OEM front foot

The hole had the remains of one nugget at the top left and looks like a manufacturing defect to me. Of course, we’re (at least) the second owners and the usual lifetime warranty no longer applies.

I can fix that.

Bandsaw a 1×¾ inch rectangle from 3/8 inch aluminum plate to match the surviving foot nut (which is steel, but aluminum will suffice for our needs). Break the edges, clamp in the Sherline, and mill a square protrusion to match the square-ish hole:

HON Lateral File – square nut – rough cut

Drill a 17/64 inch hole (looser than the nominal F drill, because I’m a sissy) for a flat-head bolt from the Drawer o’ 3/8-16 Bolts, tap, and clean up.

A trial fit showed the nugget had to go before the nut would come even close to fitting flat into the hole:

HON Lateral File – foot hole – grinding

The sheet metal around the hole had absorbed at least one mighty blow pushing the entire surface inward behind the front edge. To compensate, recess the nut’s front edge and slope the sides with a Dremel wheel to let the bottom face sit level:

HON Lateral File – square nut – taper grinding

Another trial fit showed the need for more recess:

HON Lateral File – square nut – deeper cut

Another spate of grinding made it sit mostly level on the decidedly non-level surface around the hole:

HON Lateral File – square nut – ready to install

The beveled corners fit inside the swaged hole corners.

Grind paint / crud off the sheet metal and roughen the surface for good epoxy griptivity:

HON Lateral File – foot hole – ready for install

Stand the cabinet top-side-down to make the bottom level. I wish the basement had one more course of block, but it’s not to be.

Butter the nut with JB Weld epoxy, plunk it in place, apply excess epoxy to make a fillet around the edges, apply duct tape to guy the top of the bolt level-ish, and let it cure:

HON Lateral File – square nut – epoxy curing

After the epoxy stiffened enough to hold its position, remove the bolt, file a crude ¼ inch hex, and saw a screwdriver slot to make it match the other feet:

HON Lateral File – new foot hex head

Not the fanciest job I’ve ever done, but it now behaves just like the other ones and it’s all good. The HON Storage Files FAQ points to a Troubleshooting Guide showing how to level the thing with a hex socket from inside the bottom drawer.

The flat heads on those bolts are basically 25 mm OD steel plates calling for fuzzy felt bumpers on the Sewing Room’s wood floors. When properly leveled, the front will be ⅛ inch higher than the rear. Although they suggest a pencil should roll toward the back, the top sheet metal on this one may be sufficiently warped to confuse the issue; I have a long level well suited to the task.

The original dimension doodle includes metric offsets for cutting with a ¼ inch end mill:

HON Foot nut – dimension doodles

All in all, a satisfying day in the Basement Shop …

2020-02-24
Frozen Fire Hydrant, One Year On

It seems reporting a frozen hydrant to the local fire company didn’t produce any meaningful action:

Frozen hydrant – Sheldon at Rt 376

We didn’t have any fires in the neighborhood where it might have been a problem, but I’ll try the water department this year …

Oddly, the water department repainted most of the fire hydrants along most of the roads last year. This one apparently didn’t qualify, for whatever reason, despite being only slightly off Rt 376 on Sheldon:

Frozen hydrant – Sheldon at Rt 376 – Google Streetview

When it’s not frozen, it’s not obvious …

2020-02-22
Drag Knife Blade Wear

Having used the same two drag knife blades intermittently over the last three-ish years, I wondered just how worn they’d gotten:

Drag Knife Blades – sides

For scale, the cylindrical part of the blade is 1.0 mm OD.

The blade with the longer face (left above and bottom below) has seen the most use and is definitely rounded at the tip:

Drag Knife Blades – tips

Three unused blades have sharp tips:

Drag Knife Blades – unused 60 45 30 degree

From the top, the (nominal) blade angles are 60°, 45°, and 30°, generally indicated by yellow, red, and blue plastic caps. However, various eBay sellers disagree on how to measure the angle (up from surface / outward from axis) and which cap colors correspond to which angles.

The unused 45° blade bracketed by the two used blades:

Drag Knife Blades – unused in center

The two lower blades have angles somewhere between 30° and 45°, suggesting slack grinder and QC tolerances. If the actual angle matters to you, buy an assortment (from one seller!), measure what you get, and don’t be surprised when the results aren’t anything in particular.

Perhaps, with careful attention to alignment in a non-pivoting / collet holder, one might scribe exceedingly narrow lines.

The microphotographic setup:

Drag Knife Blades – microscope stage setup

That’s the back of a sheet of carbon paper (remember carbon paper?), which is deep dark gray in normal light. It’s sitting on the sheet of 100 mil grid paper providing scale for small objects, atop the microscope stage positioner, with cold white illumination from an LED ring light.

Protip: even worn blades remain lethally sharp …

2020-02-21
MPCNC: bCNC Probe Camera Refresh

For the usual inscrutable reasons, updating bCNC killed the USB camera on the MPCNC, although it still worked fine with VLC. Rather than argue with it, I popped a more recent camera from the heap and stuck it onto the MPCNC central assembly:

bCNC – USB probe camera – attachment

This one has a nice rectangular case, although the surface might be horrible silicone that turns to snot after a few years. The fancy silver snout rotates to focus the lens from a few millimeters to infinity … and beyond!

If you think it looks a bit off-kilter, you’re absolutely right:

bCNC – USB probe camera – off-axis alignment

The lens image reflected in a mirror on the platform shows the optical axis has nothing whatsoever to do with the camera case or lens snout:

bCNC – USB probe camera – off-axis reflection

Remember, the mirror reflects the lens image back to itself only when the optical axis is perpendicular to the mirror. With the mirror flat on the platform, the lens must be directly above it.

Because the MPCNC camera rides at a constant height over the platform, the actual focus & scale depends on the material thickness, but this should be typical:

bCNC – USB Probe Camera – scale – screenshot

It set up a Tek Circuit Computer test deck within 0.2 mm and the other two within 0.1 mm, so it’s close enough.

The image looks a whole lot better: cheap USB cameras just keep improving …

2020-02-20

Bird Box Entrance Reducers: Round 2

One of the bird box entrance reducers I installed nigh onto a decade ago is still on duty, although downy woodpeckers definitely want a larger hole:

Bird Box - gray PVC pipe reducer - woodpecker damage — Bird Box – gray PVC pipe reducer – woodpecker damage

Another reducer had gone missing over the years, so I made one from a length of PVC pipe:

Bird Box - PVC pipe reducer - shaping — Bird Box – PVC pipe reducer – shaping

It started as 1-½ PVC pipe, 1-⅞ inch actual OD and should fit into a 1-½ hole, so I measured 1.5 × 3.15 around the circumference, bandsawed out the excess, draped it over a 1-½ Forstner bit, toasted it with a heat gun, and squashed it so it’s just a little bit bigger than the (enlarged!) hole in the box.

Now the entrance is 1-¼ (-ish), just like it should be:

Bird Box - PVC pipe reducer - installed — Bird Box – PVC pipe reducer – installed

The bird box in the front yard has been attracting starlings, in addition to serving as a hawk perch:

New Coopers Hawks - bird box takeoff whoops — New Coopers Hawks – bird box takeoff whoops

The oblong hole required advanced manufacturing techniques:

The front face should be too slick for larger birds and the little ones will zip right into the hole:

Bird Box - 3D printed entrance reducer — Bird Box – 3D printed entrance reducer

The two starlings who’d been evaluating the box seem to have moved on; we doubt they’re now homeless.

The OpenSCAD source code as a GitHub Gist:

	// Bird Box – oval entrance reducer
	// Ed Nisley KE4ZNU 2020-02-12

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

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

	//———————-
	// Dimensions

	EntranceID = 1.25 * inch;

	BoxHole = [1.5,2.25] * inch;
	BoxWall = 0.75 * inch;

	HoleOC = BoxHole.y – BoxHole.x;

	FlangeWidth = 5.0;
	FlangeThick = 5*ThreadThick;

	$fn = 12*4;

	//——————-
	// Build it

	difference() {
	union() {
	linear_extrude(height=BoxWall + FlangeThick)
	hull()
	for (j=[-1,1])
	translate([0,j*HoleOC/2])
	circle(d=BoxHole.x);
	linear_extrude(height=FlangeThick)
	hull()
	for (j=[-1,1])
	translate([0,j*HoleOC/2])
	circle(d=BoxHole.x + 2*FlangeWidth);
	}
	translate([0,0,-Protrusion])
	cylinder(d=EntranceID,h=2*BoxWall);
	}

view raw Oval Entrance Reducer.scad hosted with ❤ by GitHub

2020-02-19

CNC 3018XL: Arduino + Protoneer CNC

If the truth be known, I wanted to do this as soon as I discovered the CAMtool V3.3 board hardwired the DRV8825 PCBs in 1:32 microstep mode:

CNC 3018XL – Protoneer atop Arduino – installed

The Protoneer CNC board has jumpers, so selecting 1:8 microstep mode is no big deal.

As before, I epoxied another row of pins along the I/O header for Makerbot-style endstops:

Protoneer endstop power mod

I’ll probably regret not adding pins along the entire row, but, unlike the MPCNC, the CNC 3018XL won’t ever have hard limit switches. I plugged the Run-Hold switch LEDs into an unused +5 V pin and moved on.

I modified the DRV8825 driver PCBs for fast decay mode:

DRV8825 PCB – Fast Decay Mode wire

Then set the current to a bit over 1 A:

3018XL – Protoneer setup – Z 1 mm

Six hours later I hauled the once-again-functional CNC 3018XL to my presentation for the ACM:

Spirograph – intricate sample plot – detail

Memo to Self: Time to get another Prontoneer board …

2020-01-31