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.
If it used to work, it can work again
The Hobo datalogger buried in the dirt under the patio kvetched about a low battery, which produced this surprising result:
Cells from the same lot have been doing just fine in the other dataloggers, so I hope this is a one-off weak cell and not the harbinger of another run of dead cells.
The snowthrower (I’ve always called it a snowblower, but that’s just me) ate a ski pole (*), handle-tether-end first, and the right-side shear bolt worked perfectly when the right-hand auger slammed to a stop. A bit of drift punch rapping extracted the sorry lump at the bottom:
The missing nut and bolt head may eventually surface, but I’m not losing any sleep over them.
I popped a replacement shear bolt from the heap (thank you, Aitch!) and thought the nut went on rather stiffly. The nuts have a crimp in the middle to make them vibration-proof, but this one seemed stiffer than usual and, lo and behold, the bolt snapped just before I thought the nut had gotten far enough.
The nut on the second replacement shear bolt required much less torque, didn’t (let me) snap the bolt, and I finished the mission. That’s the third or fourth shear bolt I’ve used since getting the thrower in 2007, so there’s a package of six in transit.
Part Number 710-0809A, 5/16-18 x 1.5 inch.
(*) One of Mary’s gardening cronies works for a sporting goods store, has access to an unlimited supply of slightly bent ski poles, and shares the bounty for use as garden stakes.
The mica compression capacitors have a finish on the pins that turned out to be completely un-solderable:
Some casual searching suggests this is a problem with sulfur contamination of the tin-lead solder layer. I can’t vouch for any of that, as the flat areas forming the capacitor seem to be silver-plated, but …
After some flailing around, I completely disassembled the capacitor, applied 800 grit sandpaper to remove all of the solder / flux / corrosion / tarnish / surface plating from the pins, dabbed on some RMA flux, then applied a thin layer of solder to both sides. Fortunately, the capacitor could be disassembled; they don’t make ’em like that any more.
The solder layers must be thin, because the slots in the ceramic base must pass two or three pins apiece: four or six solder layers add too much thickness. Solder-wick is my friend!
For reference, the 700 pF side looks like this:
The steel washer does not have a mica washer underneath (as does the washer on the 400 pF right side). The two grayish steel plates go on the top.
Mary’s relatives encountered this repair in a rental flat during Thanksgiving week:
Don’t have a hex bolt with the right thread? No problem: just use a sheet-metal screw, perhaps with a self-drilling point:
Those hex heads let you apply more torque with less risk of stabbing yourself in the palm, which strikes me as an all-around Good Thing. I prefer socket-head cap screws, myself, but I’ll admit they’re an acquired taste.
I’d like to think I wouldn’t do that …
Pretty much as expected, the dust brush nozzle failed again, adjacent to the epoxy repair:
A bit of rummaging turned up some ¾ inch Schedule 40 PVC pipe which, despite the fact that no plumbing measurement corresponds to any physical attribute, had about the right OD to fit inside the adapter’s ID:
The enlarged bore leaves just barely enough space for a few threads around the circumference. Fortunately, the pipe OD is a controlled dimension, because it must fit inside all the molded PVC elbows / tees / caps / whatever.
The pipe ID isn’t a controlled dimension and, given that the walls seemed far too thick for this purpose, I deployed the boring bar:
That’s probably too much sticking out of the chuck, but sissy cuts saved the day. The carriage stop keeps the boring bar 1 mm away from the whirling chuck.
Bandsaw it to length and face the ends:
The PVC tube extends from about halfway along the steep taper from the handle fitting out to the end, with the section closest to the handle making the most difference.
Ram it flush with the end:
I thought about gluing it in place, but it’s a sufficiently snug press fit that I’m sure it won’t go anywhere.
Natural PETG probably isn’t the right color:
Now, let’s see how long that repair lasts …
The OpenSCAD source code as a GitHub Gist:
| //——————- | |
| // eBay horsehair dusting brush | |
| // Hacked for 3/4" Schedule 40 PVC stiffening tube | |
| module DustBrush() { | |
| union() { | |
| translate([0,0,40.0]) | |
| rotate([180,0,0]) | |
| difference() { | |
| union() { | |
| cylinder(d1=EndStop[OD1],d2=31.8,h=10.0); | |
| translate([0,0,10.0 – Protrusion]) | |
| cylinder(d1=32.0,d2=30.0,h=30.0 + Protrusion); | |
| } | |
| translate([0,0,-Protrusion]) | |
| cylinder(d1=26.0,d2=24.0,h=100); | |
| translate([0,0,-Protrusion]) // 3/4 inch Sch 40 PVC | |
| PolyCyl(27.0,100); | |
| } | |
| translate([0,0,40.0 – Protrusion]) | |
| MaleFitting(); | |
| } | |
| } |
Mary couldn’t unscrew either of the two outlet hoses emerging from one of the (many) Y valves in her Vassar Farms plot. After deploying the Lesser Vise-Grip from my bike toolkit to no avail, I brought a Greater Vise-Grip from the shop and applied brute force. During that process, the plastic inlet hose fitting ripped off the valve and sprayed all but one of its latching teeth across the plot:
As it turns out, the male outlet hose fittings on all the metal-body Gilmour Y valves in the plot have corroded:
The scarred knurls show the force required to break the brass hose ring loose and unscrew it:
Some of that crud may be hard water deposits, but the destruction of the male threads seems like a galvanic reaction among all the various metals in play.
The male fitting began rotating in the valve body, so I crushed it in the bench vise to make more headway. While I had the victim clamped down, I hacksawed a slit through the housing, pried back the edges, and freed the parts for one leg of the Y:
You’d think “not corroding” would be high on the list of attributes for a garden hose valve…
A stick in the ground marking a repair:
The white plastic glide / slide / foot / cap / whatever is molded around a simple nail that broke a divot out of the foot. Fortunately, I caught it before the nail gouged the kitchen floor.
Under normal conditions, I’d replace the foot from my heap, but, my heap having become somewhat depleted, I swapped in another chair, chipped out the broken plastic, undercut the divot, filled it with JB Kwik epoxy, gooshed the foot in place, and taped it until it cured.
We’ll see how long this lasts …
The Smell of Molten Projects in the Morning 