Category: Machine Shop

Quite some years ago, the spot weld holding half of the handle to the side of my all-time-favorite 1/3-cup measuring cup broke loose. The minuscule weld nugget suggested that the spot welder got distracted; the weld on other side of the handle is perfectly bonded.

I tried repairing it with silver solder and a torch, which simply proved that’s not within my skill set. I buffed off most of the residue and applied JB Weld epoxy, which lasted just fine until a few days ago. It’s a low-stress situation, indeed, but I’m not surprised that the epoxy didn’t really bond to a slightly scuffed stainless steel surface.

So, this time around, I did it right: sandpapered off the epoxy, scuffed up the cup and handle by shoe-shining a sandpaper strip face up and face down in the gap, then silver-soldered the handle in place using my resistance soldering gadget (which I promise to describe some day).

The setup was straightforward. Clamp the cup in the bench vise with soft copper jaws (hammered from ordinary pipe) that also grip one electrode from the soldering unit.

I used a strip of fancy Brownell’s Silvalloy 355 silver solder ribbon (which is 56% silver instead of the chintzy 4% junk I normally use) with some truly toxic silver solder flux. About ten seconds of heat melted the solder and produced a pair of nice fillets along the sides of the handle.

The flux washed off in hot water and a few licks with fine sandpaper cleaned things up just fine. The carbon electrode left a bit of schmutz on the handle, but nothing a Dremel brass brush wheel couldn’t solve.

The inside has a bit of heat discoloration, but the sandpaper knocked that back reasonably well, too.

The final product looked a lot better than these in-work pictures, but it’s tough to photograph subtle differences in a shiny silver object.

Anyhow, as you might expect, we value function over form in this household.

The discussion following that post prompted me to take a closer look at the corroded spider. I planned to pull the spider off the back of the drum and examine the pieces, but a week of dribbling thread lube around the bolts left two of them firmly affixed.

While I don’t have it completely apart yet, some observations are in order…

The bolts are stainless steel and utterly immovable with the usual screwdriver-handle-mounted Torx bit. I got the first two bolts out by putting a T30 bit in a 1/4-inch socket in a ratchet wrench and applying brute force.

A few days of thread lube (the incomparable PB B’Laster) persuaded two more out of their lairs. The remaining bolts may require even more brute force, but I’ll give the lube a few more days to work its magic.

Despite that, the bolts and holes are not corroded. They may have some thread locker down in there, but I see little evidence of that. I think it’s just a case of being torqued down hard, then set adrift in ionic water for half a decade.

The outer third of each arm has a covering of corrosion products, but the metal below that (now dried and flaking) gunk seems undamaged. The arms have severe corrosion and cracking throughout the inner two-thirds of their length.

If this were chemical corrosion, I’d expect it to apply evenly throughout the length of the arm, because the presence of corrosion products over the entire arm indicates pretty good distribution.

However, galvanic corrosion should follow the same pattern, so I’m not sure what to make of this.

The fact that an oxidation layer on the stainless steel tends to passivate it may not really matter. Compare the surface areas of the drum and the spider: there’s a whole lot more drum than spider, so even a passivated drum could provide enough current to rot the spider.

The ends of the spider spend their lives whipping through the water inside the tub at a pretty good clip. That could dislodge most of the crud and leave them reasonably clean, at least compared to the hub that moves more slowly (same rotational speed, smaller radius). It’s also true that the water level never reaches the hub, remaining below the level of the door seal.

Thus, the hub probably gets splashed, but never immersed, and thus has no way to remove any contaminants. The corrosion products simply build up there, keeping it wet throughout its life.

I maintain there’s little drying going on, even with the door open, in the relatively short intervals between washings. The hub region would be least likely to dry, however, because there’s absolutely no ventilation back there.

All that notwithstanding, this corrosion should not happen.

I’d very much like to see some measurements: we’re all obviously guessing at the conditions. The plastic tub surrounding the drum has a port for the rear vent near the perimeter, so it’s possible to get a (cramped, inconvenient) look in there without tearing the washer apart.

More later, after I get the mumble thing apart…