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.

The New Hotness

  • Shopvac Model 500A Motor Wire Repair

    The Shopvac Model 500A (1.25 HP!) inhaling dust from Tiny Bandsaw didn’t start up when I flipped the switch. It had been making horrible noises, but Shopvacs typically sound like they’re on the ragged edge of death, I wear 30 dB earmuffs when it’s running, and that wasn’t the problem anyway.

    It turned out the hot (black) wire lead to the motor burned up:

    Shopvac motor - charred wire
    Shopvac motor – charred wire

    The neutral (white) wire over on the left side looked just fine:

    Shopvac motor - good wire connector
    Shopvac motor – good wire connector

    But the hot wire connector was toasted:

    Shopvac motor - charred connector
    Shopvac motor – charred connector

    As the connector failed its resistance went up and so did the wire temperature, as shown by the plastic case:

    Shopvac motor - melted cover
    Shopvac motor – melted cover

    With barely an inch between the motor armature and the failed connector, this became a zero-Mulligan repair:

    Shopvac motor - remaining armature wire
    Shopvac motor – remaining armature wire

    I clipped the failed connector off the wire, very carefully sanded off the burned insulation, then gingerly crimped the business end of a ferrule around the wire + a doubled length of 22 AWG hookup wire:

    Shopvac motor - lengthened wire
    Shopvac motor – lengthened wire

    Doubling the wire brought it up to 19 AWG, a bit larger than the 20 AWG armature wire, and maybe improved its durability. The ferrule surely isn’t rated for this sort of abuse, so I eased some solder into its end in the belief that any amount of solder is a better conductor than a similar amount of air.

    Crimp the other end of the hookup wire into the business end of a solderless ring terminal along with the hot wire, anchor the ferrule to (and insulate it from) the armature with a wrap of silicone tape, do the same around the ring terminal, then squirt hot melt glue into the ruined connector housing to keep the wire from flopping around:

    Shopvac motor - repaired wire
    Shopvac motor – repaired wire

    If it gets hot enough to melt the hot melt glue, there are other problems about to happen.

    Reassemble in reverse order and the Shopvac once again makes its on-the-eve-of-destruction whine while inhaling chips.

    A slip of tape marked “$5” fell off during this process, reminding me it was a garage sale find from quite a few years ago: saving it from an early grave may be an overall Good Deed.