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

  • Recommended Screwdriver Set: Brownells Magna-Tip Super Set

    More on the Kenmore 158.17032 that started all this appears elsewhere, but I found myself deploying several bits from my Brownells Magna-Tip screwdriver set:

    Brownells Magna-Tip Super-Set on bench
    Brownells Magna-Tip Super-Set on bench

    The matrix of bits covers nine slot lengths (= screw head diameters) with four / five / six slot widths. This is the set with 44 bits; the 58 bit set fills the empty holes with 14 hex / square / Phillips bits that I already have in multiples.

    I reserve these lovely hollow-ground bits for specialty screws that must not be goobered; most of the time ordinary drivers work just fine and there’s no reason to chew these up.

    Even these tips won’t fit every screw in existence, but you’ll go a long way before this set isn’t the right hammer for the job at hand.

    Highly recommended, even at today’s prices …

  • Kenmore 158.17032 Handwheel Clutch Disassembly

    One of Mary’s friends asked us to take a look at her Kenmore 158.17032 sewing machine that suffered from a Showstopper Problem: the handwheel turned the main shaft, but the motor pulley spun freely. You could rev the motor to maximum speed without budging the shaft, which suggested something was wrong with the clutch joining the handwheel and the belt pulley to the main shaft. This being a slightly newer model than the others in our stable, I was mildly surprised to find a completely different clutch mechanism between the drive belt and the main shaft.

    The plastic cover plate in the handwheel yielded to an old crochet hook:

    Kenmore 158.17032 - Handwheel cap removal
    Kenmore 158.17032 – Handwheel cap removal

    Stick the hook into the tiny notch, engage hook with cover, pull outward, and it’ll fall into your other hand.

    That exposes a simple screw holding the chromed plastic handwheel in place on the motor shaft. After taking the pulley and clutch off the Hard Way, I discovered the Right Way, which is hereby documented for The Next Time Around. In order to show what’s needed, I’ll start in the middle and work outward.

    Pull the handwheel off and remove the machine’s end cover.

    With the clutch assembly removed (which you can’t do yet), you can see a pair of pot metal bands that act as a brake when the bobbin winder snaps off a full bobbin. They look like this in the normal running position:

    Kenmore 158.17032 - Clutch trip lever - normal position
    Kenmore 158.17032 – Clutch trip lever – normal position

    The black bow-tie at 9 o’clock is vertical, holding the brake bands apart and clearing the tab on the clutch asembly (which you haven’t seen yet).

    They look like this when the bobbin winder has just snapped:

    Kenmore 158.17032 - Clutch trip lever - bobbin wind position
    Kenmore 158.17032 – Clutch trip lever – bobbin wind position

    The Bobbin Winder Reset Button atop the machine (which our machines don’t have and this one does) presses on the tab sticking out toward you on the horizontal bar pivoting on the front of the machine:

    Kenmore 158.17032 - Bobbin winder reset lever
    Kenmore 158.17032 – Bobbin winder reset lever

    In that position, the button is up, the bobbin is ready to load, the brake bands are off, and you can gently tap the clutch assembly off the main crankshaft:

    Kenmore 158.17032 - Handwheel clutch assembly
    Kenmore 158.17032 – Handwheel clutch assembly

    The inner hub rotates very slightly with respect to the belt drive pulley (which has the grooves that drive the bobbin winder tire). That didn’t quite work on this machine, due to the usual lack of lubrication / mechanical wear / what-have-you.

    The innermost part (with the notches for the pin visible at 2 o’clock on the main shaft) rotates with the handwheel. The belt pulley rotates with the motor belt. The clutch lets you turn the handwheel with the motor stopped. Normal rotation is clockwise in this view; on the machine, you turn the top of the wheel toward you.

    Carefully remove the spring that retracts the clutch lever, remove both black screws, remove the big flat head screw, and slide the black lever out to the side.

    Unscrew the two remaining flat-head screws holding the hub / lever in place. The one with the longer shoulder goes into the lever:

    Kenmore 158.17032 - Handwheel clutch screws
    Kenmore 158.17032 – Handwheel clutch screws

    Removing the hub reveals the pin that engages the clutch mechanism visible through the slot at 6 o’clock in the handwheel:

    Kenmore 158.17032 - Handwheel clutch dog
    Kenmore 158.17032 – Handwheel clutch dog

    Remove the fiber washer and the steel cover plate to expose the clutch mechanism:

    Kenmore 158.17032 - Handwheel clutch - detail
    Kenmore 158.17032 – Handwheel clutch – detail

    The pin pressing against the hollow cylinder (which is the actual clutch!) has a powerful spring:

    Kenmore 158.17032 - Handwheel clutch interior
    Kenmore 158.17032 – Handwheel clutch interior

    If you hold the cylinder in place, you can rotate the clutch body enough to unload the spring just enough to let you ease the cylinder out and gently release the spring. Good luck!

    With all the parts on the bench, clean everything, lube only the parts that need it (like the spring-loaded pin, but not the clutch cylinder), put everything back together, and it should Just Work.

    The screwdriver points out the tab engaging the black bow-tie doodad:

    Kenmore 158.17032 - Handwheel clutch tab
    Kenmore 158.17032 – Handwheel clutch tab

    The object of the games is to make the tab pivot smoothly around the large flat-head screw under the spring as you press the part that sticks out, so the clutch will be either completely disengaged or firmly engaged.

    When you get it working smoothly, release the brake bands, slide the clutch assembly back on the shaft, reinstall the cover, install the handwheel, install the screw, pop the plastic hub back in, and you’re done!

    Update:

    Even though I write this stuff down to help me remember what I did, sometimes other folks find it useful:

    Just read your article about Kenmore 158.17032 Handwheel clutch and was able to repair a machine because of you. I so appreciate that you take the time to post such things. I would not have taken the thing apart had I not found your article and I just wanted to say THANKS. I browsed some of your other projects also. Wow.

    Thanks Again,
    Donnie

    … and …

    I have spent weeks searching for how to fix the Kenmore 158.1703 clutch ( a very weird one) for a friend of mine. I was pointed to your post by the Vintage Kenmore sewing machine groups.io.
    I jumped up and down with joy to read and see the photos.
    Yes! I can fix this and get it back to her. THANK YOU! I will try later today with your post printed out.
    Thank you!
    Linda

    More small victories in the struggle against entropy!

    The Kenmore Vintage Sewing Machine group may come in handy.

  • Raspberry Pi Model 2: Canakit Case Reset Button Mod

    Being a Linux box, a Raspberry Pi requires a tidy shutdown, but, because it uses so little power after that, I decided to forego a power switch and just blip the CPU reset line to start it up again. Canakit cases require a bit of flush-cutter hackage to accommodate a crude socket atop the RUN header:

    Canakit RPi Case - reset switch - header clearance
    Canakit RPi Case – reset switch – header clearance

    The switch originally had three terminals, but turned out to be SPST NO with one unused pin. Flush cutters and some hot melt glue to the rescue:

    Canakit RPi Case - reset switch - interior
    Canakit RPi Case – reset switch – interior

    The end result looks OK, modulo a few scuffs on the shiny black plastic:

    Canakit RPi Case - reset switch - exterior
    Canakit RPi Case – reset switch – exterior

    Yeah, a clumsy swipe could wipe that actuator right off the top; we’ll see how long it lasts…

  • OttLite LED Conversion

    Although Mary liked the illumination from her OttLite (an old 13 W fluorescent Folding Task Lamp), neither of us liked its tiny base and tippy nature. It recently fell / was dropped / jumped to its doom, smashing the CFL tube and wreaking havoc on the tiny plastic studs holding its large cast-iron weight and steel base in position. Given that the CFL ballast had started humming a while ago, I took it apart to see whether I could salvage anything from the rubble.

    Remove:

    • Four screws under the fuzzy felt feet
    • One screw under the label on the back
    • A final screw that becomes visible only after disemboweling the hinge assembly by unscrewing the obvious endcaps:

    OttLite LED Conversion - hinge screw
    OttLite LED Conversion – hinge screw

    Pull the hinge end of the white inside panel away from the outer stand at enough of an angle to disengage all three latches holding it to the base, then remove it just enough to let you start cutting wires around the ballast…

    I rebuilt the thing with a pair of 24 V 150 mA warm-white LED panels (good industrial surplus, not the usual cheap eBay crap) powered by a 19 V laptop adapter (from IBM, no less) through a (cheap eBay) boost converter sticky-foam-taped where the fluorescent ballast used to live:

    OttLite LED Conversion - boost supply wiring
    OttLite LED Conversion – boost supply wiring

    The power supply had only two conductors, the central wire surrounded by twisted shielding, and didn’t require a fussy interface. Hooray for simple bulk power supplies; I lopped off the connector and soldered the wires directly to the boost converter.

    The original lamp wiring has a 120 VAC switch inside the hinge that turned the lamp on as you raise the arm holding the CFL tube: exactly what I need for its new use. That eliminated figuring out how to crack the arm apart to rewire it.

    I harvested the base from a(nother) defunct CFL bulb:

    OttLite LED Conversion - harvested CFL base
    OttLite LED Conversion – harvested CFL base

    By soldering wires directly into the pins, I could reuse the existing CFL socket in the lamp arm, the existing wiring, and the switch.

    The LED panels dissipate 3-ish W each:

    OttLite LED Conversion - LED panel layout
    OttLite LED Conversion – LED panel layout

    They’re mounted on a 0.1 inch aluminum sheet from the heap that required exactly one saw cut to fit into the space available, so I defined it to be perfect. The 4-40 screws holding the panels in place continue through the plate and 3/8 inch aluminum standoffs into a quartet of knurled inserts epoxied into eyeballometrically match-drilled holes in the lamp arm:

    OttLite LED Conversion - epoxied threaded inserts
    OttLite LED Conversion – epoxied threaded inserts

    The faint yellowish discoloration from the CFL tube’s heat and UV is much more visible in real life, but nobody will ever see it again. The scrawled blue (+) and (-) marks give the socket polarity; it’s not mechanically polarized and a bit of care is in order. The black rectangle is actually a shiny metal sheet intended to reflect heat from the CFL tube’s base away from the plastic arm.

    I set the boost converter to 23.5 V, at which point the LED panels draw about 100 mA each and get just over uncomfortably warm after an hour or two:

    OttLite LED Conversion - in action
    OttLite LED Conversion – in action

    The panels run 120 °F = 50 °C and the SMD LEDs probably exceed 150 °F = 65 °C. The scant surplus doc touted “No heatsink required” and the single-sided FR4 PCB insulates the LEDs from the aluminum sheet, but I still smeared some heatsink compound behind the panels in the hopes of spreading the heat out a bit.

    I glued the shattered base studs back in place with IPS #3, surrounded them with generous epoxy fillets, plunked the cast iron weight in place atop some waxed paper to mold the epoxy to fit (and let me remove it again, if needs be), screwed everything together, and stuck a foam sheet over the steel base plate. It’s as tippy as before, but at least the LEDs won’t shatter if when it falls. It really needs a larger base; a polycarbonate plate might work, if only I could figure out how to attach it.

    All in all, the lamp looks good and the warm-white LEDs with DC drive don’t produce that horrible fluorescent flicker.

    The lamp now sports a label identifying it as a NisLite; because P-Touch labeler.

  • Tour Easy: Long-Deferred Drivetrain Maintenance

    A few months back, the 13-tooth sprocket on my Tour Easy started skipping, which reminded me that I planned to replace all the drivetrain components. Time passed, the winter remained unseasonably warm and sunny, we kept riding, the skipping got much worse, and I just shifted across that sprocket.

    Finally, the rains returned, I heaved the bike up on the workstand, and started replacing things. Judging from the accumulated crud and severe wear, it’s been on there for quite a while:

    Sprocket with broken teeth - as found
    Sprocket with broken teeth – as found

    Here’s the offending 13-tooth sprocket, all shined up;

    Sprocket with broken teeth - detail
    Sprocket with broken teeth – detail

    I don’t recall a catastrophic failure that stripped all those teeth off in one shot. A closer look showed cracks in the few remaining teeth:

    Sprocket with broken teeth - cracked teeth
    Sprocket with broken teeth – cracked teeth

    Which explains why the skipping gradually got worse: the poor sprocket shed teeth as I rode blithely along.

    Huh.

    That’s what happens with a severely worn sprocket: the chain applies tension to just the topmost tooth, rather than distributing it on the teeth around a third (or more) of the sprocket, and, one by one, that force breaks the teeth. The top picture shows at least one other sprocket with a missing tooth; all display the shark-fin profile of heavy wear.

    As you can tell from the other bike pix & repairs around here, I’d rather ride than mess around with cleaning and suchlike. We’re on our second set of drivetrain components in 15 years, so I’d say treating all that stuff as consumable seems a fair tradeoff…

  • Knurled Inserts: Epoxy Anchoring

    After taking the incandescent lamp socket off its base, I drilled the tapped (yeah, in plastic) 6-32 holes out to a firm press fit for the knurled 6-32 inserts, buttered the inserts with epoxy, and pressed them firmly in place:

    Lamp Base - epoxy knurled insert
    Lamp Base – epoxy knurled insert

    Fast forward a day and they’re stuck in there like they were glued. You can see a bit of the epoxy around the right rim of the insert; I wiped a bit more off around the other one.

    Putting The Right Amount of epoxy on the insert requires dialing back my “The bigger the blob, the better the job” enthusiasm, but wasn’t all that difficult. It’s certainly more tedious than just ramming the inserts into a printed hole and might actually produce better retention. I doubt that will make the least difference for (almost) anything I build.

    On the whole, they look good…

  • Fluorescent Shoplight Capacitor: Wow!

    You just can’t make this stuff up:

    Fluorescent Shoplights - nasty cap termination
    Fluorescent Shoplights – nasty cap termination

    That shredded plastic can’t possibly be a Good Thing; the endcap contained plenty of loose shreds.

    Perhaps I’m overly critical, but I think the only way these fixtures could have a UL approval certificate was that somebody else didn’t notice their certificate went missing. Most likely, of course, the fixtures sent for approval looked lovely and bore no relation to the junk actually sold to Lowe’s / Home Depot.

    That emerged from the fourth defunct fluorescent fixture I converted to use LED tubes.