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: Mini-lathe

Tweaking an LMS 5200 Mini-Lathe

  • Tour Easy: Extended V-brake Noodle

    Tour Easy: Extended V-brake Noodle

    Although our Tour Easy recumbents use ordinary (*) V-brakes, their frame geometry doesn’t route the rear cable quite the way the brake designers expected. Mary’s Medium-Small frame always had its rear brake cable resting against the frame tube, where it bent slightly as she applied the brakes:

    Tour Easy rear V-brake layout
    Tour Easy rear V-brake layout

    That’s looking up from under the rear wheel, with the bike on a workstand, and, yeah, it’s pretty grubby down there.

    The squashed rubber boot suggests the brake arms are too close together, but that’s where they must be to hold the brake pads in the proper position, even with new pads and big spacer washers. As a result, the cable stop over on the right at the end of the noodle rests against the frame and dings the paint.

    My first thought was to add some length to the end of the noodle inside the stirrup, so I made an adapter with the ID on the noodle end matching the OD on the fitting end:

    V-brake - larger noodle - end stop adapter
    V-brake – larger noodle – end stop adapter

    Which worked poorly, because the noodle has a straight section leading up to the fitting inside the stirrup; any additional length pushes the noodle curve against the stirrup pivot and cants it out of line:

    Tour Easy rear V-brake noodle
    Tour Easy rear V-brake noodle

    I’ve been avoiding the fallback plan of building a bigger noodle for years, but finally combined a foot of 3/32 inch brass tubing, a tube bender spring, and various large-diameter round-ish objects from the Basement Warehouse Wing:

    V-brake - larger noodle - bending
    V-brake – larger noodle – bending

    I annealed the tube by running a torch along its length until the color changed to the obvious “I’m hot enough” copper color, then let it air-cool while I did something else. Brass work-hardens quickly and required two more annealings while finishing that smooth curve; as far as I know, brass doesn’t harden with the heat-and-quench cycle used for steel.

    A little more lathe work produced a replacement fitting:

    V-brake - larger noodle - end stop
    V-brake – larger noodle – end stop

    The hole is barely one diameter deep, but I think it’ll align the tube well enough for my simple needs. The failure will most likely involve having the cable chew through the inward side of the mis-aligned tube, which should become obvious in short order.

    The fitting on the OEM noodle seems to be crimped in place, but I figure my version is unlikely to fall off in normal use:

    V-brake - larger noodle vs OEM
    V-brake – larger noodle vs OEM

    Lined up thusly, you can see the reduced straight section behind my fitting and the much larger sweep out to the cable stop.

    The OEM noodle had a (presumably) PTFE liner, so I adapted a length of PTFE brake cable liner by mashing the end with various conical objects until it kinda-sorta looked like the cable stop might capture the ragged flange:

    V-brake - larger noodle - PTFE liner
    V-brake – larger noodle – PTFE liner

    Reassembling in reverse order produces a comforting sight:

    V-brake - larger noodle - installed
    V-brake – larger noodle – installed

    Despite appearances, the new noodle sits below the frame and well above the chain in normal use. In the most extreme small-small cross gearing position the chain barely clears it, but the takeup arm on the rear derailleur starts clattering enough to remind us not to do that.

    Brass is certainly not as strong as stainless (?) steel, although I think it ended up in a reasonably hard condition after all the bending. I’m certain neither of us can squeeze the brake lever enough to come anywhere close to causing a problem.

    Making a noodle was easier than I expected and, in a month or so, we’ll see how it behaves under actual riding conditions.

    (*) “Ordinary” as of many decades ago, because the design dates back to the mid-70s, when Fast Freddy Markham broke 65 mph on a rather customized Easy Racers Gold Rush.

  • Audio Amp vs. Bananas

    Audio Amp vs. Bananas

    A low-end audio power amp destined for a pair of ancient-yet-still-serviceable speakers arrived, but attempting to poke wires through the side holes of the banana jacks showed they were oriented in random directions. Back in the day, banana jacks had D-shaped shafts fitted into D-shaped panel holes, but those days are gone.

    A few minutes with screwdriver, wrench, and (tiny) punch sufficed to line up the holes for E-Z poking:

    Fosi audio amp - jack alignment
    Fosi audio amp – jack alignment

    Despite the new convenience, I decided to solder banana plugs to the speaker wires, leading to the discovery my few remaining plugs came from the very bottom of the usability barrel:

    Cheap banana plug - solder side
    Cheap banana plug – solder side

    I have no idea how one might affix a wire to that blank stub, but poking a small center drill into the brass lump produces an easily solderable recess:

    Cheap banana plug - center drilled
    Cheap banana plug – center drilled

    Dab with flux, tin, insert wire, add solder, repeat with all four plugs, and I’m set with a boomin’ system.

  • Torchiere Lamp Shade 2

    Torchiere Lamp Shade 2

    Three and a half years later, the shade on the living room’s other torchiere lamp crumbled at a touch:

    Torchiere Lamp Shade 2 - crumbled
    Torchiere Lamp Shade 2 – crumbled

    Because I live in the future and had solved this problem in the past, eight hours of print time produced a second shade:

    Torchiere Lamp Shade 2 - on platform
    Torchiere Lamp Shade 2 – on platform

    I sliced the same STL file with PrusaSlicer to get G-Code incorporating whatever configuration changes I’ve made to the M2 over the years and include any slicing algorithm improvements; the OpenSCAD code remains unchanged.

    The as-printed shade had pretty much the same crystalline aspect as the first one:

    Torchiere Lamp Shade 2 - no epoxy
    Torchiere Lamp Shade 2 – no epoxy

    Smoothing a layer of white-tinted epoxy over the interior while spinning it slowly in the mini-lathe calmed it down enough for our simple needs, although the picture I tried to take didn’t show much difference.

    That was easy …

  • Dial Test Indicator Mount Finishing

    Dial Test Indicator Mount Finishing

    While pondering a project requiring a slitting saw, I discovered the clamp on the dial test indicator magnetic mount I’d picked up a while ago didn’t quite fit the 5/32 inch = 4 mm stem on the indicator. The clamp ring is obviously punched from sheet, then formed into its final shape, as the holes are somewhat un-round. Running the proper drill through the holes removed a minute sliver of steel:

    Dial test indicator mount - redrilling
    Dial test indicator mount – redrilling

    And then it fit just fine:

    Dial test indicator mount - in use
    Dial test indicator mount – in use

    Although it looks like I’m in the process of sawing the ball off the indicator, I’m really measuring the runout, which turned out to be maybe 5 mils = 0.13 mm. The blade is likely too small for what I’m thinking of using it for, so the pondering continues.

    The two bigger holes in the clamp fit the equally standard 3/8 inch = 9.5 mm stems just fine, so it’s just another one of those tools where I get to finish the last few percent of their manufacturing.

  • KeyboardIO Atreus: LED Diffuser

    KeyboardIO Atreus: LED Diffuser

    After staring at the RGB LED I installed in my Atreus keyboard for a while, I converted the stub of a ¼-20 nylon screw into a light diffuser:

    Atreus keyboard - LED diffuser
    Atreus keyboard – LED diffuser

    It stands slightly proud of the surface plate so I can extract it without dismantling the whole keyboard again:

    Atreus keyboard - LED diffuser installed
    Atreus keyboard – LED diffuser installed

    I’ll eventually make a better-looking diffuser from a recently arrived translucent acrylic rod, but this will reduce the accumulation of fuzz inside the keyboard until the matching Round Tuit arrives.

  • Makergear M2: New Filament Drive and Guide Tube Adapter

    Makergear M2: New Filament Drive and Guide Tube Adapter

    After replacing the M2’s nozzle, I also installed a spare filament drive:

    Makergear M2 filament drive R3 - installed
    Makergear M2 filament drive R3 – installed

    That’s the V4 R3 version, although I bought it from Makergear rather than fight with all the support required to get a proper bearing opening.

    The long M4 screw and spring apply a constant force to the filament against the drive gear, rather than the constant position from the default (and much shorter) stock screw. The lever arm does have some springiness, but not much travel, so IMO the spring works better with the fine teeth in the drive gear.

    This drive has a 5 mm hole at the top for the stock PTFE guide tube, which I long ago replaced with ¼ inch OD HDPE tubing to reduce the friction required to get the filament off the spool and into the hot end. The rather hideous hot-melt glue blob holding a ¼ inch ID tube onto the previous drive never failed enough to bother me, but a little lathe action produced a much better adapter:

    Makergear M2 filament drive R3 - guide adapter
    Makergear M2 filament drive R3 – guide adapter

    It’s a chunk of ⅜ inch = 9.5 mm Delrin rod with a 2.4 mm hole through that 5 mm spigot for easy extraction of a gear-mashed 1.75 mm filament. The other end has a 6.5 mm hole drilled 20 mm deep to hold the guide tube.

    Looks downright dressy, it does!

  • Neiko Hole Punch Accurizing

    Neiko Hole Punch Accurizing

    Having struggled to cut nice rings from gooey foam adhesive tape, I got a Neiko hollow hole punch set, despite reviews suggesting the pilot point might be a bit off. The case wrapper claims otherwise:

    Neiko hole punch - description
    Neiko hole punch – description

    As the saying (almost) goes:

    “Inconcievable! Precision!”

    “You keep using that word. I do not think it means what you think it means.”

    Goldman, The Princess Bride

    An eyeballometric measurement suggests this is another one of those Chinese tools missing the last 10% of its manufacturing process:

    Neiko hole punch - as-received off-center tip
    Neiko hole punch – as-received off-center tip

    That’s the 5 mm punch, where being (at least) half a millimeter off-center matters more than it would in the 32 mm punch.

    Unscrewing the painfully awkward screw in the side releases the pilot:

    Neiko hole punch - punch tip debris
    Neiko hole punch – punch tip debris

    The debris on the back end of the pilot is a harbinger of things to come:

    Neiko hole punch - damaged spring debris
    Neiko hole punch – damaged spring debris

    Looks like whoever was on spring-cutting duty nicked the next coil with the cutoff wheel. I have no idea where the steel curl came from, as it arrived loose inside the spring.

    Although it doesn’t appear here, I replaced that huge screw with a nice stainless steel grub screw that doesn’t stick out at all.

    Chucking the pilot in the lathe suggested it was horribly out of true, but cleaning the burrs off the outside diameter and chamfering the edges with a file improved it mightily. Filing doesn’t remove much material, so apparently the pilot is supposed to have half a millimeter of free play in the handle:

    Neiko hole punch - undersized pilot
    Neiko hole punch – undersized pilot

    That’s looking down at the handle, without a punch screwed onto the threads surrounding the pilot.

    Wrapping a rectangle of 2 mil brass shimstock into a cylinder around the pilot removed the slop:

    Neiko hole punch - cleaned tip brass shim
    Neiko hole punch – cleaned tip brass shim

    But chucking the handle in the lathe showed the pilot was still grossly off-center, so I set it up for boring:

    Neiko hole punch - boring setup
    Neiko hole punch – boring setup

    The entry of the hole was comfortingly on-axis, but the far end was way off-center. I would expect it to be drilled on a lathe and, with a hole that size, it ought to go right down the middle. I’ve drilled a few drunken holes, though.

    Truing the hole enlarged it enough to require a 0.5 mm shimstock wrap, but the pilot is now pretty much dead on:

    Neiko hole punch - accurized results
    Neiko hole punch – accurized results

    Those are 5, 6, 8, and 10 mm punches whacked into a plywood scrap; looks well under a quarter millimeter to me and plenty good enough for what I need.