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: Improvements

Making the world a better place, one piece at a time

  • Water Bottles: Adding a Vent Plug

    Those water bottles turned out to have an unexpected feature: the vent hole dribbles when they’re laid sideways. I think it’s an unfortunate side effect of a product cheapnification: the spout is slightly concave on the side that could seal the vent, so surface tension sucks water out of the hole.

    The hole is to the right of the spout, in the center of the transverse ridge. Looks like a little black dot here; clicky for a somewhat bigger image.

     

    Water bottle cap showing vent hole
    Water bottle cap showing vent hole

     

    The solution is to put a silicone plug at the Spot Marked X on the spout, which I marked by running a small punch through the vent hole and scarring the spout. You might be able to see the tiny mark on the spout if you look closely.

    The spout comes out of the cap with a firm pull, but the sockets in the cap are obviously not intended to take much of that abuse. It’s not clear to me that the designers of these things ever take cleaning into consideration; past experience says you must completely dismantle fluid-facing components to get the crud out.

    Anyway.

    Chuck the spout up in the Sherline mill, align over the spot, and mill a 1/8 inch diameter flat-bottom hole 0.100 inch deep. The spout has a large finger-friendly flange directly underneath the Spot Marked X, so this setup isn’t quite as precarious as it looks.

     

    Milling socket for vent plug
    Milling socket for vent plug

     

    Dab in a little silicone caulk, leave a mostly flat surface standing just higher than the spout’s concavity, and we’ll see how well it works.

     

    Vent plug
    Vent plug

     

    The little nub just to the left of the new plug (on the ball-shaped part of the spout) engages the edge of the socket in the cap to sorta-kinda hold the spout closed. Doesn’t really accomplish much, but it’s a nice thought.

  • New Cutting Board: Adding Feet

    So Kohl’s sent Mary a killer deal coupon and we bought some odds and ends, including a new cutting board to replace the decades-old one that I’ve been flycutting clean every few years. Evidently bamboo is the new Right Stuff for cutting boards; it’s certainly eyeshattering.

    The thing spent the last few days soaking up a slathering of canola oil, in the hope it won’t soak up other juices.

    Recess for cutting board foot
    Recess for cutting board foot

    The instructions say to store the board standing on end so it dries properly. Evidently you’re supposed to hang it from the ring screwed into one end, but a corresponding hook (not supplied) just doesn’t doesn’t have a place on our counter / cabinet / backsplash. However, we could stand it up, leaning against an under-cabinet shelf next to the toaster oven, if only it wouldn’t slide away.

    This calls for some aftermarket tweakage!

    So I hauled it to the Basement Laboratory Woodworking Wing and installed a pair of silicone rubber feet in little recesses.

    I grabbed a 7/16-inch end-cutting end mill in the drill press, because even the manual mill doesn’t have enough height for the board on end and the drill press doesn’t have enough reach for a Forstner bit without fiddling around with the emergency drop stopper clamp. The drill press does have a good vise and an XY table, so I got it pretty close to dead center on the third dark stripe from each edge.

    The feet are about 1/4 inch tall: I went down half that in the hopes they wouldn’t bump off quite so easily.

    Silicone foot in cutting board
    Silicone foot in cutting board

    But that didn’t quite work: the adhesive on the feet doesn’t grip the rather porous endgrain bamboo nearly well enough: a foot popped off after a day. I added a layer of Genuine 3M double-stick foam tape to the feet and that’s holding just fine.

  • Arduino Mega: Voltage Regulator Heatsink

    The Arduino Mega has an SMD voltage regulator soldered to a copper pad connected with thermal vias to a similar pad on the bottom surface. The datasheet says the (roughly) 10×10 mm copper pad sets RθJA=55 °C/W, more or less; probably a bit less with the double-sided setup.

    It’s the chubby black slab snuggled up just to the right of coaxial power input jack. The four vias on each side go to an isolated copper pad under the solder mask on the other side.

    Arduino Mega voltage regulator
    Arduino Mega voltage regulator

    The board draws about 75 mA with nothing fancy on the I/O pins, so the regulator dissipates half a watt with a 12 VDC input supply. Figuring an ambient of 30 °C, the junction temperature is ticking along at 50-60 °C.

    That’s all well and good, but my rule of thumb for semiconductors is:

    • If you can’t hold your thumb on it for any length of time, it’s too damn hot.

    That regulator fails my rule of thumb even before I start adding LEDs and other doodads.

    A bit of rummaging turned up an old Thermalloy sample box with a DIP heatsink. A dab of quick-setting epoxy and there it is:

    Arduino Mega regulator with heatsink
    Arduino Mega regulator with heatsink

    Now, I’ll grant you there are a number of things wrong with that approach, but my thumb is much happier. If it gets unhappy, I’ll just crack that puppy off and stick something larger in its place.

  • Arduino Mega: Mounting Standoff and Screw

    The Arduino Mega has four, count them, four mounting holes in a more-or-less rectangular pattern around the edge of the board. Three of the four have enough room for standard pan-head 4-40 screws. The fourth hole is squeezed between two pin-header sockets, to the extent that no screw in my collection will fit.

    Screw on Arduino Mega board
    Screw on Arduino Mega board

    Having a lathe, however, makes this situation no big deal… and this time, I put the Sherline drill chuck in the 3-jaw because I wanted to, not because the 3-jaw was stuck. In truth, the lathe chuck simply won’t grab a 4-40 screw at all.

    Turning down the screw
    Turning down the screw

    I had that pointy right-cutting tool in the holder, so that’s how I cleared off the burr on the backside of the head.

    The chuck did grab the hex standoff just fine, though, and the final result looks like this…

    Modified standoff and screw for Arduino Mega
    Modified standoff and screw for Arduino Mega

    For future reference, the turned-down sections are 0.180 inch in diameter; call it 4.5 mm. The snout on the standoff must clear the pins,so it’s 0.100 inch or 2.5 mm long.

  • Pull Saw Blade Sheath

    Trimming some poster frame edges brought this useful tool out of hiding. It’s an ordinary Stanley 20-331 flush-cut flexible-blade pull saw that I’d used while installing laminate flooring in the kitchen & laundry room some years ago; it cuts the bottom of moulding like nothing else.

    Anyhow, what’s of interest here is the simple cardboard sheath I made to keep those delicate little teeth from getting bashed up in the tool drawer.

    Saw and sheath
    Saw and sheath

    Here’s a closer end view. It’s nothing more than two large sheets of thin cardboard (think cereal box or maybe consumer electronics box) separated by two narrow sheets. The blade’s thinner than any practical cardboard you’ll find, so just do it. It’s held together with yellow wood glue, because that’s what I had nearby when I built it.

    Saw sheath end view
    Saw sheath end view

    The note written on the sheath reminds both my shop assistant and me which way the cutting happens. Sometimes, we need all the help we can get.

    For what it’s worth, the new Stanley 20-331 listing shows a similar saw blade with a Fat Max handle. This is the older version, from back when thin was in.

  • Homebrew Mini-ITX LPT Bracket

    I’m putting together an Atom 510 box to replace the ancient Dell currently acting as the Sherline CNC controller, with the intent of seeing whether a rather anemic low-power CPU with two cores will work as well. The system board has room for one PCI card and I figured I’d install a second parallel printer while I had the hood up.

    But then I realized that the only LPT cards in my stash had tall brackets that wouldn’t fit in the new mini-ITX case.

    Well, it turns out that the LPT card itself would fit in the box, so all I had to do was reshape the bracket:

    • A bit of filing on the bottom knocked off a millimeter and put a tidy taper on the tab
    • A brief session with Mr Hammer bent the top flange over, so as to meet the case mounting flange
    • A somewhat surprised tin snips removed the excess length
    • A cylindrical file chewed out a somewhat generous screw clearance notch
    Finished LPT bracket
    Finished LPT bracket

    And then it’s just a matter of screwing things together.

    LPT Bracket - outside
    LPT Bracket – outside
    LPT Bracket - top
    LPT Bracket – top

    I’ll admit the clearance from the top mounting screw to the flange is terrifyingly cozy, but I’m not averse to applying force majeure to either an unsuspecting LPT connector or the case itself…

    The top view omits the screwdown clamp that secures the card to the case so you can see where the screw notch goes.

  • Door Stop Bumper Fix

    After slightly over half a century, the rubber bumpers on the doorstops around the house have stiffened up and, occasionally, one falls off.

    Although I suppose I should just buy a new doorstop, molding a dab of silicone snot around the end of the nice brass post takes only a few minutes (plus an overnight cure). If what they tell us about silicone adhesives is true, this one is good until the sun goes dark…

    Re-bumpered door stop
    Re-bumpered door stop

    Another no-CNC repair!