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.

Author: Ed

  • HT GPS + Audio: Case Dimensions

    Having obtained eyeballometric measurements from the case, the next step was to doodle some shapes on graph paper and pencil in the dimensions. My motivation for not using CAD is simple: it’s easier (for me, at least) to doodle using a pencil.

    The outside of the case had pretty much the same features.

    Pack Layout - External
    Pack Layout – External

    The inside, of course, bore no resemblance to the battery pack; the shoulder and whatnot will support the circuit board.

    Pack Layout - Internal
    Pack Layout – Internal

    The original battle plan was to build the case in at least two layers, simply because it had to be so deep the Sherline couldn’t reach to the bottom with any rational end mill. It would probably make more sense to glue up four sides on a machined bottom, but that requires actual skill.

    This became the Front layer, with Front and Rear faces. The Rear layer attaches to the back of this one. In this picture, the Front layer is on the bottom, taped to the radio.

    ICOM IC-Z1A with GPS+Audio Interface
    ICOM IC-Z1A with GPS+Audio Interface

    The two layers peeled apart, with the Front layer to the right. You can barely see the internal shoulder and external tabs.

    Interface - top and bottom surfaces
    Interface – top and bottom surfaces

  • ICOM IC-Z1A and W-32A: BP-171 Battery Pack Dimensions

    Early on, I decided that the whole APRS + voice interface for our bikes had to fit on the back of the radio, which meant it had to look a lot like a BP-171 battery pack. The first step was to get all the relevant dimensions from an existing pack.

    I laid a (rebuilt) pack on the scanner and took its picture. There’s a lip on the bottom (top in the image), so I held it level with the end of the calipers you can see near the bottom. That puts it slightly above the scanner’s focal plane, but it’s close enough.

    Then I scanned some graph paper (remember that?) with 10 lines per inch, overlaid that on the pack image, rotated to line it up with the pack, scaled the grid so that the major lines were 1 cm apart on the pack in both directions, and that gave me a nice 1 mm grid to eyeball the measurements.

    Printed the image out at about twice real size and there you have it:

    Battery Pack Dimensions
    Battery Pack Dimensions

    The doodles around the bottom give the Z-axis dimensions for tabs & contact slots & suchlike.

    The notes near the top were a first pass at how to mill the thing; two years later, the actual G-Code bears little resemblance to that.

    I put the origin at the lower-left corner of the part that fits into the radio body, 2.4 mm inside the left edge that mates with the outside of the body. That was probably a mistake, as it meant I had to touch off the final part at X=-2.4 rather than just 0.0.

    We live & learn.

  • How to Solve a Parking Problem

    The Walkway Over the Hudson has been a resounding success, at least measured by the number of people using it. The Parker Avenue parking lot has about 80 spaces and, during most days, is jammed full.

    The NYS park system now owns the Walkway and, in their infinite wisdom, decided that the parking facilities should have a fee just like the rest of their lots: $5 / 4 hours.

    Here’s what the Walkway lot looked like on the day the fee went into effect…

    Walkway Parking Lot With Parking Fee In Full Effect
    Walkway Parking Lot With Parking Fee In Full Effect

    To quote from the Poughkeepsie Journal:

    State officials hope there will be no decline in visitors with the new parking fee, said State Parks spokesman Kristen Davidson.

    Basically, there’s enough free on-street parking in the area that most folks park nearby and hike in, which makes sense for a park consisting of about two miles of walking path. The parking fee amounts to a tax on handicapped and elderly visitors who find it difficult to navigate streets and ramps.

    On the bright side, it’ll be a lot easier to bike across the bridge…

  • HT GPS + Audio: Battery Case Contacts

    The case for this gadget slides into the back of the ICOM IC-Z1A HT and powers the radio through its usual battery contacts. I reshaped 5/16″ 4-40 brass machine screws into flat-top studs, then soldered 8-mil tin strips to their tops.

    Grab a screw in a pin vise, brace it on the bench vise, and file off everything that doesn’t fit:

    Reshaped 4-40 screws
    Reshaped 4-40 screws

    The result should fit neatly into the flatted recess, with the top flush in the rectangular slot:

    Studs in their recesses
    Studs in their recesses

    Cut an oversized strip of 8-mil tin and solder it to the stud. I tinned both pieces to get nice solder coverage, although the notion of tinning a piece of pure tin with silver-tin solder did give me pause. It’s all in the flux, I suppose.

    Anyhow, put the two tinned sides together and hit the combo with a half-second pulse at 100% duty cycle from my resistance soldering gadget. Perfect:

    Tin strip soldered in place
    Tin strip soldered in place

    Then snip off whatever doesn’t fit into the slot with an ordinary (albeit shop-only) scissors, making it just slightly shorter than the slot so the end doesn’t snag on anything. File the sides and corners so they’re easy on the fingers, flatten the strip so it fits neatly into the slot, buff it up a bit, and it’s all good.

    Contacts in place
    Contacts in place

    Takes longer to describe than to do it, at least the second time you do it…

  • Bike Mirror Ball Clamp Doodles

    The plastic-ball-in-plastic-socket joint found in bicycle mirrors seems to fail after a year or two of constant use. These are some doodles & thoughts about building a small, robust, adjustable joint.

    A bike mirror needs two ball joints:

    • at the helmet mount to put the mirror in the proper spot
    • at the mirror to align the image

    A flexy boom can replace the helmet joint, although rotation around X (pitch) is still handy.

    A flexy mirror mount can replace the mirror joint, but it must also be compact.

    Without heroic measures, the range of travel for a ball joint isn’t all that much.

    How to make a ball? Anneal & drill a standard ball bearing for a wire shaft? Solder onto chrome steel? CNC mill the end of a bar in a rotary table?

    How to make a socket? Some of that low-temperature themoplastic might be useful. Mold it around the ball, slit radially, and squash it in a circ clamp?

    How to adjust? Circumferential clamp around the socket or pull the whole socket into a wedge? Radial cuts through the socket to allow compression or depend on plastic/elastic deformation?

    How much friction? You want it stiff enough to hold position in a strong wind and easy enough to reposition. You definitely don’t want grub screws or fiddly knobs!

    The doodles are all far too complex, some are absurd, one can’t be built (at least by me), and I’ll probably end up using some bendy wire anyway.

    Something of this may be useful in another project … and now I can throw out that scrap of paper.

    Mirror clamp doodles
    Mirror clamp doodles

  • Red Squirrel

    Red Squrrel - front
    Red Squrrel – front

    I cleaned the compost out of the gutters yesterday and this critter came by to help with whatever missed the wheelbarrow.

    Squirrels and chipmunks show how far you can get with a snappy color scheme and a good PR agent. These things are rodents, pure and simple, but those large eyespots trip your protect-the-baby response every time.

    They’re not particularly well-behaved, either: the chipmunks and gray squirrels have had running battles with them this spring. We think the area’s chipmunks had a population explosion and are shoving into traditional red-squirrel territory. Could get ugly out there.

    Where are the hawks when you need ’em?

    Red Squirrel - side
    Red Squirrel – side

  • HT GPS + Audio: Modified Plug Alignment Plates

    As described there, I made a fixture and a small plate to hold 2.5 mm and 3.5 mm plugs in the proper alignment for the mic & speaker jacks on our ICOM IC-Z1A HTs. Knowing I was going to rebuild the interface boxes, I made several spare plates and tucked them into a small bag against future need.

    Jack Plates - Oblique
    Jack Plates – Oblique

    Time passes.

    Come to find out that the new gratuitously gold-plated 2.5 mm plugs in my stash have a slightly thicker front plate that doesn’t quite fit into the recess I milled in the plates for the old nickel-plated plugs. So I set up a little nest in on the Sherline’s table, snuggled each plate into the corner, and poked a 9/32-inch end mill 1 mm down into the plate. The net change was a 0.5 mm deeper recess. Sheesh.

    Milling the plug plate recess
    Milling the plug plate recess

    I’d originally create the recess with helical milling, but I recently uncovered a stash of shiny-new end mills in a box: 9/32 is 7.31 mm, just about exactly what you want for a 7-mm dia plug front plate surrounded by a blob of fast-curing epoxy.

    Plugs epoxied into plate
    Plugs epoxied into plate

    This epoxy just holds the plugs in the right position for wiring and initial testing. After the cable checks out, I’ll smoosh a blob of epoxy putty around the whole thing as before.