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Archive for category Machine Shop

Heavy Object. Team Lift Required

So says the label on a recent Amazon package:

Heavy Object Team Lift - foam floor mats
Heavy Object Team Lift – foam floor mats

It contains half a dozen foam floor mat sheets weighing a bit under a pound apiece.

I don’t begrudge anyone working in an Amazon warehouse a bit of humor …

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Sony NP-FM50 Battery Rebuild

With six new 18500 lithium cells in hand, I rebuilt the three weakest NP-FM50 packs.

The Sherline CNC mill setup for sawing around the midline:

Sony NP-FM50 battery - Sherline saw setup
Sony NP-FM50 battery – Sherline saw setup

Adjust the saw to cut along the seam, set X=0 at the surface, jog to about X+0.7 mm, jog the saw along the seam, then repeat for the other three sides. No real CNC involved, but it’s much easier than sawing or breaking through the seam by hand.

These two packs came with the camera:

Sony NP-FM50 battery - 2003-era cells
Sony NP-FM50 battery – 2003-era cells

The cells have only lot numbers, no manufacturer ID. Wikipedia sayeth Sony Fukushima started in 2000; perhaps these were early production units with no branding.

The center strap running the length of the pack didn’t seem long enough, because I mistakenly thought I’d straightened its end while unsoldering it. As it happens, the end was straight and secured to the PCB by structural solder:

Sony NP-FM50 battery - PCB center tab joint
Sony NP-FM50 battery – PCB center tab joint

Moral of the story: pay attention, dammit!

The other end of the center strap required a snippet of tin strip to reach the tabs:

Sony NP-FM50 battery - rebuilt center strap
Sony NP-FM50 battery – rebuilt center strap

Aligning the cells that way allowed me to just bend the other tabs over the PCB pads and solder them in place:

Sony NP-FM50 battery - rebuilt PCB contacts
Sony NP-FM50 battery – rebuilt PCB contacts

Then a strip of Kapton tape across the kerf holds the case together well enough to survive our gentle usage:

Sony NP-FM50 battery - Kapton belly band
Sony NP-FM50 battery – Kapton belly band

The battery packs require a brief stay in the charger to reset the PCB’s lockout circuitry, after which they work fine:

Sony NP-FM50 - 2019-04-12
Sony NP-FM50 – 2019-04-12

The two oldest batteries (OEM 2003 A and OEM 2003 B) have new identities to suit their new innards: 2019 E and 2019 F. The DOA eBay battery retains its 2019 D label after the rebuild, as there’s little room for confusion.

Admittedly, it’d be easier / cheaper / faster to buy third-party NP-FM50 packs directly from eBay or Amazon, but this way I know the cells aren’t complete crap and I get some Quality Shop Time™ out of the deal.

What’s not to like?

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Desk Lamp Conversion: Round 2

A bit of rummaging produced a desk lamp arm, minus whatever lamp it originally held, ready to hold the second photo lamp, after a bit of epoxy on one locking knob:

Lamp arm clamp screw rework
Lamp arm clamp screw rework

The flanged nut will seat on the wrecked part of the knob, with the epoxy holding it in place and somewhat reinforcing the perimeter. I’m not sure this will last forever, but it’ll be a start.

Printing a second cold shoe, though, worked perfectly, and everything fit:

Photo Lamp - right arm installed
Photo Lamp – right arm installed

I love it when a plan comes together!

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Sony NP-FM50 Battery Disassembly

Having won an eBay action for a known-dead Sony DSC-F717 at $0.99 (plus $15 shipping, the seller being no fool), I now have a possibly salvageable camera, a Genuine Sony AC supply, and two more NP-FM50 batteries for about the price of any one of the components.

One battery arrived stone-cold dead, suggesting the camera had been put away with the battery installed for a very long time and they died companionably. The camera still charges a (good) battery, even though it doesn’t turn on, and perusing the schematics suggests checking the power switch, because it’s always the switch contacts. That’s for another day, though.

For the record, the battery status:

NP-FM50 - 2019-03-30
NP-FM50 – 2019-03-30

The red and green traces come from the two batteries I’ve been cycling through the camera since, um, 2003, so they’re getting on in years and correspondingly low in capacity.

The fourth battery (2019 D, the date showing when it arrived, not its manufacturing date) went from “fully charged” to “dead” in about three seconds with a 500 mA load, producing the nearly invisible purple trace dropping straight down along the Y axis.

Sawing the dead battery case around its welded joint at a depth of 0.75 mm, then prying with a small chisel, exposed the contents without histrionics:

Sony NP-FM50 battery - cell label
Sony NP-FM50 battery – cell label

Now, there’s a name to conjure with. Turns out Sony sold off its Fukushima battery business a while back, so these must be collectibles. Who knew?

The lower cell is lifeless, the upper cell may still have some capacity. Three pairs of 18500 lithium cells are on their way, in the expectation of rebuilding the weakest packs.

After desoldering the battery tab on the right from the PCB, it occurred to me I needed pictures:

Sony NP-FM50 battery - PCB exposed
Sony NP-FM50 battery – PCB exposed

Yeah, that’s a nasty melted spot on the case, due to inept solder-wickage.

Unsoldering the three tabs closest to the case releases the cells + PCB from confinement:

Sony NP-FM50 battery - PCB overview
Sony NP-FM50 battery – PCB overview

I’m still bemused by battery packs with a microcontroller, even though all lithium packs require serious charge controllers. At least this is an Atmel 8-bitter, rather than 32-bit ARM hotness with, yo, WiFi.

The cells have shaped tabs which will require some gimmicking to reproduce:

Sony NP-FM50 battery - cell tabs
Sony NP-FM50 battery – cell tabs

Now, if only I could reboot the camera …

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Broken Spoke

On the drive side, of course:

Tour Easy - broken rear spoke
Tour Easy – broken rear spoke

I’d noticed some brake drag on our last few rides, but forgot to check until I saw the rim wobble while extracting images from the rear camera.

It’s a lot easier to fix in the Basement Shop than on the road. After nigh onto a decade since replacing the last broken spoke, perhaps this is a harbinger of doom to come.

Memo to Self: spoke tension is now 20-ish on the drive side, 15-ish on the left.

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Seam Ripper Cover

The cover for Mary’s favorite seam ripper cracked long ago, has been repaired several times, and now needs a replacement:

Seam Ripper cover - overview
Seam Ripper cover – overview

The first pass (at the top) matched the interior and exterior shapes, but was entirely too rigid. Unlike the Clover seam ripper, the handle has too much taper for a thick-walled piece of plastic.

The flexy thinwall cover on the ripper comes from a model of the interior shape:

Seam Ripper Cover - handle model
Seam Ripper Cover – handle model

It’s not conspicuously tapered, but OpenSCAD’s perspective view makes the taper hard to see. The wedge on top helps the slicer bridge the opening; it’s not perfect, just close enough to work.

A similar model of the outer surface is one thread width wider on all sides, so subtracting the handle model from the interior produces a single-thread shell with a wedge-shaped interior invisible in this Slic3r preview:

Seam Ripper Cover - exterior - Slic3r preview
Seam Ripper Cover – exterior – Slic3r preview

The brim around the bottom improves platform griptivity. The rounded top (because pretty) precludes building it upside-down, but if you could tolerate a square-ish top, that’s the way to go.

Both models consist of hulls around eight strategically placed spheres, with the wedge on the top of the handle due to the intersection of the hull and a suitable cube. This view shows the situation without the hull:

Seam Ripper Cover - handle model - cube intersection
Seam Ripper Cover – handle model – cube intersection

The spheres overlap, with the top set barely distinguishable, to produce the proper taper. I measured the handle and cover’s wall thicknesses, then guesstimated the cover’s interior dimensions from its outer size.

The handle’s spheres have a radius matching its curvature. The cover’s spheres have a radius exactly one thread width larger, so the difference produces the one-thread-wide shell.

Came out pretty nicely, if I do say so myself: the cover seats fully with an easy push-on fit and stays firmly in place. Best of all, should it get lost (despite the retina-burn orange PETG plastic), I can make another with nearly zero effort.

The Basement Laboratory remains winter-cool, so I taped a paper shield over the platform as insulation from the fan cooling the PETG:

Seam Ripper Cover - platform insulation
Seam Ripper Cover – platform insulation

The shield goes on after the nozzle finishes the first layer. The masking tape adhesive turned into loathesome goo and required acetone to get it off the platform; fortunately, the borosilicate glass didn’t mind.

The OpenSCAD source code as a GitHub Gist:

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Desk Lamp Conversion: Photo Light Cold Shoe

Having recently acquired a pair of photo lights and desirous of eliminating some desktop clutter, I decided this ancient incandescent (!) magnifying desk lamp had outlived its usefulness:

Desk Lamp - original magnifiying head
Desk Lamp – original magnifiying head

The styrene plastic shell isn’t quite so yellowed in real life, but it’s close.

Stripping off the frippery reveals the tilt stem on the arm:

Desk Lamp - OEM mount arm
Desk Lamp – OEM mount arm

The photo lights have a tilt-pan mount intended for a camera’s cold (or hot) shoe, so I conjured an adapter from the vasty digital deep:

Photo Light Bracket for Desk Lamp Arm - solid model
Photo Light Bracket for Desk Lamp Arm – solid model

Printing with a brim improved platform griptivity:

Photo Light Bracket for Desk Lamp Arm - Slic3r preview
Photo Light Bracket for Desk Lamp Arm – Slic3r preview

Fortunately, the photo lights aren’t very heavy and shouldn’t apply too much stress to the layers across the joint between the stem and the cold shoe. Enlarging the stem perpendicular to the shoe probably didn’t make much difference, but it was easy enough.

Of course, you (well, I) always forget a detail in the first solid model, so I had to mill recesses around the screw hole to clear the centering bosses in the metal arm plates:

Photo Lamp - bracket recess milling
Photo Lamp – bracket recess milling

Which let it fit perfectly into the arm:

Desk Lamp - photo lamp mount installed
Desk Lamp – photo lamp mount installed

The grody threads on the upper surface around the end of the slot came from poor bridging across a hexagon, so the new version has a simple and tity flat end. The slot is mostly invisible with the tilt-pan adapter in place, anyway.

There being no need for a quick-disconnect fitting, a 1/4-20 button head screw locks the adapter in place:

Photo Lamp - screw detail
Photo Lamp – screw detail

I stripped the line cord from inside the arm struts and zip-tied the photo lamp’s wall wart cable to the outside:

Photo Lamp - installed
Photo Lamp – installed

And then It Just Works™:

Photo Lamp - test image
Photo Lamp – test image

The lens and its retaining clips now live in the Big Box o’ Optical parts, where it may come in handy some day.

The OpenSCAD source code as a GitHub Gist:

The original dimension doodles, made before I removed the stem and discovered the recesses around the screw hole:

Photo Light - Desk Lamp Arm Dimensions
Photo Light – Desk Lamp Arm Dimensions

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