Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The batteries I rebuilt for our much-beloved Sony DSC-F505V camera back in early 2010 have faded away with constant use. Having already sawed the cases open, rebuilding three of them didn’t pose much of a challenge; this time I added a short tab of Kapton tape to help extract them from the camera socket.
Rebuilt NP-FS11 batteries
Three batteries seems to be about the minimax for ordinary use:
One in the camera
One in the carrying case
One in the charger
You (well, we) can’t keep track of more than three: it always seems one battery gets overused and another gets lost in the dark. We’ll see how three works in practice; there’s a set of six more raw cells lying in wait.
The new batteries produced these results on their first two charge-discharge cycles:
Sony NP-FS11 2011 Packs – First Charges
One battery didn’t come up to speed on the first charge, but after that they’re all pretty close.
The Skeinforge Craft window presents a formidable array of buttons, one for each possible plugin:
Skeinforge standard
I’ve disabled many of those plugins because, for example, limiting Z-axis speed isn’t relevant on my printer. If you’re sure you won’t use some of the plugins, remove them by editing /where-it's-installed/skeinforge_application/skeinforge_plugins/profile_plugins/extrusion.py thusly…
In getCraftSequence(), located at about the midpoint of that file, duplicate the line that lists the plugins and add an octothorpe (OK, a hash) to make one line a Python comment, then remove the plugins you don’t care about from the other line:
def getCraftSequence():
'Get the extrusion craft sequence.'
# return 'carve scale bottom preface widen inset fill multiply speed temperature raft skirt chamber tower jitter clip smooth stretch skin comb cool hop wipe oozebane splodge home lash fillet limit unpause dimension alteration export'.split()
return 'carve scale preface inset fill multiply speed temperature raft skirt jitter clip smooth skin cool dimension alteration export'.split()
This being Python, do not change the indentation. If you get overenthusiastic and toss something useful overboard or just pine for the Good Old Days, swap the octothorpe to your modified line to restore the original plugin assortment.
Save the result and you’ll see only the useful buttons:
I set up Xubuntu 11.10 on the Dell 531S driving the Thing-O-Matic, as the Unity UI seems surprisingly like crippleware: every feature that isn’t mandatory is prohibited. However, Xubuntu’s XFCE UI also has a long list of things that should be easy and aren’t, such as enabling remote desktop sharing. Gotta have that so I can fire up the printer and monitor progress from upstairs.
It turns out that the Vino server is installed, but not enabled, so you must start by firing up vino-preferences in a terminal to set some preferences:
This is a local machine behind a firewall, so a moderately secure password with no confirmation will suffice. Your paranoia may vary.
Then drill down through the menu from Settings → Settings Manager → Session and Startup to the Application Autostart tab, then Add the Vino VNC Server to the list: /usr/lib/vino/vino-server. You can start it manually if you have the hots for immediate sharing.
This seems to be impossible in Unity, trivially easy in GNOME, and unduly mysterious in XFCE.
The 0.5 mm nozzle came off the hot end with surprisingly little effort; the high-temperature lube did its job! I dismantled the tensioner, clipped the filament at the top of the drive wheel, and extracted it (with the red PTFE insulation / guide tube) through the bottom of the Thermal Core. Getting the filament out of the tube required the gentle suasion of a pin punch, but eventually I found this:
Filament melt zone – overview
Although you can’t tell from the picture, the filament seems completely melted for about 20 mm, well-softened for another 20 mm, and soft for about 10 mm. Here’s a detail of the transition from well-softened to soft to hard:
Filament melt zone – detail
Notice how the notches from the drive wheel gradually fade out over about 10 mm, whereupon the filament expands to fill the PTFE tube. You can’t see the shallow depression from an air pocket offscreen at about 30 mm, but it suggests the filament isn’t quite molten from 20 mm onward. Given that the distance from the nozzle tip to the top of the Thermal Core is about 40 mm, all this makes sense, particularly when you figure the filament was stationary as the Core cooled off after the last print: the melted-to-melty sections are inside the Core and the softened section is just above the Core.
In round numbers, the Thermal Core supplies enough heat through the PTFE tube to fully melt the filament for about 20 mm above the nozzle when printing at 2 rev/min. The effective drive diameter is 9.6 mm, so 1 rev = 9.6 π = 30 mm and the Core must melt 60 mm/min = 1 mm/s. This is obviously a grossly nonlinear situation, but if you get only 20 mm of molten filament at 1 mm/s, the maximum speed can’t be much more than 4 mm/s or so.
The rest of the Thing-O-Matic’s mechanics set an upper limit for, say, printed octopi at 80 mm/s and 4 rev/min = 2 mm/s, but the extruder will definitely be the limiting factor for speeds over, say, 150 mm/s. Not much risk of that happening here, I’d say.
I’ve settled on Reversal for 125 ms at 25 rev/min, so the retraction distance is:
Mary prefers dim digits on the bedroom alarm clock, far below what the usual DIM switch setting provides. I’d slipped a two-stop neutral density filter in front of our old clock’s VFD tube, but the new one has nice green LED digits that ought to have a tweakable current-setting resistor behind the switch. Indeed, a bit of surgery revealed the switch & resistors:
RCA clock – DIM switch and resistors
It turns out that the 220 Ω resistors set the DIM current, with the 100 Ω resistors in parallel to set the BRIGHT current. Weirdly, the display operates in two halves: one resistor for the lower and middle segments, the other for the top segments. The resistor numbers give a hint of what the schematic might look like:
RCA clock – LED current-set resistors
The current control isn’t all that good, because the brightness varies with the number of active segments. With 470 Ω resistors (yes, from that assortment) in place, the variation became much more obvious; the LEDs are operating far down on their exponential I-vs-V curve. We defined the result to be Good Enough for the purpose.
Four short screws hold the circuit board in place, but one of them arrived loosely held in a pre-stripped hole. I cut eight lengths of black Skirt filament, anointed them with solvent adhesive, dropped two apiece into each screw hole, and ran the screws back in place. I likely won’t be back in there, so it should be a lifetime fix:
RCA clock – ABS filament in screw hole
Done!
As with all the trade names you remember from back in the Old Days, the present incarnation of “RCA” has nothing whatosever to do with the original Radio Corporation of America:
This pitiful excuse for a hinge actually lasted far longer than I expected:
Brita pitcher lid hinge pins
Also much to my surprise, the plastic solvent-bonded to itself, although I doubt either of those pins will survive another four years.
The yellow discoloration seems to be most prominent on the inside of the lid, which suggests the water is nastier than they’d have you believe. The disinfection additive has switched from chlorine to chloramine and back to chlorine over the last few years, which may have something to do with it.
While fiddling around with those SMD capacitors, it occurred to me that I really needed some SMD tweezers: small forceps with isolated jaws, connected to the capacitance meter’s terminals. In the nature of a proof-of-concept, I sacrificed a (surplus) Tektronix banana plug cable and an old plain-steel tweezer (stamped Made in Japan back in the day when that had the same quality connotations as does Made in Pakistan right about now) and lashed them together:
SMD tweezers – overview
I chopped off the tweezer joint with a bolt cutter, scuffed up the steel with a file, soldered the cable wires, cut a small wood block to fit, and epoxied the whole mess together:
SMD tweezers – epoxy joint
When the epoxy cured, a generous wrap of silicone tape hid most of the hackage. Two lengths of clear heatstink tubing insulate the handles from my sweaty fingers:
SMD tweezers – joint detail
Part of the reason for picking this victim was its cheap-and-bendy steel: more easily soldered than stainless, no regrets about filing the jaws to suit. They’re flattened on the bottom and filed to grip SMD chips along their length:
SMD tweezers – tip shape
That’s on the top panel of my indispensable AADE LC meter. The stray capacitance of that cable is around 50 pF, but the meter can null it to a fraction of a pF. At least as long as I don’t change my grip, that is, which isn’t too severe a restriction. [Update: got the link right this time.]
That gorgeous Tek cable turned out to be entirely too stiff and the natural curve doesn’t lie in the correct direction. The next version will probably use a length of RG-174 mini coax and a dual banana plug. I think I’d like angled jaws, too, so as to attack the chips from the top down.
But even this version works wonderfully well, as I sorted out a few hundred random SMD caps in two half-hour sessions that I’d been putting off for far too long. This is the last batch; I’ve learned the hard way that it pays to transfer batches of chips to their storage bins long before I think I should:
Sorting SMD caps
Yeah, it’s false economy, but it keeps me off the streets at night. OK?
The Smell of Molten Projects in the Morning 