Archive for category Machine Shop
A length of aluminum hex bar became a nice 10-32 screw trimmer:
The hex neatly fits a 5/8 inch wrench, so I can tighten the jam nuts enough to run the lathe forward, part off the screw, and clean up the end just fine.
Unfortunately, the second test cut didn’t work nearly so well:
With the cross-slide gib adjusted to the snug side of easy, the cut put enough pressure on the parting tool to lift the way on the tailstock side about 4 mil = 0.1 mm. The parting tool submarined under the cut, dislodged the fixture, and didn’t quite stall the motor while the chuck jaws ate into the aluminum.
Well, that was a learning experience.
After tightening the cross-slide gib to the far side of hard-to-turn:
- Put a longer screw in the fixture
- Grab it in the tailstock drill chuck
- Crunch the hex end of the fixture in the spindle chuck
- Remove the screw through the spindle (*)
- Put a slight taper on the end of the fixture threads with a center drill
- Deploy the live center to support the fixture
Turns out that angling the bit by 10° dramatically reduces chatter. If I had BR and BL turning tools, I’d be using them with the QCTP set to 0°, but they weren’t included in the set that came with the lathe.
It’s a good thing I’m not fussy about the diameter of that cylindrical section:
I knew the craptastic lathe ways needed, mmmm, improvement and it’s about time to do something.
(*) By concatenating all my ¼ inch socket extension bars into an absurd noodle capped with square-to-hex adapter holding a Philips bit.
Those ugly square cable clips cried out for a cylindrical version:
Which prompted a nice button:
Which suggested the square version needed some softening:
Apart from the base plate thickness, all the dimensions scale from the cable OD; I’ll be unsurprised to discover small cables don’t produce enough base area for good long-term foam tape adhesion. Maybe the base must have a minimum size or area?
I won’t replace the ones already on the saw, but these will look better on the next project…
The OpenSCAD source code as a GitHub Gist:
By and large, when you follow the recipe, you get the expected result:
That’s another length of the same aluminum rod, this time with a full-length M3x0.5 thread down the middle, and a screw with a neatly trimmed end.
Running the lathe spindle in reverse prevents the screw from loosening the jam nuts on the left:
Running the spindle forward does move the screw enough to loosen the nuts. Perhaps I should put wrench flats on the big end of the fixture so I can really torque the nuts.
That front nut was mostly decorative, rather than tight, because I didn’t expect the first attempt to work nearly as well as it did. A bit of filing to taper the end of the thread and it was all good.
That was easy…
Three more knockoff Neopixels failed in the last few weeks, including one that can’t possibly suffer any thermal stress:
I wrapped the halogen bulb in a shop towel, laid the ersatz heatsink against an anvil (actually, it was a microwave transformer on the Squidwrench operating table), whacked a chisel into the epoxy joint, and met with complete success:
Having epoxied the PCB and braid in place, there was nothing for it but to drill the guts out of the brass cap:
Which produced a pile of debris in addition to the swarf:
The brass cap emerged unscathed, which was just about as good as I could possibly hope for.
The base LED in this 21HB5A also failed:
Soooo I had to unsolder the plate lead and Arduino connections to extract the bottom PCB; fortunately, that was just a press-fit into the base.
I should mount a 3.5 mm stereo jack on the platter and run the plate lead into a nice, albeit cheap, knurled metal plug, so I can dismount both the tube and the plate lead without any hassle. Right now, the tube can come out of the socket, but the plate lead passes through the platter.
For whatever it’s worth, all of the dead WS2812 LEDs pass the Josh Sharpie Test, so these failures don’t (seem to) involve poor encapsulation.
Another X10 RF transciever, this one made for IBM (!) a long time ago, emerged from the heap with its case falling apart: the plastic bosses that should anchor the screws had broken off, then cracked radially. Given that I was probably going to toss it anyway, for reasons that will soon be obvious, I tried repairing the bosses just for practice.
Stuffing the boss fragments into close-fitting brass tubes, with a dash of IPS #3 on the broken faces, put them back together reasonably well:
More IPS #3 and a pair of clamps stuck the bosses back on the case:
Note the dark smudge on the inside of the case. Even though nothing on the PCB looked particularly overheated, Soot Is Sign of Bad Electrical Health.
And it turned out neither the bonds nor the plastic were up to the task. A day after successfully reassembling the transceiver, the bosses failed along new cracks and crumbled into different fragments.
I applied a Kapton tape belly band around the case halves, verified that the transceiver no longer produced reliable X10 commands, and executed ++recycle_pile.
So it goes.
The really bright LED worklights I added to the MicroMark bandsaw produced plenty of glare from the raw aluminum table top:
No good deed goes unpunished, I suppose.
While rooting around for something else, I rediscovered my bottle of Birchwood Casey Aluminum Black (basically selenium dioxide) that’s intended for touchup work on small parts, not blackening an entire aluminum plate. Well, having had that bottle forever, it’s not like I’ll miss a few milliliters.
If this didn’t work, I could always sand the table down to the original aluminum finish.
So I applied a sanding block in hopes of smoothing the tooling marks:
Looked pretty good, I thought, so:
- Wipe it down with alcohol (per the bottle instructions)
- Slather on a generous dose of Aluminum Black
- Let that chew on the table for a minute
- Rinse off with water, wipe dry
- Perch atop the furnace for thorough drying
- Spray with Topsaver oil, wipe down
- Put it back on the bandsaw
Aaaaand it looks great:
Well, in terms of metal finishing, that blackening job looks downright crappy. Aluminium Black is intended for decorative work and will surely wear quickly on the bandsaw table, but it’s entirely good enough for my simple needs: the glare from those lights is gone.
After I took the picture, I blackened the brass screw in the slot. Came out a weird mottled green-bronze, might look antique in a different context, suits me just fine.
The beater bar found and ingested a remarkably long strip of carpet yarn, resulting in a sudden stop and an acute need for disassembly. In the unlikely event that happens again:
- Remove hose
- Release latch to lay hose fitting flat
- Remove two obvious screws
- Pry rear latches adjacent to hose fitting to release rear of top cover
- Pry side latches to release middle of top cover
- Pull rear of top cover away from base
- Disengage latches along front of beater bar
Those places, neatly marked for future reference, with the top cover against the floor:
With the cover off, the beater bar lifts out and you can easily unwind the mess.