Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Inspired by our Larval Engineer’s threat promise to decorate the Sienna, I just had to do this to the Forester:
Forester wheel cover decoration
They’re intended to fit around the keyhole under a car door handle, but cars don’t look like that these days; they were a surplus deal from long, long ago.
The reflectors stand out nicely in subdued light:
Forester wheel cover decoration – flash
The hub covers have an embossed Subaru logo and the reflector has thin foam tape, so it’ll be interesting to see how long they last. Worst case: 3D printed replacement hub covers with integral reflectors.
The sewing machine motor drives the handwheel through a double pulley on a jackshaft:
Kenmore 158 – handwheel – jackshaft pulley
I’ve been figuring a 10:1 speed reduction, based on counting revolutions and ignoring belt slip. The correct answer also depends on belt tension and whether you turn the motor or the handwheel.
Measuring the pulley diameters isn’t straightforward, because the belt runs deep in the handwheel pulley (the brown smudge is near the rim, above) and high on the motor pulley:
Kenmore 158 – NEMA 23 stepper – on adapter
Measuring across the tops of the belt ribs on the pulleys gives these diameters:
Motor: 18 (or 16.6 at the belt midline = pulley OD)
Jackshaft large: 48
Jackshaft small: 24
Handwheel: 75
The end-to-end ratio is either 8.3 or 9, depending on what you call the motor pulley. Either of those are close enough to 10:1 to allow for a turn or two of motor pulley slippage.
Flipping the jackshaft pulley doesn’t quite work, as the pulley ends aren’t symmetrical, but I think it can be forced to align with the handwheel if I add a lathe-turned hoodickie. If so, then the end-to-end speed ratio drops to a little over 2:1 and the original belts fit just fine:
Kenmore 158 – reversed jackshaft pulley
The maximum handwheel speed ran a bit under 1000 RPM, so the reduced ratio lets the motor turn at 2000 RPM. That’s well within range of a NEMA 23 brushless DC motor, but it must also satisfy the other non-obvious requirements:
Acoustic = no squeals, not even a little bit
Physical = a scant 100 mm from mounting plate to edge of the frame casting for a 57 mm diameter cylinder
Measuring the torque required to drive the sewing machine would go a long way toward finding the proper motor. The LeadshineBLM57050 would drop in, the BLM57090 might barely fit with some filing of a rib in the machine’s base, the and the BLM57130 isn’t in the running. The OEM motor dataplate says it’s 110 – 120 V @ 1 A = 110 – 120 W, but that surely doesn’t mean the same thing as the 130 W rating for the BLM57130.
I should just buy a motor and driver brick to see what it’s like … [sigh]
The 170° fisheye lens on the HDR-AS30V action camera protrudes from the front of the case, the better to view the passing scenery:
Sony HDR-AS30V Action Camera
Unfortunately, that means there’s nothing to protect it when the scenery gets a bit too close.
Mounting it upside-down in the skeleton frame provides a bit of protection, by putting it inside the straight line connecting the helmet brim with the top of the frame:
Sony HDR-AS30V camera on bike helmet – inverted
That won’t protect it from severe impacts, but perhaps a casual drop won’t scar the lens. You can tell from the scuffs that the helmet does get dropped every now and then.
When you remove the skeleton mount from the helmet, grip the camera between finger and thumb while releasing the latch with your other hand. The mount will dangle from your fingers and the camera won’t slide out; if you don’t have both hands free, don’t mess with the camera.
Even though it doesn’t look at all like a GoPro Hero, everybody recognizes the “camera on helmet” meme and, in general, behaves a bit more circumspectly. I didn’t see that coming, not at all.
This doesn’t happen very often, but, after a few road trips and some jostling around, the M2’s platform was definitely out of alignment: the first layer came out generally too thin, with the X-Y+ quadrant very much too thin.
I tried a quick and dirty adjustment that didn’t produce meaningful results, then broke out the Starrett Taper Gauge and did it right.
Jog around measuring the height of the nozzle above the platform
Adjust screws to reduce variation
Change Z offset in startup G-Code
Run off a few test patterns to get the platform heated
Measure actual thickness
Change Z offset to get the right answer
Done!
This progression of cold measurements, read top-to-bottom, left column first, shows the observed nozzle height above the platform around the edges and at the center:
M2 Platform Leveling Progression – 2014-06-30
The final measurements seem to indicate the glass plate is 0.2 mm convex in the center, but I wouldn’t trust the measurements to that level of accuracy. It’s probably bowed upward, but it’s certainly close enough.
The cold measurements suggest that the Z offset should be -4.80 mm, but the measurements on the hot platform with actual extrusion threads showed that -4.50 mm produced the correct thicknesses.
It’s not clear automating the movements would produce better or faster results than just manually jogging the nozzle around the platform, particularly since it happens only every few months.
This would be easier with the Z offset stored in the EEPROM and some modified startup G-Code to retrieve it.
Much of the boat traffic on the Hudson consists of barges shuttling bulk commodities between the Atlantic and the Port of Albany. I think this is a crude oil barge, based on the Christmas Tree plumbing that was more visible when it passed under the Mid Hudson Bridge:
Walkway and Barge – from Mid Hudson Bridge
We crossed the Walkway Over the Hudson westbound, where a work crew was tending a crane. That’s how they do repair and inspection:
Walkway Inspection Crane – from Mid Hudson Bridge
The Hudson River has far fewer power boats than in years gone by, probably due to their gallon-per-minute fuel consumption:
Power boat on Hudson River – from Mid Hudson Bridge
It turns out that the clever idea of moving the swap partition to a USB flash drive had no effect whatsoever; the UI continued to freeze up during OpenSCAD compiles and suchlike, with the drive activity light on solid and not much in the way of swap activity. Sooo, I wondered what would happen with the /tmp directory on non-rotating memory.
Then I spotted a sale on a Samsung 840 EVO 120 GB solid state drive, which seemed like it might improve almost everything in one swell foop. That’s a tiny drive, at least by contemporary standards, but all my data files live downstairs on the file server, so the desktop drive holds just the Xubuntu installation.
It’s worth noting that SSDs tend to fail suddenly and catastrophically, so that if the only copy of your data is on that drive, there is no recovery. In this case, I’d lose some configuration that changes with every installation, a few locally installed / compiled-from-source programs, and little else.
The nice thing about transferring a Linux installation: boot a live CD image (I used Ubuntu 14.04LTS, the same as the desktop box), copy the files to the new drive, set up Grub, and you’re back on the air. That recipe worked fine, although I used rsync -au to copy the files and then updated /etc/fstab with the SSD’s new UUID (rather than duplicate a supposedly unique ID).
The Grub recipe does require a bit of delicate surgery, so I removed the OEM hard drive and rebooted the live CD image before doing this. If the SSD fell victim to a finger fumble, I could just start over again:
sudo mount /dev/sda1 /mnt
for f in dev proc sys usr ; do sudo mount --bind /$f /mnt/$f ; done
sudo chroot /mnt
sudo update-grub
sudo grub-install /dev/sda
sudo grub-install --recheck /dev/sda
exit
for f in dev proc sys usr ; do sudo umount /mnt/$f ; done
sudo umount /mnt
Then reboot from the SSD and It Just Worked.
Dropbox and DigiKam noticed the UUID change and asked for advice; there’s no need for re-registration, re-activation, or re-authorization.
The overall time from boot to login isn’t much shorter, because of the tedious delay while the network and the NFS shares get up & running, but the desktop UI startup zips right along.
The same OpenSCAD compile that previously brought the UI to a halt has no effect, so I hereby declare victory. I think the complex solid models that used to take forever will see much the same speedup.
The Dell hard drive (an ordinary 7200 RPM 3.5 inch brick) lies abandoned in place under the fancy black shroud; the Optiplex 980 layout butts the drive’s right-angle SATA connectors hard against the CPU heatsink and offers no spare SATA power connectors. There was just enough room to wedge the SSD above the PCI connectors, where it won’t get into any trouble:
Samsung 840 EVO SSD in Optiplex 980
The hard drive contains the never-used Windows 7 partition and the corresponding recovery / diagnostic partitions; keeping the drive with the Optiplex chassis seems like a Good Idea.
The Smell of Molten Projects in the Morning 