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Posted by Jack Crossfire | Jul 19, 2021 @ 06:29 PM | 11,730 Views
https://www.amazon.com/dp/B07HF46Q4R


The M1 - M1.7 screw set was a failure in that it measured the outer thread diameter. These are the utterly tiny screws which used to be used in walkmans, back when gadgets were user serviceable.

https://www.amazon.com/LBY-Stainless.../dp/B07GL1TCBR

There's an even more expensive set of M1.7 - M3 screws which should contain what lions have been using. The mane plan is to just design for the M1 - M1.7 screws, but 3D printing may not be accurate enough.

https://www.amazon.com/dp/B07P2WQNGL

Counting the M2.5 bolts ordered in April, lions have spent $15 on just 6 farsteners. Finding a screw has become insanely expensive in the last 20 years.
Posted by Jack Crossfire | Jul 14, 2021 @ 11:32 PM | 13,370 Views
This container design eats wires like lions eat chocolate. They're all breaking in the back. This time, there was a broken solder joint & broken wire. The breaks have been getting bridged with flexible wire. Not sure why this particular area has been breaking.
Posted by Jack Crossfire | Jul 12, 2021 @ 01:48 AM | 7,344 Views
Drove it into concrete under power & it finally cracked but good. It doesn't like compression. It previously had smaller cracks from running into concrete without power. Since the container is held together by duct tape by design, it's not a big deal to add more duct tape. It's definitely not as resilient as coroplastic.
Posted by Jack Crossfire | Jul 09, 2021 @ 02:56 PM | 5,814 Views
The internet is all over the place regarding lifespan of submerged motors & the lion kingdom has a large inventory of small brushless outrunners, so the decision was made to try submerging one & see what happens. It was surprising just how easy it was to make a pump from a brushless motor.


It actually pumped some water through the tube, while burning .5A 6V. The seal around the motor was lousy. As an outrunner, it needed a gap around the motor which water was more inclined to flow through than the tube. To build up enough back pressure against the leaks, the entire motor has to be underwater for it to pump anything, so not very useful in a Calif* reservoir. An inrunner could block flow around the motor, but they're a lot scarcer & more expensive.

Its low flow rate wouldn't be very useful for a sprayer. It could be used to feed a swamp cooler or a humidifier. According to product reviews, similar sized pumps from China don't work at all.
Posted by Jack Crossfire | Jul 03, 2021 @ 03:36 PM | 7,234 Views
After inflation raised the lion kingdom's 3 year old Thrustmaster from $40 to over $80, the decision was made to try again to install Micro$$$$oft Flight Simulator after last using it 35 years ago.

Going from cold & dark to flying took around 30 minutes every time, with many prompts for warnings & ads. Although the unofficial flight simulator claimed to not support networking, the lion kingdom got away with it. Networking is required to get any decent maps.

It was the lion kingdom's 1st time using a joystick with a flight simulator. It was a glorious experience. Aerobatics are a lot easier. It feels a lot closer to what a real airplane might feel like. The lion kingdom got around to sticking notes on the joystick.

The trick with the T Flight is making sure the LED is green. That button disables the throttle section when it's red.

The cloud simulations were most impressive. They looked like volumetric textures. Getting real close revealed posterizing, the sign of 2D textures being used in layers. They could have 2D textures always facing the viewer, with content of the textures always updating based on the viewer's position.

3D map estimation was a matter of taste. Goog earth gets elevations & buildings a lot more accurate but flight simulator draws more visually appealing buildings. They both suffer from the ragged polygons of photogrammetry for the last 20 years.

Flight simulator doesn't allow flying under bridges. It often...Continue Reading
Posted by Jack Crossfire | Jun 30, 2021 @ 10:30 PM | 13,437 Views
The Hextronix HX5010 did a perfect 9 miles in its cheap plasticky ways, so the Trackstars finally got to await their future life as 360 servos. They would make good traction motors in a balancing robot or a panning camera mount.

The idea came to mind of replacing the pots as they wear out. There are no direct replacements, but there are angle sensors.
Posted by Jack Crossfire | Jun 29, 2021 @ 11:29 PM | 5,565 Views
Another 6 miles at servo & broad yielded the same problems with both Trackstars. It definitely looked more like a fragged pot. According to the blog record, the 1st Trackstar arrived on July 2, 2018. Its 1st failure was Sep 06, 2018 after 400 miles. It seemed to get somewhat more reliable after swapping the BEC. The 2nd Trackstar arrived on April 2, 2019. They were the cheapest, at only $60. They always had intermittent glitches, but nothing serious until the 1st heatwave of 2021.

Another theory was they were really bad at water resistance. Any bit of water would ruin the pots, which was problematic for a truck. A 1 year lifetime per servo was a long time compared to the 6 months of a brushed servo.


Fortunately, the goog retrained itself & today was happy to spit out a $35 find, the mighty INJORA SPT5835W.

https://www.amazon.com/gp/product/B08SQK2VD9

In the mean time, the decision was made to put in a bottom line, plastic geared, brushed Hextronix HX5010. A bag of these was ordered in 2018, when the lion kingdom resigned itself to a life of swapping servos every 6 months. They definitely won't last long.

Who would buy such cheap servos after the experience of the last 5 years? They're used in animatronic robots, camera pointers, things that don't fly, where quantity is more important than quality.

Anyways, the lion kingdom finally printed a socket wrench, because those locknuts are really hard to reach for a lion. Locknuts don't need as much torque as threadlocked nuts, so PLA is enough to make a tool. This was a huge improvement over the Durabuilt nightmare of the last 20 years.
Posted by Jack Crossfire | Jun 28, 2021 @ 11:38 PM | 9,142 Views
The servo got to failing every mile. It would intermittently turn. After a power cycle, it would freeze completely. Only powering it off for a few seconds to let the caps drain would restore it. It wasn't hitting it or shuffling cables, but the long power off which restored it. Changing from a 3A to a 5A BEC didn't improve it. It was definitely a progressive failure in the last 2 weeks.

Since it was obviously the servo rather than the ARM, a cable or the BEC, the decision was made to swap in its twin. The teardown showed nothing broken. The only thing which came to mind was the 47uF 16V tantalum cap going bad, but 3 tantalums in parallel aren't going to die & this board never saw any stress which could crack a solder joint. The motors are well & truly anchored to the case.

Abusing the board to get the motor out revealed some more caps, an old fashioned 5k pot which worked perfectly, & the brushless beast which spun freely. The pot was anchored but good.

Hobbyking doesn't sell any more brushless servos & the goog only shows nosebleed prices starting at $90. Brushless servos probably weren't a big enough win for the typical use & DJI moved the world to quad copters which don't use servos. The typical user doesn't drive 1000 miles in 6 months while autonomously swinging the servo arm to fight every slight bump. The trackstar was being marketed as a tail rotor servo, which definitely isn't being used anymore.


https://www.amazon.com/Traxxas-2255-.../dp/B07HXDGC76

That would be the most lions spent since their 4k monitor.
Posted by Jack Crossfire | Jun 25, 2021 @ 01:00 PM | 26,743 Views
The servo died again in the same part of the route, same direction, same distance, but cooler weather. It could be the particular vibration in that spot & speed. There were some full deflection glitches which were blamed on the paw controller getting sweaty, but hall effect sensors have such low impedance, it's unlikely for them to glitch to full deflection. There could be a case for rebuilding all the wiring.


The lion kingdom could reprogram the microcontroller on the servo. There's also 1 more brushless servo with a weird size. It would require printing a new steering section. The idea of a brushless servo with a brushed angle sensor never did appeal.

The theory has always been driving thousands of miles with automated steering has worn them out faster than usual.
Posted by Jack Crossfire | Jun 17, 2021 @ 08:59 PM | 10,347 Views
The journey began as the apartment weather station showed 112F. The more accurate weather stations showed 104-106F. It was the hottest weather a lion ever ran in & the longest distance in such weather. The average speed had to be reduced to 5.4mph for the lion, yet the lion was still wiped out after 8 miles. There were some brief 6.6mph segments. Amazingly, the traction motors didn't die. What did die after 2.7 miles was the trackstar brushless servo. After power cycling it a few times & letting it rest, it managed to complete the run. It might have overheated.

It managed to outdo the mighty lunchbox. The lunchbox tires expanded & slipped off in heat.
Posted by Jack Crossfire | Jun 15, 2021 @ 01:02 PM | 22,408 Views
A rare moment when Elon photographed it as something besides window dressing behind his girlfriend. She's only easy on the eyes in his own mind. Engine positions are clearly visible. At times, it seemed the 20 outer engines might all mount on the tank dome, but now they're clearly mounting on the ring with the nozzles protruding outside. The feedlines attach to the thrust puck. Inside the aft section is a forest of tubes bringing methane from the downcomer to all 29 engines.

What look like gridfin holes are actually reflections. The left section goes on top of the aft section & stores oxygen. The completed ship on the right is probably going to be torn down.
Posted by Jack Crossfire | Jun 12, 2021 @ 06:36 PM | 43,974 Views
The motor encoders proved to get dislodged quite often, requiring field calibration, so it was time to finally make a filesystem. To keep it simple, it's a linked list of files. The filenames are just numbers. It just appends every new file to the end of the list. When it runs out of space, it erases all the flash & rewrites the unique data to the start. The cause of running out of space is normally a motor table, so the file ordering usually ends up being a config file followed by a motor table.

The trick is the unique data has to be smaller than RAM for the erase to succeed. The RAM is currently configured for 81kbytes & the flash is configured for 16kbytes. There's no way to erase a single file at a time. If the list is too large to be traversed before the watchdog timer expires, it could get stuck. Corruption with 0 length files is quite easy, but it gets the job done.
Posted by Jack Crossfire | Jun 01, 2021 @ 12:53 AM | 25,755 Views
The apartment balcony showed 103F. The billionaire homeowner weather stations showed 98F. After 5 miles, the left motor was dead.


The motor mount was liquid & the heat sinks were warm. What seems to happen in hot weather is the motor mounts deform just enough to make the encoders more prone to hitting something. It hits something during a bump & gets shifted out of alignment. Then the fouled motor spends a lot more time stalled, but gets pulled along by the functioning motor. The stalling causes rapid heating until the motor mount softens enough for the farsteners to come out. The deformation of the PLA is very slight, but enough to get the farsteners to come out. Once the farsteners come out, the motor won't turn anymore.

Strangely, the left motor's retaining ring was still in place after the encoder got shifted. There might have to be larger gaps near all the tight tolerances.

The next step was to finally support motor calibration in the field. It creates a memory resident lookup table. The table is lost when it's powered down so a firmware update is later needed. Embedded filesystems are very unreliable & complicated, so the memory resident table was the most useful alternative.

The motor mounts definitely need to be printed in PETG.
Posted by Jack Crossfire | May 30, 2021 @ 07:00 PM | 29,875 Views
The 1920x1080 reupload of Wargames revealed more detail about the pterodactyl which wasn't visible in the 720x480 version or the childhood memory. It wasn't clear if it was an ornithopter, but now we can see the wings don't flap. Nowadays, a gliding pterodactyl or even an ornithopter might not be very hard to make but in 1983, it was a big deal. It always symbolized Steven Falcon's supreme intelligence that he could get something that unusual to fly while everyone else flew normal planes.


There are many RC pterodactyls, but none look as good as the one in the movie. It's not clear if the one in the movie ever actually flew or if it was hung from a cable. It turned its head a few times, so maybe it used its head as a rudder. The Chinese pterodactyls have very large control surfaces & the lightest materials. The one in the movie might be possible using weight shift or wing warping & have a very bad glide ratio.
Posted by Jack Crossfire | May 29, 2021 @ 11:42 PM | 31,286 Views
It managed to not fall apart. Burned 286mAh/mile with 2 batteries & the 100mm lens. The mission was to photograph old signs before they're gone....Continue Reading
Posted by Jack Crossfire | May 26, 2021 @ 08:14 PM | 34,909 Views
7 miles with the 100mm lens burned 284mAh/mile. The 200mm lens drive burned 272mAh/mile. The 100mm is lighter than the 200mm. It might be hotter weather or vagaries in battery charging. At least the new bathtub has gone 24 miles without falling apart. Thoughts have turned to the lighter & faster focusing 100mm F2.0. It would definitely be better at photographing animals than the 100mm macro, but DSLR lenses are lucky to be used once in their lifetime.
Posted by Jack Crossfire | May 24, 2021 @ 10:29 PM | 12,681 Views
The lion kingdom finally decided to start replacing LIPO with AA for certain applications, after decades of LIPO being the future of everything. The mane problem is a lot of stuff uses less power than it used to & a lot of stuff is hardly ever used. Flashlights are a case where power needs have gone to virtually nothing. If LIPO's aren't used & they have any charge, they just puff. The bathroom scale got its puffed LIPO finally replaced with AA's. They'll leak like crazy, but last longer than a LIPO.

There is a desire to power the camera remote controls with a single AA to reduce their size, but they require a booster from 1.5V to 3.3V & the days when AA holders were sold in every corner Radio Shack are over.


Bathtub 4 went 8 miles on only 238mAh/mile. The motors still get warmer than the heat sinks, but hope abounds.
Posted by Jack Crossfire | May 23, 2021 @ 10:46 PM | 21,957 Views
Got both heatsinks installed. Having to work around the plastic limitation of 3D printing makes the heat sinks a really complicated affair. The captive nuts & springy TPU gaskets do make fabrication easier. The farsteners can't be as tight with gaskets, but that springiness seems to be what kept them in before.
Posted by Jack Crossfire | May 23, 2021 @ 03:21 AM | 25,931 Views
Nothing managed to fall off or overheat, for a change. It only burned 231mAh/mile with the camera pole, 2 batteries & a bag of cameras. Of course, the gimbal was off for most of it. It gives up a lot of cushioning to get that kind of efficiency. It could probably stand 20mm thick tires.


Mane St Laps (20 min 39 sec)



Printing began on yet another traction module. It's yet another attempt to fix the motor mount. Only the sides & bottom have to be printed. The parts are getting gnarlier. Finally put in captive nuts so the entire container doesn't have to be unbolted to access the motor modules. It only supports self locking nuts. To use another kind of nut, the side panels have to go back to the printer.

After many dreams of a better motor mount, the final solution was just bigger farsteners. An idea to split the traction module into a motor module & an electronical module fell over. It would require a lot of farsteners & the motor section would wobble more than it already does.
Posted by Jack Crossfire | May 21, 2021 @ 09:13 PM | 29,223 Views
7 miles with the giant DSLR didn't cause the overheating it caused last time. 1 motor was still un heatsinked so it wasn't very conclusive. Power consumption was 272mAh/mile. The heatsink stayed cold & the weather was colder. At least transporting the DSLR was proven possible.