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Posted by Jack Crossfire | Nov 27, 2021 @ 02:07 AM | 25,423 Views
The left motor went to valhalla while slinging the DSLR 10 miles. Thus another day went to rewinding a motor with 20 turns of 26 AWG. The PETG motor mounts are taking the heat nicely, letting motor after motor fry. The retaining ring was documented to show future lion it was properly reinstalled. Those retaining ring pliers have proven essential.

Some notes during the replacement were crash damage to the bottom panel. The 1.6mm tread tire still delaminated. The next step would be 250C printing, but delamination doesn't seem to have any impact unless it picks up a branch.
Posted by Jack Crossfire | Nov 25, 2021 @ 01:29 AM | 14,799 Views
So the power burn with the DSLR + rudolf + headlights was 410mAh/mile. Tried to get the red glow reflecting from a tree tunnel. It shows up more when seen from behind. The EOS RP seems to have less noise in HDR mode. It takes 3 pictures with varying shutter speeds & might average areas which are properly exposed in all 3 areas.
Posted by Jack Crossfire | Nov 20, 2021 @ 07:12 PM | 14,591 Views
The amerikan people are in such war against pork, let alone meat, it's a rare day that rudolf brings back any pork flavor. Lions now manely buy grocery bags for garbage bags instead of putting food in. At what point are there so many restrictions on foods & grocery bags that it's no longer worth staying?
Posted by Jack Crossfire | Nov 17, 2021 @ 06:46 PM | 7,906 Views
The phone didn't do any better against TPU than it did against ziplock bags. The case got a piece of leather on the bottom, since that's where it slams down. There's still a lot of adhesive gunk near the bottom & scratching near the top because that's where it moves. The next meaningful improvement would require a PLA case with felt tape. There's no need for it to be flexible. The bottom needs a larger space to tape down. The bottom inside needs foam. The sides & especially the top need felt tape.

Otherwise, the goat wasn't fooled by the reindeer costume.

Goat vs Rudolf (2 min 4 sec)

Posted by Jack Crossfire | Nov 14, 2021 @ 09:40 PM | 5,487 Views
Another speed run after recalibrating the encoders was back to its norminal speed.

# dist sec min/mile
1 202 43 5:43
2 202 43 5:40
3 212 43 5:39
4 209 45 5:40
5 209 46 5:51
6 203 51 6:37

Power went from 324mAh/mile to 220mAh/mile. So the encoder system continues to be balky & drift for no reason. The motors don't stall when it starts drifting. They just get less efficient. It must be a bee's dick of alignment change making the difference.

Then, the lion kingdom set to the task of designing a new phone holder for today's gigantic phones. The ziplock bags of the last 5 years have been very abrasive & short lasting. They also haven't dried out. TPU is seen as more forgiving on the plastic, but bonding a TPU clamshell has proven the biggest challenge. There was an attempt to tack weld it with the heat gun while simultaneously gluing it. It was impossible to keep the heat gun from melting the wrong areas. The result was a really ugly & weak seam.

The leading plans for the clamshell are sewing it & metal rods. The problem with metal rods is the corners not having any bond. It might be good enough for the corners to flop around. The problem with sewing is getting it tight enough & longevity.

Another idea is to abandon TPU & line a PLA phone holder with felt. It would be very bulky on top of already ridiculously large modern phones.
Posted by Jack Crossfire | Nov 13, 2021 @ 02:59 AM | 6,252 Views
Another speed run with no headlights & no payload besides a shirt was the same as the full headlights.

# dist sec min/mile
1 202 48 6:15
2 200 49 6:29
3 311 73 6:31
4 305 76 6:38
5 310 75 6:41
6 409 103 6:44
7 411 100 6:41
8 406 104 6:50

The speed governor may actually have been set to 6 min/mile for the 400m. 300m & below were definitely set to 6 min/mile.

So definitely an aversion to a slight headwind. It's moved up plans to upgrade to 16.8V. That involves new motor drivers with bigger caps, a new mane board with support for thermisters, new motor mounts with spots for thermisters. The wiring will have to be more organized.
Posted by Jack Crossfire | Nov 08, 2021 @ 06:56 PM | 5,201 Views
Widened the tread to 1.6mm, increased the temperature to 230C, & baked the filament for 10 minutes. It still had voids, but some of these voids might be from horizontal expansion of underlying layers. Another thing which might improve layer adhesion is breaking up the smooth tread with slight angles. A smooth tread still has the best traction with TPU.

As bad as these tires are, they're under $2 & they still last much longer than lunchbox tires. Lunchbox tires were out of stock after 2019, due to that pesky transient supply chain disruption.

The old tire was destroyed. The lion kingdom's last bottle of rubber cement was done. Clear school glue has proven more effective. Haven't seen rubber cement locally since 2018 when it was 1st used to bond tires to wheels. It might have been banned for its unholy non vegan fumes.
Posted by Jack Crossfire | Nov 06, 2021 @ 02:56 AM | 19,973 Views
Without cyclops light:
# dist sec min/mile
1 204 46 5:57
2 212 46 6:6
3 203 46 6:1
4 209 45 6:1
5 211 47 6:14

With cyclops light:
# dist sec min/mile
1 207 50 6:25
2 205 49 6:19
3 207 49 6:19
4 203 49 6:23
5 210 48 6:23
6 209 49 6:31

It burns 130mA on a full 12.6V, rising to 146mA at 11.2V. It gets drastically dimmer below 11.1V. The $1 buck converter has a 3V dropout.

For 150mA to make such a difference in all out speed, it might be saturating the wires. Hauling a spare battery for the light wouldn't make it so slow. The original headlights are also obviously slowing it down.

The string came loose. Hitting it with the glue stick might keep it on. The good news is it made it possible to see the cracks in the pavement by virtue of its wide angle more than its brightness.
Posted by Jack Crossfire | Oct 30, 2021 @ 06:56 PM | 16,858 Views
Every iteration of robo rudolf gets better & this year was definitely a big leap.

Orange PLA with a brown sharpie made a surprisingly realistic woodgrain texture. The lion kingdom couldn't afford to dunk it in wood stain. It was surprising to find brown sharpies still in existence, in a time when 31 flavors of ice cream are the enemy of equality.

It was designed in a time when 25 zip ties were $1. 3mm zip ties aren't even made anymore. A better design would use bolts. The new nose mount could use a lot of changes to make it easier to screw in the clamps & use string instead of zip ties....Continue Reading
Posted by Jack Crossfire | Oct 27, 2021 @ 02:36 PM | 16,407 Views
While hacking 60W lightbulbs is a cheap way to get bright white light, 100W RGB lightbulbs are absolutely a waste of money for making colored light. The rated brightness on these is for white light only. The colored light is a different mode & uses a small number of dimmer RGB leds on 13V. The white LEDs run on 140V & can't be ground down to run on 12V. The 2 sets of LEDs aren't used simultaneously. The cheapest way to get colored light is the good old snail mailed COB.

https://www.amazon.com/Chanzon-Inten...01DBZJZ7E?th=1...Continue Reading
Posted by Jack Crossfire | Oct 23, 2021 @ 10:33 PM | 25,616 Views
After an unfortunate toe injury, the decision was made to install a very bright, removable light to try to improve the visibility of the path. A 60W LED bulb was converted to 8.2V 200mA. Then a heat resistant mount was printed out of PETG. The prolific jump in zip tie prices has led to string.

It was hard to make any conclusions in a parking lot. That was the last of the dry weather for 36 hours. The mane problem is without a reflector, it's very diffuse.
Posted by Jack Crossfire | Oct 09, 2021 @ 03:21 PM | 25,427 Views
Epic DIY 3D Printed Planeprint Eagle Build (18 min 47 sec)

On the road to a pterodactyl glider, there appeared a 3D printed bald eagle. It involved an ABS motor mount. The lion kingdom wasn't happy about the servo lids being glued on, the glued TPU hinges, the TPU tensioners. TPU doesn't stretch like a rubber band & it doesn't stick to CA. There were a lot of good clamshells & techniques for a 3D printed pterodactyle. The mane obstacle continues to be renting enough space to store it.
Posted by Jack Crossfire | Sep 30, 2021 @ 10:02 PM | 15,649 Views
So 8.7 miles with the latest motor rewinding sucked a whopping 190mAh/mile. Solid core 26 AWG might actually be more efficient than quad 32 AWG. The best explanation lions have is the skin effect. In a high frequency PWM application, skin effect causes more resistance as wire diameter decreases. Laminated quad 32 AWG has 4 times more surface area than solid core 26 AWG, so the quad 32 AWG would have a lot more resistance than solid core 26 AWG. You'd think it would matter more for kilometers of wire & megahertz than a motor winding.

It's become clear that the motor encoder is getting knocked out of alignment & the reason probably isn't loose cables snagging it. Lacking any reason, the idea of farstening thermisters to the motors is gaining traction. In 1985, thermisters might have been available in every corner Radio Shack, but in the future they're a little hard to come by.

Today's repair work was a failure of the happy meal controller to charge anymore. It had salt water damage around the battery management chip, so the latest clamshell still isn't repelling water.
Posted by Jack Crossfire | Sep 30, 2021 @ 02:33 AM | 19,832 Views
After 3 miles with the locknut motor plates, the right motor let out the magic smoke. It manifested itself as a loss of torque despite accurate commutation. There was no evidence of the encoder failing, the locknuts getting loose, a stall, or debris. The motor just stopped providing torque & overheated after successfully ascending part of a hill.

Decided to rewind it over the next 4 hours & see if the problem happened again. Sadly, the 32 AWG got tangled. If 32 AWG gets tangled, the only solution is to cut it off & throw it away. It can't be untangled. Ended up doing 2 of the fields in the last of the 26 AWG & ordered another spool of 26 AWG since there is going to be a lot of magic smoke.

What's probably going to happen is a switch back to self tappers. There was no evidence of the locknuts causing the failure, but they were the only explanation. The best explanation is the rebuild was slightly off, causing the encoder to miss just enough to suck more power but not stall. The overheating would have caused the motor to stall before burning up, with self tappers. The locknuts allowed it to overheat without stalling until it died.

Chinese direct drive motors don't have these problems because their sensors are epoxied into solid steel & their motor mounts are solid steel to suck away any heat.
Posted by Jack Crossfire | Sep 28, 2021 @ 11:38 PM | 26,178 Views
It occurred to the lion kingdom that the use of self tappers as load bearing farsteners has been a disaster of biblical proportions. The latest thinking was to use captive 4-40 locknuts & hot glue to farsten the locknuts. The new motor module still managed to have acceptible tolerances with the .8mm nozzle.

The hot glue actually seemed to work. If it got in the way, it managed to be compliant enough for the screw to not push it out. The captive nut walls are still too thick. The nuts aren't going to break PLA. It's going to compress.

The mane unknowns are if the 4-40 bolts are going to stay on as well as the self tappers did & if the motor will find another way to stall when it overheats or if it'll just destroy itself.
Posted by Jack Crossfire | Sep 26, 2021 @ 03:59 PM | 31,131 Views
The answer is yes. Running a swamp cooler hydrated the TPU. It's not an internet myth. Swamp coolers, bathroom exhaust, & rain storms destroy TPU. If TPU absorbs water, it makes structurally weak prints. You can get away with baking it in an oven & storing it outside, but best results are going to require food dehydrators & enclosing the printer.

The lion kingdom is keen on making a dehydrator out of a peltier cooler & heat sink. A peltier cooler is seen as a more useful heater than a resistor, since the cold side can extract water. In this case, all the air in the filament chamber would be recirculating over the heat sink with the goal of manetaining a certain temperature. If the chamber is too hot, the peltier shuts down. If the chamber is too cold, the peltier turns on. The only fresh air comes from the cold side of the peltier junction. If the cold side is above a desired temperature, no new air enters. If the peltier junction is below a desired temperature, new air enters.

The theory is this system gives off heat on the outside of the chamber. There could also be a way to switch between outside & inside air for cooling the heat sink. It requires both temperature & humidity measurement. A dehydrator isn't as efficient at making water as a water generator though. A dehydrator has to be concerned with the humidity of its exhaust while the water generator doesn't care about the humidity of its exhaust.
Posted by Jack Crossfire | Sep 25, 2021 @ 10:23 PM | 27,259 Views
The lion kingdom couldn't even print the same exact tire without something going wrong. The pancake tire was as soft as sponge while the lofted tire was a brick. The slicer put slightly more material into the lofted tire, despite failing to print sections. The lofted tire also had less curved sections. It's strange because the pancaked offroad tires were as hard as rocks. Another theory is the filament was more hydrated in the pancake tire.
Posted by Jack Crossfire | Sep 24, 2021 @ 03:56 PM | 18,592 Views
After continued motor overheating, the latest theory is the motor wiring is getting snared in the encoder, causing the motor to stall. It's a tangled mess after many rebuilds. The right tire, right wheel, motor cover, motor plate all need to be reprinted. It needs to be rebuilt, with the cable untangled. It's a several day job. The short term solution is keeping the wires under tension so they don't flop into the encoder.

The CAD model doesn't show any obvious way for a cable to get into the encoder. The cables are on the outside of the TPU.
Posted by Jack Crossfire | Sep 22, 2021 @ 08:11 PM | 25,280 Views
Heat sinks went in on


May 20 & worked well for a few months. Then came another case of a screw coming loose, the encoder going out of alignment, & the motor stalling. It quickly overheated & melted the PLA, feeding back into the stall. The heat sink was initially only slightly warm. The good news is the heat sink quickly got hot. It definitely took out some heat. The motor cooled down more quickly than it did without it.

The lion kingdom stopped using PETG because it's heavier than PLA & it requires enormous heat to print. The melted PLA has never permanently killed it. What's really needed is a screwdriver which can tighten the screws in the field. Those screwdrivers are gigantic.
Posted by Jack Crossfire | Sep 20, 2021 @ 09:55 PM | 15,960 Views
There is a plan forming to replace the current fleet of 3 cell batteries with 4 cell batteries of varying size. There would be 1Ah, 3Ah & a 4Ah. 4 cells are believed to have more range per Ah than 3 cells. The mane reason for a 1Ah is for trips under 2 miles. It's a lot easier to lug around a 1Ah than a 4Ah. There's still a desire to use a phone for 1 more mile. It would be charging the traction battery in USB host mode or it would have a direct battery connector soldered in. A phone equals a 4cell of 660mAh.

No matter what, the voltage is going up to 16.8. It takes a lot of volts to run a direct drive motor.

It should be noted the lion kingdom tried rubbing the electrodes together from a battery which was discharged all the way to 0.5V. There was rubbing lithium on graphite, lithium on lithium, & graphite on graphite. They never exploded or got hot. Part of the trick is it was all the way at 0.5V. Big clive had the electrodes burst into flames, but his may have been only down to 3V.

The experimentation on Lipos that abounded 15 years ago is no more. Even electroboom never bothered with lipos. Sometimes, it's not the danger as much as the fad.