Percy’s New Wheels

There is a little progress each evening toward re-wheeling and re-motoring Percy. The old wheels proved remarkably robust when it came time to disassemble them. Assembled with one of the red LocTites, the only way to get them apart was to break the plastic centres. It was a savage evening!

I printed new centres, and then found the orientation for the axles that makes the two slots line up. I want to avoid solder on the steel tyres this time, and so, I’m using a shorting wire that makes a mechanical connection by being trapped in a groove against the tyre and axle.

Things were going swimmingly until I tried mounting some of these wheels on the axles. Two were nowhere near perpendicular to the axle for some reason, and a third was so badly out of quarter, it completely crushed the key. It was at that time that I decided to take a break and start the printer going for a new set of wheel centres. Maybe tomorrow I will have skills!

#percy #wheels

Bike Corpses

#bikes #corpes #bicycles #thieves #frenchriviera #parking #urban #target #wheels #cobblestones
#photography #blackandwhitephotography #bnwphotography #photos #streetphotography #photos #urbanphotography
#jlbouzou

Pretend engineering

Before we proceed to make a decision about the best path forward for attaching wheels to axles here in North Vancouver, I have one more round of experiments to share. I still believe that a keyed wheel will be superior in holding onto the axle compared to any sort of a glue bond, but the first key I tried was only .008″ (0.2mm) of plastic, which nobody should expect to be strong.

It turns out that my hacksaw blade makes a .029″ slot, and so I devised one more experiment with a key of that width. This time, the axle included an isolated central core, effectively bringing the experiments on split axles together with those on wheels. The results are encouraging, and indeed the plastic key improves the performance not only of the wheel, but of the split axle as well:

Let’s summarize the findings of all the experiments from the past month:

While soldering the wheel to the axle clearly makes the best joint with the axle, it also far out-strips the performance of the split axle itself. I’ve not (yet) devised a method to hold the axle together with the same strength. However, these joints only need to be as strong as the maximum of the torque delivered by the motor to the gearbox and the joint between the final gear and the axle.

I was unable to find the original specs for either motor. However, I was able to find specs for Maxon 12mm motors, which are similar. These range from 2.88 to 4.12 mNm of torque. At the output end of a 28:1 gearbox, that corresponds to no more than 115 mNm.

The options for mounting the final gear to the axle are more open than for mounting the wheels; I don’t recall what exactly I used. I could use Loctite 271, which according to the spec sheet would result in a 4700 mNm failure point. Even Loctite 242 would yield a 2300 mNm joint. According to my experiments, mounting the final gear with CA would yield a 106 mNm joint that ranges over 70 to 135 mNm and is therefore likely to break before the motor stalls.

If the mechanism jams due to derailment or a dropped connecting rod, we would prefer the motor to stall, rather than compromising the future running of the locomotive by breaking one of the glued joints. For a 12mm motor and 28:1 gearbox as with #622, that means the following:

• Loctite 242 or 271, but not 290 for assembling the final gear to the axle.
• A good epoxy bond and a plain split axle (this is the failure)
• Either a soldered or a .029″ keyed joint with the wheel

#10 sports a 12×24 motor and a High Level Kits 120:1 gearbox. The output torque from this combination could be as high as 494 mNm, which is well beyond any of the joints tested, with the possible exception of solder. I shall have to come up with a plan before fixing that engine.

#10 #622 #percy #wheels

Neues Live-Album von Fink: Wheels Turn Beneath My Feet II

#fink #album #review #rezension #music #livemusic #wheels #live

Rezension: https://music-on-net.de/fink-wheels-turn-beneath-my-feet-ii-rezension/

At first we thought it was the Smart Appliances that led the #rebellion. No one saw it coming, but the clues were all there…
Later we realised, we were so wrong.
It was not the #machines with minds that betrayed us - looking back, the true source of the technological #revolution should have been so obvious.

But we didn't realise until the #wheels had well and truly turned against us.

#CanveyIsland #TellingStories #Estuary
#Southend #free #photography

Wheels for free-threaded Python now available for psutil

https://gmpy.dev/blog/2025/wheels-for-free-threaded-python-now-available-in-psutil

#HackerNews #Wheels #psutil #Python #FreeThreaded #Development #OpenSource