This thread is privately moderated by --Oz--, who may elect to delete unwanted replies.
May 21, 2019, 12:05 AM
Discussion

# Ultimate Acceleration! 0 rpm to 3.2 million rpm in 25ms! 130,000rpm/1ms

Look at the picture, this picture is amazing once you figure out what happened. The "T" in the top left of the picture is the scope trigger point, ball at rest (0 rpm) 25ms later, the ball is at 3.2 million rpm!

EDIT: Here is 0 to 3.4 million RPM in 15ms, thats an average of 227,000 RPM per 1ms (0.001 second)!

EDIT: Here is 0 to 2.1 million RPM in 1ms (0.001 second)!
In 20 pules, it does 0 to 2.1 million plus rpm, 20V, 16Arms (320W) to spin a 0,1g ball
Some math:
1 revolution = 27.65us,
36,170 revolutions per second,
2,170,000 rpm

I always set the vertical cursors to my current record (in microseconds), so I can see when I beat my personal best.
I usually prepare 10~15 balls for testing that day, one day, I got to this one ball, I guess things were just right (ball/container/angle/settings). What happened was amazing and unbelievable, with about ~250W (18V ~13A). First hall sensor trigger, it gave a ~0.25 second burst, I could hear the power supply give a quick 60Hz hum, sucking some juice, then the scope displayed high 2 million rpms! The major keys it was legit was no vibrations and the ball was still spinning down from momentum. I have been running the scope at 10us/div (since going for 2+ mil), but I decided to get the big picture, zoomed out the scope to 100ms/div and set single trigger and tried again, moved the hall sensor into position and it happened again, a burst of around ~250ms then hall stops triggering the coil. I zoom the scope into the end of the coil drive signal, this time just over 3 million in a quarter second! I stopped to think about it, no Ford transmission vib's, just pure signing spinning ball. Blown away I called a friend to witness what happened, I did it 4 more times, the most impressive time was in the picture, it shows 0 rpm to 3.2 million rpm in ~25ms! This is what happens when you pump in~ 250W (1/3HP) to spin a 3mm ball that weighs nothing (~0.11g) AND everything is semi close to optimal. I have seen something similar before during testing, just not starting at 0 rpm, it hit 3.5 mil and 4.1 mil once, but I did not believe it, I did not know what was going on then, so I never posted it.

From my 40+ years playing with motors and racing, I knew the first time I saw 300K rpm on YT that containing the ball was a key instead of letting it thrashing around, efficiently coupling the flux to the ball and timing. 5mm balls were relatively simple, switching to 3mm balls was much tougher to solve. My method works (nylon standoff drilled to let the ball drop in, then contain with with a nylon screw), but by far it is not optimum, I liked that it was low cost, I can prepare a bunch before testing and provides some safety, much more than the 5mm ball spontaneously disassembles with a punch. I have some more ideas, but each one is more \$\$ and more time to develop it.

Here is my 3.3Mrpm video, this is not the ultimate accelerating I am talking about, but it gives my setup.
Last edited by --Oz--; Jun 08, 2021 at 02:57 PM.