by smarter controller do you mean "driver"?
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The Engine Whisperer - fixer of things

LOL, This driver is always out of control! Some of the better car radios have 'anti-spin' control that ramps up the speed over a few seconds. There is also an in-line widget I saw that connects between the reciever and the ESC that does the same thing.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Dammit that thing's scary! I hope my thin steel scoop can cope with that!
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( •_•)

( •_•)>⌐■-■

(⌐■_■)

YEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH

lol i think that was a paradox
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

I performed a 'right side up' weapon test at the arena yesterday and while it worked OK, It showed up a few design problems. Starting the weapon up at full speed spins the rest of the bot around 360 degrees, which is cool to watch but not so good for controlability. It seems I will have to spin up at the start of a match and just keep the weapon going the whole time.

Once the disk is at full speed there is no vibration and in the arena the sound is far less deafening than on my test bench; it seems that everything is balanced and the the bearings are working even better than expected.

I measured the current to the brushless motor and at full speed it is only drawing 6A. That means the battery, controller and motor will barely get warm during a match, but I could have saved weight by using a smaller motor and batttery. The battery is good for about 27A (short term) and the motor can run at 20A comfortably.

Slash is shaping up to be the beetleweight 'Totally Offensive' . Next up is wiring the Scorpion controller and the receiver to complete the project.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

I finished Slash last night and gave it a test run in the basement. On a smooth concrete floor it had WAY too much weapon backlash and far too little wheel traction. When the weapon was spun up, the entire bot would spin in the opposite direction and it didn't stop spinning until the weapon was stopped . In the Marayong arena, a spin up only caused a single 360 spin, but it looks like the weapon has to be toned down and grippier wheels used.

By coincidence, the B16 motors and smaller rubber wheels finally arrived and might just save the day. The rubber seems to stick better than the original foam wheels and the smaller size will lower the back of the chassis and level out the weapon.

If that doesn't work, I will have to reduce the battery voltage and use a smaller or slower motor; at the current disk RPM, its acting more like a saw than a kinetic transfer weapon. I would change the pulley ratios, except I am already on the largest reduction available.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Slash did OK in the full arena test; rather than spinning continuously, it spun around2 to 4 times and then settled down. Driving was difficult but not impossible with the weapon spinning and it had a surprising amount of pushing power for something so small. One possible reason the driving was poor is that the large rear wheels are tilting the disk about 10 deg. off horizontal, which might be adding some gyro forces .

The blade is spinning too fast to transfer any kinetic energy and just acts as a saw - I figure it's RPM is 3.5 to 4K rpm. I am increasing the gearing ratio from 4.2:1 down to 6:1 and also getting a slower brushless motor, which should reduce the rpm to around 2.5K rpm. With a lower maximum speed and possibly a slightly slower spin-up time, the backlash body spin should be eliminated and the driving will be better.

I weighed Slash today and it's only 8 grams over weight. That's excellent, as I will be saving around 30 grams just by swapping to the B16 drive motors.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Personally i do not think the prob is motors too fast, i think the design of the disc is that the teeth r far too small to be honest to get a good enough bite at the reqwuired rpm.

I bet u if u simply get a nice Phat bar on slash instead of that disc and tried it out it would be pretty nasty. Hell u may as well try it out if it could prevent getting all them other fancy stuff like new motor etc.

If u have any spare beetleweight stuff from redoing stuff and changing stuff u wanna sell also id be interested
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Andrew Welch, Team Unconventional Robotics

quote:

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Originally posted by Nick:

The blade is spinning too fast to transfer any kinetic energy and just acts as a saw - I figure it's RPM is 3.5 to 4K rpm. I am increasing the gearing ratio from 4.2:1 down to 6:1 and also getting a slower brushless motor, which should reduce the rpm to around 2.5K rpm. .

---

ha ha, see nick. thats two against one. now u ,ust use a nar.


Seriously though dude, the teeth on that disc r very small and at that speed no wonder its diong nothing.

Make it a PROPER mini totally offensive with a PHAT bar and i bet u anything therewill be a huge difference and itll grab and tear nicely.
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Andrew Welch, Team Unconventional Robotics

was it just me or was that last post totally illegible

what where you hitting with it anyway
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

A spinning bar at the RPM will also give it more chance to flip it self over from it's own energy. The disc will cause more gyro forces to keep it from tipping over as much during impacts. Just speed limit the weapon to a RPM where it damages effectively, will save you a bit on battery power too.
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https://www.halfdonethings.com/

Yeah, Andrew has been sniffing too much printer's ink from his english study guide !

I take the point though and while I don't want to dial the weapon back that far, I am going for a "tri bar" made from the remains of the badly cut disk. Its basicaly the three spokes minus the rim and has 1.5 times the mass of a straight bar. I already spent an hour or two grinding it into shape, so its the next thing to try.

I pulled apart the dud LiPo battery pack and it looks really easy to rewire the other packs down from a four cell to a three cell configuration. The B16 motors will like 11.1V and the lower voltage will give the weapon motor a slower start up time to reduce the backlash spin. It would be much easier to solve the problem electronically rather than via machining, so I will give that a go first...
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Check out Maddox's little antweight.
http://home.hccnet.nl/h.bouwens/TEST.AVI

75watt brushless motor and the little shell spins at 13K rpm..... All within 150g....
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https://www.halfdonethings.com/

WOW cool