Another New Nanoweight...

If Fleaweights are just too big...

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Max
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Re: Another New Nanoweight...

Post by Max » Tue Jan 13, 2015 1:51 pm

Have a look at this page:
http://en.m.wikipedia.org/wiki/Balancin ... ing_masses

Your blade is statically ballanced as you have the centre if gravity on the motor shaft but it is not dynamically ballanced due to the shape of that blade. I think you could fix this by either using a simple rectangular blade or by making matching "teeth" on the other sides of the blade (ie. so that it is symmetrical about its length).
I'm no expert but I think that could be the issue.

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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Tue Jan 13, 2015 6:15 pm

Thanks, you were right Max; the blade was mounted centrally, but at a bit of a tilt. I've corrected the tilt and it's a lot better :) I'll have to bear that in mind for future builds..
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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Tue Jan 13, 2015 10:53 pm

This Nano does not want to work! Tried a 4th motor controller for the spinner, but whilst I was fitting that, something must have shorted out the Lipo and it went pop. The motor controller finally works at least, but now I have nothing to power it with... *sigh*
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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Wed Jan 14, 2015 9:11 pm

All this talk of undercutters being really stable on the Antweight community thread gave me an idea:

Image

Sadly it doesn't look as cool, but it does work so much better. The blade's been shortened by about 5mm so it can fit between the wheels, so that's also helped stability. The big battery is only temporary as I have no more 60mAh ones (it currently weighs 27g)
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AntRoboteer
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Re: Another New Nanoweight...

Post by AntRoboteer » Wed Jan 14, 2015 9:27 pm

I don't know about not looking cool; looks pretty awesome to me!

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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Fri Jan 16, 2015 1:19 am

Alex gave me a spare 60mAh battery to replace the one which blew up. This robot's now more or less finished, I even had just enough weight spare to add a little armour:

Image

I'm pretty pleased with it finally; very stable to drive, still has pretty good power in the blade, and even drives upside down well :)
Rory Mangles - Team Nuts

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NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc

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Shakey
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Re: Another New Nanoweight...

Post by Shakey » Fri Jan 16, 2015 2:25 am

I have the other white wheel sitting next to me :P
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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Fri Jan 16, 2015 12:58 pm

Ooh, that'd be nice :P

Decided to call this one Nibble.
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Max
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Re: Another New Nanoweight...

Post by Max » Fri Jan 16, 2015 1:46 pm

Why are you using a brushed motor for the spinner rather than brushless? I would have assumed brushless would be lighter/more powerful?

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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Fri Jan 16, 2015 4:41 pm

They are, but they are a lot more expensive as well :P it cost me about £18 for Spini's motor and ESC... This was free from a hacked servo and works pretty well :P
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Hogi
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Re: Another New Nanoweight...

Post by Hogi » Sat Jan 17, 2015 9:16 am

that's awesome Rory! nibble is a cool name as well. this is probably the nano that i'm most afraid of figghting, if i can get my one in the cube that is :)
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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Sat Jan 17, 2015 11:44 pm

I dunno; Spinni's pretty nasty now, and if Pete's sorted the reliability issues with his then I'm definitely scared of that one :P
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Max
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Re: Another New Nanoweight...

Post by Max » Mon Jan 19, 2015 6:39 pm

Out of interest how do you go about balancing the blade? Do just just spin it and see which side stops at the bottom and if the same side is always at the bottom file a small bit off that side?

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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Mon Jan 19, 2015 6:57 pm

To drill the hole centrally, I balance the blade on the point of a center punch (or more commonly, a nail), then hit it with a hammer to mark the center of mass. I drill that out, and then balance it on a knife blade lengthways then sideways and see where the blade sits in relation to the center hole. If it's a little off then I just file a bit until it sits spot on in the center.
When the blade's fitted, the weight offset is usually too small to tell by letting it rotates under gravity. However with my single tooth bar designs, I prop them so the single tooth is just touching a surface, so that it makes a noise when spinning up. If the noise gets quieter as vibrations increase, it means the counter weight is too heavy. If it gets louder, the tooth end is too heavy. Very crude, but surprisingly effective.
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NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc

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Rapidrory
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Re: Another New Nanoweight...

Post by Rapidrory » Fri Feb 13, 2015 9:59 am

Well, this happened:

Image

The new Nano drive units arrived, and I wanted to see how they performed on a 2 cell.
As it turns out, pretty well! they have far more speed than you'd ever really want, but they've got pretty decent torque for their size.

Planning on maybe using one split in half to drive Bad Idea; as it stands I only have 15g spare to build Bad Idea's chassis. Since 3 of these motors (if you cut them up) and wheels weighs the same as one gearmotor and polou wheel, then it'll almost double the weight my chassis can be. It would be fine to move, just may not have much pushing power... But it's spinner so if it's pushing it's doing it wrong.

I also might make a fleaweight BullyDozer thing using them, maybe implementing some geared drive to turn some of that speed into useful torque.
Rory Mangles - Team Nuts

Robots: Nuts 2 and many more...

NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc

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