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Sep 15, 2019, 06:16 AM
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Dantiel's Avatar
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Gralha Azul


Hey folks,

i got a CNC machine to working and am finally able to cut carbon underwater, which works pretty fine and easier as i thought. Just that i need to let it run suuuperslow, because otherwise drills will break or stepper motors cannot keep up messing up the result and also breaking drills... etc. My plan is to make a bigger bird but i made this one resembling a small blue jay as a test using very cheap plastic gears. Sadly the maiden flight showed the model has some deficiencies: Gears get stripped, are not running free enough, 6A ESC may be a bit small for 1811 brusless motor, plus in the end wings and their amplitude may be smaller than optimal for 2s 180mah lipo.

Theres video of some maiden flights without and with body from extra cloth:
Blue Jay Maiden flight (2 min 30 sec)
Last edited by Dantiel; Sep 15, 2019 at 03:58 PM.
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Sep 15, 2019, 06:30 PM
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Are you using regular end mills or diamond bits? I suspect diamond would work a lot better for carbon fiber. I know it does for drilling small holes. I used to use regular drill bits, but they get dull quickly and then cut very slowly (if at all). Lately I've been using one of the pointy diamond bits from the set of 30 you can get cheap on ebay, and it's still going strong after over 100 holes. The cylindrical bits from that set should be good for routing shapes from carbon panels.
Sep 15, 2019, 10:50 PM
DIY Mania from Taiwan
Quote:
Originally Posted by Dantiel
Hey folks,

i got a CNC machine to working and am finally able to cut carbon underwater, which works pretty fine and easier as i thought. Just that i need to let it run suuuperslow, because otherwise drills will break or stepper motors cannot keep up messing up the result and also breaking drills... etc. My plan is to make a bigger bird but i made this one resembling a small blue jay as a test using very cheap plastic gears. Sadly the maiden flight showed the model has some deficiencies: Gears get stripped, are not running free enough, 6A ESC may be a bit small for 1811 brusless motor, plus in the end wings and their amplitude may be smaller than optimal for 2s 180mah lipo.

Theres video of some maiden flights without and with body from extra cloth: https://youtu.be/GoY3lMWp7gQ
nice job my friend.
Sam
Sep 16, 2019, 12:13 AM
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therealthing691's Avatar
great work
Sep 16, 2019, 10:03 PM
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Dantiel's Avatar
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thanks @realthing @samwei

@decutree
Quote:
Lately I've been using one of the pointy diamond bits from the set of 30 you can get cheap on ebay, and it's still going strong after over 100 holes.
in the it is saying its for nails?? im not sure.. might also be i set some parameters wrong in the program... maybe i need a stronger motor? because the motor is getting slower with more feed until it cannot keep up.

then, i fixed some parts in the model and made sure the gears may run without distraction and it can finally fly very high, the tiny motor is a bit incredible. but then gears stripping... need to rebuild the model or replace the gearing.
Oct 09, 2019, 04:36 AM
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Dantiel's Avatar
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Carbon cutting is still very slow, i found the diamont bits break more easily than other bits, but it may also be faulty fine-settings in my program.
Also the bird performs much better after i made the mechanism more rigid and smooth.

There is a new video, however power is still low, hence the bird usually cannot return to flapping from gliding.

Blue Jay Flights (14 min 17 sec)
Oct 09, 2019, 10:22 AM
Registered User
Sorry, I didn't see your Sep 16 post until now. I'm still working on my overly elaborate feathered wings, which need one or two holes drilled in each feather shaft to string them together. Each wing has 10 primaries, 19 secondaries, and two covert feathers for most of them, so it's quite a lot of holes

Your CNC steppers are definitely strong enough if you're breaking bits, but if the spindle motor is slowing down under pressure then a stronger one would probably help.

The diamond bits work better at high speed since they're grinding the carbon into dust, so it could be that your motor is too slow even when it's not overloaded. Do you know what the RPM is?

You could try bypassing the control board and running the motor straight from a higher voltage power supply to spin it faster. But check that it doesn't overheat, especially if it starts slowing down under pressure.
Oct 09, 2019, 02:32 PM
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@dekutree, if you're able to make feathered wings that is big. still they'll probably lack the microscopic surface structure of real feathers although it be interesting if that can be printed. maybe 3d printing feathers structure onto a woven membrane, creating a reinforced cloth.

thanks you for the explanation about diamond bits. youre right. probably ill need another spindle motor... current has 7000rpm and description said it was made feasible for metal. but there was also a virus on driver installion cd haha


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