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3D RoboticsPermalink Reply by Chris Anderson on October 1, 2011 at 8:27am

Thanks for the update on this. I assume you've brought this to Jdrones' attention? Most people use the smaller 850 motors, which seem to be fine (I've heard no reports of problems), but I hope you've shared this with them.

 

The DIY Drones store sources its own motors, although they look similar. No issues so far there.

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Permalink Reply by Greg on October 1, 2011 at 4:43pm

Chris: Yes I have started a dialogue with Jani at jDrones. I mainly wanted to alert others to check their 880Kvs carefully for any loose shaft grub screws or issues like mine where there is two screws tapped on one side of the motor. This causes undue vibration and higher risk of failure due the imbalance resulting. It may also create enough vibration noise translated down the frame motor support arm to make the APM work harder to correct the axis affeceted.

Thank you for the tip on the motors. I was not aware they are from different OEMs. I assumed the AC2836_358_880Kv motors sold by jDrones were the same as the ones sold on the DIYdrones store. I selected the 880Kv with 12x4.5 prop as I assumed both motors and arducopter kits are closely tied to the default values in the code. i.e while understanding the system architecture I did not have to make too many PID ajustments. Also I wanted a heavier lift quad. I might try some other 840 or 880-Kvs from the diydrones store while I wait for my Axi motors to arrive. I am building a new hexacopter to get away from motor single points of failure :-)

Thanks again for the feedback

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Permalink Reply by Kristian on October 8, 2011 at 8:33am

Hi Greg! If I understand you correct, you are building a new hexacopter to avoid disaster if one motor fails. To get redundancy you need a Y6 or octocopter(8 motors). From what I have read, a hexacopter will not be able to stabilize itself in the event of a motor/esc failure. I'm planning to build a Y6 instead of hexa, because these are redundant. Please correct me if I'm wrong.

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Permalink Reply by James Roney on October 1, 2011 at 9:51am

Shesh, and I thought I had rotten luck.  Hope you have better success.

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Permalink Reply by Greg on October 1, 2011 at 8:46pm

James: I am hoping for better luck soon on the motor front.

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Permalink Reply by Anis Nielsen on October 1, 2011 at 9:18pm

Hi Greg ; Im a 100% new to this and i only know those 880kv motors on my HEXA, from jdrones;  I've got what i think is a quite real fresh batch (end of august)

 

Also, i wanted to send you some good vibes, and some good echos from these; Can't be possible i took them all ;)

 

Until now, i've flown around 10x 10-12 minutes like a newbie (thottle up and down like a drunk monkey)

Esc warm a bit, lipo ok, motors a bit hot to my taste after a 10min run but as i don't have any previous experience with any rc motors and im not sure my props are 100% correctly balanced , i can't say if its not good ; But at least they made it until here;

 

I notice from time to time, i can hear a bit more "motor crunching" , but not always ; I hope its just a question of using them a bit to get them to their final mechanically constrained configuration and being sure its correctly leveled and Cog'd each time

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Permalink Reply by Greg on October 2, 2011 at 2:05am

Good to know your getting more flight time out of the 880Kv motors.  I should have built a hexa to start with to cope with the odd motor problem  Like you I just received a fresh batch (Early Sept).

I have used two out of the 4 new ones I purchased  last month. One is ok the other is the one in the photo with a two holes drilled and tapped on the top of the motor.  I have the other two in reserve.

 

I have my arducopter quad fixed again today.  I definitely advise balancing the props and watching out for the alloy prop mounts that come with the 880Kv's motors. There not that well made.  Some have oval rather than round holes where the prop shaft goes through the main body.  I bought some others that look identical to the ones you get with the 880Kv's and these are off a higher quality alloy and machining.   Any vibration you can remove helps with stabilizing the copter.

 

I am planing to switch motors soon to AXi's once their manufacturing picks up.  There in short supply at the moment.  Also I am determined to get a few flights out of the 880Kv's and learn more about tuning the software before going more experimental.

 

I would love to know what that motor clicking / crunching is on the 880Kv's.  I hear this again and again despite replacing the motors. The QA issues with these motors is a concern.  I found another interesting problem last night on one of the new bunch motors which I suspect is in the others to a lesser degree.  The coating on the armature is inconsistent and I found two hard lumps sticking out which has been catching on the magnets in the outer spinning casing.  Some other motors I have found loose pieces of metal left over from the machining process.  The worst example was a 3mm round chunk in the armature wiring just waiting to short something out.

I believe the metal chucnk came from when the lower motor mount holes were drilled.  Its common and you need to debur the holes drilled in alloy.  In mass produced motors like these there are bound to be some which are not cleaned up properly before wiring is completed.

 

Thank you for the encouraging news on the motors you have been testing.

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Permalink Reply by James Roney on October 5, 2011 at 4:22am

Are the motors in the picture above re-branded rc-timer motors?

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Permalink Reply by Greg on October 5, 2011 at 4:34am

James I really do not know. They are the 880Kv motors sold by jDrones  This company have their own OEM motor supplier. 

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Permalink Reply by James Roney on October 5, 2011 at 4:35am

http://www.ebay.com/itm/New-RC-Timer-BC2836-9-880KV-Outrunner-Brush...

 

Check the link.

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Permalink Reply by Greg on October 8, 2011 at 5:58am

Well guys I must be having some bad luck this month or there is some quality issues with the latest batch of 880Kv motors from jDrones.  I had another one of the new motors I just put in my quad feel like it was seizing up after a good flight on 2.0.45.   I removed the motor today and found a similar problem to my last post in that the shaft has moved.  This time it causd the "C" clip to rub against the motor mount.  I checked my ast two new motors this afternoon and one is catching on something inside the motor (have not even powered this up yet) and the other which I have installed in my arducopter. the shaft grub screw was not tight on the shaft.  

 

I have sent a detailed report off to JDrones earlier this week. With some more photos.  So just in case you have some new 880Kv's recently, might be worth checking the small grub screw holding the shaft is tight :-)

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Permalink Reply by arashi on October 8, 2011 at 12:45pm

@colbym, They are very similar to these:

 

2830-14 750KV With 40cm Cable Outrunner Brushless Motor Free Mounts

 

BC2836-9 With 40cm Cable 880KV Outrunner Brushless Motor

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