Hello Everyone,
I'll start by introducing myself. This is my first post to the community but have been following for quite some time now and have been following the progression of multicopters over the last many years. I recently found the time to finally jump in and build my own multicopter.
The amount and quality of work that this community has put in to the project is flat out amazing. What an awesome group of products. So thanks to all of you who put in the work to make this what it is. I hope as soon as my life settles down, I'll find time to contribute some to some niche of the project with my diverse background.
Anyway, on to the questions. I'm hoping someone may be able to provide a little guidance.
I purchaced the JDrones hexacopter kit (very cool kit and creative design) to have a proven platform for my first copter. I have a Du-Bro prop balancer and before flying, began to balance the 12x45 EPP props from JDrones. They were easy to get into horizontal balance, but it would appear to me that the hubs are very unevenly balanced. No matter what position I put the props in, they would fall perfectly horizontal with one (the same) side facing down. Even adding generous CA to the hub didnt remedy the unbalance. Does anyone have any experience balancing these? Is it just the way they are made, or is there something obvious that I am doing wrong? Does anyone have any other prop suggestions? I saw that APC has a 12x3.8 counterrotating set, are these appropriate?
With the props mounted and balanced (as good as I can get), there is only slightly more vibration in the system than running the motors without the props, so I assume they are satisfactory. Has anyone determined a rough way to quantify what "too much vibration" is? While I've only flown once for about ten minutes, the copter flies great. But during bench testing, I noticed that three of my six motors are very rough to rotate, almost as if the bearings are bad. I'd compare the noise they make (during manual turning) to spinning a skateboard wheel with bad bearings, kind of rough and gritty part way through a revolution. Furthermore, sometimes these motors hesitate to start, often jittering at low throttle before spooling up.
I'm wondering if anyone has has problems like this with these motors? Any ideas on potential causes? Bad batch from the factory? Upon close examination of the motors, they look to have been "deburred" poorly, several burrs holding on from machining in the top and bottom vent areas. It would appear as if the quality control at the factory is rough. Any similar experiences? Remendys? Are the motors salvageable, or at this point should I just be looking into high end motors?
Regardless, I'm anxious to get these problems properly resolved and get to some flying and testing. Thanks in advance for any advice. Looking forward to being a part of this community.
Replies
It looks like on our latest batch there were some rotten eggs on the basket. This is first time we ever seen so "many" problematic motors and I can say that we are working hard to keep motor quality as high as possible.
We already informed our factory and discussed with them about quality issues we have seen on this thread. Measures we took already to avoid any future problems with these motors are: we created another layer of check procedures before they are even shipped out to jDrones. Out factory also changed ball bearing supplier for our motors.
To make sure that everything goes better in future, we will visit the factory on next month to check their new procedures and QA lines.
Again my deepest apologies on this QA failure. People who have problems with their motors, I suggest to contact jDrones directly with jDrones contact form, give your order number and explain your problem, send as small video that shows running them and we are happy to replace those rotten eggs for you.
As in all hardware projects replacements are something that just happens sometimes even thou no matter what you do. Our general QA level is really high compared to many others and I am happy about it. Till now our general replacement level has been around 0.05% of all shipped motors/esc. I would say that it is rather good and I would like to keep it that way and make it even smaller as time goes.
We are also working to create set of highend motors. ETA this year. Will post more information about that later.
Regards,
Jani
I am using 750kv motors + 10x4.7 APC.
My copter has a lot of power and the flight time is about 20-25min with a quadro, 2800mAh and 1,3kg.
How long can your 12x3,8 APC quad fly?
1. occasional metal shavings and rough burring in the casing. I removed a small circular piece of metal in the windings on one motor.
2. Variability in magnet strength between motors;
3. Wiring issues, one motor burnt out on first start and another stalled 40 seconds in flight and caused my quad to crash.
4. Some spin with a little more noisy than others.
5. The prop mounts do not align properly.
For your first question. I found the hole in the centre of the lower prop flange varies depending on batch. If you pull the shaft up into the countersunk lower mount flange keeping it centred before mounting the prop and then carefully tighten the spinner it will level better against the prop and reduce the vibration. I am currently looking at alternative motors like the Pulso and Axi brands. I preferred the more robust prop mount and higher precision prop shaft. Dont get me wrong the 880KV is made to a price point so there is bound to be a few odd ones and issues like you describe.
The 880 Kv arducopter motors themselves do vary a little in the quality of finish and I have wondered if my recent crash due to motor failure may have resulted from a looose metal shaving like the one I found in another motor a few weeks ago. The motor still works but it occassionaly cuts out. It sounds awefull like its grinding something up inside.
There still a good general purpose motor but if your looking for less vibration I would suggest the pulso or AXi. The latter is quite expensive but reports show they are a popular choice for more stable platforms for professional filming.
I can comment on the 12x3.8s from APC. Nice props. These are what I'm using on a quad at the moment after trying just about all of the cheapies (I think RCTimers were the worst- brittle and very unbalanced). I don't think you'll be disappointed in a set of the APCs..