S800 evo + zenmuse z15 vibrating / shaking like crazy

gottabebrett

gottabebrett

Member
I am trying to figure out what I am doing wrong, (see video) I have no idea why the Zenmuse and everything is shaking so badly (you can visually see the zenmuse and batteries wobbling like wild). The footage is unusable until I figure this out. Any tips would be greatly appreciated! My setup: S800 EVO, Wookong M, Zenmuse Z15N, (2) 6000mah batteries, 5.8 GHZ FPV downlink, 5.8 GHZ rx for flight controls, 2.4 GHZ rx for Zenmuse, IMU mounted on IMU bracket (but has also been mounted on hex core itself, no difference in vibration).http://www.youtube.com/watch?v=BlD2Fpr9oTU&feature=c4-overview&list=UUHzMg_w6HcAPlrpMv2gLLBA
 

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boranup

Member
Brett I noticed similar on my craft, after getting the retracts working though it was no longer an issue but I will fly again today to check - I would expect the top assembly to vibrate but not the bottom - look forward to getting to the bottom of it all!!
 

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boranup

Member
Brett I think I have the issue in hand - need to check how easily the props can move under centrifugal force to the correct position - one of my front arms is very tight and it didnt line up exactly where it should and the shudder was evident. Stopped the motors and aligned and was then good to go shudder was gone - I think the props may be a little too tight - will do some further investigation on this but was clear that it was causing the issue.
 

gottabebrett

gottabebrett

Member
great, thanks! let me know how it goes! I have never balanced the props OR motors, is that necessary? and if so, do you know where I can find how to do it?
 


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boranup

Member
This is definitely your problem I was able to recreate it several times yesterday - I have a video somewhere showing how much it vibrates - it is not like a typical prop or motor vibration which are usually high frequency small movement - what you and I have or had are very large vibrations. Balancing the props and motors is something we should all do and will only make your video better - but to get rid of this vibration the cause is how tight your foldable props are.

I reckon at least two of your props (an individual half) is actually quite firm to rotate. If you align them as best you can and just idle up watch the metal clamp and they should spin almost vibration free. Then stop motors, put the blades out of whack and idle up again you should see the vibration - the metal clamp no longer keeps a perfect vircle and the vibration is very aggressive
 

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boranup

Member
Brett here is the video

As you can see on one of my flights I had the same problem as you before I realised what the cause was.
 
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ddikie

Member
Tightening the props on an Evo needs to be quite precise due to the folding mechanism..the actual bolts holding the props need to be at about 4 NM pressure..thats not a lot..and should allow the props to find there own alignment with the centrifugal force...its the other 2 bolts holding the metal plate to the motor housing which retaines the props in place that needs to be tighter..its also a very good idea to use tokens on the bolt heads and inspect as part of your pre flight check list.
 

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Louis O'Dwyer

Skydiver
ddikie said:
Tightening the props on an Evo needs to be quite precise due to the folding mechanism..the actual bolts holding the props need to be at about 4 NM pressure..thats not a lot..and should allow the props to find there own alignment with the centrifugal force...its the other 2 bolts holding the metal plate to the motor housing which retaines the props in place that needs to be tighter..its also a very good idea to use tokens on the bolt heads and inspect as part of your pre flight check list.
Click to expand...

Hi Richard,

How does one measure 4NM? And what do you mean by "tokens" on the bolt heads?
Would you use loctite on them?
My EVO props had some sort of white paint on the bolts.. (before I had my minor accident :)
Now I have probably tightened them too much, they are quite stiff... I haven't flown it yet, trying to sort out an issue with an ESC, might have to replace it..
 

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boranup

Member
U need a torque wrench to measure the NM of force applied to tighten

Tokens or markings to see if any of the bolts have loosened - similar as the Evo's come from the factory - the white paint markings

Definitely need loctite - medium strength

DJI website says:


The key point is the props need to be loose enough to aligned during rotation
 

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Louis O'Dwyer

Skydiver
boranup said:
U need a torque wrench to measure the NM of force applied to tighten

Tokens or markings to see if any of the bolts have loosened - similar as the Evo's come from the factory - the white paint markings

Definitely need loctite - medium strength

DJI website says:


The key point is the props need to be loose enough to aligned during rotation
Click to expand...

Thanks for your prompt reply! I think I asked you another question on some other thread, can't remember which one, but here is the question anyway (not related to this thread):
I had a slight accident with my S800 EVO (my own stupidity, I won't go into it), but I had to replace three arms.
With the EVO arms/ESC/motors, you need to un-solder the motor from the ESC, and the ESC from the arm.
I replaced all three and when I power up, I get the tones, but the LED (red one) underneath the arm flashes intermittently. I think I may have damaged the ESC with the soldering process, by heating it too much (the original soldering on the board is very hard and heat resistant).
Do you have any ideas about checking the ESC's on an S800 EVO?
Many thanks,
Louis
 

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Topflight

Member
My experience with prop vibration mirrors what has been said here. My EVO flies pretty smoothly, but I was curious to see if centrifugal force would put the props in the proper position on their own, so I purposely off set the props, then spooled up the motors while on the ground. The one arm that I misaligned the prop on vibrated like crazy. The prop was still out of alignment when I stopped and visualized. Right now I just visually align the props, but I'm going to try and loosen them up a little to see if they will then align themselves. While on the S800 EVO subject, I'm flying 5.24, so far no issues. Has anyone gone to the latest (5.26) and are you satisfied with it? I also noticed that on the vibration kit, that a couple of the arms don't make contact with the top of the blue rubber damper devices. Some are just misaligned (which I think I can adjust) but two of them are not even touching the arm. Can post picture if not explaining this well enough. Check yours and see. It looks like the top piece of the blue damper is supposed to rest into the hole in the screw under the arm. Anyone know where to purchase torque wrench for the purpose of tightening the props?
 

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boranup

Member
Hey Topflight post a pic mate so we can see exactly what you are talking about - I will check mine and report back.

Torque wrenches of the requirement can often be found at cycle shops - I dont have one yet but Im thinking its going to be more of the feel of the props and using enough/correct loctite rather that pressure. Im not 100% comfortable of the uniformity of the blade thickness at the connection point at the moment.
 

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Topflight

Member

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Topflight

Member
boranup said:
Topflight none of my arms touch the top of the the blue absorbers and in flight these obviously compress downwards away from the arms - having them actually make contact would be undesired I would think.

They are all fairly consistent in their distance from the arms and I make sure the blocks align as per page 17
http://download.dji-innovations.com/downloads/s800evo/en/S800_EVO_User_Manual_v1.04_en.pdf
Click to expand...

There is a little metal protrusion out of the blue absorbers that fits into the hole in the screw above it on the underside of the arm. 4 of the 6 absorbers are in the hole on my bird. Not sure, but I would think that as your flying, the arms would want to pull up and away from the absorbers. What you think?
 
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boranup

Member
Hi Topflight mine are all about 3mm from touching them and when I lift the S800 they are even further - that is with the Z15 and GH2 plus the 2 lipos mounted

The only time these would ever touch is maybe on a heavy landing - as long as the blocks are aligned Im not sure the aligning of the bolts matters as they aren't designed to touch?

Thats my logic anyway mate not sure or cant see what else could be going on there - but I will pay some close attention next time and will mount a gopro to check it out during flight sometime this weekend.
 

gottabebrett

gottabebrett

Member
Thanks, boranup. I think my problem is slightly more embarrassing. I don't understand gains and I had them all way too high (170-200). I started reducing them and immediately see the vibration getting less and less and less. Does that seem about right? I am just such a beginner to this stuff. What gains do you use AND did you mount the IMU on the IMU bracket like I did (because they said to further reduce the gains if so).
boranup said:
This is definitely your problem I was able to recreate it several times yesterday - I have a video somewhere showing how much it vibrates - it is not like a typical prop or motor vibration which are usually high frequency small movement - what you and I have or had are very large vibrations. Balancing the props and motors is something we should all do and will only make your video better - but to get rid of this vibration the cause is how tight your foldable props are.

I reckon at least two of your props (an individual half) is actually quite firm to rotate. If you align them as best you can and just idle up watch the metal clamp and they should spin almost vibration free. Then stop motors, put the blades out of whack and idle up again you should see the vibration - the metal clamp no longer keeps a perfect vircle and the vibration is very aggressive
Click to expand...
 

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boranup

Member
My gains with two 5050 lipos and GH2 Zenmuse are around the 170 and 130 mark - this gives me quite smooth flying and makes the craft far less twitchy. I agree the gains may be a cause to your vibrations and you need to dial these in but the 'shudder' I see in your Zenmuse is the same that I had and it was caused by misaligned props as my gains havent changed. My IMU is mounted on the landing gear on the supplied tray

To have a pre flight check list is a good thing or a solid routine that you stick to regardless of how much of a rush you are in to fly. not only are these things dangerous they are expensive - sound consistent practice is your best bet for enjoyable flight experiences
 

gottabebrett

gottabebrett

Member
I'm still fighting vibration on my video, I am going to try loosening my props so that they can spin more freely via centrifugal force (per boranup's suggestion). Has anyone balanced these folding props? Do we need to? And if so, how the heck do we balance these puppies??!
 

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