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Prop Balance Vibration?
882 35 2018-3-30
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Pilot H
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So, a very basic question, but after getting inconsistent answers, I figure I'll make a post and ask. Could unbalanced OEM DJI props that are unbalanced cause lots of vibration which could lead to stress cracks? I've noticed stress cracks developing again on my P3S, I plan to ship it out to CA tomorrow. Round 2 of support work. Should I balance my OEM DJI props to minimize any vibrations which coud lead to stress cracks under the motors?
2018-3-30
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Labroides
Captain
Flight distance : 9991457 ft
Australia
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DJI already go to a lot of trouble to ensure their props are balanced.  Your cracking is due to poor materials or moulding technique in the plastic used for the shell.
2018-3-30
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Hellsgate
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Yes unbalanced props could cause severe vibrations and could lead to cracks in the arms of the drone.
Should you balance them? Well first you need to confirm that they or at least one of them is unbalanced.
If you already have cracks in your drone then i certainly would not attempt to fly again until you get it repaired.
2018-3-30
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Hellsgate
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If you suspect your props maybe faulty i would just buy a new set they are not that expensive.
2018-3-30
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Pilot H
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Labroides Posted at 2018-3-30 17:37
DJI already go to a lot of trouble to ensure their props are balanced.  Your cracking is due to poor materials or moulding technique in the plastic used for the shell.

That's what I assumed, but I was just curious.

Only the calmest of weather and prettiest of flights to you!

Pilot H.
2018-3-30
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Pilot H
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Hellsgate Posted at 2018-3-30 17:41
Yes unbalanced props could cause severe vibrations and could lead to cracks in the arms of the drone.
Should you balance them? Well first you need to confirm that they or at least one of them is unbalanced.
If you already have cracks in your drone then i certainly would not attempt to fly again until you get it repaired.

Yeah, shipping it off to the CA center tomorrow, also, total rookie question, what's the easiest way to check my probs for balance, and if they are unbalanced what's the easiest way to balance them?
2018-3-30
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Hellsgate
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You can do a search on ebay for prop balancers or you could have a go at making your own from the examples on ebay.
If you find a prop is unbalanced then you will need to remove some material from the heavy end of the prop this is usually done using an extremly fine sand paper.
Usually i believe the very tip of the blade is sanded back a bit to achieve balance dont sand the leading or trailing edges of the prop.
2018-3-30
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Pilot H
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Hellsgate Posted at 2018-3-30 18:06
You can do a search on ebay for prop balancers or you could have a go at making your own from the examples on ebay.
If you find a prop is unbalanced then you will need to remove some material from the heavy end of the prop this is usually done using an extremly fine sand paper.
Usually i believe the very tip of the blade is sanded back a bit to achieve balance dont sand the leading or trailing edges of the prop.

Alrighty, I'll look into it. Thanks for all the help!

Only the calmest of weather and prettiest of flights to you!

Pilot H
2018-3-30
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Bashy
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Watch videos on YT to see how its not, not so sure ive seen it taken from the tip of the blade as yet though?
2018-3-30
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Texas-Mark
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Labroides Posted at 2018-3-30 17:37
DJI already go to a lot of trouble to ensure their props are balanced.  

I'm going to disagree with this.  I have a prop balancer and have found some brand new props to be dead on and others to be significantly unbalanced.  

Of course if you hit anything (even just grass) with the props, there is a good chance they will become unbalanced.  Whether it is enough to cause excessive vibration, I don't know as I keep mine balanced.
2018-3-30
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Hellsgate
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Bashy Posted at 2018-3-30 19:55
Watch videos on YT to see how its not, not so sure ive seen it taken from the tip of the blade as yet though?

I may be wrong about it but from previous experience prop balancing was always done from the very tip of the blade..
Im no expert in this field and certainly dont know the science behind it but only going on what ive been told and experienced myself.
After trimming a cple of hedges with previous drones in the past i asked the same questions the op is and i was also told to not touch leading or trailing edges except to smooth out any rough spots, but for balancing it should be taken off the tip. They did give some big long explanation about the aerodynamics of the prop being effected in a bad way and the debate lasted for weeks as to which is the best way to do it untill an aeronautical engineer jumped in and said to only smooth out the edges and balance from the tip.
So that is what i have done ever since and has worked for me very well.
Luckily (touch wood) ive not had to touch my dji props at all
2018-3-31
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Pilot H
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Bashy Posted at 2018-3-30 19:55
Watch videos on YT to see how its not, not so sure ive seen it taken from the tip of the blade as yet though?

I'll hit the forums and Youtube looking around. Thanks, have a good one.

Only the calmest of days and prettiest of flights to you!

Pilot H.
2018-3-31
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Bashy
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Hellsgate Posted at 2018-3-31 01:22
I may be wrong about it but from previous experience prop balancing was always done from the very tip of the blade..
Im no expert in this field and certainly dont know the science behind it but only going on what ive been told and experienced myself.
After trimming a cple of hedges with previous drones in the past i asked the same questions the op is and i was also told to not touch leading or trailing edges except to smooth out any rough spots, but for balancing it should be taken off the tip. They did give some big long explanation about the aerodynamics of the prop being effected in a bad way and the debate lasted for weeks as to which is the best way to do it untill an aeronautical engineer jumped in and said to only smooth out the edges and balance from the tip.

I was just going by all the videos i have watched and its a quite few, because i was trying to find one for the P4P quick release blade balancing, theres some that will add a strip of tape and others that will use some glue or varnish and some that will sand some of the blade, the amount that you actually remove is small enough that it will not do any noticeable harm to the blade.  I have just seen a few where the add a little nail polish to the tips (just watched some i hadnt seen yet before i answered your reply) but not removing from the tips as yet. The way it looks is that some do it one way, others do it another way.

Horizon Hobby at 7:40 show to sand the blade


2018-3-31
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Hellsgate
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Bashy Posted at 2018-3-31 20:49
I was just going by all the videos i have watched and its a quite few, because i was trying to find one for the P4P quick release blade balancing, theres some that will add a strip of tape and others that will use some glue or varnish and some that will sand some of the blade, the amount that you actually remove is small enough that it will not do any noticeable harm to the blade.  I have just seen a few where the add a little nail polish to the tips (just watched some i hadnt seen yet before i answered your reply) but not removing from the tips as yet. The way it looks is that some do it one way, others do it another way.

Horizon Hobby at 7:40 show to sand the blade

I guess it comes down to personal preference maybe it makes no difference how its done.Maybe the guy that explained it to us was wrong in his explanation. But i did note he didnt take any of the leading or trailing edges which i think may be the point that was explained to us.
2018-3-31
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DJI Susan
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It is not recommended to fly the drone if there is any crack in the motor. If you encounter any difficulties during the repair progress, feel free to contact us with the case number, we'll be here for help.
2018-4-1
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Pilot H
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DJI Susan Posted at 2018-4-1 23:08
It is not recommended to fly the drone if there is any crack in the motor. If you encounter any difficulties during the repair progress, feel free to contact us with the case number, we'll be here for help.

Thank you DJI Susan, I should have it to my local shipping outlet within a day or two, it's packed and ready to head out to Cerritos.

Happy Easter and have a great week

Pilot H
2018-4-2
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DJI Susan
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Pilot H Posted at 2018-4-2 13:49
Thank you DJI Susan, I should have it to my local shipping outlet within a day or two, it's packed and ready to head out to Cerritos.

Happy Easter and have a great week

The same to you. Wish you get the drone back in the air soon.
2018-4-3
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Amateur Droner
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Stick with DJI props, save yourself a lot of headache, and sanding/gluing. I have the same prop balancer (DU-BRO Tru-Spin Prop Balancer),  and check all my props.
I tried the after market  (cheap) props, and had to spend way too much time balancing around 80% of them needed balancing.
Time is money.
2018-4-4
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solentlife
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Hellsgate Posted at 2018-3-30 18:06
You can do a search on ebay for prop balancers or you could have a go at making your own from the examples on ebay.
If you find a prop is unbalanced then you will need to remove some material from the heavy end of the prop this is usually done using an extremly fine sand paper.
Usually i believe the very tip of the blade is sanded back a bit to achieve balance dont sand the leading or trailing edges of the prop.


DuBro or the ODay balancer is the best for DJI props as the hub is closed one end. Typical balancers need shaft hole open both sides.

As to balancing a prop - if you just sand the tip - then you can alter the aerodynamic of the blade ... not a good idea. What is best is to run the fine grade sandpaper along the back of the heavy blade for its length - that way you maintain the overall pattern of the blade.

Nigel
2018-4-5
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Hellsgate
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Well lucky i havent had to do one on my p4p so all good.
But i do understand were your coming from.
As i mentioned before the debate was a few years ago and lasted quit a few weeks with many peeps putting forth different ways to do it, i kinda sat back and watched it unfold, i was very new to the world of drones at the time.
But when this one guy popped up then the debate stopped so i assumed he was correct obviously not.
Never even thought about googling it lol. Your never to old to learn something new.
2018-4-5
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solentlife
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Been balancing props for over 55yrs ...... and I was taught to take care not to alter blade form.

The guidelines given to me over the years :

1. Use the back of blade to correct by lengthwise sanding to lessen .... or add lacquer along back to make light blade heavier.
2. A combo of the lighten / increase is perfectly acceptable to avoid too much work on one blade.
3. Clear tape folded over leading edge and joined at Trailing edge ... excess sliced away is better than excessive 1 + 2
4. Never sand or increase front of blade

Heli blades are best by tape folded over leading edge and joined at trailing edge ... sharp knife along T/E to remove excess.

Folding blades - bolt blades together and then balance as normal.

Nigel
2018-4-5
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Pilot H
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solentlife Posted at 2018-4-5 08:45
Been balancing props for over 55yrs ...... and I was taught to take care not to alter blade form.

The guidelines given to me over the years :

Thanks for the tips! I'll have to check my prop's balance when the Phantom gets back from CA.

Only the calmest of weather and prettiest of flights to you.

Pilot H
2018-4-5
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repairman
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yes,check balance on all props.yes excess vibration causes cracks in airframe.
2018-4-9
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Pilot H
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repairman Posted at 2018-4-9 07:42
yes,check balance on all props.yes excess vibration causes cracks in airframe.

Thanks, I'll check them when the Phantom gets back from CA from service.


Only the calmest of weather and prettiest of flights to you!

Pilot H
2018-4-9
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ArgenBrewer
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solentlife Posted at 2018-4-5 08:45
Been balancing props for over 55yrs ...... and I was taught to take care not to alter blade form.

The guidelines given to me over the years :

Hello, can I ask you if you can post a picture of how you put the adhesive tape for better illustration? Thank you
2018-4-9
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repairman
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Pilot H Posted at 2018-4-9 10:57
Thanks, I'll check them when the Phantom gets back from CA from service.

yea waiting on good weather here to. it has been windy,rainy
2018-4-10
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solentlife
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ArgenBrewer Posted at 2018-4-9 17:49
Hello, can I ask you if you can post a picture of how you put the adhesive tape for better illustration? Thank you

I'll try ... not easy !

Description :

Take a piece of tape of length 2x the width of blade. Place prop in balancer and then place tape on edge of lightest blade moving it along till blade balances. Note the position.

Take a new piece of tape longer than 2x width and place end overhanging trailing edge, then carefully smooth tape fwd to leading edge .. folding it round and back to trailing edge. close the two ends together. Take sharp knife and slice of the excess. The tape joint needs to be at trailing edge of blade.

check balance again.

Nigel
2018-4-10
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sSkyPilot
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Hi, I've seen the topic before. To id what going on. Weigh eack prop. Inspect ea. for flash... use a emery board to shape. A large nail on a pin with athe prop base on may reveal something. Last resort a prop balancer sold by most model airplane shops. Cheers
2018-4-10
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Texas-Mark
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I think some of these suggestions are over-complicating things.  I use the scotch tape method but don't wrap it around the prop. For these plastic props, I just cut a small piece and stick it on the bottom of the light side. Never had it peel off or anything. Takes about 30 seconds to balance a prop. I do use one of the prop balancers made for the Phantom props.
2018-4-10
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Bashy
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I have just recently balanced all 4 full sets of my p4p quick release, i did buy just the rod for the quick release props with the idea of using a glass, then decided to buy the oday one, they dont come with the tip of the quick release props so glad i already bought it, i do not have any fine dining glasses so none of mine are perfectly uniform, i realised this when i checked all the props again on the oday, it also turns out that the oday is not very good on precision work, so, i have found the sweet spot on the glass (took a while) and use that in combination with the oday, more so for the hub balancing.


I used the super glue method (note to self: get some activator) using this method i was able to repair one of the props that had a wee nick in it from hitting the ceiling of that small bridge and all probs are finely balanced now
2018-4-10
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solentlife
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The ODay comes with a push on silicon tube for the rod ... that tube is a snug fit for the DJI P3 hub. No need for any other extra.

I have many balancers as I fly many different types of prop / model. I have checked my Oday against them and it comes out as good as and better than some.

As to the tape - yes many only put a sliver on back side of prop ... but wrapping it round the L/E creates a smooth form without any tiny ridge that a small piece on one side alone does.

Nigel
2018-4-10
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Bashy
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solentlife Posted at 2018-4-10 22:38
The ODay comes with a push on silicon tube for the rod ... that tube is a snug fit for the DJI P3 hub. No need for any other extra.

I have many balancers as I fly many different types of prop / model. I have checked my Oday against them and it comes out as good as and better than some.

Not for the P4P props though, well, mine didnt...
2018-4-10
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KedDK
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Bashy Posted at 2018-4-10 23:28
Not for the P4P props though, well, mine didnt...

What was your overall conclusion, do you also see that the balance even not being catastrophic could be improved from factory?
2018-4-11
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solentlife
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Bashy Posted at 2018-4-10 23:28
Not for the P4P props though, well, mine didnt...

mmm some of us are still on old P3 models !!

nigel
2018-4-11
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Pilot H
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solentlife Posted at 2018-4-10 22:38
The ODay comes with a push on silicon tube for the rod ... that tube is a snug fit for the DJI P3 hub. No need for any other extra.

I have many balancers as I fly many different types of prop / model. I have checked my Oday against them and it comes out as good as and better than some.

Right, I'll look into the ODay. This whole thing is a good learning experience for me. Always good to learn more.


Pilot H
2018-4-11
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Bashy
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KedDK Posted at 2018-4-11 02:25
What was your overall conclusion, do you also see that the balance even not being catastrophic could be improved from factory?

Original DJI props from the factory are pretty darn good from the get go, thats not to say they all will be, more so the hub do to some factory finishing...
2018-4-11
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