Phantom 4 Prop Balance Inconsistency

[jogforfitness]

I recently purchased a DuBro 499 prop balancer to balance/adjust, if necessary, my P4 props. I also purchased the P4 DuBro 3mm balancing rod. To this point I've had difficulty getting consistent balancing results. Sometimes the prop will show balanced. Then, after pulling out, rotating the rod a bit then, reinserting the rod into the same prop and rebalancing the results are often different. I've made a video (link below) displaying some examples. I've called DuBro and they are sending me another balancing rod to see if that makes a difference.

In the meantime can someone whose done this before offer some advice as to what I may be doing wrong (assuming it's not the rod causing the issue)?

Thanks.
Prop balancing inconsistency

 

[Meta4]

DJI props are generally pretty good without any need for balancing.
Have you noticed issues?

 

[jogforfitness]

DJI props are generally pretty good without any need for balancing.
Have you noticed issues?

Trying to do the best I can to reduce vibration and lower the probably of another stress crack. Strictly a preventative measure on my behalf.

 

[N017RW]

Did not watch vid....No air currents in room?

 

[jogforfitness]

Did not watch vid....No air currents in room?

No air currents.

I balanced table with level beforehand and balancing rod was completely inserted into the prop hub each time.

 

[Brockrock]

After watching your video, it's my opinion that that prop is perfectly serviceable as is. If that prop was out of balance to any degree that could be a possible issue, it would have consistently showed this with each testing attempt. That very little bit of 'out of balance' that was seen a few times could be possibly due to a disproportionate quantity of finger oils on the two blades.

I have found that my DJI OEM props have all been near perfect, but if you want to see what an out of balance prop looks like, place a small piece of tape on one of the blades and try it again. I tried this when I got my balancer - just for grins and giggles - and that's when I realized that the DJI OEM props were fairly spot on. But, if you do get one that is not, it will be very obvious.

 

[jogforfitness]

Initially I did put a small strip of scotch tape on the light side of a blade to balance it (not the blade in video)and it worked. It worked until I took the rod out and then reinserted after a slight rod rotation. Then it showed out of balance. Then tried to balance again with 'success' only until the next rod removal and reinsertion. Then it showed out of balance again. At this point I started to realize I was chasing my tail. I have no experience to rebut that this could be oils, etc. Perhaps it is. I thank you for your input!

 

[Brockrock]

Maybe you could try putting the balance rod onto a piece of glass and then roll it to see if it is ever so slightly bent. Also, the common change here that is occurring is the removal and reinsertion of the rod's tip into the prop hub. Perhaps there is a very small burr on the tip that is causing a slight misalignment. Some very fine Emery Paper could make short work of that.

I do understand your frustration as your intention to even get the balancer in the first place was motivated by a sense of precision. Hopefully the new rod they are sending you sorts this out.

 

[jogforfitness]

Well, I've given up trying to balance my props with the DuBro 499 balancer. I just flat out could not achieve consistent results. Each time the balancing rod was inserted into a P4 prop the results were different as explained and displayed in my video above. DuBro sent me a new balancing rod but, the same inconsistent results prevailed. For me, this was a waste of money , time, and energy.

 

[Sprtbkryder]

I do not understand why you are having these problems as I use the same balancer and do not have this issue. I think you may be "over thinking" the process?

 

[jogforfitness]

I don't think so. The process is not complicated. My video shows the inconsistency when balancing a blade, then rechecking. No one has pointed out that I'm doing something wrong....

 

[ussvertigo]

If you had a Phantom 2 you would know what an out of balance prop does on drone. I have the DuBro and since P4 had no need to even check, there's no vibration, legs are lot calmer than mine. The props are that good.

 

[ussvertigo]

Anything shaking when hover in no wind?

 

[Brockrock]

I don't think so. The process is not complicated. My video shows the inconsistency when balancing a blade, then rechecking. No one has pointed out that I'm doing something wrong....

To put your mind at rest though - as I know you were also hoping to rule this out as a reason for shell cracking - you would know if one was grossly out of balance to a point of possibly causing vibration cracks on the shell.

 

[jogforfitness]

Anything shaking when hover in no wind?

Seems okay. I've not seen a prop out of balance to know it's out of balance. When you've owned 2 different Phantoms and both eventually developed stress cracks it's makes me wonder if the props may have been even slightly out of balance to lead to the crack.

 

[RémyHeli]

I'm used to balance heli blades both static and dynamic and I'm familiar with behaviors of balancers and watched your vid.

When you insert the rod it might be not all the time perfectly straight/horizontal/centered, which is causing the variety of behaviors shown in your vid.

Ideally the rod should traverse whole prop with cones on each side to center but we can't with these.

Using simple glass instead balance is very well known alternative which works also.

My answer is that if you got one iteration being in balance then it's all good (as rod nicely position).

Finally P4 props are very well balanced stock and consistent manufacturing batches. DJI is absolutely successful with this manufacturing design.

 

[RémyHeli]

This we can't with P4 props:

 

[ussvertigo]

Seems okay. I've not seen a prop out of balance to know it's out of balance. When you've owned 2 different Phantoms and both eventually developed stress cracks it's makes me wonder if the props may have been even slightly out of balance to lead to the crack.

Hover 6-7 feet in a calm wind and walk up to drone and lightly place a finger on bottom part of leg and see how it feels, then try move props front to back and try again

 

[wa5tef]

I also bought that DU-BRO prop ballancer. I had previously used a mechanical pencil that had a point size that just fit the prop hub. All of my DJI props were in perfect balance. I bought two sets of carbon fiber props and exactly half of them (4) were out of balance. I got my DU-BRO balancer in and repeated the tests on all my props and again, the DJI ones were perfect, even some I had flown several times. The carbon fiber props again exhibited the same ratio of out of balance props. If you have a good mechanical pencil with the proper size point (no lead run out), try that and see if you get the same results.

Good luck!
Jim
WA5TEF

 

[Brockrock]

Seems okay. I've not seen a prop out of balance to know it's out of balance. When you've owned 2 different Phantoms and both eventually developed stress cracks it's makes me wonder if the props may have been even slightly out of balance to lead to the crack.

I forgot to mention this until now, but when I bought my Dubro balancer, I bought this rod to go with it: Amazon.com : Prop Balance Rod - DJI Phantom 4 : Camera & Photo

I don't recall where I read that this is the best rod to purchase for the P4 props, but prior to making the purchase, I did some research, and this was the one. It may have been on Amazon reviews, but not sure. Anyway, it works great, and the fit into the prop hub is perfection...very precise. Maybe give this rod a try prior to scrapping the mission.

A word about shell cracking. When I first began reading about some P4's suffering cracks - like prior Phantoms - I immediately set all of my Gain & Expo setting to lower than default values - particularly 'Braking'. I also rarely use 'Sports' mode, but I set all the Expo setting for both 'P' and 'S' modes to 35. I think the default 'Braking' sensitivity value is less than the maximum possible value, but I set it even lower to whatever 50% is of the spread. I don't recall the actual number. I had to get used to it being less responsive, but now that I am, no issues flying, and I'm sure these values are much better for the motors and shell..