Propellers hard to install

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Hi everyone,
On my P3S I've noticed that while the silver propellers are easy to install (they just spin on and then I tighten them a little), the black propellers go on effortlesly about halfway and then they become more difficult to screw on, and I have to manually turn them all the way until the end. I also noticed a small crack inside the hole in one of them.
I got a brand new propellor and installed it, and it went on easily just like the silver ones but when I looked inside it, there was now a crack like the one before.
Is it still safe to fly with these propellors? Why is this happening?
 
No, it isn't safe to fly with props which have a cracked hub - would you drive a car with an obvious crack in a tyre? Replace them before you fly again.
 
Hi everyone,
On my P3S I've noticed that while the silver propellers are easy to install (they just spin on and then I tighten them a little), the black propellers go on effortlesly about halfway and then they become more difficult to screw on, and I have to manually turn them all the way until the end. I also noticed a small crack inside the hole in one of them.
I got a brand new propellor and installed it, and it went on easily just like the silver ones but when I looked inside it, there was now a crack like the one before.
Is it still safe to fly with these propellors? Why is this happening?
I agree that it's not safe to fly with such a prop.

Did the crack on the black replacement propeller appear as a result of you fitting the prop, was it there before, or didn't you notice?

You could either have been supplied with 2 defective props or possibly you have some sort of problem with your motor spindle - a bad thread or maybe a bent shaft. Give it a good close visual inspection. I know you said that the black replacement screwed on nice and easily but it's worth checking all possibilities
 
I can't view these photos. Message is "You do not have permission to view media within this album."

I think you need to alter the permissions or simply attach the photos to your post.
 
Yes, I can now, thanks. I'm not questioning your technical competence, but how do you tighten your props?

The reason I ask is that I've just had a close look at some of my used composite hubs and there is no sign of the 'swarf', (for want of a better word), meaning dark discolouration on the surfaces of the composite threads, which can only come from the threads of the motor shaft. Nor are my threads at all 'mangled', as can be seen particularly in your first photo.

Are you sure that you're not overtightening the props?
 
I only make them hand tight
I don't even need to use the wrench to get them off
 
Also no such thing can be seen on my silver props, which I put on exactly the same as my black ones
1503222448293260818566.jpg
I've been using the above prop since day one
 
I only make them hand tight
I don't even need to use the wrench to get them off
OK - just thought I'd check. Did you buy all your props from the same source? As I said, I have no discolouration on my used ones and if it's not overtightening, then inaccurately dimensioned prop threads (but for blacks only?) is the only other thing I can think of.

Perhaps the thread hole is too short for the motor shaft? I've just measured one of mine and it's about 13.8 mm from the bottom of the thread-hole shoulder to the bottom of the thread hole interior.

Perhaps you could measure yours, both black and silver and see if the silver thread hole is longer?

As an afterthought, the other possibility (assuming there are no defective motor shafts as manufactured) is that the threads on the props have been moulded too far down the thread hole.

In either case the effect would be the same. The top of the motor shaft contacts the end of the hole as you snug the props up, thus pushing back on the threads (and cracking the hub in the process) which would also explain the 'swarf', which you don't have on your silver props.
 
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What did you use to measure it? I'm finding it difficult to measure it accurately. I did find that the distance from the very bottom of the thread hole to the outside is 18mm on both.

I flew for another 8 or so minutes, and the prop that isn't cracked is still ok and the crack didn't worsen in the other one.
 
What did you use to measure it? I'm finding it difficult to measure it accurately. I did find that the distance from the very bottom of the thread hole to the outside is 18mm on both.

I flew for another 8 or so minutes, and the prop that isn't cracked is still ok and the crack didn't worsen in the other one.
I inserted a very thin rod right to the bottom and in the centre of the thread hole, and carefully scribed a mark level with the exterior shoulder of the prop on the rod. I then used a digital micrometer to measure the distance from the end of the rod to my scribed mark.

I've got a P3P though - but with, I believe, the same motors as yours, 2312a's,
 
Yeah all the P3 models have the same motors and props I'm pretty sure.

Still not sure if I'm measuring the right thing but I got 15mm, from the bottom of the hole to the little lip inside just below the very top.
 
Yeah all the P3 models have the same motors and props I'm pretty sure.

Still not sure if I'm measuring the right thing but I got 15mm, from the bottom of the hole to the little lip inside just below the very top.
They didn't actually - P3 Advanced and Pro had an earlier version motor called 2312 fitted initially but this was then replaced with a new version called 2312a. The standard was released later and only ever had the later 2312a motor fitted. But that's immaterial as I am pretty sure our motor versions are the same.

What you need to do is accurately measure (I know it's not easy!) the various dimensions within your prop thread hole. (end of thread to end of hole, beginning of thread to end of hole, etc etc) It seems fairly obvious that the crack (is it visible on the outside too?) is being caused by the top of the motor shaft being screwed in too far and this is supported by the black discolouration on the composite threads as the motor shaft gets screwed onto the threads but is also pushing hard against where the crack appears.

You need to find out why, so measure as best you can all the dimensions within the prop screw hole then do the same measurements on your motor shaft.

One other difference I've noticed between my props and yours is that the bottom of the thread hole on mine is not flat - it tapers, approximately following the contours of the outside of the prop hub. I wonder if that bit of plastic in which the crack has appeared is not actually an integral part of the prop, but merely an extra bit of moulded plastic which was left over after the manufacturing process? Looking at the crack it appears to be hollow beyond the crack (or it wouldn't have cracked, just locked against the motor shaft).

There's only one way to find out and with nothing to lose I would carefully drill out the bit of cracked plastic with a suitable sized drill bit and see what you can see. If it then looks tapered just like mine, then providing you have drilled very, very carefully, your prop should (in theory) still be as strong as mine.

However, as regards the above, if you're not a 'chancer', then I'd recommend binning the props and buying some new ones.
 
I probably won't replace them because I don't want to spend $26 on props just for the same thing to happen again lol DJI 9450 Self-tightening Propellers for Phantom 3
Could you post a photo of your props so I can compare them to mine? I might try drilling it tomorrow when I have more time.
Failing that, I'll call up the store and see if they can do anything about it (replace props or drone perhaps)
Or, would I be fine just flying it as they are? They don't seem to be worsening. Doesn't seem to be too much of a risk

I guess DJI's quality control with the P3S isn't as good as their more expensive drones. I've had no issues like this with my Mavic
 
Yep - I was just trying to get a couple of good shots of a prop for you when you were writing. Had to go outside and it's the best I can do. Here they are:-

DSC08470.JPG DSC08472.JPG
 
questions:
how long has this issue been going on?
Are the props turning in opposite directions when turning freely?
Obviously, if you have installed props b4 with no issue and these are new props, there is something wrong with the black props.
If these are the first props you have installed, you may be forcing them on by turning the wrong way. Black turns opposite from white.
Also, they are self tightening so when it stops free spinning on, just a small budge will do with the "wrench". That keeps them from unwinding when stopping.
 
Are you sure you are buying/getting OEM props?
Knockoffs could be the issue. Package should have a cardboard peg board holder attached to the plastic bag and DJI should be stamped into the blade.
 

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