Props for F450 (APC / Gem Fan / stock)

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fredor

Member
abonto said:
One more question though. How do you balance the DJI stock prop or the new 1038, it has that flat hole that will only fit the DJI motor. I bought the Dubro balancer. I would appreciate all your thoughts on this. :)
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Turn that side around so that the flat part is against the prop as the original mold for the prop will be almost exact
 

D

Dewster

Member
When thinking about prop: Think about what you lose if one breaks in flight. APC prop take a beating, flex and are very cheap. DJI props certainly look stronger in the comparison, but have had a past history of self destructing in flight. I had a full carbon fiber Gemfan blade snap at the hub during flight. Besides almost causing property damage, my craft was wrecked. Graupners may be expensive, but they are reliable. APCs are reliable and cheap, especially if you want to thrash around your craft. Props may be the cheapest part of your craft, but could cost you a lot if they fail. Be careful when adding glue, or boring props to fit your motors. A hairline fracture is all it takes to send your craft into the ground.
 

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FourFiveOh

New Member
mrbonk said:
Correct, but it still needs to be corrected in order to eliminate vibration. Doesn't matter *why* it's out of balance, unless the hole is also not perpendicular to the plane of the prop (as the video points out).
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In fact, it does matter *why*. The "out of balance" is either from a bad prop design or the prop shaft hole not being centered in the hub. The plastic changing density in different areas or interior voids in the plastic mold are unlikely. Chances are the mold for the prop was done based on a cad drawing and cut with a precision milling machine. Most likely is that the prop shaft hole was drilled without the prop being centered in the drilling jig.

If you go with the problem being the prop shaft hole, there's no amount of modification that you can do to correct the problem. It is more than a balance problem, it is an asymmetrical problem. This can cause harmonics problems as well as vibrations, which in turn can lead to failure. I'm not saying that this is always the problem with an out of balance prop, just that if you suspect this problem then it's better to go with another prop. Cheap insurance.
 
Last edited by a moderator:

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fredor

Member
FourFiveOh said:
In fact, it does matter *why*. The "out of balance" is either from a bad prop design or the prop shaft hole not being centered in the hub. The plastic changing density in different areas or interior voids in the plastic mold are unlikely. Chances are the mold for the prop was done based on a cad drawing and cut with a precision milling machine. Most likely is that the prop shaft hole was drilled without the prop being centered in the drilling jig.

If you go with the problem being the prop shaft hole, there's no amount of modification that you can do to correct the problem. It is more than a balance problem, it is an asymmetrical problem. This can cause harmonics problems as well as vibrations, which in turn can lead to failure. I'm not saying that this is always the problem with an out of balance prop, just that if you suspect this problem then it's better to go with another prop. Cheap insurance.
Click to expand...

I find it hard to believe that in a mass production setup the prop would be in a position that allowed movement
 



M

mrbonk

Member
fredor said:
I find it hard to believe that in a mass production setup the prop would be in a position that allowed movement
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Same. I think that's incredibly unlikely. Far more likely that a user would attempt to ream the prop and get it wrong, resulting in an off centre hole. I've seen that waaaaay too many times at the field :)
 

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