Preflight prop screw check

[tonydeli7]

Hello,everybody. I am thinking of checking if the prop screws are tight enough. No reason,just checking.
But if I tighten them,the thread locker will be gone and I'll need to reapply it? Or is it ok?

 

[rehkram]

Careful - too tight and you can break the plastic edge of the dished area of the prop boss that the screw head sits in. I found two blades with half-moon chunks out of the boss edge after I went through an OCD screw-tightening phase.

Dji should ship "the world's tiniest torque wrench" to go with "the world's tiniest screwdriver".

I don't know whether retorquing the screws affects the Dji magic thread locker goop, but would guess it probably might.

 

[old man mavic]

the screws should just be nipped tight the surface area of the bottom of the part that the blade fits on will give a friction lock and that combined with the thread lock should keep everything in place ,with regards to damaging the props it is impossible to to damage the props as the screws will only tighten down till the thread ends, the damage you talk about is caused when the head of the screw has not gone into the dished part of the prop, because it was not going in straight and caught on the edge ,it is very easy to do this and care is required when changing them

 

[rehkram]

Not so. I know how to not cross-thread tiny screws. The design, metal on plastic, is the problem. The screws will, in fact, tighten down until the plastic breaks.

 

[tonydeli7]

Thanks you all for the info,I will check/tighten them later today!

 

[old man mavic]

Not so. I know how to not cross-thread tiny screws. The design, metal on plastic, is the problem. The screws will, in fact, tighten down until the plastic breaks.

hello my friend exactly which screws are you talking about here ,i would hate for us to be disagreeing about different screws
have you looked at the prop holding screws close up my friend, the length of the unthreaded part is slightly longer than the depth of the prop which means no matter how much it is tightened up it cannot tighten down on the plastic and break it,as far as metal on plastic is concerned the screw is metal the motor is metal ,so where does the plastic come in

 

[rehkram]

Hmmm... since you're clearly sure of what you're saying you've now got me thinking.

I'll dig out the third party screws involved from my parts tray and compare. I'm now wondering if the screws were either a) slightly countersink heads, and/or b) otherwise different to the Dji screws (longer thread / no shoulder). I'll post a close-up photo later showing the Dji alongside the third party screws, and details of which third party props they were.

 

[old man mavic]

Hmmm... since you're clearly sure of what you're saying you've now got me thinking.

I'll dig out the third party screws involved from my parts tray and compare. I'm now wondering if the screws were either a) slightly countersink heads, and/or b) otherwise different to the Dji screws (longer thread / no shoulder). I'll post a close-up photo later showing the Dji alongside the third party screws, and details of which third party props they were.

that would be interesting i am sure we can resolve the problem thanks for your reply

 

[rehkram]

Apologies I intended to get this completed today but farm issues intervened. I've had time this evening to dig out the saved prop blades and screws and have a quick look so here are some preliminary findings.

Note that the screws I've looked at are a mix of Dji & third party; I did not store them separately, and have not separated them out yet. I have 19 used screws, and 14 used prop blades.

I need to check them with calipers tomorrow to attempt to separate the Dji- and TP (third party) machine screws. There are differences but they are very subtle. I have new, unopened sets of both screws I can measure to get a baseline that I hope will allow me to identify the used ones as OEM or TP

o All the saved screws' heads are flat on top, flat underneath, with no countersink
o All appear to have the same length unthreaded portion
o I think I see some screws have a minutely longer threaded portion
o Checking the screw gauges will need calipers to be sure but I think some are slimmer
o I'm pretty sure the more petite screws are the Djis, having worked with Djis during the last prop change, specifically shorter thread, smaller gauge

 

[Deleted member 103366]

A very late response but if the kosher screws had a shoulder length that was less than the depth of the prop hub's bore the prop hub would be pinched between the underside of the screw head and the top of the motor. This would prevent the prop from swinging freely on its pivot.

 

[rehkram]

It's been a while since this originally came up but, suffice to say, my bottom line since this event has been to always use Dji replacement blades and screws and stay away from cheaper vendor offerings on amazon, etc. Haven't had a prop catastrophe since, so far.

You would need a microscope to be sure. I actually use a microscope on a regular basis, counting bacteria. I have zero desire to spend even more time peering into the scope than I already do, trying to figure out minute differences between OEM- and 3rd party screws

 

[m80116]

I am wondering wth is going with all this screw(ing) craze... I only removed the ones on my Mini twice, and always reused them.

They're tight (the tiniest amount reasonable) and the AC never fell from the skies.