Low down on tightening Graupner 10 x 5 props onto F550 (stock DJI motors)

[ohunt]

Hi Guys,

I've read multiple posts on different forums on whether or not washers (below or above prop)/spacers/locknuts/etc. are required to adequately secure the Graupner 10 x 5 props to the stock DJI motor shaft. The responses have been varied to say the least.

Long story short - If I use the stock nuts with the Graupner 10 x 5's, they do not seem to hold well (I can spin the props on the shaft with some force applied). If I add an 8mm washer under the prop, same thing. I haven't tried placing a 6mm above the prop (will try that later this evening).

The nearest hobby shop builds these units regularly and they never add any washers or spacers and they claim no issues.

Logic would indicate that I am not tightening the stock nuts down enough but I am applying substantial force (I believe) without clamping the motors down.

Perhaps the tolerances on DJI motors/nuts vary from batch to batch?

Any help/perspective/ideas will be greatly appreciated!

- Flustered

 

[kloner]

if you put something under the prop and tighten it and still slips, you just need to tighten it more. the 6mm on top work

this is how the graupner prop adapters are, washer on top and it doesn't even need it for your reason, is just how they are. the raised letters there don't help much. you don't want to overtighten it either, it'll crack it.

This weekend i flew a few flights then went back sunday, spooled it up and heard a squeek, shut it off, turned a prop and the motor didn't move...... almost tried lifting off

 

[ohunt]

Thanks - I will try tightening the nut more with a washer under the prop - the problem with the 6mm washer on top is that it results in less surface area touching the prop.

 

[DesJardins]

The set from gothelirc worked perfect for me "under the prop"
Prop washers for Graupners on DJI motors - (ID 8mm, OD 16mm, thickness 1.7mm)

 

[Kentjjl]

I don't use washers. I fly with the stock nuts and 10 inch groupers no problems.

 

[ohunt]

Thanks for the specs and great picture! Looks like it is a matter of me applying more torque while tightening. (replying to DesJardins)

 

[DesJardins]

Thanks for the specs and great picture! Looks like it is a matter of me applying more torque while tightening. (replying to DesJardins)

Yup, better to be safe!

I've heard the "no washer needed" and then bam down goes a quad...

 

[Razzil]

I was flying over a year not having an issue. Then one day I noticed when I replaced my props, the adapters weren't as tight as before.
Sure enough, they were slipping, I put a washer on the bottom (the adapters stick out a little bit)
Made sure the washer had the extra bit of adapter within, then put a smaller washer on top along with the nut.
I was amazed that I was flying all that while and never had a prop spin out.

 

[bruce365]

Hi ohunt, the graupner props are level with the shoulder between the 8mm dia and threaded part of the shaft. What I have done is counter sink the original DJI aluminium nut with a 90 degree counter sinking tool (if you do not have one you can sharpen a drill and grind the tip so the cutting edges are at 90 degrees to one another). Aluminium is soft so be very carefull, cut the counter sink by hand if you are using a drill just a bit at a time it does not take long. This will allow your nut to rotate another 1/2 or 3/4 of a turn past the shoulder on the motor shaft (approx an extra 0.6mm to 0.9mm) depending on how deep you cut the countersink.
I did this because it saves using a washer, getting a snug fitting washer here was not possible and if the washer is not centrally located it will cause out of balance vibrations.

 

[DesJardins]

The washers I mentioned caused no vibs... Having a counter-sunk nut if you can do so is a better solution for sure though

 

[cwg25]

I have no issues without washers, too. But I'm new to this so I hope it's not a false sense of security I have.

I got 10.5 Graupners from gothelirc.com, they fit nice and snug on my stock DJI motors.

What exactly is the issue for some people? Why is it only an issue for some?

 

[kloner]

if you cup the motor in the tuft of your hand you can move the props..... it gets worse the more there on and off from them letters getting ground down from the nut tightening/loosening. the washers or countersinking both work.....

 

[cwg25]

Thanks for the info. I'll pick some up.

Can anybody provide a link to the exact product?

 

[kloner]

3rd down

http://gothelirc.com/shopdisplayproducts.asp?id=156&cat=Graupner+Props

 

[cwg25]

These ones mention 8 inch props. Can I use these for my 10's as well? Is there a separate washer for the 10's?

 

[DesJardins]

These ones mention 8 inch props. Can I use these for my 10's as well? Is there a separate washer for the 10's?

Those are for any prop that needs more bit, 8's, 9's,10's....etc

 

[kloner]

it is 8cm as in the diameter inside i think is what your seeing

 

[Olemil]

The washers I mentioned caused no vibs... Having a counter-sunk nut if you can do so is a better solution for sure though

Sorry to dig up an old post but figured it was easier than starting yet another one on the same topic. I just received a set of Graupner 10"x5" props and already have the 8mm washers you mentioned from gothelirc. Just wondering if you tried to some what center the washer on the motor shaft (DJI 2212/920kv) for balance purposes or just stuck them under the prop hubs? I found like many others have mentioned the washer id is a bit bigger than the DJI motor shafts and hate to have a balance problem. Thank you. P.S. Thanks for the great YouTube videos you made on setting up the 8FG/Naza system, they were very helpful to me!!!!!

 

[bruce365]

Hi Olemil, Depending on material of the washer, if the washer is steel then I would worry about centering. When balancing motors and props one tends to be very fussy to get it right, it only takes 0.005 grams to make a difference between balance or not at 7000 to 10000 RPM that is why I did a counter sink on the DJI aluminium nuts/spinners. Regards - bruce

 

[Olemil]

Thanks Bruce. I just happened to stumble upon some nice hardened steel washers that are a much better fit than the ones I bought. They are a slight bit larger OD (1mm), same thickness and a slip fit on the DJI motor shafts compared to the ones I mentioned above that are quite sloppy. I checked a few from ID to OD and they seem to be real good on being centered. I might do some experimenting on trying to check balance on them with my DuBro, not sure how that will work. Maybe I'll try to put a small dab of glue between a washer and the prop and balance as an assembly like another member mentioned. I know the best way is to balance the complete assembly including motor but not sure if I am up to that task or not. Thanks again for the info, I really appreciate it!!