I finally got through most of the configuration issues and was ready to attach the propellers and fly.  There are both the wiki (picture) and text directions for 3D propeller attachment however the aluminum mounts that come with the kit were straightforward and I attached the propeller directly without using any of the plastic rings that came with the kit.  Snugged them down by hand.

When I tried to fly it some of the propellers flew off and/or came loose pretty much instantly. 

I returned to the directions and tried using the plastic rings that came with the blades per the directions  but they don't seem to work--the stock metal mounts already have a collar that sticks up and goes into the indent in the blade so the plastic rings just make matters worse.

Do I just need to crank these things down?  Should I locktite the threads?  I see there is a little hole in the tip--does that fit some special tightening device?

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Yes you should insert the plastic ring so it fits snugly on the thread shaft, then the prop and then the top piece. The hole in the prop top piece is so you can use a small nail and tighten the prop. You need to tighten it till the nail just about bends. It needs to be really tight. I experienced the same problem with my first built. Broke 2 props and lost one of the prop nuts.

Check this link for the instructions.


Merry Christmas and happy flying.

I understand that the directions say to put in the plastic collar but my metal hub has a raised inner ring that is the same size as the ring:

and if I put the plastic ring into the propeller I can't get the hub to clamp down on the propeller:

First the whole assembly needs to be on the motors shaft and you need to tighten with a nail in the hole till the nail almost bends. Then take a picture again.

John, I have the same problem!  I'm using the 880Kv motors and 11x4.7 props supplies from 3D Robotics with my Quad-C.

Last night I put the collar in the back of the prop, balanced it, then slide it onto to the threaded prop shaft when I realized that the last 2mm or so of the shaft are wider than the threads and this prevents the prop from fitting snug against the lower piece.  You show this clearly in your second picture but for fun here's a pic of my setup.

This is a serious problem because that lower piece locks the entire aluminum prop assembly by squeezing the slotted interior of the prop assembly (see below) around the shaft of the motor.  This is a elegantly simple design however it requires constant pressure against that lower piece (from the nut pressing the prop against it) or the prop assembly will fly right off as soon as it spins up.


I think the easiest solution would be to put one or more washers below the prop but the washers would have to fit perfectly over the wider part just below the threads or else you'll have balance problems.

We really need a thinner prop collar that will fit the wider diameter at the base of the prop shaft.  Or better yet a new propeller assembly that will accommodate the collars supplied with the props.

Yes I am admit I am a little reluctant to proceed without some advice from the manufacturer given all the issues folks seem to have with prop attachment on these beasts.  Unfortunately they are out for the week + their response time isn't exactly stellar so looks like this thing isn't going to make its first flight for a while.

Hi John,
Did your prop come with a selection of these plastic propeller inserts, if so this is so that the prop can be used with a selection of prop adapters with differing shaft diameters.
I presume that you have selected the ring that is the tightest fit and then when you slide it down the shaft it is getting stuck on the plain section of shaft below the threaded section.
All you need to do, is file out the centre of the plastic insert very slightly.
You can do this using a round or oval needle file, carefully open out the centre of the plastic insert little by little until it sits down over the small step in the shaft, and the insert sits down snuggly onto the tapered ring that locks down and squeezes the slotted section of the adaptor onto the motor shaft.
Obviously you need to file away as little of the plastic insert as possible, just enough to allow it to slip over the slight lip, but not so much that it is loose, but don't get too hung up about it, when you tighten down the top nut the looseness will get taken up.
Hope I have explained this properly.

I guess I could get out the trusty Dremel and ream it out a little but as you can see that only would buy .5mm(?) beyond just having no plastic collar.  Is it really better with both the collar and the aluminum "ledge" on the shaft?

From this discussion, here are possible reasons for failure:

  • The male threaded section (of the collet) is bottoming out in the spinner nut section before clamping is achieved
  • The collet flutes (slotted section of the lowest piece) are not gripping enough motor shaft
  • The collet flutes shaft hole is incorrect size for the motor shaft
  • The wrong prop hub adapter is being used with combinations of previous points

The prop and hub spacer should have parallel surfaces (once the hub spacer is in the prop hub). When the prop and hub adapter are on the collet (with bottom coned plate), there should be no unthreaded portion of the male threads above the prop hub.

THIS thread shows a problem..

His solution was a washer to take up the unthreaded space to prevent the spinner nut from bottoming out.

I have been pondering a discussion post on the mechanics but the idea has been around before WW2.. really. It is a common machine tool item.

The flutes of the collet (the part with the male threads) must clamp the motor shaft *before* the thread bottoms out in the spinner nut. Also the motor shaft should be inserted to nearly the full depth of the lower collet piece.

There should never be an air gap between the prop and the pressure plates, above or below the prop hub.

When assembled properly, you are affecting two actions - sandwhich-clamping the prop hub between two plates AND gripping the motor shaft with the collet flutes.

I can find no good cross-section drawings of this so it may come to making one for safety education.


Hi John,

As long as you can get the prop to push the tapered locking ring down to secure the prop adapter on to the motorshaft.

It wouldn't matter whether you took the aluminium shoulder away or trimmed the plastic insert. The plastic insert is only to keep the prop centred and take up any slack, have you tried putting the props on without an insert.

Maybe if you try this when you screw it up it might be okay without them. It really depends how close a fit the prop is to the shaft. It might be an exact fit without the inserts.

So without the insert you would achieve both of these objectives with the only downside being that the propeller may be off center by ~ 1 mm.  Carving out the insert would actually achieve three objectives but is somewhat non-reversible.    Maybe I have logged too many hours as a corporate weasel but I don't think I'll actually finalize on a solution until the manufacturer weighs in since theoretically there is some level of guarantee on the kit.


I think I found a solution to the problem of the plastic rings that are a bit too small to fit on the base aluminium collet.

The problem was :

-plastic rings have an internal diameter of 6 mm

-the base of the aluminium collet is 6.3 mm


The obvious solution is thus to enlarge the internal diameter from 6mm to 6.3 mm. How to do this practically ?:

-Take a caliper (vernier). These calipers are usually in metal and have two sliding parts able to measure the distance between two internal parts of an object. What useful is for our purpose is that these metal parts are also quite sharped

-Extend the two metal measuring parts of the caliper inside the plastic ring. It will give you the reading of the internal diameter (6mm)

-Then slide the ring in circles around these metal caliper parts while maintaining the caliper open to the max. Gradually this will scrape the plastic and enlarge the diameter.

-Stop doing this when the measurement reads 6.3mm


That's it! It has worked for assembling my 3DR quadcopter, 880kv. Hope this will help others with this problem.

Happy new year to all,


I followed this procedure and it worked well.  I finished off with a little Dremel reamer bit.  Thanks.   Good idea.

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