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We are doing a quadcopter project and we are at the stage of building the vehicle. However due to lack of attention, the screw holes of the Brushless Motors (Emax CF2822) we bought do not align with the holes which are placed on the Quadcopter Frame (F450). Only one of the holes align and it is not enough to stabilize them.

This is one of the arms of the quadcopter frame:

enter image description here

I pointed out to one of the screw holes.

Here below you can see the motor I use and one of the screw holes:

enter image description here

Below is what I experience with my setup:

enter image description here

As it is obvious from the picture, the screw holes of the motor do not align with the ones on the frame, therefore I can only mount one screw whereas I need to mount four of them.

Other than buying a new frame, I wanted to find alternative methods to mount these motors. I thought about using Silicone and then mounting the motors on top of the silicone. How can I solve this problem?

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  • $\begingroup$ Uploaded a picture, sorry for the lack of information. $\endgroup$
    – kucar
    Feb 10, 2022 at 21:46
  • $\begingroup$ you could make an adapter plate ... you could also drill more holes ... there is not enough information though ... do you really think that you provided adequate information by posting only one picture that has the view of the arm covered by the motor? $\endgroup$
    – jsotola
    Feb 10, 2022 at 22:21
  • $\begingroup$ I thought I did, but it seems like I was mistaken. Uploaded new photos, hope it sheds some light on what I am experiencing. $\endgroup$
    – kucar
    Feb 11, 2022 at 14:43
  • $\begingroup$ The easiest, cheapest, most straightforward way to fix this is to design and 3D print an adapter plate that mates with the motor and with the frame. One bolt pattern matches the motor, you'd mount to the motor first, and then another bolt pattern or extrusions to mate with the slots on the frame and you'd attach that way. The other quality alternative is to send the quadcopter arms out to a machine shop and have them drill your holes to get the motor bolt pattern in the frame directly. $\endgroup$
    – Chuck ♦
    Feb 11, 2022 at 15:08
  • $\begingroup$ Any attempt at drilling this yourself WILL wind up with the motors off-center. Any attempt at gluing the motors WILL wind up with the motors off-center and also with an unbalanced frame. This is not something you're going to fix by hand. Redesign and re-print the frame, have an adapter made, or have the frame professionally modified. $\endgroup$
    – Chuck ♦
    Feb 11, 2022 at 15:08

1 Answer 1

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As people suggested in comments, you have limited options.

  • Replace the motors to fit the frame
  • Replace the frame to fit the motors
  • Design an adaptor plate
  • Modify the existing frame

Replacing the frame or motors

The first two options just require shopping, so don't need addressing here.

Pros

  • You get exactly what you need for your project Cons
  • Cost

Design an adaptor plate

Designing an adaptor plate should not be difficult, if you have engineering drawings for the motor and frame..

Cons

  • Short run bespoke manufacturing can be expensive
  • Adds weight, of the plate, and of the extra bolts
  • Changes the position of the motor and thus the centre of gravity of the craft.

Modify the existing frame

This can be further subdivided into DIY and professional modifications.

Pros

  • If done correctly, would not change the position of the motor Cons
  • It changes the design of the frame, it removes weight, but may alter the stiffness of the frame, and many more dynamic parameters, such as torsional strength, which would require Finite element analysis to fully assess
  • If these arems are not as solid as they appear, modification may not be an option, and this may not be apparent until making the first hole

DIY

If you are skilled with precision machining, and have equipment like a pillar drill or CNC machine, you could modify the arms yourself.

Cons

  • Mistakes at this stage may turn your frame into scrap, or even worse, could store up hidden problems for the future

Professional modification

This will require similar design work to designing an adaptor plate

Cons

  • Short run bespoke manufacturing can be expensive

If at first...

Finally, if one of these techniques doesn't work, you can always move on to another. For instance, if you have the budget to buy another frame if you botch a modification, then that is a less risky option. Do not underestimate the potential cost of taking the cheaper option though.

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