Difficulty with purchasing drone frames

Question

Recently I purchased the following five inch frame to house my BR2212 2200KV brushless motors from racestar:

The arms of this frame contain slits that are too small for the screws used on the base of my motor. I was under the assumption that drone frames had standards for their sizes e.g. the mounting holes of 5 inch frames would always be Xmm in diameter and evenly spaced along a Ymm PCD. What makes my issue even more bewildering is that the holes on the base of my motor perfectly align with the slits. Were the slits 1mm wider then my motor would have been able to fit on this frame.

My questions are:

a) What is the method for attaching motors onto the slits of those frames? I cannot find anything on Youtube or anywhere on the internet.

b) Is there a standard for the mounting holes on drone frames? I need to know so that I do not purchase another incompatible frame.

Answer 1

There is no 'standard'. Motors are available in a wide range of sizes for different applications. You wouldn't expect to fit a tinywhoop motor or a 10hp giant scale motor on this frame.

Most motors at about this size use M3 bolts. However some slightly smaller ones (such as 1608 motors that used to be common on 250 size quads) use M2. It looks like your frame has both 2mm and 3mm slots, giving you the option of smaller motors.

2212 motors are quite big for a 5" prop / 250mm diagonal frame. 2207 or 2306 is common now, 2204 or 1608 used to be common. So it looks like you're putting large motors on an old frame.

There are a variety of common bolt spacings, and most motors and frames have two slightly different bolt spacings. This increases the chance of being able to use at least 2 bolts, which is adequate for most uses.

4 bolts is better than 2, so I'd drill out the frame to accept M3 bolts. If you have a metal 'X' mount for the motor, you could use that as a guide. You could also use needle files to enlarge the hole. Either way, avoid breathing the carbon dust.