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I am using this gimbal motor.

picture of gimbal motor

I need to know what size screws do I need to use. I am developing egg and a frame that has 5 mm thick walls, and based on the chart I know I need to use 4m screws. I want to know how much longer do I need to make the screws to perfectly fit this motor. I need help with this because I do not want to buy the wrong size screws and then have to buy more because I don't want them to be so short with a camera or far off mid-flight or I don't want them too long to short them.

Here's a picture of the chart I'm referencing to may provide some further help.

reference chart

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  • $\begingroup$ How long to make the screws fit into what? $\endgroup$
    – ifconfig ♦
    Oct 27, 2020 at 18:13
  • $\begingroup$ Into the all eight mount holes $\endgroup$
    – Terrel Ross
    Oct 27, 2020 at 20:32
  • $\begingroup$ Also, what's a 4M screw? $\endgroup$
    – ifconfig ♦
    Oct 27, 2020 at 21:35
  • $\begingroup$ None of those pictures have depth information for the holes. $\endgroup$
    – ifconfig ♦
    Oct 27, 2020 at 21:36
  • $\begingroup$ That diagram is saying there are 4 M3 threads. If you have a hacksaw and file you could just buy something too long like M3x20 screws and cut them down. $\endgroup$
    – PeterJ
    Oct 28, 2020 at 1:14

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4-M3 means that you need four screws (on each side), each with a metric M3 thread. M3 is 3mm diameter.

The length of the screw obviously depends on the thickness of the thing you're bolting the motor to, plus a little for the base of the motor.

The amount of bolt in the motor is important. Obviously you need at least a couple of mm so that it grips, and there's another couple of mm of clearance, but any more and it'll touch the coils. It won't stop you spinning the motor by hand but it'll break the insulation on the coils, short the coil to the case and the motor won't work.

So if you're bolting through a 5mm thick frame, order 8mm long M3 screws. They tend to only come in 2mm steps. The length quoted is the specification is the length of the thread, not counting the head.

If you don't fancy cutting and filing a slightly long screw, you can put extra washers under the head.

Also, when ordering screws, you want 'cap head' not 'dome head' or 'countersunk' in order to use the largest possible Allen key. The small ones tend to round off and slip.

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  • $\begingroup$ Thank you so much I now have the confidence to order the screws $\endgroup$
    – Terrel Ross
    Oct 28, 2020 at 19:17

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