MegaV Z motor mount screws.

[jginvc]

I just had my Z motor “pop” off and when I take a good look at how it is mounted I am left scratching my head a little. The mounting flanges on the motors is 5mm thick. The spacers you are supposed to use are 1/4”, 6.35mm. So that’s a total of 11.35mm. The screws are M4x12mm. That means the threads only have .63mm to hold! That’s barely 1 turn. How’s this supposed to work?
The mounting plate is 6.5mm thick. So maybe they should be (5+6.35+6.5 = 17.85) M4x16??

[jginvc]

Apr 18, 2020 21:16:01 GMT jginvc said:

I just had my Z motor “pop” off and when I take a good look at how it is mounted I am left scratching my head a little. The mounting flanges on the motors is 5mm thick. The spacers you are supposed to use are 1/4”, 6.35mm. So that’s a total of 11.35mm. The screws are M4x12mm. That means the threads only have .63mm to hold! That’s barely 1 turn. How’s this supposed to work?
The mounting plate is 6.5mm thick. So maybe they should be (5+6.35+6.5 = 17.85) M4x16??

Derrick “mistakenly” says M4x14 and corrects himself to say M4x12 but it looks to me like he is actually using M4x14 by how much they stick out the top.

[Derek the Admin]

You are forgetting that the Z motor mount has a slot pocketed down where it mounts to the top of the X plate.

[billiam]

I don't quite understand your comment Derek.

If the screws, which just pass through the Z motor and spacers into the Z plate threads, are too short to have good thread engagement, what impact does the Z motor mount's pocketed slot have?

[Derek the Admin]

I thought you were talking about where the Z motor mount itself, not the Z motor.

Keep in mind that an M4 nut is about 3mm thick. That's really all you need to hold.

[shockme]

I suspect OP is correct.
I am in the process of building my Mega V- I’d hit a snag at mounting the z motor. I could only get 3 of the M4 12 mm screws cited in the video to engage, the fourth simply would not. I believe the problem is that 12 mm screws are too short for them all to engage simultaneously -
By OP’s measurements, only a fraction of a mm protrudes through the spacer to engage.
Admins response that an M4 nut is 3 mm, suggests that a 14 mm screw is correct as it would have slightly more than 2mm engaged.

Moreover, my kit has a bag of 4 M4 x 14 mm screws (which hopefully I won't need in a future step) whereas the M4 x 12 mm screws were supplied in a bag of 20.

The 14 mm screws worked beautifully, just as easy as in the video, after failing for over an hour with the 12 mm screws.

I’m thinking the video presenter was correct the first time when he said “M4 x 14mm screws”

[mike1332]

Hit a snag here too. The m4 12mm screws are too short. The m4 14mm mentioned first (as a mistake), seems to be the correct option. I am going to install the 14mm as well, and hope that I do not need these later. I will report back after the build. This definetly needs some attention with a correction. First snag so far.

[gofer]

Do yourself a favor and use M4 x 20 with nylock nuts added under the mounting bracket

[mike1332]

I installed the 14mm and it worked perfectly. I should be done with the build tomorrow and i will test everything. Seems nice and snug