Hey guys. Need some help. What size/thread are the little screws used to mount motors to motor mount plates? Thanks!
M4 socket cap, usually 8mm~12mm. Gear drives with a motor spacer like 3DServisas, i use 16mm and above.
2 Likes
standard are usually dome or cap head M4, 8mm long. longest i’ve used is 15mm
1 Like
You need to pay good attention to the length you need.
Too short and over time your motors can fall off due to not having enough engaged thread
Too long and you can penetrate the windings in the motors and produce dangerous shorts.
9 Likes
I have heard of motor shorting from long screws. I get the impression grinding screws to a custom length is not uncommon.
Have a bunch of different lengths around. For me i have 8mm, 12mm, 15mm, 20mm
2 Likes
I think a selection of 8mm, 10mm and 12mm will be good for now.
2 Likes
Do people use stainless?
1 Like
Bad idea. Shearing a motor mount screws head off sucks. Stick to 12.9
6 Likes
i use titanium TC4 (aka grade 5, or Ti-6Al-4V)
1 Like
Where do you get them?
taobao 
I get blue zinc dyed from McMaster Car. I’ll send you some extra’s (12mm and 16mm long) as I’ll be sending you a package next week anyway.
( they are m4 x .7). The .7 is the pitch of the thread)
2 Likes
Thanks! Do you have any shorter ones?
1 Like
def stick to grade 12.9. titanium isn’t recommended for fasteners, they can gall and cold weld. theres a reason you dont see them on high performance machines.
2 Likes