Hello all I am drawing a hole for M3 countersunk screw(flathead) I have checked the specs online the diameter of the head is largest 5.5mm thick 1.65 90degree

But when I draw a 5.5 hole 90degree it's only 1.3 thick as I remember, so I measure the actual product that comes with M3 countersunk it's roughly 6.5mm diameter

So my question is which size should I draw for a M3 countersunk screw? they're on 3mm abs plastic and 2mm aluminum, thank you very much.


1 Answer 1


This is what Inventor recommends for a clearance hole:

enter image description here

And for a tapped hole:

enter image description here

  • $\begingroup$ I just run the fusion 360 if I choose clearance it do have the specs like your picture, so I am curious what's the difference between clearance and simple? If I am planning to use the M3 self tapping countersunk screw do I need that extra 0.2mm? Thank you $\endgroup$
    – tempo3010
    Mar 29, 2019 at 4:36
  • $\begingroup$ A clearance hole isn't tapped, the screw just drops straight through and normallly screws in another part behind (which has a tapped hole), hence the extra 0.2mm to allow the screw to go through. $\endgroup$
    – am304
    Mar 29, 2019 at 9:08

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