Just like for any other hole in any other material. I assume the hole is not plated. If plated, add a bit more clearance. Call your board manufacturer - they may not carry every drill size anyhow.For a machine screw 2 x 8 how would I calculate the hole clearance diameter for a PCB?
s that a 2" x #8 screw? Or 8mm?
8mm lengthIs that a 2" x #8 screw? Or 8mm?
So my screw is listed as 2 x 8mm. The "2" must be talking about screw width in mm. Now when I actually measure the screw diameter it comes out as 1.6 - 1.7mm. Which do I rely on? I cant determine the screw clearance hole if I don't know what the actual mm width of it is.Remember to include extra clearance to allow for mechanical tolerances on whatever to screws are going to be attached to.
Generally hardware measure slightly different than the declared size due to machining.So my screw is listed as 2 x 8mm. The "2" must be talking about screw width in mm. Now when I actually measure the screw diameter it comes out as 1.6 - 1.7mm. Which do I rely on? I cant determine the screw clearance hole if I don't know what the actual mm width of it is.
ok Thx Erichi clang,
Choose a standard drill size diameter , close to 2.0mm dia, say 2.1mm
E
https://www.custompartnet.com/drill-size-chart
So should I go on my measurements or the machine machine specs? I think you are saying go on your measured specs. Its the rea life values that we need.Generally hardware measure slightly different than the declared size due to machining.
Metric screws normally have three numbers, starting with M.So my screw is listed as 2 x 8mm. The "2" must be talking about screw width in mm. Now when I actually measure the screw diameter it comes out as 1.6 - 1.7mm. Which do I rely on? I cant determine the screw clearance hole if I don't know what the actual mm width of it is.
Yes, measure the actual hardware you intend using.So should I go on my measurements or the machine machine specs? I think you are saying go on your measured specs. Its the rea life values that we need.
As a rule of thumb how far away from the PCB can I put a through hole?Yes, measure the actual hardware you intend using.
As well as a digital caliper, I have my old mechanical Moore & Wright micrometer that has a larger dia anvil, so the measurement is a little more accurate for screw threads.
I messed up: what I meant to ask -If you are referring to hardware mounting hole for the board, I usually keep ~2mm or 3mm foil clearance from any hardware mounting, nut or screw maximum diameter.
When using nylon style mounting, concern is not as great.
That will depend to some degree on what it is being used for -- i.e., what kinds of loads will be placed on it.I messed up: what I meant to ask -
As a rule of thumb how far away from the PCB edge can I put a through hole?
Depends on the composition, I don't think my fingers would be close to shearing a 2mm steel, or even brass screw?A 2mm screw does not have a lot of strength. Much tighter tthan finger-tight and it will shear.