These are my charts for using common machine screws in printed parts.

Socket Cap Screws

To be safe, drill the printed hole to the proper diameter. The printed parts may crack if the hole is printed too small. Also most pritned parts work just fine without drilling.

Diameter Drive Size Tap Size (printed hole) US Drill size
3mm 2.5mm 2.5mm between 3/32” or 7/64”

Set Screws

4mm set screws are the smallest screws available at Home Depot

Size Diameter US Drill size Allen Wrench (Drive Size)
4mm 3.4 mm between 1/8” and 9/64” 2mm
5mm 4.3 mm 11/64” 2.5mm
6mm 5.2 mm 13/64” 4 mm

Wood Screws

Flat head wood screws. With this table, the wood screw will not cut the printed part.

Size Diameter Max Head Diameter
#6 3.5 mm 7.1 mm
#8 4.2 mm 8.4 mm

Printing Countersink Hole

The most common angles for screw heads are 82deg and 90deg. Assume 90 degrees because that’s ther easier number.

For a chamfer operation (Fusion 360 and friends):

Size Chamfer Distance Chamfer Angle
#6 1.8 mm 45
#8 2.1 mm 45

For a cylinder with a top and bottom diameter use this table [TODO]

Size Bottom Diameter Top Diameter Height
#6 TODO 7.1 mm TODO
#8 TODO 8.4 mm TODO