4-40 screw for cutting a thread

thingiverse

I've provided the STL because publishing requires it - but the intention behind this is to insert it into your 3D model and subtract it from the model, in order to cut a threaded screw shaft. You shouldn't use the full length of it, as it would have too much resistance against the screw. Typically, I put the end of it in the bottom part of small project box enclosures and subtract it. I'm not sure why I made it so long; you can chop it up if you'd prefer. For the top part of project boxes, don't use a screw thread: cut a straight circular shaft through the model of 0.118" diameter. This accommodates the screw shaft. Use whatever larger hole that you prefer at the top to accommodate the screw head. I use flathead screws for a neater look. For this, I make a slightly indented circle above the shaft (0.005" or so) then chamfer it down to meet the unthreaded screw shaft. See second picture. This should accommodate most brands of flathead 4-40s. You should print models with this screwshaft on 0.15mm layers minimum. It works - yes, it does, over multiple unscrewings and rescrewings. I don't see the point of cutting screw threads after printing - many modern printers are good enough to print a small screw shaft like this without having to use inserts or cutting threads post-print. I use PLA for boxes as it's a hard plastic conducive to screws. PET-G is not conducive to screws, btw; it's too flexible. I saved this as a STEP file, and I'm pretty sure this works universally on different design software.