I won't bore you with project details, but I need to replace a very tiny screw and I'm having a lot of trouble both determining the size and finding a supplier for screws this small. So far I have tried two different sizes(one U.S., one metric) and both were too small.

what I think I know at this point:

  • flat counter-sunk head(100 degree angle)
  • Imprecise self-measurement of 1/4" length, 1/16" diameter, 32 threads/in
  • larger diameter than m1.6x.35x6 machine screw
  • larger diameter than 1/4" Length, #0-80

the screws

the screw in question

edit: Yes, it does screw into plastic, but I'm primarily concerned with figuring out the diameter, thread pitch, etc.

  • Would think something to screw into material instead of threaded nut/hole. Maybe wood or metal(thin). Wood screws usually have pointed end.
    – crip659
    Commented Mar 11, 2021 at 19:30
  • Threads look like ones found on lag bolts. Heavy holding wood screws/bolts.
    – crip659
    Commented Mar 11, 2021 at 19:37
  • 1
    Go pull one out of a "screw goes into plastic" section of the computer equipment you were going to get around to recycling. If you already recycled it, you missed out on reduce, reuse, then recycle.
    – Ecnerwal
    Commented Mar 11, 2021 at 20:11
  • 4
    I appreciate that you don't want to bore us with details, but sometimes the details are what will lead us to an answer. What sort of device did the very tiny screw come from? What types of materials was it holding together?
    – Doug Deden
    Commented Mar 11, 2021 at 20:25

2 Answers 2


That looks very much like a PC fan mounting screw. They typically go through the thin sheet metal of the computer case, then self-tap into the plastic mounting holes in the fan housing.

If you don't have any spares lying around (OK, I guess not everyone is a computer geek with piles of spare parts and mountains of spare screws - I'm on a 27-step program to cut back...), pull one out of your current desktop computer and compare it. If it is a match, either order some from someplace like Newegg or Amazon, or just order a replacement fan sized to fit your computer (they do die eventually, so having a spare won't hurt) and canabilize the screws from it. When your fan dies in the computer, you'll have the spare on hand and can reuse the screws to mount the new one.

  • Agree, although I think it is smaller than the usual size (which in my experience is rare, but not unheard of)
    – izzy
    Commented Mar 12, 2021 at 14:35
  • I've never held one up to a tape measure, @izzy, so I'm not certain. That was the first thing that hit my mind when I saw it, though, so I'm willing to bet that's it. I suppose that if one were in the 30-50mm fan range, the screws would be smaller, but for your standard 70mm and up case fan, I've only ever seen the "standard" size mounting screw. Except for the "ultra quiet" fans that come with rubber mounting "pins" instead of screws...
    – FreeMan
    Commented Mar 12, 2021 at 14:40

You've tried using machine-thread screws for a wood thread (or spaced thread) scenario. Wood threads aren't usually described by pitch--they just cut into the soft material arbitrarily.

I'm guessing that this screw came out of plastic or some other soft material. The blunt end implies a molded bore. If that's the case, the only critical factors here are head shape/size, shaft diameter, and length.

I'd try a #3 or #4 x 7/32" flat-head screw.

  • Gah. My carpenter's habits shifted scale on me.
    – isherwood
    Commented Mar 11, 2021 at 20:43
  • I agree with the answer as-is, even though the OP says "1/16 in. diameter" it is quite evident from the picture that the screw in question is larger than that. Commented Mar 11, 2021 at 20:51
  • No, it isn't. The shaft of that screw is about two of the 1/32" delineations on that tape measure.
    – isherwood
    Commented Mar 11, 2021 at 21:27
  • Well a #6 screw is 1/8", so I don't think a "#3 or #4" is very far off, either way the answer points out the key: this is NOT a machine screw with standardized threads Commented Mar 11, 2021 at 23:54
  • Any place selling used electronics and computers will have these screws. No need to cannibalize good equipment....
    – DAS
    Commented Mar 13, 2021 at 7:24

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