Hello,
I'm looking for a replacement screw for a toy car. The toy could be from the 1970s if that's relevant.
Sorry to mix my units, but the diameter of the screw is 3mm and the length is 8mm if you do not include the head, and 10mm if you do. It has 24 tpi and I can't find anything that matches this: I've looked on the internet as BSW, BA, UNC, UNF, etc. Can anyone help me identify this?
Thanks, Stephen.
24 tpi is an unusual thread, the nearest common one is 25.4 tpi, equivalent to 1mm pitch. 1mm pitch is, however too coarse for a 3mm diameter thread - that would usualy be 0.5mm.
Where was the toy made?
1 mm pitch sounds almost like a self-tapping screw for plastic or Mazac.
Will not a self tapper have a pointed tip?
If it's M3 screw just compare it with the screw that holds the light switch or mains socket faceplate to the back box (M3 has a 0.5mm pitch).
No, ones which are designed for pre-drilled holes may just have a slight lead-in. But they are usually recognisable because the thread profile isn't symmetric ("gaps" wider than "threads").
1mm is the normal pitch for 6mm and 7mm diameter threads.
But they are M3.5....
Yes, my mistake.
Are you sure it is not 26tpi and 1/8" diameter, which would be 1/8" British Standard Brass?
If not, browse through this site, which is the most comprehensive site I know for screw threads:
Colin Bignell
Good link - thank you Rob
Thanks, perhaps I have been barking up the wrong tree. It is a metal screw for a Tonka toy car from I think the 1970s and it holds the top and bottom halves (both metal) of the car together. Over the years the other screws have fallen out and I am left with only one. Perhaps I have been looking at bolts and threads when I need to be looking at screws?
Now that I take a closer look, it is screw shaped in that it tapers in diameter at the end. The head is unusual as it isn't slotted or pozi, it's not quite bolt like with flats, it looks more like a mushroom but there are "segments" so that I can grip this pattern with my pliers to screw/unscrew it.
Thanks, Stephen.
From the application it sounds like a self tapping screw with a tamperproof/machine assembly head.
If you had linked to a photo with your post, you would possibly had this resolved quickly.
nearest I can think of is
1/8" brass thread has 26 tpiANF uses 24 tpi ... but not in 3mm diameter (Only on 5/16 and 3/8)
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