Hi there: this screw from my bathroom vanity handle has broken. I'm curious about the two grooves that you might be able to see on the remaining screw. Do they serve any purpose? Should I be trying to find a replacement that offers those two grooves? Or are they not necessary? om

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    It may help if you at least post the manufacturer of your faucet, and maybe a picture. There may be a plumber lurking about who might recognize it. Failing that and Khrrck's answer, contact the manufacturer and ask them, or your local plumbing supply house. (Unlikely that a big-box store would know or stock 'em.) – FreeMan May 27 '20 at 16:26
  • Did the screw break off inside the faucet? If so, have you been able to extract the remaining part? – FreeMan May 27 '20 at 17:26
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    These are the screws for a cabinet door handle, not a faucet. – Khrrck May 27 '20 at 17:30

Those are called breakaway machine screws or just breakaway screws.

They come in handy when installing cabinet hardware (handles/knobs etc.) in materials that differ in thickness or you don't know the thickness. As you have seen, they are also used in many other applications such as bathroom hardware.

The slits in the thread make it easier to adjust the size of the screw to the application without messing up the threads.

Hold the head of the screw in pliers/vise etc. And use another pair of pliers just past the slit on the threads you don't need... Bend the slit up and down and snap.... The piece you don't need breaks off and the thread is still good on the part you need.

You could also just use lineman pliers to cut the screw at the slit of the length you need.

Do you need them? No, you could just match the length and thread type and get that screw. But if you have to cut non breakaway screws, you can mess the thread up and it wont grab the object you are securing. I would personally get the breakaway screws.

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    #TIL! However, if these were the screws installed in the OP's faucet, then he needs the screws at their full length and there's no need for breakaway screws since he'll need the full length. He can just get a regular screw of that length and call it good. – FreeMan May 27 '20 at 17:25
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    Well spotted, I didn't know about breakaway screws. For the job of holding a cabinet handle on, though, I think a solid screw of the correct length should be more than sufficient and easier to find. – Khrrck May 27 '20 at 17:31
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    :derp: Indeed he does. The questions still stand, though. A) If it broke off in the handle, did OP get it extracted, B) Why spend the time & effort to get a breakaway screw when the other one doesn't appear to have been broken away? Simply get a "regular" screw of the same length & thread pitch as the unbroken one. – FreeMan May 27 '20 at 17:53
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    If you have to cut non breakaway screws put a nut on it first so when you take it off, it re-cuts the threads for you. Work it a little bit right before it falls off, because it ain't going back on if you don't. – Mazura May 28 '20 at 2:11
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    Also, don't use your good pair of linesmen, or you'll 'learn that today' too. – Mazura May 28 '20 at 2:21

The screw with grooves is a breakaway screw, made so that it can be easily cut or snapped to the correct length. Perhaps the broken one was over-tightened, causing the breakable portion to snap. They probably came as part of the installation kit (so that it could fit many different doors) and aren't strictly required.

In either case I would just take the broken screw(s) in to a hardware store and pick out a replacement. One with thread on the entire length is probably slightly stronger and cheaper, if available in an appropriate length. I recommend replacing both of the screws at the same time, and any associated nuts/washers - it'll save you a second trip and make sure that everything is the same size.

  • I very strongly agree with you except... those flats look like they were intentionally machined in. I have no idea why, and, frankly I agree with the rest of your answer. If they're really needed, a narrow file to eliminate the threads in those locations may be the expedient way of getting there. – FreeMan May 27 '20 at 16:24
  • Updated to be more accurate. Thank you Gunner for identifying the screws. – Khrrck May 27 '20 at 17:34
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    Yale-type door cylinder locks always come with these to compensate for different door thicknesses. Despite being called "breakaway", the sections without thread are almost the same effective diameter as the rest, and the same material, so you can't just lever off the lock to get into the property. It just save you having to fix up the thread where you cut it (either by backing out a nut, or filing). – Paul_Pedant May 28 '20 at 9:17

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