Wood Screw or Machine Screw?

[Tungsten dipper]

Anyone know what these screws are? What are they used for?

[Bented]

Ask yourself a question, what application would be improved by having different thread forms on a single fastener?

[MrWhoopee]

The ones I've seen came with door hinges. No clue why.

[Bobj]

Universal screws found in commercial door hardware like hinges. Works in wood or metal.

[chipmaker4130]

Bobj got it, but I see them most often with locksets, used for the strike plates. They're typically poor quality steel too.

[JoeLee]

I've seen double threaded studs half wood screw thread half machine thread.

JL..............

[Bob La Londe]

The ones I've seen came with door hinges. No clue why.

Yup! Same here. Also sometimes with electric strikes.

[J Tiers]

The ones I've seen came with door hinges. No clue why.

So they can be used in cases of wood or metal doors and frames. Same hinge part number, one universal "fits all" screw. The fact that the screw can end up being a "fits nothing in a usable way" is not relevant to the maker........

[Doozer]

12-24 on the machine thread part.

-Doozer

[MrWhoopee]

I've seen double threaded studs half wood screw thread half machine thread.

JL..............

I used those to secure the fenders to the frame on my '51 Riley DHC. I used to know what they're called.


Edit: They're called hanger bolts
.

[boslab]

Pvc window screws, friction stays use those, at lest over here, the course bit into the frame then the slightly larger bit screws into the stay, apparently it’s a tri lobed thread forming thing or so I’m told, not round
mark

[lynnl]

I used those to secure the fenders to the frame on my '51 Riley DHC. I used to know what they're called.

"...double threaded studs half wood screw thread half machine thread."

Hangar bolts ...I think. Or maybe it's hanger, not hangar.

[epicfail48]

Already been said, but those are the screws that generally come with door hardware like strike plates. I believe the theory is that they work in both wood and metal frames. For wood, the threads at the tip provide the holding power, for metal the fine thread is the part that grabs and the wood thread extends through the frame and into the air. My understanding of it at least

That said, worth avoiding using the supplies hardware when possible. Easy way to improve home security is to replace the screws in door hinges and strike plates with much longer screws that reach all the way into the studs. Pretty easy to kick a door in that just has the factory screws holding the strikeplate, much harder when the plate is secured to the stud

[OaklandGB]

Found in door hinge and striker plate kits. Used with wood or steel clad/wood core doors.
Opinion: They are a compromise too far. Pick your anchoring material and use the correct screws for it.

[Paul Alciatore]

I can see how they work for wood. But for metal the wood screw thread has to pass through the sheet(?) metal frame first and then the machine screw thread. So the metal frame has been distorted by the wood thread before the machine screw thread does. There is a lot going on there. I don't think this is a good idea.