How to make threads

[racker]

First I want to know why the screw strips like that. I drill pilot holes into a thin piece of metal. I am trying to fit bolts in this structure. The first side worked perfectly and is held together with a nut. The second one didn't work because I drilled the pilot hole on an angle. I am hoping to solve the problem with a bigger bolt. How can I create threads? Do I need to tap and die this thing piece of metal.

[Roadracer_Al]

Yes, a tap and die are how one cuts female and male threads, respectively.

They can be purchased individually, or in sets, usually cheaper per piece compared to buying individually.

IMHO, very inexpensive taps are often so poorly ground and of inferior quality steel that they are a poor value. I avoid the cheapest tap & die sets like the plague.

[Pete O]

It appears that you have been trying to create a thread by screwing a screw into a non-threaded hole, you have already discovered the result as the thread on the screw is not a cutting tool. The thing you are working on is a bit hard to identify in your photos, it might be suitable for a simple self-tapping screw if it is a thin-walled tube and the screw is not holding a load, or, if you want to use a nut instead of threading into the metal itself, the hole must be drilled to the diameter of the full thickness of the screw (or bolt) including the thread. Otherwise you will need a tap in the appropriate size for the screw you intend to use.

[PixMan]

It's not a good idea to thread (tap) such a thin piece of tubing because you'll only get one turn or less of thread. That's VERY weak.

As Pete mentioned, you would be better to drill a clear hole through and put a nut on the other side. That doesn't work if you're trying to clamp something that's sliding inside the tube. In that case you'd have to weld a nut to the outside of the tube.

See if you can get better photos and description of what the task actually is, and we can better help you.

And.....

[Roadracer_Al]

Also, have a look at RivNuts. They're a combination of rivet and nut, and are designed to be installed in thin sheet metal. They can be set using ordinary hand tools: you don't need an expensive setter, although they are much faster.

[Sunset Machine]

There's also a 3 sided screw that is thread forming. It will mushroom a bit, so maybe start it from the "wrong" side to get threads formed towards the inside?
You might get two, or even three threads in that thin stock.