Reel Repair by Alan Tani

Hi!

What are these screws with wide threads called in english ? Is it possible to find them in some kind of sortimentbox ? Stainless and in some different sizes ? Haven't found any that small here in Sweden. I just took the measures on the picture as an example.

Thanks in advance!

Self tapping screws?

Looks  to me like these fall into the category of thread forming screws.   Thread forming screws are used in untapped holes in softer materials, usually plastics . Plastite is a common brand.
-J

Thanks! 

I have also referred to them as sheet metal screws. - john

Panhead SS self tappers down here.

Quote from: Brewcrafter on December 06, 2024, 04:37:53 AMI have also referred to them as sheet metal screws. - john

Quote from: ReelClean on December 06, 2024, 04:41:15 AMPanhead SS self tappers down here.

1. Sheet metal screws have a tighter thread pitch, a different thread geometry, and a pointed tip.  Sheet metal screws are technically thread rolling screws,  as rolling (using the sheet metal working term) is how the thread is shaped in the sheet metal hole.

2. Thread forming screws squeeze the plastic around the screw thread to form the female threads, forming the plastic into the thread shape in 3D, without any cutting to remove  material, and minimizing any surface deformation.

3. "Self-tapping" is a generic term for any type of screw that does not require a hole  with female threads.

I am nitpicking here because this is important for work on reels with plastic parts. When you are putting screws into plastic holes without threaded inserts, the only proper screw type is a thread forming screw.

-J

One more note:  I am not sure if there is a standard for thread geometry and pitch for thread forming screws like these.  If so, best to use the original thread screw or official replacement part if possible.

-J

Truss or pan head self tapping

Bought them in 50# cartons of 304 or 316 stainless in both 1 and 1 1/4" lengths depending on the contract.

What's your application?

In reels I find them in the Chinese cheapo's, quick production, lifespan not so much.

As Dave noted they are specialty fasteners made specifically to join and tap into plastic parts. The tell tale sign is they have a flat tip, not pointed or material cutting.

I must remember to avoid using TEK fasteners for reel repair; no matter how handy they are...   - john

This is the self tapping sheet metal screws previously mentioned. I've installed a few million of these screws in my many years of installing HVAC systems

https://www.amazon.com/dp/B07HF46Q4R/ref
may have to cut off to right lenght

Once more...

While thread rolling (AKA sheet metal)  screws might look similar to  thread forming screws, they are not the same, and they are not interchangeable.

The screws that go into the plastic/graphite holes on reel parts are thread forming screws.

There are all sorts of thread forming screws, including some where the shaft is not even round, but triangular.  These are called tri-lobal thread forming screws.


Ted (Maxed Out) has kindly posted a photo of  thread rolling (AKA sheet metal) screws to help us compare to the thread forming screws in the original post.


For the folk that read the full posts, here a a bonus:  Thread forming screws are actually pretty interesting topic if you make stuff out of plastic. I played with a bunch on some design projects using HDPE, and found that I  got much better holding strength with these than I got from pressing in threaded inserts into blind holes.  Inserts can be better if you can use shouldered ones that are pressed from the back side, but that is not always an option.  Blind threaded inserts in plastic are mostly useful for situations where you take apart frequently, but do not need lots of holding power.  It is also nice to not have to worry about saltwater corrosion in the threads by skipping the inserts.  And thread forming screws don't hold or last as well in FDM 3D printed parts, so inserts are about as good as it gets there.

-J

Blind inserts can save the day in modern reels that have to be opened for service often. The undersize screws in plastic is no good. The manufacturers act like you will never take the darn thing apart; and I guess they are right more often than not.