On Thu, 25 Jun 2015 19:42:25 +0800, Techman
wrote:

On 25-Jun-15 3:37 PM, Techman wrote:
I'm looking for some screws for use in production work.

*Sick of tapping lots of M4 and M4 holes.
*Used for attaching small brackets and DIN rail etc.
*Fixing to to mild steel 3mm thick or to 1.6mm thick Zinc Anneal sheet.

I've seen screws like in the links below but am having trouble finding
them. When I look for self tapping screws I find the coarse thread type
rather than the defined M4x0.7 or M5x0.8 threads.

Is there a proper name for these screws:


https://dl.dropboxusercontent.com/u/92240200/Tapping%20Screw%20(1).JPG

https://dl.dropboxusercontent.com/u/92240200/Tapping%20Screw%20(2).JPG


Thanks.


I'm getting closer.

Some seem to be called Taptite,

http://www.shakeproof.com/images/products/taptite/taptite_160px_wide.png

"Thread forming machine screw"


And others "Type 23"


http://www.boltproducts.com/images/thread%20cutting%20-%20type%2023.gif

Thread cutting machine screw..or self tapping machine screw

If it has the "cut" in the tip..its a self tapping or self cutting
fastener.

If it is triangular..its a thread forming screw. The thread forming
screws take a fair amount of pressure to form the threads and are
generally used only in softer materials such as aluminum. Try using
them in steel..and you will be drilling out a fair number of them,
UNLESS you drill a bigger pilot hole before installing them. Though to
be fair....they do give better engagement IF the proper pilot hole has
been drilled...but they are still generally..generally used in softer
materials and will often have a coarser thread pitch as well.

Gunner