I sold and installed window draperies for 18 years. Without know better, I tied what is know as an "overhand knot" on each end of the cord (2nd photo). The disadvantage of this knot is that it can twist and slip if the strength of the pull varies. It also can damage the cord, When I had a knot slip and the cord came unthreaded, it required a service call and made my customer very unhappy. I thought there must be a better way.
Step 1: Why Use This Knot?
Without know it, I re-invented a knot that had been used for thousands of years. I found out later it is one of the dozen basic knots, called the "figure 8 knot". It performs all the necessities of a good knot. It is easy to tie, holds the end of the cord securely when running the cord through a hole or slot and is very easy to untie. In 18 years, I never had one slip or come untied.
Step 2: Tying the Figure 8 Knot
Photo 1): Thread the end of the cord (or rope) through the hole.
Photo 2): Make a bend.
Photo 3&4): Go over, forming a loop, then under the cord.
Photo 5): Thread the end down through the loop
Step 3: Finish the Knot
Finish the knot, pulling it tight. Now, wasn't that easy?
This is a very versatile knot that you will be able to adapt to many different functions and activities. I use this knot everyday without without giving it a thought. I used it to keep the ends of my baler twine from fraying out in this 'ible: https://www.instructables.com/id/Spool-for-Twine-or... and on both ends of the paracord in this one: https://www.instructables.com/id/Shoulder-Rotary-Cu...
There have been instructables on tying this knot, but none explained exactly where or why it was used. I hope this helps someone. Questions & comments welcome.
If you like this, please scroll back to the top and push the VOTE button & vote for this in the contests. Thanks.