Hi thanks your detailed reply, I have a few 50 cm fiber optic cables.I want to straighten the cables all along.Try looking for a tutorial in youtube?
The process is basically something like this...
Insert one end thru so it protrudes about 2 mm. Heat that protruding tip with a flame and as soon as it melts and forms a molten bulb, give it a slight tug backwards and it will sit in snugly on that end. The melted bulb will form the first anchor.
Now, snip off the other end, again leaving about 1-2 mm. Heat up this other end. What should happen is that the melting end starts to create tension and tighten on itself, making a nice straight fibre installation. Do not get any heat on to the centre of the fibre or you will just deform it. Hope this description helps with ypur reinstallation.
I can't be precise about how much to excess length to leave but if you estimate it right, it will work out. About 1 to 2 mm. If its too much, the fibre wont straighten and the bulb will be too big. If it's too little, it might not work... a little trial and error mighy be required?
If the cable lies in the gap and there is no point to provide resistance, the curvature in the cable does not improve, for example my last design safety pin fo sight.