Retrievable Blocks / Pin Block
How to tie
On February 12, 2012, I and Scott Swaney posted the pictures of the first-ever use of a retrievable blocking device. Then we called it the "pin block". I have had the idea after the first descent of Salamander Canyon in April of 2007. After talking and discussing it with Scott Swaney for years, finally, we put it in use. Once we set the original pin block with a clove hitch, we also backed it up with a biner block. After quite a few times of use, we realized that the pin block was safe without backing it up with a biner block. Scott Swaney was the first-ever person to rappel on a retrievable block. I originally used round, aluminum tent stake for the retrievable block and I still use it today. It has worked well for me. But, about a year and a half to two years after we started using this device, two other commercially made versions came to market under Fiddlestick and Smooth Operator names. IMO, for a retrievable block device, it should be rounded to spread the force evenly to all areas of the device material.
When to use
Retrievable blocks or pin blocks can be used for any rappel. This system will avoid leaving webbing or rings beyond for the anchors. It also eliminates excessive wear and tears on ropes due to pulling friction. When the pin is pulled out, the pull cord and rope falls on to the ground.