Saturday, December 5, 2009

Torsional Troubles

Day 16028, entry 142. I can now add garage door repairman to my resume. And I still have all ten fingers to prove I'm qualified.

You would not believe how many parameters must be specified to get a correct torsion spring replacement. Coil diameter, wire diameter, spring length, pulley diameter, door height, door turning radius, and even direction of wind. All that so you can get a correctly distributed resistance to gravity which will allow a 1/2 hp motor or a little old lady raise a hundred pound door overhead easily.

Smitty helped, which was comforting. He has scars to prove he can tangle with tightly wound devices. An industrial roll-up he was working on broke his arm once. I also had Google help, with kudos to Richard Kinch's webpage which not only explains how to do it and survive, but illuminates the physics behind springs and what to look for in a repairman should your courage fail. He also points you to suppliers willing to overlook the seven day waiting period. Wait, that was the pistol . . .

It only takes seven and one-half turns to achieve lethal quantities of stored energy. And it is held in place by two small set bolts. It did take me three weeks and one incorrect part to get it right. Three weeks corresponds with the cold shoulder my wife gave me while being deprived of the use of her garage during an unseasonal cold snap. Maybe I should have just called the repair man.


Gail said...

Good job! Years ago we had one spring break and the repairman insisted that we had to replace both because they "had" to match or one would kill off the other one. Went with the one. Still kicking as far as I know!

Eldon and Janeil Olsen said...

Wow, ours broke this month too. Janeil made a histerical call for help, something about being trapped in the garage on her way to doing last minute Christmas shopping. When the repairman arrived within the hour the door was so heavy he had to call his assistant to come to lift it up. I was proud of Janeil on handling this emergency herself (I was driving for Dial-A-Bus).