On Sunday, December 23, 2012 11:05:09 AM UTC-7, Frank Whiteley wrote:
On Sunday, December 23, 2012 9:20:25 AM UTC-7, JohnDeRosa wrote:

We had an overhead bi-fold hangar door cable snap yesterday (one of



five). Of course those on the field opened the door anyway. Sigh.







The cable had rusted through inside the guide tube on the wind up



spool. We had one hell of a time getting the old rusty cable out of



that old rusty tube. We are wondering when the other cables will



suffer the same fate.







Questions;







- What type of cable (3/16") should be used? Aviation? Stainless?



Galvanized?



- What kind of swedged stop sleeves should be used? Aluminum?



Copper? Steel?



- How to prevent rusting inside the tube? We greased the cable end in



hopes that this will help.







Thanks, John



How heavy is the door? 3/16" 7/7 Galvanized Aircraft (industry term, not normally used in aircraft like 7/19) Steel Wire Rope is 3500lbs breaking strength, therefore the safe working load is a around 700lbs (1/5). I presume you have multiple ropes lifting from a driven shaft. Search on lubricating steel wire ropes. Sounds like you want grease, but you also need a penetrating lubricant. Tubes probably need a good cleaning also.



Properly swaged copper sleeves will exceed the breaking strength of the wire rope and can be done with a proper hand tool. We used aluminum when we used to winch with steel wire rope, but that was a cost consideration. In the UK, we used copper. Winching would load the rope at over twice the safe working load during launches and a splice would only fail when the three swage marks on the aluminum sleeves were worn smooth. Steel sleeves are unnecessary. I've only found them impossible to swage properly with a hand tool, requiring a hydraulic press. Maybe I need to work on the pecs more?



You could hire a door pro, but where's the fun in that? Your club has a great member involvement in projects from what I've seen.



Frank Whiteley

The right stuff
http://www.mcmaster.com/#hand-swaging-tools/=kqn118