The barn needed a sliding door, and so a little research revealed some high end prices and searches on ebay and other sites revealed some really high pricing on the used versions. Apparently, sliding doors are hot in the hipster community or something, and the rusty old items have been moved from the category of used into the category of vintage. So two hundred bucks for sliding mechanism emerged as the established price. The ones at places like Tractor Supply cost well upwards of two hundred, so I looked for another solution.
At this point, I have 418 dollars in the building. (Mr. Money Mustache would be proud) The sliding door added approximately two dollars. I say approximately because I had a few large hooks around, and I must have paid for them at some point. My neighbor Fred gave me a 7/8 inch steel bar. It was a tensioning mechanism on an old barn that had fallen down on his property years ago. So I cut the bar to length, which gave me the added benefit of a workout as I had to use a relatively dull hacksaw on the thing. I mounted the bar 2 and 3/4 inches off the wall with some wooden mounts (see Will I Never Learn ) . I used two hooks on the top of the door and checked if it worked. It slid with ease, but it produced a "nails on the blackboard" screech that would assure that I'd never want to open it. This was solved, no problem, with a little grease, and now I have a quiet slider for two bucks and some labor of love. I assume I'll have to grease it once a year or so, but I can live with that. The open hooks allow me to remove the door if ever needed. ( It only weighs about 50 pounds.) This will be nice when I go to paint it next year.
The one engineering trick that worked was to support the bar in the middle while allowing the door to slide completely open. I did this by mounting the hooks at the ends of the door. One hook is on one side of the center, the other is on the other. When it slides, the center support acts as a stopper. This eliminated the half inch or so of sag that was generated by the weight of the door.