At my place, I used an old corded Black and Decker string trimmer and a new Black and Decker cordless string trimmer. Both of them work great, and putting new line into an old spool, or replacing a spool, are easy processes. I just spin new line onto an old spool, thread it through one hole, and I am done. The line feeds out automatically on both the old and the new trimmer, and I rarely have to take the spool out unless I try to cut something that is too thick and tough, like a big blackberry vine.
I also helped a friend in Portland weedwhack his yard this summer (hey, I am a nice guy) and used his corded Ryobi string trimmer. He warned me ahead of time that putting new line in the Ryobi was a pain in the neck. Sure enough, trying to put new line (as opposed to buying a pre-threaded spool) was incredibly difficult. I had to thread the line both ways and put both ends through a hole in the spool. I could not simply thread a bunch of line on the spool until it looked full -- no, I had to cut a length of about five feet of line in advance and guess whether it would be too long. It took me a full hour to figure out and thread the line. I would not recommend a Ryobi trimmer at all.
Here are directions on how to re-string a Ryobi weedeater, from:
http://homeguides.sfgate.com/replace-lines-ryobi-string-trimmers-100427.html
You have to be sure to cut no more than 25 feet, or you will find yourself screwed. With the Black and Decker, putting new string on a spool is so much easier! Just wind on as much string as you want and until the spool looks full, then pop it in.
Reel Easy String Head
1
Stop the engine of a Ryobi string trimmer that has a Reel Easy string head. Disable the machine by disconnecting its spark plug wire, unplugging it from an electrical outlet or removing its battery.
2
Cut a 25-foot-long piece of 0.095-inch-diameter monofilament trimmer line from a roll, using a utility knife or scissors for cutting.
3
Rotate the knob on top of the head until the arrow on the knob lines up with the arrows on the head. Feed one end of the 25-foot-long trimmer line through the hole on the side of the head, and pull the line through from the head's other side until you have two equal lengths of line, or string.
4
Wind the knob until only 8 inches of string are left on both sides of the head. Wind counterclockwise if your trimmer has a curved shaft, and wind clockwise if it's a straight-shaft model or a brush cutter.
