Found this on http://runescape.wikia.com/wiki/Fletching_training. Dont know if it's right, but it's something. Broad arrows can be made at 52 fletching after the ability to make them is bought using Slayer Points. They give 15 xp per arrow and are made in sets of 15 using a make-10 (sets) option, which makes 1 set every 1.2 seconds. They are made from broad arrowtips, bought from Slayer Masters for 50 coins each, and headless arrows, bought on the Grand Exchange for about 60 coins each. Broad arrows are untradeable, so the loss is 90 coins per arrow, or 6 coins per xp. Approximately 2500 sets of arrows can be made per hour for 563k fletching xp per hour at a loss of 2.25m per hour. Broad arrows are not very commonly made because of their great cost. Also, not many people have the ability to make them, and still others don't even know how fast xp they are. However, players with large amounts of money have been known to make broad arrows, sometimes even to 200m fletching xp. Fletching xp can essentially be "banked" by buying headless arrows on the Grand Exchange, which have a buy limit of 10k per 4 hours. This costs about 1/6 of the total cost of making the arrows. Once many headless arrows have been accumulated, the xp can be realised, and the remaining 5/6 of the loss taken, by buying the arrowtips.