This is how I made my last batch of phragmites arrows:
1. Cut the reeds at a point where they are about 1/2" diameter at the big end.
2. Cut off the other end @ 40".
3. Match nodes as closely as I can (nock and point), then cut to length...depending on draw length (mine is between 22-26"). I leave about 2" of reed in front of the "point" node for the foreshaft. If I line up the nock nodes, the point nodes are not more than 3/4" out of alignment.
4. Trim or sand nodes.
5. Weigh and match within 20 grains.
6. Straighten.
7. Spine to match within 10% deflection.
8. Cut, sand, weigh, and match foreshafts.
9. Add foreshafts. The heaviest foreshafts are attached to the lightest shafts.
10. Cut nocks and shoot to test (without fletching). Weed out "crazy" fliers.
11. Add points.
12. Weigh and spine entire arrow....just for grins.
13. Paint.
14. Fletch.
I don't mess with the shaft diameters at all (except to trim the nodes). I get about 3 matched arrows for every 20-30 reeds...depending on how many break during the construction process.