Al Maclaine in his encyclopedia of fishing has a chapter on bamboo rodmaking, in which he describes heat treating with a torch and length of black iron pipe.

You can go one better, which I have done (on about a dozen rods or so back when I first started) by getting equal lengths of half inch and three-quarter inch copper pipes, put one inside the other, then shim them apart with bamboo wedges (so that you can see an air gap completely around the inner pipe).  Heat the other pipe with a propane torch, which then conducts the heat evenly to the air in between, which evenly heats the copper inner pipe (you get astonishingly even heating from the copper, with no hot spots to burn you sections).  keep the torch moving from one end of the pipe to the other, and rotate the pipe after every trip down and back.

Use this set up to heat treat the bound rough tapered strips prior to final planing.  Cook it long enough to see steam jetting out the open ends (usually around 8 minutes for tips, 10-12 for butts).

Or, just flame.  That's the way Paul Young did it with his "ring of fire", the way Daryl Whitehead and crew at Bellinger's do it, and some other production maker used to do it (though I'm currently blanking on who it was).

The real advantage to heat treating in a oven is that you can do multiple rods or sections at one time.

I opt for both; flame for a nice brown tone, then heat treat in a vertical heat gun oven (based on Frank Neunemann's model) using Garrison's recipe.  After nearly ten years and close to forty rods I've haven't had a problem with sets or with broken, brittle rods.  (Chris Obuchowski)