Sixdogs,
I was scanning your harrow rebuild project and just, a thought. When I need to heat a very large area and only have one acetylene. big bud torch, I use inexpensive propane torches to heat the overall area and keep the temperature of the project even and cover a larger area. The propane torches I am speaking of are sometimes referred to a weed burners with a three or four inch diameter burner head. They don't get as hot as an acetylene. torch, but they will turn the metal a bright orange. eventually. The main advantage is having the ability to apply a lot of heat over a large area and then heat specific areas with the acetylene. bud torch to fine tune your bends.
I have all kinds of heavy duty farm equipment that I never would have bent in my shop, by myself without the propane torches providing overall heat back up. With the wand handle on the propane torch it is easy to clamp them to a fixed object or stand to free your hands to do other things.
This may by something you have already done and are well aware of the assistance the propane torches can be and best of all, they are very inexpensive and only need a hose connection to a standard propane bottle.
Good job on the harrow, I am impressed. With handy people like you around there would be a significantly reduced market for new machinery.
Keep up the good work,
Nick,
North West Farmer