A hacksaw is all you really need for a handsaw.
I lived in the far north of Canada for a lot of years, now I'm just in the southern north of Canada. I've seen a LOT of hand made Ulu's. Own a fair number of them and have made a fair number of my own.
Usually Inuit (Eskimo is no longer politically correct) used circular saw blades by perference. Handsaw blades were used when they didn't have or couldn't get a circular saw blade. These were usually broken blades from log cutters, have to remember there was no electricity then and these were gas or disel units with big blades. 3ft plus in diameter some of them. Have to remember on the coast of the arctic there are no growing trees. These are drift logs they were cutting or they'd trade for the blades from those down in the trees or those building settlements along the coast.
Handsaws were more valuable in some ways back then. Plus the average person had one and could sharpen one with a file.
To cut a big circular saw blade, they would heat it up in a fire and take the temper out of it. Cut it with a hacksaw in the general shape then file it out. Sharpen it up some what then retemper it with a kerosene blow torch, a large coffee can or Klim can packed with sand was used as a oven. Even seen single burner coleman stoves a length of stove pipe as a duct and the same can technique used as ovens.
Handsaws are not usually detempered before cutting to shape. The are hardened afterwards. Often case hardened. Heat till red hot hold for a few mins then dunk in cold salt water. Then they will slowly heat but not red hot and hold for awhile then dunk. These are NOT great blades, just usable. Give them better steel and better conditions and they will make better Ulus. Their home built from saw blades are what they had at hand, and what they could afford. Don't see this being done much anymore.
Actually blank Ulu's in various sizes were available all over the north a few (20+) years ago. Steel was pretty crappy though. Dept of Economic Development had them produced in the thousands. I've got a few of the smaller blanks kicking around somewhere. One even got to the case hardening stage. I can't post pictures or I'd dig them out and borrow a camera.
Thing is with making Ulu's is that it requires a fair size piece of metal. 7 x 5 inches will make a fair size Ulu for kitchen work. Most knife supply places don't sell in the width one needs. Length no problem. So a circular saw blade does offer an alternative. Detemper it before cutting and use a diamond blade in a scrolling saw. Get it how you want then send it out for hardening or use the blow torch and sand packed can.
