1/4" thick steel is too thick in my mind. That would be more like a falcion/langsax than a machete. Go thinner if a machete is what you want. Also, you will not want to use mild steel. Go High Carbon or go home.
The first thing will depend on the quality of the steel you are using. A friend and I have made some very nice cane knives, machetes, and dirks out of discarded bandsaw blades from a sawmill. Here are some of our experiences.
The first cane knife was cut out with a regular cutting torch. The results were good, but only after some tweaking. The torch hardened the edge to the extent that a coarse bastard file would slide over it like glass. So, we annealed it by heating the edge of the blade to red in the forge and then sticking it in the annealing bucket, which is full of sand. This softened the blade so that it could be shaped/sharpened. After shaping, we tempered it by again heating the edge, watching it cool to ~ straw yellow and quenching it in water. We drilled the rivet holes and slapped the handle slabs on. It is heavier than your standard cane knife, but it holds a good edge, resharpens fairly easily, and cuts like Fotbitr.
The next 2 cane knives were cut with a plasma cutter. The edges did not suffer the same heat damage as the first blade, so we decided to "normalize" the edges this time instead of annealing. We just heated the blades to dull red, and let them cool in the open. This worked fine. We shaped them, tempered them, slapped on handles, and called them good. They are a little lighter than the first (smaller too) but still cut sugar-cane like it was butter.
I made a dirk with a very acute point at the same time. We cut out 3 blanks with the intention of making three of them, but 2 of the blanks "warped" near the tip due to the heat. I probably could have straightened them on the anvil, but I never got around to it. I won't go into the making of the dirk, but suffice it to say that if the blade design you want has a narrow (< 2" wide) expect some warping.
So, in a nutshell, here are the steps.
1) Cut out a blank
2) Anneal or Normalize
3) Shape/ drill rivet holes
4) Temper
5) <optional>Finish the blade (polish, blue/brown, ect...)
6) Put on a handle
7) Sharpen
8) Cut stuff
Best of luck to you.
