For my own purposes I have a 2x72" belt grinder and use that, doing initial bevel setting at about 12-15° per side with a 36+ grit Cubitron belt, followed by an 80 grit Trizact "gator" belt, then a 220 grit silicon carbide-embedded cork belt loaded with coarse "stainless" polishing compound, then a grit-free cork belt loaded with a fine polishing compound. This gives a bright mirror shine, though I don't worry about erasing all of the marks from the previous belt 'cause that's really a cosmetic concern so long as the edge has been properly hit.
For hand sharpening, the method of filing varies depending on the portion of the blade I'm working on. If working the middle or base of the blade I'll usually stick the tip against a wooden surface to help brace it, then either using my chest or upper arm to brace the handle or base of the blade, and my off hand to hold the spine adjacent to where I'm working to control the deflection under pressure. For the distal end of the blade I'll sit with the handle/base of the blade under one thigh and the middle/tip of the blade riding over the other to clamp it firmly in place. After filing I'll go over it with a Bull Thistle scythe stone followed by an Arctic Fox.
Regarding convex vs. flat, in either method it ends up a little convex, though more so when hand sharpening due to flex under pressure. Convex vs. flat doesn't really meaningfully matter for most machetes so long as the apex/gross geometry is thin enough and I advise folks not to worry about that aspect much. A convex is best understood as being a flat bevel of a given angle with its shoulder thinned out/rounded back. However, the way they're usually produced in use is by deflection of either the blade, the sharpening medium, variation in the stroke, or a combo of the three, which results in thickening of the apex angle. The key is that the apex angle be thin enough as most good machetes are thin enough stock that convex vs. flat will have no meaningful impact on performance compared to the apex angle. The apex angle is also responsible for glancing blows if too thick, as (and this is simplified for ease of understanding) the blade can only bite into the target when it is impacting at an angle greater than the edge angle, or else the cheeks are just slapping the target.
Deburring occurs at any point in the sharpening operation where it's viable. You should always be attempting to remove the burr at any stage, though depending on the method you're using it may be markedly easier at one stage than another.
I do not sharpen different portions of the edge differently, as the entire blade being thin means it all cuts well, and will only microbevel the sweet spot in the rare circumstances where I'm chopping something that actually damages the edge, like extremely hard small-diameter dry wood like fully seasoned black locust branches. 99.99% of all machete work is handled just fine by a 12-15° per side angle without sustaining damage. If removing small, finger-thick dry branches you can just flip the blade around to strike with the spine and save your edge. The only time edge damage really occurs when following this practice is when the branches are between thumb and wrist thickness and of exceptionally hard, dry wood, too thick to easily break with the spine, but small enough that they put a lot of concentrated force on the edge. Most wood species you encounter are soft enough even when fully dry that the edge will not be damaged, even in frozen wood full of knots.
The amount of the blade that I sharpen is typically wherever the factory "courtesy grind" is, no more, no less. However, I do sometimes put a partial back edge on some models, depending on how I intend on using them. But that's all a matter of context rather than general practice, and I have so many machetes that I can freely do that sort of thing without hampering myself in any way because if my context of use changes, I pick a different machete.
FortyTwoBlades
I hereby request a complete start-to-finish guide to sharpening a machete the way you like it. I have searched for your comments on machete sharpening and quoted them below, but I am hoping for something more systematic.
