Tom,
I think for these purposes it is sobering to reflect on the difference between perfect and rough as..... and it is not much at all.
The blades you had originally were probably from the Dans stable of blades, and to this end they "got it" and went for sturdy and simple, and still gave very good service.
For the enthusiast, getting the blade calculator and doing it perfect is more for themselves and less for the power generation process. The furling on these things is woeful, and makes perfect blade carving a academic thing, rather than practical..... so.....
Firstly, get an idea of what Melonos is talking about with his single jig system. Once you have that in mind, maybe whittle a little 12 inch prop just to see it in real life....... like just sitting on the porch with the mutt, a stick and a whittling knife.
I depart from Melonos at this point. I would NOT cut out the blade shape (root to tip profile) as this limits your ability to fix the blank board in your jig.By all means draw it in in order to get an idea of where your end profile will be..... but cut the whole plank as one with the chain saw.... then cut the root to tip shape.
Now you have seen the result from whittling, you can see one side ( the lee side) will stay virtually flat, and we won't need to do anything with this side until later. Normally the windward side has a flat leading edge..... but this is opposite thinking with this method.
The windward side is what we now need a jig for.
Using the Dans idea, just draw a shape on the end grain (outer tip) with the profile of your blade.
Now we know from the video, the spine will be flat on the table/jig, and so ALL measurements will be from here. The thickest point will be spine, and it will be 1/3rd in from the leading edge.... whatever the chord is at any point.
We want the thickness to be about 1/8th the chord at any point, and that will be from the spine.
You want about 3 degrees for the end profile to drop, about 6 degrees halfway down, and whatever makes you feel good at the root. It will make no appreciable difference what you do here with an axial flux, as start torque is nil.
Doing this you can see the blade virtually describes itself at any point. The cord will dictate the thickness.... simple.
The chord is a simple tip to root area straight line.... and the degree angle is the only thing to make you think a abit, but this picture from Melonos
says it all. Take it steady and try to fathom it, and it will come if necessary......
Draw the tip profile on the tip getting the 3 degrees offset, then do the same (on the end too) with the 6 degree mid point... simply get the midpoint from your "tip drawing of it's position) and place that offset at your halfway point.... and draw the line.... and down to the root as you please.... your done.
....throw the blade calculator down the toilet.... it's only for perfectionists, and will do little if any good at all. Matching the load a bit better will make much more difference, as will SOC of the bank etc..... it's no big deal.
If you mark this information on the sides of the blade blank, you will end up with really only one line on the leading and trailing edge of the blank... always referenced from the lee side which will remain flat on the table/jig.... THE SPINE TOUCHES THE TABLE ALL THE WAY ALONG..... ALWAYS.
Those two lines show where the timber will be removed. It will be on the windward side of that line on each side...... so we now only need to know what the blade depth of the chainsaw will be, and make two boards on the sides for the chainsaw to follow.... ie our jig.
If we now mark a line to reflect the offset that the blade arrangement will use.... thats where these rails/boards need to be.
Now you can see that the blade will travel on the jig board, and actually cut along the original line you marked.
It takes some mental gymnastics to get the hang of....... just like the gravity furling did... but the moment you do one, it all falls into place.
I know the purists will go bippy , but thats what will work. The next set you can get all purdy with perhaps.
..................oztules