Hi Thomas, Are all those from the same maker or is it a mixed set?
Most likely more than half of the molding planes available today have had their blades buggered by a previous owner. Often the center of the blade gets all the abrasive action and the edges are untouched, especially on hollows.
Here is an old post of mine on rehabbing old molding planes >
https://sawmillcreek.org/showthread.php?242156
Way down in the thread is this link >
https://blog.lostartpress.com/2017/0...plane-cutters/ < it is an article on sharpening molding plane blades.
The tapered diamond stones seem to have one problem, they are tapered. The area that can be used for a smaller blade is limited.
Using dowels our rods wrapped in abrasive sheets works okay, but it gets tedious fast.
When first starting on this when a blade got sharp enough to make a decent cut a profile would be cut and then abrasive sheets would be used on the profile to further refine the blade. Now a similar technique is used for stropping.
My current set up uses both oil and water slip stones.
Water stones are available here >
https://www.leevalley.com/en-us/shop...s?item=60M9000 < They carry others, search their site for > slip stones <.
My oil slip stones are mostly from Dan's Whetstones >
https://www.danswhetstone.com/product/slip-stones/ < They also have others including carver's slip stones. They also have round and oval Arkansas stone files that are useful on molding plane blades.
A couple of my oilstone slips are from Norton >
https://www.nortonabrasives.com/en-u...ound-edge-slip < one is a crystolon and another is an India stone.
A good book on using hollows & rounds for making moldings is
Mouldings in Practice by Matthew Sheldon Bickford from Lost Art Press.
One thing to remember is the shape of the blade is more elliptical than round since it is 1/6th of a circle at an angle.
jtk