Needing some advice when it comes to sharpening stones. I'm a couple of years into woodworking with hand tools and started with diamond stones. Sometime back, I decided to try some water stones so I purchased 1000 and 8000 grit Naniwa Super Stones along with a Norton 'Flattening' Stone. Things were great for a while, then I noticed something I wasn't expecting... my planes were cutting in the corners but not the middle - the exact opposite of what you want. Much to my surprise, the flattening stone had become concave (valley in the middle) - leading to my waterstones becoming convex (hump in the middle). This of course, is no good and explains why the plane irons were cutting like they were....
So my first question - why would the flattening stone not stay flat? I guess I assumed it was made for flattening so it should stay flat.
Second question - what should I do? To use the water stones, it seems I will have to buy a lapping plate which seems to be the cost of a whole kit of DMT Diamond Stones. Given they are basically the same cost, is there any reason to go for one over the other (besides personal preference)?
Finally, let me say this, I don't have any loyalties to water stones vs diamond stones... I don't care much for arguments of this vs that. I just want it to be as fast and easy as possible and give me the best edge possible (within reason) that will remain sharp as long as possible. I wan't to get to planing wood and be able to get my smoothing plane sharp enough to not have to get out the sander when it is time for finish.