Are all the cutters the same size? I mean, would a square blade from X company fit B companys tool, assuming all same like 14mm or 16 etc?
, im liking the idea of making one myself, so i want to make sure i can get blades from anyone and still use the tool.
Well, a 14mm square cutter is not physically the same size as a 16mm square cutter.
Obviously you need to pay attention to the physical specifications of the cutter provided by the manufacturer - ie, the dimensions and the screw size. That said, if you are making your own rod and handle, you probably can grind the platform on the rod to accept a range of cutter sizes. For example, I would think that you could easily make a platform that would accept either 14 or 16mm square cutters. Ultimately, the issues that limit this flexibility are the amount of support that the rod provides to the cutter - you don't want a lot of unsupported overhang, so you probably would taper the rod below the platform - and the size of the screw that attaches the cutter to the platform.
One other thought - the round versus square issue for the rod itself. The heart of this issue is that cutters are very aggressive when they are exactly horizontal, and easier to control when they are skewed at an angle. I prefer a round rod myself because I know that I'm going to have to roll it slightly to the left, and that's easier to do when the rod is round (and also because my local Ace Hardware doesn't stock square mild steel bar stock). But the square crowd believe that its easier to control when the rod is square. That's probably one of those discussions that is ideally suited for late on Friday night over a couple of pitchers of beer - there's no absolute right answer, but it's fun to discuss.
There is a toolmaker in England who uses square rods, but who then grinds the platform on the diagonal. That means that the natural alignment of the square rod puts the cutter at a comfortable 45 degrees. I think that's a neat idea.
I've noticed that the folks who sell cutters provide very explicit specifications for the products they sell, but my casual search of information on completed tools has yet to disclose a situation where the manufacturer actually specified the dimensions of the cutter. That's because they want you to come back to them for replacement cutters. But wood turners are accustomed to measuring things, so buying aftermarket cutters is not really all that hard - just measure what came with the preassembled tool.
