I am sure this question has been asked before, but I am curious of the answer and could not find the answer using the Search tool. I am sure many of the plane historians know the answer.
I see BU planes having many advantages over BD blades.
1. Easy to change blade angle (by changing blade)
2. No chip breaker required.
3. The entire blade surface is supported by the mass of the frog (or whatever you call the blade holder), vs. the BD having the thin part of the blade having no support behind it.
These seem like significant advantages vs. BD. I am sure they are some small differences that aren't worth mentioning.... but my question is, to create a BU plane took NO technological breakthroughs. So hundreds of years ago, why weren't all planes BU? There must be some reason for this, as in the pre 1900's, the hand plane was probably the most used tool in every shop.
OH yeah, and btw, is there is any significant advantages to BD?