My 1 by 30 has made several knives, it couldn't hold a candle to a proper grinder but it does get the job done. Most serious knife makers seem to go with a 2 by 72 and assuming your motor is sufficient pretty much any 2 by 72 grinder would be faster and should be better suited to grinding a consistent bevel although even a relatively affordable 2 by 72 is approaching 10 times what my 1 by 30 cost so it isn't really a fair comparison. so if i understand your question correctly a 1 by 30 or 1 by 42 grinder should be perfectly adequate for sharpening and profiling work and some minor grinding but if you want to make knives and cost isn't an issue than a larger grinder would probably be a better choice.