I think the bubble jig is the most helpful tool available for new guys (like myself) that are self teaching themselves.
That is a very good point, having used the Bubble Jig now for around 3 years now, I can also tell everyone that it is not ONLY a jig, it's a TEACHER AS WELL! See, as far as grinding goes (and several other areas), I have a handicap that almost destroyed my knife making dreams before I got started, being blind in my left eye left me with little to zero depth perception, some areas I would have a little and in other areas I would have absolutely none, it seemed to depend on what I was doing, some things I just learned how to adjust for, others I just had to start ignoring because in my sight it looked all wrong, like with my wife driving, pulling into a parking place freaked me out so many times, I would literally yell out loud, not STOP! or LOOK OUT!, no nothing ingenious as that, it was more like all of the alphabet at once, minus the vowels. Basically a guttural sound that tried to come out all at once, because it scared the crap out of me and I would be trying to say something as fast as possible. In my eye, it looked like we were going to hit the car we were parking next to, never did, now I'm sure everyone is thinking that well once you know that you can make adjustments, "REMEMBER" not to do that...see the key word, "REMEMBER", another of my handicaps, I have acute memory issues I deal with all the time, I know a lot of folks on here know me, some even personally, honestly I probably just forgot to tell you,<ha!could NOT resist>, I know I joke about it, but I did have a very serious condition that had to be fixed back in 2001, so I am very happy to ONLY have memory issues.
ANYWAY! Back on topic, I bought the Bubble Jig after destroying several feet of fine knife making steel, sure in my first few, I made some that passed muster, barely, but none that completely made me happy with the type of grind I was looking for, sure practice is huge, there is nothing that will make a maker better than making another knife. But I was getting to the point that no matter what I did, I just could not 'see' the angle, even if I changed the angle a bit then looked at what I did I could not figure out how I did it, because I could not tell the distance the blade was away from the belt, the angle eluded me and I could not figure out why, and out of complete desperation I bought The Bubble Jig, and like magic it worked! I was astounded, I tucked my elbows and moved my body just like I had read, which never worked before but I knew that was right, from reading on here and Mr Fred's many YouTube video's, I looked at my blade and literally had tears well up in my eyes. No it was not perfect, but it was closer to an even smooth grind across the blade I had ever done. Of course I do keep using it, but what I have noticed is that after I have done a lot of grinding, with it fresh on my memory, I can grind a decent blade free hand, sometimes I just get the grind started with the jig and then take it off, and check it every once in a while, it works for me! So those of you that want to learn how to grind knives free hand, there is probably no easier way than the Bubble Jig, not only will you be learning to grind with out realizing it, you will also be finishing MORE knives in the mean time!
I hope this helps someone, Rex