its such a simple concept, and it sounds so nice but i cant do it. I can bend notes up to the desired pitch perfectly fine, but when i try and add a bit off vibrato it goes sharp or just sounds really weird. You know the SRV cover song of little wing? When he breaks into the lead solo and bends the 15th fret on the B string up a step, thats the kind of vibrato im looking for. Anyone got any tips?
lol id love to know aswell. Can use vibrato on a single note perfectly well but when I bend up, and go to vibrate, I let the string down so much it goes out of tune! The resistance from the bend causes my hand to give way when I start to use vibrato!
Lots and lots of practice

It takes a great deal of time to develop a personal vibrato. I would just steadily practice bending up to the target pitch until you can build the strength and control to move the string to the vibrato you want. Practice it so your doing it to something to and that it's nice and in time.
You need to practice bending vibratos a lot. Practice with a metronome and listen to players who have great vibrato; Paul Gilbert, Yngwie Malmsteen, Zakk Wylde, Steve Lukather.

Just keep at it.
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yeah took me a while to learn to do a vibrato while bending one of the strings up.
Never really saw the importance of it..till i started to listen to Queen

thats when it all began :P
i just had an epiphany and figured it out. I was trying to bend, and do vibrato in a down motion, like i do when im not bending. But then, the simple fact that i had to do it UP first is how i figured it out lo.