Hey guys started to learn sweep picking a little while ago and making decent progress, but really having trouble with finger rolling. I can't figure what I'm doing wrong; I just can't stop the notes ringing together.

Any help and/or links to good video lessons greatly appreciated, cheers.
'Lovely' does NOT have guitar solos!

Monterey Stage Series Electric
Some bright orange Ashton acoustic
Line 6 Spider 2 112
Variax 300
I'll give you advice as far as I know. I can only do 3 string sweeps (with a limited ability to do 4 string sweeps), at least with an efficiency. I had the same questions when I started. I felt I was doing the motion right but not getting the sound that is so sick in many videos. The key to sweeping is purely practicing. That may sound stupid but there is no other way. Watch videos of people sweeping, and then try to mimic that movement. You will want to start of slower in order to get those notes to sound good. I know for a while I had a problem matching my right hand with my left hand (perhaps the problem you may be having). Simply put, slowing it down may just make it easier; than gradually speeding up.

Sorry I can't advise you like an expert or anything, but I try! haha.
Most likely if the strings are ringing out from your rolling, either:
A: You're over a harmonic node point and have the right idea but need to change your finger placement just slightly to get it muted.
B: You're really just barring the notes and not rolling your finger.
C: You have the right idea but when you roll for the second note you aren't lightly lifting your finger off the first note in order to mute it.
D: You're lifting your fingers completely off the string without muting them with that hand, causing open strings to ring out.

It may not necessarily be one of those, but those are the most common reasons why strings would ring out that I can think of off the top of my head. It's up to you to figure out if one of those is it.
Are you rolling from your wrist, or with your fingers?
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A. Make sure you're NOT rolling from your wrist.
B. Palm muting+sweep picking can't hurt. Just make sure to put the least amount of pressure as possible on the muting area of your hand.
C. As described in 'B' with your muting hand, make sure you arn't pressing too hard with your fretting hand fingers. Only use enough pressure to get a note to sound.
Yeah I do roll with my fingers, so I suppose that's a good thing at least.

Thanks for th help guys, it's really useful!
'Lovely' does NOT have guitar solos!

Monterey Stage Series Electric
Some bright orange Ashton acoustic
Line 6 Spider 2 112
Variax 300
Finger roll's are what I'd consider a very important technique and not just for sweeps.
A good way to practice them is diatonic 4ths up and down the scale in a single finger
position, position by position. That will get you used to doing them with every finger.
This is also a great workout for inside and outside picking.