I’m really liking grinds but most of my throws don’t grind so well. So far my best grinder is my Duncan echo I would like something that can do thumb grinds , arm grinds,and finger grinds . Any type of grind really.
I would all so like something floaty and maybe mid/ undersized .
Puffin and Cascade come to mind. However, mid and undersized, I can’t really recommend any great grinders with your floaty request.
Well the spin dynamics smooth move is designed with a focus on grinds.
General Yo M10 sounds like just the ticket.
Yuki
Disclaimer: despite having some opinions, I’m not claiming to be much of an authority on grinds. Take what I say without too much seriousness. 
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Lots of hits in the SPYY lineup: Punch Line is a grinding classic; Pro handles any kind of grind very well (the IRG doesn’t have a crazy deep area like some, but it has “something”); if you want undersized the Supra also fits the bill except no IRG; thumb grinds are possible (and even easy) with the yoyo at a very slight angle, though.
MonkeyfingeR Lesula is insane for finger grinds and is mid-sized. I suspect the thin rims will make arm grinds will vary from person to person. No true IRG but there’s a teeeeeeny lip that helps thumb grinds.
Puffin is a brilliant one except for thumb grinds, and fits the mid-sized description.
Deadly Spins Wrath is a thing of beauty for grinds, too. Decent IRG ‘n’ stuff.
I have a Smooth Move but I can’t comment too intelligently on its grinding; I have a polished-ish finish (the Snow Drift finish) and it isn’t media-blasted for grinds. Certainly the shape seems like it would lend itself well to grinds, but I can’t pull’em off very well due to the finish.
Model 10 is a beast at grinding. The shape just makes it perfect for it really, coupled with the blast… pff…
But might not fit OP’s definition of mid/undersized. I would consider it “full” sized… but what does that even mean anymore? hahaha
Onedrop cafe racer excels at all grinds aside from thumb grinds, and meets all the other criteria.
The Cascade is pretty good.
the single best yoyo I’ve ever used for grinding was the x^3 stampede. I’ve gotten over 10 seconds (literally, I timed it) on a finger grind before, with enough spin left to bind easily.
The monkey finger lesula is the best grinding yoyo ever!
I second that, its a grinding machine.
Wrath and puffin
The wrath is an AMAZING GRINDER!!!
Just ask anyone who owns one!
But puffin is mid sized and i can get 6 second finger grinds
My YYF John Ando edition Superstar feels like nothing when it grinds. Amazing grinds.
Note: I don’t know if the John Ando Superstar and Superstar have different finishes.
Grind Machine! no im messin, I dont even know what they’re like but they have the word grind in them…
I’m not much of a fan of the Grind Machine… Anyway, a yoyo that’s good for grinding, pretty much any yoyo with a blasted finish, I would check out some of the candy blasted ILYYs.
yea, I haven’t heard much good stuff about the grind machines.
the og grind machine, the metal one, seems to be good. It has a bead-blasted finish and and a shape that seems to lend itself to grinds. I think i saw a couple on the bst
The Majesty is one of the best grinding yoyos that is currently in production. The best grinding yoyo of all time in my opinion is the second version 5-Star.
I’m going to second that. The majesty has a nice shape for the finger while also having a small igr
(if you have the first run)