You can grind to dry sift ( but you better be good at the cleaning part ) but i would never suggest grinding for bubblebags.
The bubblebags will produce a purity of resin heads for you that will IF YOU HAVE THE QUALITY produce a nice melty hash. THats all the bags can do is PURIFY. they cannot control your quality. ONly increase the purity which if your quality is killer will produce super melty hash.
Its a no brainer with the bags cause the water does the work for you. HOwever with the dry sifting box you need to be careful and patient. its a fairly counter intuitive process that many screw up by thinking they are doing the right thing but actualy doing the wrong.
here is a great thread for water extraction with tons of tips and photos
http://www.fullmeltbubble.com/forum/showthread.php?t=40

and here is one for the dry sifting.. to help you on your way to achieving the fullmelt clear dome hash.
https://www.icmag.com/ic/showthread.php?t=253284

hope that helps and also i should reiterate that what GS mentioned above will stand true.. The material used will be the deciding factor on wether it melts or not.. once youve achieved purity!!!

Peace
Bubble man