Not sure how fine you want it but often I will just take the top two pieces, remove ALL stems if I want it fine, load it up, turn it upside down and just keep turning it back and forth like a wheel. I made my 4 piece a 3 piece and I like it much more like that. Lately I have been breaking it up by hand again. Usually I just grind up stems and all so long as they are small enough, makes a good placeholder and no waste either. Same with any leafy stuff, I just pack it on in. It's all medicine.
I'm not sure that you can get a 'finishing grind' from a regular grinder but I could be wrong. Poor man's solution I think is a coffee grinder, but I think I have heard negatives about it and it's not something I would do myself since if I ground some it would take me too long to get through it.
There is a grinder thread here, which has a lot of good info, much better than I could give you.
Do you want it super fine for a MFLB or something to that effect, or just fine? I use a Solo and too fine will kinda plug up after a few pulls. Too coarse/whole and I don't really like it as much. Generally I only grind enough for one stem at a time because it seems like it loses taste overnight after being ground up.
Here is the grinder thread:
http://fuckcombustion.com/threads/herb-grinders.15/