Hey! Thanks for your question, I love to talk about this stuff. I use a mr85 bearing (2.5mm wide) with a nice surface finish - filled with steel epoxy. The key for me is a thin polyester string with a pretty tight wind. I like the Twisted Stringz regulars. Start off with the string over torqued and then gradually let off torsion as the string breaks in. Each individual string breaks in a little different, it’s all about finding that nice responsiveness with clean spin at neutral torsion.
I’ve been back and forth several times with having stainless steel bearing blanks made, but I just can’t justify the order size needed (100-200 units) vs what I think is likely a limited demand. So I have left that be for now. The glued bearings work well for me. I’ve been using the same one for almost 2 years once I got it dialed in.
I actually plan to make more in the future, I already have bearings cleaned and ready. It’s just tedious work to fill them - plus Canada post I currently on strike.
Regarding the spacers you use. Are those aluminum and 3mm wide? I tried a 3mm wide mr85 bearing that I made into a blank a while back and liked it initially but then determined that it caused too much kickback for my liking.