I've spent waaaay too much time and money on sharpening gear. I've got maybe 15 Japanese natural stones, some of them pretty rare and expensive, and probably 50 Japanese synthetics- nearly all of the Naniwa Chocera stones, some Sigma Powers, a ton of Shaptons (both GlassStones and Pro Stones), an assortment of other Naniwa stones like the Aotoshi & synthetic Ohmuras, and a bunch of diamond plates for repairs and flattening of stones. My 140 Atoma is my favorite diamond although I have six or eight DMT Dia-Sharps, too. For volume work and/or heavy duty repairs like fixing broken tips I have three belt grinders, one 42" x 1" and a pair of 30" x 1" (although in practical terms the little grinders were pretty much retired when I bought the larger one).
Of course, as a chef I really do a lot of sharpening just to keep my own knives going. I have a work case that holds 10 blades, and I rotate knives in and out as they get dull. When a gyuto won't shave anymore, I give it two licks per side on a special glass honing rod; that's generally enough to bring it back to shaving sharp. When that doesn't do I try 2-3 licks per side on a fine ceramic. When that's not enough it goes back to the waterstones. So basically everything in my work case will shave or I leave it at home.
I actually do a bit of pro sharpening, just on a p/t basis. I have an arrangement with an online vendor that has me do finish sharpening of new knives before he sells them. And I have a few "customers" that ship me knives to work on. If I ever have time I'll probably formally hang out my shingle. My brother bought me a domain name and is (slowly) coding a sharpening site for me. Just another thing waiting for few of my rare "spare" moments!
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman