I have been using the $10 Dremel chain saw sharpening guide / attachment for a quick touch-up after each tank on my new Echo w/ Oregon chain to keep it cutting like new. My only complaint is that the stones wear out quickly (Particularly after needing to do the 4-5 passes after touching dirt / removing a stump, etc.) The typical Dremel 2-pack of stones (#453, 5/32, 4.0mm, blue; or #455, 7/32, 5.6mm, pink are the two I need for my saws.) are $6, not bad, but I noticed Widget supply ((broken link removed to http://www.widgetsupply.com/page/WS/CTGY/dremel-chain-saw) - I might also try their diamond hand files.) offers 5/32 in quantity for more like $1 each. 7/32 bits are harder to find. Does anyone have any info on sources or comparison to diamond? I assume diamond costs more but lasts longer?