Back when I first got a fly box (my dad's) it had some bivisibles in that he'd tied up. Over the years I've tried recreating his tie but without the same success. I bought a rotary vise 5-6 years ago and have enjoyed the rotary function for winding dubbed bodies and ribbing. A month or two ago I was doing some old flies and fixed on the Bivisible. I had some nice, smaller dry quality saddle hackles and was struck with the thought of using the rotary to hackle the fly. Boy it sure does make tying those flies fast, and neat. One issue with it is it's possible to get the fly hackled too tight and might make it harder for a fish to "crush" the fly and get hooked. I tied some more up today and put less hackle on it. Now for the local wind to die down and try skating some Bivisibles during a chironomid (notice the full word) emergence.