Whenever I tie in calf tail for an upright wing (as you might do for a Wulff or parachute post) I seem unable to neatly cut and taper the hair butts. 
To be honest, by the time I thread-wrap the butts and finish the body of the fly, it doesn’t make a difference how well the hair butts were trimmed. 
However, I would be interested in any tips you might have in trimming the butts so they look neatly tapered.
Thanks.
Peter
Just a thought Peter, but have you tried holding the scissors more parallel to the hook shank when trimming. This might result in a taper instead of a cross-cut trim. Also using curved manicure scissors with the curve facing upward might help here also.
Hi Peter,
Take a look at Tip 8, on page 63 of Fly Tyer magazine. Take care & …
Tight Lines - Al Beatty
www.btsflyfishing.com
Calf tail can be rather bulky and slick. Try working with less material and see if that helps. Too much material at the tie in point and the whole thing will rotate and move around on you.
If you want a real dense wing you might try attaching it in 2 or three layers.
To get a good taper I grasp the butt ends and bend them up 90 degrees from the hook shank, then holding my scissors parallel to the hook shank I slice through the bundle, cutting from front to back. With practice this should give you about a 45 degree taper. I then wrap the cut ends towards the hook bend with loose wraps, increasing thread tension as I wrap down the slope. Then wrap tight wraps back up the hill with heavy tension. The first layer compacts the fibers, the second layer locks them into place. Pull the wings up vertical and wrap a thread dam in front to post the fibers upright.
I cut mine with three snips and get a nice taper that way . It probably takes a little longer , but I’m in no hurry .
Exactly what I was looking for! Thanks so much.
Peter
If you’re tying in a white wing or parachute post get some badger & leave the calf tail for the tail! 8)
Take a look at steps 5, 6 and 7