i have never met a crown i couldn`t cut to fit. the face/angle cut on both edges should be the same. cut a couple of test pieces and hold them in place until u get them to match. remember that you can rotate the piece inside the 90 degree and over 90 degree ceiling angles to produce a perfect or close match. two planes will intersect to produce a straight line. how you rotate the two matching cuts will make alot of difference in how they match up. keep cutting matching pieces (mirror imaged-right handed, left handed) and you should find a match. remember the back side of the wood is a flat plane and two planes will/can lineup and intersect in a straight line. basic euclidean geometery. good luck. p.s. check the accuracy of you`re miter box. if you're cutting free hand it`s a whole different can of worms. it`s frustrating now, but it should be fun by the time you figure it out. definitely a real trick of eye hand skill. post again if u have problems. others out here know more than me.