I've done a some carpet work in my house and also for other family members and have gotten pretty decent at it. I can seam two pieces together pretty good. Have used a straight edge on the back of the carpet and also have "ran some rows" to get straight cuts for seaming. But one thing I haven't figured out is how to trim two pieces of carpet to seam at a doorway. Like where a bedroom meets a hallway. I haven't found a good way to trim both pieces straight to get a good seam. Any tips or tricks on this?