I used these for the first time to cut down a BT-60 body tube and was surprised at how well they worked. Before I used them I was skeptical as to whether or not they would move while cutting, but they fit over a tube tight enough that they don't move at all! While the guide is on your tube it is very easy to slowly rotate the whole thing while you score it in one smooth motion with a sharp hobby knife. Keep in mind that you don't want to cut right through, but rotating and scoring several times will result in a nice smooth cut. After your cut, lay a piece of sandpaper on your table and sand the end of your tube in a circular motion. Using this method will result in a nice factory edge on your tube. These also come in handy for drawing a line around a tube for fin placement or for engine mounting rings. I love these guides and will use them over and over!

I had been cutting tubes using rings of tape and had never been happy with the results. Since I bought these, I've tried them with BT-5, BT-20, and BT-50, all with excellent results. Patience and a sharp blade gives a near perfect cut. For me, these were an easy way to step up the quality of my builds.

This worked a lot better than I expected. I have started to make a lot of custom rockets and I find myself using these on every project. Make sure you have a sharp blade and be patient!