hi stardelta. If you are doing more than a couple of frames, it might be worth getting some cramps, like these: corner clamp or to do the whole frame frame clamp , these are a bit fiddlyto use at first and the overall size size of the frame is restricted. You can get string ones that work in the same way. The first set you join a corner at a time. My local market does them cheaper in pairs, so you make two L shapes then join them up. If you get the bug and do lots, get your own mitre saw, this sort will give great results mitre saw . Hope that helps and I haven't bored you to tears!