I used an old solid axle with nuts on either side of one dropout and it was very easy to align the dropout by putting pressure on the end of the axle. The dropouts don't bend, the narrow ends of the stays bend. I reinstalled it with the axle running through both dropouts to check the alignment. It's not as accurate as professional tools, but I think I got it close enough. It's a Reynolds 531 frame with Huret dropouts. A threaded rod would give you so much leverage that you'd need to be careful not to overbend.