I dont think that Houdini was a particular lock expert. I think he had a good working knowledge of locks. More than the average person. Of Houdinis day, the locks were comparatively simple affairs. Not very complicated. Handcuffs in particular werent as strong as Houdini would like the public to believe. But the public didnt see handcuffs, unless they were locked up for the night. Theyd no chance of opening them. They were very simple. They were made to escort a prisoner, normally with a policeman, from one point to another point. They were called escort cuffs. So that the handcuffs werent particularly strong.