reply to u/orionis1 at https://reddit.com/r/typewriters/comments/1wxhe3q/bloquer_lavanc%C3%A9e_du_chariot_sur_une_underwood/
I presume you're going the route in this video https://www.youtube.com/watch?v=1upTPepErTY and miming/pretending all the typing with the carriage stuck at a set point by setting the margins so that the carriage doesn't move at all? The typist is then the tenth chair percussionist who is really only playing a desk bell.
I think the illusion is best when the bell is hidden from the audience in front of the typewriter and the typist actually only spaces and machine and does (quiet) carriage returns. The typing sound is then done by electronic keyboard and the carriage returns are played by wooden guiro, washboard or something similar.
You'll notice by watching any dozens of versions of performances of Leroy Anderson's "The Typewriter" that they're ALWAYS CHEATNG on the actual use of a typewriter. As an example, the bell on the typewriter in your video has been disabled/removed and the performer is using a separate bell mounted on the table next to it. It appears that he's finger pecking only two keys and/or only using the spacebar which moves the carriage. Many performances don't even attempt to properly time the carriage returns to the sound. Half of the "performance" is the attempt at comedy in the playing or presentation . You're trying to one up Jerry Lewis in 1963's Who's Minding the Store, which is never easy.
If you've got a practiced enough percussionist/typist, you can do the typing in reality though you may need to mic it up for volume/projection, but I recommend putting the paper up a few inches and not using the paper bale to get a louder percussion of the slug hitting the paper. If you go this route, I would recommend not using a machine with Perspex card guides, removing/disabling the paper fingers if there are any. It's impossible to get carriage returns done properly via sound as there are a few points at which the carriage hasn't moved enough to go more than a space or two.