While sitting in a self-help sales brainwashing pitch a friend invited me to, I zoned out (for about 3 hours) and thought over the flattened roller issue on my 1930 Royal Portable. I did not snap photos when I took everything apart so I’m borrowing Teeritz’s photo of his Corona Four to illustrate:
As you can see, that rubber roller has a depressed flat side. This makes paper feeding very difficult. TONS have been written on the internet about softening rubber, replacing platens, etc. There are some companies out there that will do it, and knife141 at Instructables has a wonderful bit about doing it yourself. I cannot speak to the success of either as I’ve not gotten this far, but their work looks really great.
So there I was, trying to be polite, and not say something I would regret about the expensive forum for leadership drink the Kool Aid and be happy whatever, when it occurred to me: Why not fill in the flat? Bear with me for just a moment.. Imagine a cylinder, like a soup can, and cut a vertical slice of the cylinder off. If you wrapped paper around that cylinder you would see an arc where that slice was. Why can’t we imagine the arc as a space to be filled?
Here’s a drawing to illustrate where I’m at in this thinking…
So that area at the top, which I’ve kept the outline of the circle to illustrate the arc, that’s how I’m looking at the flattened platen issue. I’m thinking it’s possible – maybe – to fill in that arc. Perhaps with another piece of rubber, although cutting might be an issue. A good thought that came to me was a glue stick, as I have this in mind for the smaller rollers. What about 3D printing this arc to fill in the flattened part?
Granted you’ve still got (probably) a hardened roller that is very old. Never the less, maybe it’s possible. Heck maybe it’s possible to 3D print the whole roller using some soft compound that mimics the rubber from an original platen.