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Proposed solution online: Straight surface + diameter gauge?
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Gameplan:
Circularize interior using an engine hone
- Attaches to a drill and rotates three spring loaded grindstones that remove more or less material based on their spring pressure.
Circularize exterior using an improvised lathe
- Attach cylinder to a motor after the interior has been circularized (friction fit with laser cut wood circle?)
- Attach other end to a bearing so it can rotate (also friction fit with laser cut wood circle?)
- Fix a piece of sandpaper at a set diameter and move it up and down the cylinder until the entire thing matches that diameter (check tolerance at multiple locations to reduce error).
Backup method: Use a centerless grinder (more work but potentially better results)
- Cylinder sits on a rest while a grinder is rotated next to it
- A second regulating wheel is moved in to apply pressure and rotates without slipping with the cylinder
[As seen on Wikipedia ^]