This post chronicles a beautifully precise repair: u/Joebobb22 bought a Futura 800 vintage typewriter on eBay, only to discover that two teeth were missing from the escapement starwheel — the small toothed gear that controls carriage advance with every keystroke. Without it, the typewriter won't type. With it damaged, every line of text drifts.

What makes this repair fascinating is that the OP couldn't just source a replacement part. Vintage typewriter spares for a Futura 800 effectively don't exist, and the starwheel is hardened steel cut to tight tolerances. So instead of replacing the wheel, they rebuilt the missing teeth by fabricating new steel onto the original part.

The technique involved:

• Cleaning and prepping the damaged area down to bright metal so new material would bond.
• Building up new material in the void left by the broken teeth — essentially adding metal where there was none — using welding/brazing on a part barely larger than a fingernail.
• Filing and shaping the new teeth by hand to match the geometry of the surviving teeth on the wheel, working off the original profile as a reference.
• Re-hardening so the new teeth wear at roughly the same rate as the originals — otherwise they'd deform under the constant snap of the escapement.

The educational value here is twofold. First, it's a great demonstration of the "can't buy it, so make it" mindset that defines repair culture for obsolete mechanisms — a skill set increasingly relevant as more 20th-century machinery passes out of the spare-parts economy. Second, it shows how much of fine metalwork is really about reading the original part: the surviving teeth tell you the pitch, the pressure angle, the depth, and the hardness target. The repair isn't designed from scratch; it's reverse-engineered tooth by tooth.

Comments dig into the choice of filler material, whether silver brazing would have been gentler on the surrounding heat-affected zone, and how to test the repaired wheel under the spring tension of an assembled escapement before committing it back to service.

For anyone interested in horology, watchmaking, or precision mechanical repair, this is a small but rich case study in working at the millimeter scale on a part that can't fail.