Dym-Mite Tapewriter 9mm tape adapter

The 1960s Dymo-mite tapewriter is a fantastic bit of kit, however, it is designed to take the 1/2 inch (12mm) tape which is a lot harder to come by these days and in my opinion doesn't look as nice. You can use 3/8 inch (9mm) tape without modification but it has a tendency to wander in the head and result in the letters being printed too high or too low on the tape.

This insert simply clips into the handle and centres the 9mm tape while still allowing you to feed 12mm tape over without removing it.

Material

While this part will work in PLA I would recommend you print it in PETG. PETG generally creeps less, has a lower coefficient of friction and is a bit more flexible.

Tolerance

This part uses fairly close tolerance so you may have to print it once or twice with adjusted flow rates to get a size that works well. You want the tape to fit through the adapter without dragging but also without too much slop. Alternatively, some fine files can open up the channel a bit and will also give a nice smooth edge for the tape to run on.