New 7/16" ribbon for the Burroughs Portable adding machine

Even though it all works with a standard half-inch ribbon, the Burroughs is actually built to take a 7/16" ribbon. These are not too common anymore, but can still be bought. They can also be found in some cassettes for more modern printers or cash-registers. In this case, a cassette for an Olivetti PR4 was opened up.

This cassette contains a 7/16th ribbon in an endless loop. First thing is to find the splice, i.e. the spot where the ribbon was welded together to make a loop. To avoid having a 'hard bit' somewhere halfway on the ribbon, that's the spot to cut it.

Then the new ribbon is wound on a spool or simply onto a toothpick. This helps to remove any kinks from having been zig-zagged on the cassette. It also be convenient for re-inking the ribbon.

These cassette ribbons were probably not very heavily inked to start with, especially when intended for a pretty aggressive needle-printer. These cassettes often are old stock, so perhaps already dried out as well -despite the cellophane wrapping. (Probably not actually cellophane, but whatever transparent plastic material it is; it probably isn't fully airtight.)

To work well in an adding machine, a ribbon needs to fairly heavily inked. (Same for a Hammond, but an Oliver could be fine with a lightly inked ribbon as it packs quite a punch.) To add more ink, ideally a little inking-machine should be used. Proper inking is done by first fully soaking the ribbon and then squeezing out excess by feeding it through pressure-rollers. Level of inking is regulated by the pressure on the rollers.

Not having such a machine (not yet :) the inking was done by hand. Either place droplets of ink onto the coiled ribbon and let it seep in, or apply drops/streak along lengths as it is wound from spool to spool. Stamp-pad ink, either 'water' based or metal-stamp ink that should be oil-based. It can help to leave the ribbon a day or two after applying ink to let it all even -out and properly soak in the fabric.

Whichever inking method was used; a final and messy step that is essential for a usable ribbon is to squeeze and spread-out the ink. To do this manually, the ribbon is wiped with a bit of absorbing card or towel over paper. As lengths of ribbon are pulled through this wiper, excess is removed and evened out. It's messy, but not hard and makes a lot of difference. 

With the little Burroughs spool full, the ribbon cut to length and firmly fixed to the other spool. Note that the Burroughs Portable -like many other adding machines- uses tension on the ribbon to reverse the ribbon-transport. That means it should be very firmly fixed to the spool - e.g. tied to the spool-core with a knot. Double knot.

The spools with freshly inked 7/16th ribbon then placed on the adding machine. The ribbon winding directions are obvious from the spool driving ratchets, routed around capstans as shown below.

Net result: a better fitting ribbon and a legible printing line on the Burroughs Portable adding machine.