Saturday, June 24, 2017

Remington Portable ribbon mechanism assembly

Getting round again to tinkering with the 'lost cause' Remington Portable 2 typewriter, the next step after mounting all the typebar linkages was the ribbon mechanism.

The change of ribbon travel direction is done by sliding the shaft to the left or right, engaging either of the spool holders with its conical drive gear. To keep it in engagement, there is a spring loaded mechanism located under the left spool.


Two cups are held with a single spring-clip, pressing against a thinned section of the shaft.


The shaft has nicely flattened areas for the set screws to get a proper grip. The thinned section can be seen jutting out of the hole in the spool-base. When assembled, the spring-clip should fit underneath the shaft, pressing the cups into the two holes either side of the spool-base.


The spool holder can then be screwed on, consisting of its base gear, spool-plate and the pillar.


The conical gear on the advance shaft is in engagement with either left or right spool holder when the shaft is pushed in its left or right position. The pillar is stationary and the gear with spool-plate rotates. (The slots in the spool-plate hole engage notches on the special Remington Portable spools. Spool-plate not yet screwed on in picture below.)


At every keypress that actuates the universal bar, the ribbon advance shaft is rotated a little by a push against the advance gearwheel. To prevent it from rotating back again, a pawl locks it in place. When sliding the shaft with all its parts back in position again, this pawl needs to be lifted on top of the advance gear.


As can be seen in the above picture at the arrow, that is what I failed to do. The pawl that can be seen hiding in the dark should have been lying on top of the finely geared advance wheel. (Something we'll know about a next time :)

The shaft can then be fitted with the end control-knobs. These also have the cam-slopes that are actuated by the prongs on the ribbon-fingers that 'measure' the amount of ribbon left on the spool.


In this machine, the parts are oddly of the old pattern - more usually found on older, pre-'25 Portables. This also goes for the spool-locking clips. It seems that the British factory still assembled some machines with the old pattern fittings as late as '27.

With the knobs fitted again and a little tweaking on the position of the gears, the ribbon and spool mechanism is again in place.


 (The dastardly pawl has since been lifted to its proper position.)



Friday, June 9, 2017

Produx pocket calculator

A very simple mechanical calculator of the Troncet-type, more commonly known here as 'an addiator'. This Produx was probably the main competitor to the Addiator. 


This particular little calculator likely dates to the 1950-ies. The protective sleeve is made of a plastic (PVC or vinyl) and it is made in Germany - West.


The Produx was manufactured mostly unchanged from the start around '28 (?). Even though the competitor Addiator became the generic name for these calculators, the Produx was made by Otto Meuter who was the inventor of these little devices. Addiator was founded by Carl Kuebler who licensed Meuter's patent. (May be that the royalties from Addiator sales then enabled Meuter to set up his own manufacturing.)

It is of very simple and low-cost construction. The Produx is quite compact at 4½ by 2¼ inch and very thin. The stylus made of rolled-up brass is a bit too flimsy; the tip is often broken off as it is in this case. A toothpick inserted in the stylus makes it usable again. Both adding and subtracting are on the front of the calculator, making it a bit more convenient to use than the original Addiator.


The sliders protrude through the bottom of the device, so resetting to zero is a simple pushing back - set it on the desk and push down.

These take a bit of getting used to, but then work surprisingly well :)