Friday, April 17, 2015

Remington Portable with new platen rubber

After making the keyboard look nicer, the next item was an attempt to make the quality of typing better. The machine was already quite usable, yet the platen was rock hard (noisy!) and was actually bent. When turning a full rotation, the centre section would move about 1 or 2 mm. This is not good for the imprint of the type and also can make the linefeed go off at an angle, when one set of feedrollers wins out over the other on the platen.

This time the weeks of letting oil seep in the platen knob screw payed off. After also applying some white petrol (basically making creeping oil), thankfully the platen knob screw came off without needing much force. This has a large screwhead, but actually is a very small screw with delicate thread. (Probably just as well that I didn't try to force it in any way on this or the other RP2 machine.)

With the screw removed, the platen knob can be coaxed off the rod. Then the platen rod can be pulled out to the left. This leaves the platen loose in the paper well between its brackets and can be manouevred out, taking care to not to bend the line guide. Lifting up at the right side, the linespacing ratchet is shifted from under the spring loaded roller and all comes out.

The platen lifted out of the machine, the paper well is now accessible to remove the rust. The platen knob has two small notches that fit two indents in the platen-rod end to fix it against rotating.

The platen-rod keyway fits the notch in the hole of the platen flange. The stud at the end of the keyway prevents the platen-rod being pulled out to the right side, this is the stop that the rod is pulled against when unlocking the carriage.

Now with the platen out, the linefeed pawl assembly is loose on its flange, can be good to store it somewhere safe or to fix it in place with some rubber bands.

Having the platen out it turned out that the platen itself was not bent, but the rubber of the platen had dried out so much to come unstuck from the core and deform. Luckily the rubber of the platen came off easily like a sleeve from the core. On this machine, the platen core is made of wood (not brass) with metal flanges at the ends. (Forgot to take a picture of the core...)

Before replacing the rubber, made an attempt at rejuvenating the old rubber sleeve to see if it could be made more flexible again. That actually worked very well and also made the rubber sleeve unusable. With some thought about drying out of rubber, seemed to make sense that some light fractions of simple hydrocarbon could enter the material again. Wrapped in a rag with white petrol and sealed in aluminium foil, the rubber was left to 'soak'. Left too long actually. After a day soaking, the rubber is again rubbery (feels more like Shore 90 than slate stone).

Fitting it back onto the platen and in the machine it has not only become flexible again but also grown by 1 or 2 % in size. Should have realized...

Typing on it was very quiet in the middle of a line, louder at the ends. The platen being larger, floated free over the core and could be flexed and moved by hand. End result is experience and knowing more about old rubber, but not a usable platen.

So then to the recovering with new rubber. Instead of sending off to a professional platen recovery service, used rubber sleeves stacked onto the core. Bicycle innertubes are a good source of about the right sizes, but too soft and too grippy for the outer layer.

The new platen was then built from three layers of innertube with the outer layer from heatshrink tubing. The thin heatshrink tubing also allows for getting closer to the target platen diameter (about 28 mm).

This way the platen feels about right in stiffness and in surface. The idea behind this way of stacking the materials was to have the heatshrink layer as the outer, harder and smooth layer to take the type and have a softer rubber tickness underneath to dampen the strike of the type.

The end-result is not as quiet as the 'floating rubber' was or the way a Noiseless is, but definitely it has removed the sharp clack of the machine. The linefeed also no longer veers off course and the quality of the type print is much improved. A clearer, crisper imprint, with less striking force needed for a good, complete character.

All in all this Remington Portable typewriter is a fun machine to tinker with!


  1. This is great. Wonderful job you're making of this machine. I have three, and can't get the platen knob screws to shift on any of them. I'll definitely try the oil and see if that helps! Your improvised rubber layering looks super.

    1. Good luck; very rewarding little machines. (and after spending 80-odd yrs to get stuck, seems fair to allow the screw a cpl of weeks with creeping oil to loosen :)
      Hope here that the heatshrink tube holds up and can take the type-strikes with the soft support it has.
      Oh, and cutting the sides to size turned out to be hard! Next time I'll cut the innertube to size and then shrink the tube over the end to make a clean edge.