Remington Portable with new feet

Carrying on the steady tinkering with the Remington Portable #2 typewriter, on to the machine's rubber feet. After nearly 90 years, the machine's feet that are part of the cushioned fixing to the case bottom have lost their shape and resilience. If the feet are still present at all, that is. Also on this black machine, the feet seem to have melted and given way before solidifying like stone.

As replacement, new rubber grommets of a right size can be fitted. These can however be hard to find and a grommet of the right diameter (for a 15mm hole) rarely has the right heights and inner diameter.

This led to the question, could one-off replacement feet be manufactured? (Well, of course that is always possible, but what is meant is within reasonable expense too :)  With flexible materials in black, an FDM (Fused Deposition Method) printer could be used to manufacture a set of feet with the correct dimensions perhaps.

Some time ago had some experience with Arnitel. Parts made from Arnitel are fairly resilient like rubber, however not grippy at all. Similar for the fairly standard Flex-PLA (Polylactic Acid) materials, flexible rather than resilient and not grippy. Recently there is added a new material to the palette with the tradename Ninjaflex, a PU (Polyurethane) with according to spec sheet a durometer value of Shore 80. It also is grippy.

Looking at the remnants of the tired old feet and taking measurement of the hole in the machine frame and the pillars on the base, the likely shape of the original feet was drawn in CAD in 3D. For printing in Ninjaflex on an FDM printer, this proved however to be not an ideal shape. Over several iterations, a 3D geometry was developed that works well on the machine and prints fine in Ninjaflex (From left to right in images below).

The first test prints were all done in red Ninjaflex, the final functional feet in the black Ninjaflex. The one key dimension is the outer diameter of the top flange, that should be 15.5mm +/-0.2.

This iterating in design was actually made possible by an online service (www.3DHubs.com) that provides access to thousands of 3D printers. Via this service it is possible to find a 3D printing hub globally locally. For this project I was very happy to be able to work with Martin's Hub, a local hub with fast turn-around and solid know-how on the printing process with Ninjaflex.

With the successful design file, a set of feet was ordered and printed. The old feet were removed from the machine. (Not a rare machine and the feet were rather far gone, so felt no qualms about removing these.) The front feet were indeed hard like glass, the rear feet turned out to have a consistency of licorice - weird what happens with rubber over time.

With this latest design of the printed feet, these are a simple press-fit into the holes in the machine's outer frame. The new feet have a very firm grip on the table with the smooth flat base and fit nicely over the pillars of the base of the case. With the machine screwed to the base, the screw holds against rubber again and not wedge the metal pillar itself, so again the optimal cushioning of the machine to the base.

Both my Remington Portable 2 typewriters now have new feet and sit very firmly either on their base or on the table.

In case you have an RP2 machine (there are many around still) and it has disintegrating or missing feet (many will have), you may well want to get yourself a set of newly printed PU feet.

The 3D file for printing can be downloaded here or be downloaded from Thingiverse here. Then take the downloaded STL file of the feet and upload it to 3DHubs. (You will need to make an account in case you don't already have one.) Choose the amount of prints you want of the part (e.g. 4 pcs :-)  Then you can select a local hub that can print in Ninjaflex in black or of course select Martin's Hub and have the parts then mailed to you.

With the 3D file uploaded and a hub selected, you can order the parts via 3DHubs. After a few days (or perhaps hours, as the case may be), you can pick up the feet or have them in the mail heading towards your typewriter.

Will be very curious if and how your experiences are with this!

New technology keeping old technology in parts :-)