Olympia SM2/SM3/SM4 Frame Bushing and Washer

Old Olympia SM* typewriters are known to have frame-to-shell bushings that collapse with age and cause the typewriter's carriage to grind, collide with the frame, and just generally cause all sorts of headaches.

The current go-to solution seems to be stacking rubber washers to get roughly the right height, or cutting steel-reinforced fuel injection hose to the right size. Beyond the obvious issues with consistency there seems to be no real consensus about how big the bushings need to be. If they lift the frame too far the typewriter will not clip into its case; if they don't lift it far enough they won't actually fix the problem. 

After trial-and-erroring it with fuel hose and putting myself in a situation where the left side of my SM4 would clip into its case but its right side WOULDN'T, I decided to just print the things out of TPU. They should be more resistant to abrasion, crushing, softening, and permanently deforming than rubber and they come with no puncture-wound/rust risk like cheap steel-belted hose.

This is a simple model - obviously - but it's tested and I don't want to keep it to myself given how common this problem is in the Olympia community. It will lift an SM* typewriter (or at least an SM3 or SM4) far enough off its body shell for the carriage to cleanly move across its full range but not so far that it won't clip into its carrying case.

Print out of 95A TPU at 100% infill. I used Overture high-speed with five perimeter walls, five top walls, and five top bottom walls, but that shouldn't matter given the infill. I tried it in 90A as well and they seemed to have just a bit too much squish.

The (thinner) washer goes between the screw and the frame and the (thicker) bushing goes between the frame and the body shell. Tighten until either the bushing or washer just BARELY starts to squish. I highly recommend doing replacing all four at the same time, or at least doing the front and back as a pair. However many you do, replace them one-at-a-time (i.e., only have one frame screw out at a time) so you don't throw the frame-body alignment off.

ID: 5.5mm

OD: 12mm for the washer, 15mm for the bushing.

These figures closely match what was left of my factory originals. The height was trial-and-error; I settled on 4.6mm but you can probably get away with up to 5.2-5.4-ish without having issues if 4.6 isn't enough. At 6.2mm my typewriter would no longer reliably clip into its case and at 4.0 the carriage would grind on more aggressive returns.