Repairing the exhaust bracket on a Remington Standard 12

 Repairing an exhaust bracket

(English version of the original French article)

This article describes the repair of an exhaust bracket from a 1929 Remington Standard 12 manual typewriter.

As we can see in the photo, the exhaust bracket is broken at the bearing on the drive gear side of the carriage (the piece is shown to the right of the system).

This part is essential for the machine to function properly.

We could replace it with one from a “donor” machine, but finding a Remington Standard “for parts” with the same exhaust bracket is likely to be a long and complicated process.

Another option: try to repair it. The base is made of gray cast iron, which explains why it broke rather than bent. To minimize the risk, the repair was performed by brazing at 650–700 °C using a 45% phosphorus-free silver rod (silver-copper-zinc or silver-copper-zinc-tin).

Removing the exhaust system

Removing the exhaust system (after removing the carriage) is fairly simple. You need to remove seven screws and a pin..

Step 1: Remove the three screws shown in the photo and remove the tab mechanism.

Step 2: Remove the two screws securing the exhaust ratchet bracket and remove the bracket.

Step 3: Remove the split pin located at the bottom of the escape lever.

Location: at the bottom, at the back of the machine, in front of the key stem springs.

Final step: Unscrew the two screws securing the bracket to the frame and remove the exhaust system.

After easily removing the remaining parts, the bare bracket can be repaired using silver brazing.

The parts attached to the bracket have been removed.

We can see the fracture on the bracket side and on the broken bearing side.

The bracket was repaired by following these steps:

- Mechanical cleaning with a brass brush. The goal is to remove all impurities firmly, but without scratching the parts.

- Chemical cleaning with C-grade gasoline for effective degreasing.

- Precise assembly of the two parts; for the broken bearing, a third hand for soldering was used (a soldering stand with clamps used for tin soldering).

- Application of a thin layer of suitable etching paste to the fracture surfaces and surrounding areas.

- Heat the area with a small oxy-acetylene torch. Heat gently until the cast iron turns a dark red color while remaining matte (650 to 700°C).

- Apply a 45% silver (phosphorus-free) brazing rod around the entire perimeter of the break. The rod should melt and “flow” into the break.

- Allow to cool naturally. Do not subject the piece to thermal shock with water, and do not handle it immediately. 

Here is the repaired bracket after it has cooled down.

A quick file over the excess solder, and it looks brand new.

The two challenges are to align the two parts properly for soldering and to avoid overheating the gray cast iron.

The reinstallation of the shaft, along with its gear wheels and gearing, was successful.

The two plain bearings are properly aligned, and the shaft rotates freely without any mechanical play.

The solder joint appears to be strong, so the machine should operate reliably once again.

 

Small gray cast iron parts can therefore be brazed with a 45% silver alloy that is phosphorus-free.