Friday, 13 November 2015

Progress this week on the Steam Reverser

Silver soldering takes place on the stuffing gland

This week at college Ben has go to the stage of silver soldering the first of the newly manufactured bushes into the first of three stuffing glands to be treated.  This was carried out with the help and guidance of Ian Furguson.

The pieces of the assembly were thoroughly cleaned and prepared for the operation. This required the use of a fine emery cloth to remove any surface impurities and the application of an "easyflow" flux.

The cleaned stuffing gland having easyflow flux applied at the start of the operation (all photos: Ben Dingley)
The gland was surrounded with fire bricks which hold the heat and help to keep the temperature correct during the operation.  the gland was then heated to 670 degrees centigrade, which is the melting point of the silver solder.

The heating commences and the flux starts to run
The heat is applied using two heat sources, creating a "vortex" of heat around the piece.  this helps to get an even temperature throughout the gland.  the silver solder is then fed into the joint to start the soldering process.

Heat applied to the bottom of the item to draw the solder through
The heat is then transferred top the bottom of the joint to draw the silver solder through the joint to create a firm and solid connection. The stuffing gland was then turned over and the process repeated on the other end.
Heat, flux and silver solder being applied to the other end of the gland 
Once a good joint was made, the heat was removed and the entire assembly allowed to cool down before the final process could take place.
The stuffing gland cooling from the extreme heat applied
In the picture it is possible to see the areas of silver solder showing against the cherry red of the brass stuffing gland and bush which have been joined.  The gland was left to cool before the final part of the proceedure which was to "pickle" the gland in a bath of dilute sulphuric acid.  This process is intended to remove the residue of the flux and other impurities.

The stuffing gland relaxing in a nice bath of dilute sulphuric acid!
Following this procedure, a final machining will to take place to ensure that the bore dimension is correct and the faces are square to the bore.

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