BUILDING A

METRIC MINNIE

Part eight by Franco Pucci

The Boiler - part 5

Machining the fire ring hole from copper stock. This was not going to end up round, so I had to do a little maths here to get the final dimensions for the oval shape.


I was not sure how this was going to work out, but in the end it did the job just fine. I annealed the copper before flattening.


The finished fire ring hole.


Ready for soldering.


Trial fit to the boiler back head.


Soldering complete on the fire door plate.


Back head stays soldered in place.


Assembled firebox ready for soldering.


Front boiler view showing the stays and tubes in place, ready for the final big solder job.


Soldering for the firebox and stays was done with the entire assembly in the gas barbecue with all burners on, and two hand held propane gas torches in order to get enough heat on the assembly. This was probably my riskiest moment in the entire build - hoping that my choice of temperatures for the two solder types was correct. As it turned out, it was fine. I then dunked the whole thing into a dilute sulphuric acid solution for a few minutes to clean it up.


The setup for the initial pressure test. This was to be repeated once all the fittings were in place. The boiler was tested to 8 Bar (116 PSI). It has a working pressure of 3.5 Bar.

In the next part, I partly assemble the boiler and I make a start on the backend.



Part one here  Part two  Part three  Part four  Part five  Part six  Part seven  Part eight 

Part nine  Part 10   Part 11  Part 12  Part 13  Part 14  Part 15  Part 16  Part 17  Part 18 Part 19 Part 20  Part 21