Saturday, 9 January 2010

Boiler Fittings: Steam Saftey Valve

The boiler I am making requires a safety valve to bleed excess pressure from the boiler during operation. I am using the same design as the last boiler I made. It consists of a body and a bridge, both made from bronze and a stainless steel pintle that uses a spring to hold a stainless ball against a seat in the body. A pair of stainless rods hold the bridge above the body.


A picture tells a thousand words so here is the finished article:



http://farm5.static.flickr.com/4144/5189193382_ed6c7bbbdc.jpg


The body and bridge were both turned on the lathe and then shaped using the CNC mill. Here is a video of this process on the body.









Now we can make a start on the two stainless steel rods that hold the bridge up. Here they are cut roughly to length. The observant amongst you may notice the stupid 22.2250mm dimension which is simply a result of printing out metric drawings originally dimensioned in imperial.
http://farm5.static.flickr.com/4132/5188591491_4a28fe6b94.jpg
To get the rods to length they are faced in the lathe. I also take to opportunity to knock the sharp edges off as well.

http://farm2.static.flickr.com/1280/5188591693_41017697c1.jpg
I changed the headstock chuck over to a small Jacobs chuck which will hold the rod much more firmly than the normal 3 jaw turning chuck. I will thread the rods from both ends 7BA using a tail-stock die holder.

http://farm2.static.flickr.com/1267/5188591953_dfef85c668.jpg
Here are are the finished rods.

http://farm2.static.flickr.com/1386/5189193168_89838318cf.jpg



1 comment:

Elizabeth J. Neal said...

Sub £5 kettles from Tesco and Argos are also suitable, Plumber Parsons Green although we know that the pins on a Wilkinson's cheap kettle are too short to take a 3-pin kettle lead.