Henner Meinhold
Tue, 15 Feb 2005 20:36:28 -0800
Message text written by INTERNET:sslivesteam@colegroup.com > Henner is of course entitled to his opinion but cutting decent threads > in bushings, regardless of material, is not the point. A very nice thread > can be coaxed through a copper however the greatest need, and the primary > purpose in using bronze, is to retain the fullest and strongest thread for< Harry, my opinion on using copper as bushings is based on the following: #1 LBSC in his book about building TICH (page 156) recommends as bushing material copper with "The next best thing is bronze". #2 The Tich boiler kit we are currently building for my friend David's garratt was supplied by Reeves with material for copper bushings. #3 The draft of the Australian live steamers on medium pressure "gauge 1" boilers allows copper bushings. The link to this draft was somewhere in the thread about boilers in mylargescale. Unfortunately I downloaded the draft, but can't find the link any more #4 We built a small vertical boiler a couple of years ago with copper bushings. The bushing for the safety valve doubles up as filler valve and is removed for every filling/topping up. The thread is M6 x 0.75, finer than 1/4" 28TPI. As of today not a trace of wear is visible. #5 With copper as bushing, the choice of material for the fittings is wider, as bronze can be used (unless the bronze for bushing/fitting is of a different grade) #6 I agree with Vance, that tapping directly into a backplate is not to be recommended. My point was/is that at least for gauge "1" boilers copper bushings are as safe as bronze bushings, in case copper rod is more easily available. For larger boilers I would probably switch to bronze for the reasons you indicated. Regards Henner