John, You don't really have to "travel far" to find a good welder of cast Iron. Although they are fewer today, than in yesteryears, good welders can be found. The most unlikely place is a "farm" welder. These unheralded craftsman are out and about. Every day they weld cast iron farm machinery, such as drive wheels with spokes, etc. This is basically the same approach as a plate. After all, the plate really has "spokes". The technique that I have found to be workable, is in the use of "Nickle Rod". The welds are "V'd" and it takes quite a long time to accomplish the actual weld(s). No more than an inch at a time. Then the new weld is beaten, (unmercifully), with a slag hammer, to relieve the stress. Allowed to cool. And then another inch is welded. It is time consuming, but is doable. Once the weld is complete, the plate should be put aside for at least 6 weeks. I have had new cracks appear, on a welded plate, while it is languishing in my dust bin, (so to speak). The whole process is not one for the faint of heart or those who are in a hurry. As to a guarantee, there should NEVER be a guarantee, not even with "stitching", as we do not know if there are other flaws in the original casting, due to the fact that it is covered with filler and gilt. The client should ALWAYS be warned of this fact. My track record, on this process, has been fairly good, (knock on real wood<G>), to date. The process of heating the entire plate, IMHO, opens up a very large can of worms and I don't think is advisable. Regards, Joe Garrett, RPT, (Oregon)
This PTG archive page provided courtesy of Moy Piano Service, LLC