Installing Crown StaysSaturday, March 15, 2014
After the hole in the crown of the firebox has been reamed with the tapered reamer it is threaded with a tapered tap. In this picture the tap has been inserted (lead threads are threaded up into the already threaded hole in the boiler). At this point a little cutting oil and a bit of brute strength enable us to cut the threads. You can see an orange mark on the tap which is used as an indicator of how deep to cut the threads. This depth is critical as about 1/4 inch of the staybolt must be left exposed so that it can bee peened over. Note the staybolt that have already been placed (the hex head is used to insert the staybolt and will be cut off before peening).
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