I'm not certain how I came by this information, however it appears here as I found it in my "Workman" folder.
Hammy did make pipes during the 1980's and made pipes to the time of his untimely death in 1990. He made about 30 some sets and most were fully mounted imitation ivory with one exception of a silver and ivory mounted set. I had the pleasure of playing one of the imitation ivory sets that he made for a pupil of Sandy Jones. Quite nice sounding set of drones.
While in Scotland, he was a turner with both Henderson and Lawrie. He loved to make pipes and shortly before he died, he had a chanter he had turned at the NAAP school. He was still tuning it, but it had promise.
I was fortunate to know and learn from Hammy for many years as were others. If you're fortunate enough to find one of his sets for sale, you would be assured of a fine instrument. I'm not sure what make of drones he based his sets on, they might have been a set of MacDougalls.
I first met Hammy in 1974 in his capacity as a piping judge. I attended many of the NAAP summer schools while he was there from 1981 to 1990. Brian Yates, one of his former pupils also had some tuition and contact with Hector Cameron and I recall that both spoke highly of him. Hammy taught piobaireachd at the NAAP and gave much insight into the playing and teaching of PM William Maclean whom he highly regarded. Hammy was a most musical player and a serious injury to his bottom hand may have detracted from his technique, but the music really came through on the many tapes I have from the school.