Machine-made Tzitzit

At the end of World War I, the Rebbe Rashab saw to it that machine-made Tzitzit would be manufactured for the Jewish refugees, and he ruled that one may make a brocho (blessing) on them.

In 5712, the Rebbe sent a letter to Kfar Chabad, where they had received a proposal to establish a factory for machine-made Tzitzit, and market them world over. The Rebbe rejected that proposal and explained that when the Rebbe Rashab authorized machine-made Tzitzit, it was after the war and a time of emergency. These are his holy words:

I do not know and am in great doubt whether the proposal is relevant also from the commercial standpoint, in addition to the spiritual one. Even though it is known that the Rebbe Rashab permitted the use of machine-made Tzitzit during the First World War … this was surely a leniency due to the difficult situation, as there were refugees from Poland and Lithuania who came to Russia. It is clear that this is not a mehadrin way to do it, and since it is not expected to be a significant source of income, rather a public expense, at the very time that hand-made Tzitzit are widely available, Lubavitch comes and and allows and publicly authorizes machine-made Tzitzit, for a minimal profit? This is not worthwhile materially or spiritually.