The actual cause of the riot in "The Tomahawk Factory" is the rising up of long-cherished resentments and wounds between the narrator's mother and Marie Kashpaw. It is when Lipsha brings down the fake tomahawk "with the crack of a sentencing gavel" after these two women have traded insults that the riot really begins, when "Order popped like a bubble." Of course, it is important to recognise the way that this simmering atmosphere of resentment and anger was in part created by the lack of success of the factory. Lyman, the narrator, himself admits that the factory is struggling to make money:

Layoffs. By mid-January, we had received only a few new orders. I had done such an efficient job of fulfilling the demands of suppliers that they couldn't sell their stock. I'd hired on to many people in the first place, produced more than I could ship.

The long-held anger and resentment between the different characters was always there, but what triggers it is the layoffs and the insecurity produced by the tomahawk factory, giving rise to an incipient rage and destructive power that results in the tearing down of the factory and Lyman's hopes of business success.