"I just grabbed my hand and walked down to the office swearing my head off ... I really thought I was going to die."
His colleagues taped his hand up and told him to try to manage his breathing.
He was then taken by ambulance to Te Kuiti Hospital about 45 minutes away before the Westpac Waikato Air Ambulance took him to Waikato Hospital with his hand "very loosely attached" to his arm.
Dr Sami al Ani, a registrar of plastic surgery at Waikato Hospital, said Mr Speers had cut through bones, tendons and ligaments in his hand.
"Some of the bones were still attached but the hand was only very loosely attached to his arm when he arrived," he said.
The tendons, ligaments and nerves would later be stitched together with painstaking microscopic surgery but the procedure was complicated further.
Dr Katerina Anesti said: "He had nearly cut off the same arm before about five centimetres up his arm.
"The scarring made it difficult to know what was what," she said.
The surgeons said Mr Speers, a keen hunter, rugby player and fisherman, was likely to be in hospital for a few more days.
But full rehabilitation of his hand could take months and his wrist joint will probably require fusion.