Lewis Maker, 18 at the time of the incident, was using the panel saw to cut a piece of board, which he was holding steady with his left hand. As he operated the saw his hand got dragged into the blade and the top half was cut off. Although surgeons were able to reattach part of his hand, he has regained very little use.
The Health and Safety Executive (HSE), prosecuting, told Truro Magistrates' Court that the lad had only just started work five days before the incident on 20 July 2009 and was given very little instruction on how to use the saw safely.
Frame Homes (South West) Ltd, of Jenson House, Cardrew Industrial Estate, Redruth, pleaded guilty to breaching Section 2 (1) of the Health and Safety at Work etc Act 1974 and was fined £20,000 and ordered to pay £13,700 in costs.
HSE inspector Gareth Cottle said: "This was a devastating, life-changing injury for Lewis which could have been avoided if Frame Homes had provided adequate training.
"Woodworking machines have a serious accident history which is well known in the industry. It is the employer's responsibility to ensure that workers are given sufficient information and training to work safely, as well as access to fully trained and competent supervisors.
"New workers are particularly vulnerable to workplace incidents and Lewis had every right to expect far more protection than Frame Homes afforded him."