The measuring depth should be a quarter of the wood diameter. In the worst case you have to cut away a part of the diameter. Choose a part of the wood. WITHOUT bark, knots, pitch pockets or cracks and drive the ram electrode in the right angle to the grain into the wood. Hold the top of the electrode with one hand, take the handhold with the other hand and push down the handhold with active force. Drive the nails about 2 cm deep into the wood.