Metal in Oak Sawlog

Metal in Oak Sawlog

It is a Sawyer’s nightmare, we found metal in Oak we were milling. This caused us a bit of a setback after going so well during the day. We were on the bottom half of the last log when we struck an old nail buried deep inside.

At the beginning of the day we arrived at the site after a fairly long journey. The location was at the edge of Dartmoor not too far North of Ivybridge, Devon. We set our mill up at the top of a slope where the ground leveled out. This area was the best location for our mobile sawmill. This particular job involved going steady to get specific large beam sizes from the available logs. We milled Oak and Sweet Chestnut. These were certainly not good grades of hardwood, but suitable for the end use. The Oak was being used for lintels in a building restoration project and the Sweet Chestnut for gate posts. The sawlogs had come from nearby woodland grown trees, so not your typical high risk hedgerow or farm trees, nor were they commercially forest grown.

Oak Sawlog

Cut beam from Oak Sawlog, Devon

Sweet Chestnut saw milling

Sweet Chestnut log ready for saw milling, Devon

Partially milled Oak

This picture was taken a few cuts prior to the nail strike. We were already two-thirds through the log. Apart from a few areas of fungal decay there were no ferrous stains to be seen.

Oak sawlog saw milling

Oak sawlog part milled with a mobile sawmill, Devon

After the sawblade struck some metal we axed away the area to reveal an old nail. This was at a depth between 6 to 8 inches from the horizontal plane. The nail strike brought some metal fragments up, which immediately reacted with the wet Oak tannins, thus increasing the amount of black staining. Judging by the orientation of the nail it could have been used to fix a sign when it was a standing tree. Had the vertical cut been 5mm to the right we would have completely missed the nail.

metal in Oak

A cut away section where we found metal in Oak, specifically an old nail.

metal in Oak

Metal in Oak sawlog that was hit by a blade

The sawblade had lost two tips and suffered some chipping to the other tips. After discussing the options we decided to grind out the chipped tips. We tried a test cut and it was still cutting well, apart from a minor drop in performance. We went slowly with the remaining cuts and completed the log without further encounters with buried metal.

Metal detection devices for logs

Reliable and cost effective metal detection devices are not readily available, as this is a niche market. Previously, we had spent time researching the market for metal detection devices. There is one manufacturer’s device that we are going to evaluate further, we’ll post and update when we have our own results of using this equipment in the field.

From our perspective we are classifying trees from woodlands without a long history of commercial management in a higher risk category than before. We know that you can’t completely eliminate the risk of damage from metal in wood. However, we will aim to offer customers an enhanced milling service where we can carry out a range of checks before and during milling. There’s also the opportunity to reduce the risk of damage to other woodworking equipment when secondary processing occurs in a workshop.

For now this sawblade will be collected by EPS sawblade repairs and servicing