The time to have your chain professionally ground is when you find that as you cut through the timber the cut curves right or left. This is usually because the filing angles on your right and left cutters are uneven, making your saw cut with a bias. The most usual cause is when you accidentally hit some abrasive material with one side of the saw.

The other time when you need your chain grinding is when the saw only produces sawdust or just tries to burn its way through the wood. This is usually because you've hit some abrasive material and ground the top of the cutter down.

When this happens the cutter needs grinding back to a good chrome edge. This can mean taking out a lot of material. Providing there is still leave at least 1mm on the heel of the cutter the chain will still cut.

Chainsaw Specialists offer a professional sharpening service, see their website at http://www.chainsawspecialists.co.uk where you can also purchase new chains.

See also how to look after your chain, information on depth gauges, anad when to get your chain professionally sharpened.