Chainsaws used to be tools for professional loggers and gardeners only. Modern models are lighter and easier to handle, so they have become everyday helpers in gardens and on smallholdings. For home use the most common choice is a saw with a bar of about 40 cm.
The chain and bar work under heavy friction and load, so they wear out first. It makes sense to combine a chain change with cleaning and lubrication, so the new chain lasts longer.
What you will need
Important: Before changing the chain, stop the engine and pull off the spark plug cap, unplug a corded saw or remove the battery from a cordless one. Always handle the chain with gloves: the teeth are sharp even on a worn chain.
Step 1
Remove the bar and old chain
Slacken the tension with the adjusting screw, undo the nuts and take off the drive sprocket cover. Lift the chain off the bar and sprocket, then remove the bar.
Clean off the sawdust and old chain lubricant first, or it will quickly wear the new chain.
Step 2
Clean the bar, sprocket and housing
Brush off the coarse dirt, then spray WD-40 Multi-Use onto the bar, sprocket and the area under the cover. It softens hardened lubricant and resin so the grime wipes away easily with paper towel.
Thoroughly clean the groove all the way round the bar where the chain runs, and the oil hole. A thin scraper or the cleaning tool supplied with the saw works well.
Step 3
Inspect and lubricate the bar
Check the bar: the rails must be even, without burrs or steps. Remove burrs with a flat file. A badly worn bar is best replaced together with the chain.
Grease the nose sprocket with WD-40 Specialist White Lithium Grease through its hole, turn it and wipe off the excess. Refit the bar flipped over from its previous position so it wears evenly.
Step 4
Prepare the new chain
Make sure the pitch and number of drive links of the new chain match your bar. Lightly treat the link joints with WD-40 Specialist Silicone: it helps the chain bed in and protects against corrosion in storage, without attracting sawdust.
A serviceable old chain can be cleaned, sharpened with a round file and kept as a spare.
Step 5
Fit the chain the right way round
Place the bar on the studs, loop the chain over the drive sprocket and into the groove. The cutting edges on top of the bar must face forward, away from the body towards the bar tip. The direction of travel is usually marked with an arrow on the housing.
Refit the cover and start the nuts by hand.
Step 6
Set the tension and check lubrication
Tighten the chain with the screw while lifting the bar tip slightly. Correct tension: the chain sits snugly against the underside of the bar but still turns easily by gloved hand. Tighten the nuts fully.
Fill the tank with chain lubricant and start the saw: a line of spray should appear over a light surface. A new chain stretches, so check the tension again after the first 10-15 minutes of work.
Tip: Buy two chains and alternate them: the bar and sprocket wear more evenly, and a dull chain can be sharpened without stopping work.
What next
Replace the chain when it no longer holds an edge, has stretched beyond the adjustment range or has damaged links. Between changes, clean the saw and protect the metal from moisture with WD-40 Multi-Use.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».