Chain sharpening, dull-chain signs and bar length: what regulators and makers state

This page reports what the named codes, regulators and makers say. It is not training and does not teach the work. Filing is taught on courses; the guides on chainsaw tickets and the UK maintenance and crosscutting award cover them, and the sizes of files are in the guide on chain pitch, gauge and file size.

What regulators say about sharpening

WorkSafe Western Australia (page updated April 1, 2025) links a sharper chain to safer work, and says a blunt chain needs more effort and increases fatigue, both of which can lead to kickback accidents. It says dusty wood shavings are a sign the chain could need sharpening. It lists a file and file guide for sharpening after every refuel among the items to have nearby, and says the depth gauge is set to the maker's recommendations in the operator's manual.
CCOHS, in its maintenance fact sheet (revised April 24, 2024), says two files are needed: a flat file for adjusting the depth gauge and a round file of uniform diameter for the cutters. It says depth gauges are checked every third or fourth time the chain is sharpened, and that cutters are filed to the same length as existing cutters when replaced. It lists a chain kept sharpened to specification, with correct depth and angle, among the points that reduce kickback.
HSE, in the top-handled saw leaflet AFAG308, lists equal cutter lengths, specified cutter angles and depth gauge profiles on a maintenance checklist, with the chain inspected at each sharpening for abnormal wear patterns and damage. In INDG317 HSE says operators need to be trained in the correct chain-sharpening techniques.

Signs of a dull or worn chain as two makers list them

Maker and page	Signs listed
A saw chain maker's sharpening page (read October 9, 2026)	The page lists damage to look for before sharpening: tie straps and drive links not installed properly, cracked or broken cutters, top plates or tie straps, bent, cracked or burned drive links, severe abrasive damage, abnormally worn chain, wear patterns that may point to a worn bar or sprocket, and loose rivets, which it says are too loose if they turn with the fingers
A saw maker's United Kingdom sharpening page (October 1, 2024)	Five signs: the cutting attachment does not pull itself into the wood and has to be forced; cross cutting produces fine sawdust rather than coarse chips; smoke appears while cutting even with correct lubrication and tension; the cut pulls to one side, which the page says can mean teeth of uneven length; and the saw chatters and bounces
The same saw maker's United Kingdom page on replacing a chain (August 16, 2026)	The page says every tooth has wear markers, that the chain is replaced once they are met, and that filing past a marker reduces cutting performance and raises the risk of the tooth breaking. It says all teeth being a uniform length prevents increased vibration and the chain snatching mid cut

Filing figures the makers print

Maker	Figures stated
Oregon	A round file sits with 1/5 inch, or 20 percent, of its diameter above the top plate of the cutter. The gullets are cleaned with a 7/32 inch round file at approximately every fifth sharpening, the page says. It says the sharpening angle for a chain is in the saw's manual or on the chain pack
STIHL	A sharpening angle of 30 degrees for its chains, with the exception of one chain type at 25 degrees. The file protrudes above the top plate by a quarter of its diameter. The page ties the file diameter to chain pitch on a chart, and says a depth gauge set too low raises the kickback risk

Both pages add that a filing aid or file guide helps hold the file in position.

Bar length

HSE, in INDG317, says that as a general rule a chainsaw with the shortest guide bar suitable for the work is chosen, and that a range of saws with different bar lengths may be needed.
WorkSafe Western Australia says someone buying or using a chainsaw for the first time starts on one with a short bar, 30 cm to 40 cm long, and still needs initial instruction, training and supervision.
CCOHS says the weight, power and bar length are all suitable for the job. In its kickback fact sheet it describes a safety tip that covers the nose of the bar, which is removed for bore cuts or for wood thicker than the bar is long.
For top-handled saws, the City and Guilds assessment pack for the NPTC chainsaw-from-rope-and-harness unit lists a bar of 15 inches at most, as set out in the guide on first climbing saws.
Oregon defines bar length as the cutting length, from the front of the saw to the tip of the bar, rounded to the nearest inch.

On bar wear, CCOHS says a nicked or distorted bar is replaced, and WorkSafe Western Australia lists reversing the bar top to bottom after use to avoid wear on one side. HSE's AFAG308 lists checking the bar rails for cracks and distortion.

Credit: the HSE statements are adapted from HSE publications INDG317 and AFAG308, Crown copyright, used under the Open Government Licence v3.0.