Winter is the time cylinder mowers actually get the attention they deserve. During the season there is always something more pressing. November through January is when the work can be done properly, without the pressure of needing the machine on the green by Thursday.

What a cylinder mower is actually doing

A cylinder mower cuts by scissor action: helical blades on the rotating cylinder shear grass against a fixed bottom blade called the bedknife. That geometry has to be right for the cut to be clean. On a golf tee or bowling green mower, the clearance between cylinder blades and bedknife can be less than 0.1 mm. After a full mowing season, blades chip, metal fatigues and the bedknife wears unevenly at high-traffic points along its length.

The result is tearing rather than cutting, which shows as a brownish, bruised finish on fine turf. No amount of spring renovation fixes that if you just carry on with a blunt unit. The damage is in the cut.

Cylinder grinding

If blades are chipped or bent at the tips, or the cylinder has lost its shape through uneven wear, the unit needs grinding. Spin grinding (sometimes called relief grinding) uses a motor-driven abrasive wheel running along the cylinder as it rotates, to restore the cutting geometry across the full working width. The bedknife is reground at the same time to match.

Most estates and grounds teams send cutting units to a machinery dealer or specialist service centre for this. If you are outsourcing it, book now. Dealers get busy from February onwards, and turning up with four machines as the season opens is a familiar problem with an easily avoided cause.

After grinding, the standard check is the paper test: pull a sheet of thin paper through the nip as the cylinder runs, at several positions across the width. A correctly ground and set unit cuts it cleanly at every point. If the paper tears or slides through, something is still off.

Back-lapping: what it does and when it helps

Lapping is a honing process. An abrasive compound (traditionally carborundum paste, though various proprietary lapping compounds are now used) is applied to the cylinder blades. The cylinder is then driven backwards at slow speed, drawing the abrasive between blade and bedknife to polish both surfaces and improve contact uniformity.

This works when blades are dull but not physically damaged. Overdoing it changes blade geometry gradually, so it is not something to use every week as a workaround for avoiding proper grinding. But when the geometry is right and you need to refine the edge, lapping is the correct tool.

Most professional grounds teams can back-lap on site using a purpose-built lapping motor, or by engaging reverse drive on machines designed for it. Clean the compound off thoroughly when finished. Residual grit left on the blades will score the cutting edges faster than a season of normal use.

Winter storage for cutting units

Once serviced, store the unit so the work is not undone over the winter months. Remove all clippings and soil from the cylinder, bedknife, roller scrapers and grass box. Damp organic matter holds moisture against the metal and accelerates corrosion.

Apply a light coat of oil to the blades and bedknife. A clean rag with hydraulic or light machine oil is adequate on a dry surface. Avoid anything that leaves a thick film: residual oil attracts grit and can score the fresh cutting edge when the machine starts up again.

For petrol machines, drain the tank and carburettor before storage, or add a fuel stabiliser if the machine may need running during the winter. Stale petrol varnishes carburettor jets and is one of the most common causes of spring starting problems. Store fuel following HSE guidance on flammable liquids and keep mowers in a dry, ventilated building. Unheated metal sheds with wide temperature swings can cause condensation on oiled surfaces even over a short winter.

Before the first cut of spring

Even after careful storage, run the paper test again before using the machine. Check that the bedknife adjuster screws move freely and have not corroded in position. If the unit was ground over winter, a brief back-lap session in late February removes any surface rust and restores the edge before work starts.

Leave all this for March and the season begins with machines that are not quite right. Winter is when it gets done properly.

Did you know? On a fine-turf cylinder mower, the gap between blade tips and the bedknife is often set to less than 0.1 mm. A small chip or burr in the bedknife is enough to open that gap and turn a scissors cut into a tear.

Frequently asked questions

What is the difference between cylinder grinding and back-lapping?

Grinding uses an abrasive wheel to regrind the cylinder blades and bedknife, restoring cutting geometry after significant wear or damage. Back-lapping uses an abrasive compound to hone and improve contact between blades and bedknife when they are dull but not chipped or bent. Both are sometimes needed: grind first, then lap.

How do I know if my cylinder mower needs grinding rather than lapping?

If blades are chipped, visibly bent at the tips, or the mower leaves streaks even after lapping, the unit needs grinding. The paper test is a useful check: pull thin paper through the nip across the full width while the cylinder runs. If it fails to cut cleanly at any point, lapping alone will not fix it.

Can I back-lap a cylinder mower on site, or does it need a specialist?

Back-lapping on site is practical if you have a lapping motor or a machine with a reverse-drive facility. Cylinder grinding requires specialist equipment and is usually carried out by a machinery dealer or service centre. Book grinding well before the season starts, as demand increases from February onwards.

What should I do with a petrol mower being stored over winter?

Drain the fuel tank and carburettor completely before storage, or add a fuel stabiliser if the machine may be needed during the winter. Stale petrol breaks down over a few months and can varnish carburettor jets, causing difficult starting in spring. Store fuel in line with HSE guidance on flammable liquid storage.

How often should cylinder mower blades be ground?

This depends on mowing frequency, ground conditions and the type of turf being cut. A machine working on a fine bowling green or golf tee may need grinding annually or more often. A rough-area cylinder mower may go several seasons between grinds. Condition rather than a fixed schedule should drive the decision.