Scalping and Uneven Cut Correction Visit

Purpose

Turn a scalp complaint into a diagnosed cause and a corrected machine, not a free re-cut. A scalp is the deck cutting into the crown on a high spot, and the plant does not recover by being cut again. Nearly every one traces to the deck not sitting where the operator thinks, or the ground not being the plane the operator assumed, so this ends the return visit that re-scalps the same ridge three weeks running.

Scope

Covers the corrective visit after a scalping or uneven-cut complaint on residential and light commercial turf: blade-tip cut height, deck attitude, high-spot mapping, a reset height of cut (HOC, blade tip to ground), pattern, and regrowth.

Does not cover the routine weekly cut (weekly mowing route service standard), blade sharpening and pre-shift checks (daily equipment blade and fuel check), regrading or seeding a bare area (sod installation standard, new lawn seeding and establishment SOP), or a machine that struck an object (property damage on a mowing route response).

Roles and handoffs

Read the cause word across properties: several contour causes in one neighborhood is settlement or a builder's grade; several machine causes on one unit is a machine the route is carrying.

Procedure

Step 1 - Stop the machine and confirm this is a scalp

Shut the engine off, pocket the key, then read the strip. A scalp is mechanical: a sharp edge following a contour or wheel line, bare soil at the peak. Acceptance: the boundary follows a contour or wheel line and green tissue survives on the flanks. Stop rule: a boundary following neither ends this procedure and starts the turf disease response visit. Hazard: a deck holds enough rotating energy to take a finger for seconds after shutdown, so nothing goes under it until the blades are visibly still, and a blade still turning past its own stopping limit is a defective brake that red-tags the machine - 3 seconds from release of the operator presence control on a walk-behind rotary, the time 16 CFR 1205.5 requires, or 5 seconds on a ride-on under ANSI/OPEI B71.1 in the edition it was built to.

Step 2 - Measure the real cut height at the blade tip

On level hard ground with the ignition disabled, rotate each blade fore and aft and measure ground to blade tip on both sides. Acceptance: left and right tips within 1/8 in of each other and within 1/4 in of the indicator setting, front tip 1/8 to 1/4 in lower where the manufacturer specifies forward rake. Wrong looks like reading height off the lever detent, which is how a deck half an inch low keeps cutting to a number nobody verified. Stop rule: spread over 1/8 in, or indicator error over 1/4 in, halts the cause hunt and sends the machine to the mechanic first. Hazard: a partial compression stroke turns a blade against a hand, so disconnect the spark plug lead and secure it clear of the plug, or disconnect the battery negative and pull the key, keep gloves on, and wedge a block against the blade if the lead will not stay put.

Step 3 - Check the four things that set deck attitude

Still disabled: tire pressures against the operator's manual, spindle play by rocking each blade at the tip, roller and skid height, hanger adjustment. Acceptance: every tire at the manual's pressure, play inside the manufacturer's limit, rollers clearing ground at the working HOC rather than carrying the deck, no bent hanger. Wrong looks like one soft tire, which drops that side of the deck and scalps along the wheel path on one heading only. Stop rule: play beyond the limit or a bent hanger takes the machine out of service that day; a worn spindle will not hold an adjustment. Hazard: a tire seating over a rim throws the chuck, so stand to the side of the sidewall, never over the tread, in the eye and face protection 29 CFR 1910.133 requires against flying particles, to ANSI Z87.1 in the edition your program names; a tire that will not hold pressure comes off for repair.

Step 4 - Map the high spots with a straightedge

Lay a straightedge at least as long as the deck's wheel-to-wheel span across each suspect ridge, both ends on undamaged turf, and measure the rise at the crown; a 4 ft board covers most mid-mount decks, but measure your own span. Acceptance: a rise in inches per ridge, located from a fixed feature, with a note of what sits under it where knowable - a settled trench, a lateral, a root, a fill seam. Stop rule: a ridge running dead straight across the lawn is a buried run, not contour, so propose no dirt work until the office confirms what is in that trench. Hazard: probing is excavation, so nothing enters the ground until utility locates are marked, and a probe meeting resistance at shallow depth stops rather than being driven; a struck line stops all digging and is reported to the utility and the office from clear ground.

Step 5 - Assign one cause, then compute the corrected HOC

Put steps 2, 3 and 4 together and name one cause: machine, contour, pattern (damage following a turn radius on one heading), or moisture (rutting on wet ground). A second finding that is not the cause, a settled trench or a buried run, is logged as a standing site condition for the office, never as a second cause: a card carrying two causes gets one of them fixed. Where a rise was mapped, cut at the crown equals set HOC minus that rise, valid only if the rise was read under a straightedge at least as long as the deck's wheel-to-wheel span, since a shorter one reports rise the deck partly rides over; the corrected HOC is whatever puts that difference at or above the species floor on the card. Raising HOC raises the mow-before height with it: the one-third leaf removal rule puts the next cut due at one and a half times set HOC, so a card moved to 4.0 in is due at 6.0 in and the route interval tightens to match. Acceptance: one cause with its finding, any site condition logged separately, and a corrected HOC with its crown cut and mow-before height beside it. Wrong looks like raising the deck one detent because it feels safer, without checking what the crown then gets. Stop rule: where the arithmetic needs an HOC the customer will not accept on the flanks, the answer is dirt work quoted by the office, not a higher cut absorbed as warranty. Hazard: none added, the machine is off.

Step 6 - Change the pattern and set the wet-ground rule

Rotate the heading from the last visit and move turn points off the ridge. Acceptance: a heading recorded that differs from the last, turns relocated to flat ground, and a note that this property is skipped when soil prints under a boot. Stop rule: the crew does not mow saturated soil to hold a route slot, because rutting a wet lawn turns a scalp complaint into a grading complaint. Hazard: ground soft enough to rut is soft enough to slide a ride-on, so it comes off any slope where the tires break traction and that strip is cut with a walk-behind across the face; if it slides anyway the operator steers downhill rather than turning across it.

Step 7 - Restore the machine and prove its safety functions

Reconnect the plug lead or battery negative, reinstall every guard and the discharge deflector, then start on flat ground with nobody in the discharge arc and test the operator presence control. Acceptance: lead or battery reconnected, guards and deflector in place and free to swing, blades stopping inside step 1's limit for this machine type (3 seconds walk-behind, 5 seconds ride-on), no fuel weep at cap or line. Stop rule: a control that does not stop the blades inside that time, or a missing guard, red-tags the machine. Hazard: an engine tilted during adjustment releases gasoline vapor, heavier than air, which pools at ground level, lights off a hot muffler and is a nervous system hazard breathed, so work upwind in open air, let spills evaporate before starting, and never run an engine in a closed trailer, where the exhaust carries carbon monoxide; a fuel-soaked mat comes off the truck first.

Step 8 - Set the regrowth plan and tell the customer what to expect

Flag the scalped area and exclude it from cutting until it recovers. Acceptance: area flagged and excluded on the route note, a recovery expectation in weeks, and a written check date. Wrong looks like promising green next week, or dropping heavy nitrogen on a scalped crown to force color, which pushes leaf growth from a plant that just lost the tissue feeding it. Stop rule: bare soil with no green tissue at the base of any plant will not regrow and goes to seeding or sod as a separate scope. Hazard: none added.

The record this produces

Work order: the rise at each crown with the feature it was measured from, the set HOC beside the cut the crown got, and the one cause, in one word, that the owner reads across properties. Customer card, same day: the corrected HOC and its mow-before height, since the next crew mows to the card. Machine file: blade-stop seconds and the machine type judged against, for the mechanic. Office: any standing site condition.

One pass through this procedure

Property: 6,000 sq ft of tall fescue, card HOC 3.0 in, summer floor 2.5 in, cut by a mid-mount ride-on. Complaint: a brown strip about 12 ft long across the front lawn, second visit running.

Step 1 passes: one contour line, stubble, a sharp edge, green tissue either side. Step 2 fails: blade tips measure 2.6 in left and 3.1 in right against a 3.0 in indicator, a spread of 0.5 in against a 1/8 in gate, and the cause hunt pauses on that stop rule. Step 3 finds the right rear tire at 8 psi against the manual's 12 psi, and no spindle play. Tire inflated, deck re-leveled, step 2 re-run: 2.95 in and 3.0 in, a spread of 0.05 in, inside the gate.

Step 4 maps the ridge with a 4 ft straightedge, which clears this deck's wheel-to-wheel span: the crown stands 1.4 in proud, running dead straight toward the back of the house, and the office confirms an irrigation lateral was replaced on that line two seasons ago. Settled trench, not contour. Step 5 names machine as the single cause, since a deck half an inch low scalped a ridge the correct setting would have cleared; the trench is logged as a standing site condition for the office, not carried as a second cause. The arithmetic: at 3.0 in the crown gets 3.0 minus 1.4, or 1.6 in, below the 2.5 in floor; at 4.0 in it gets 2.6 in, at or above it. The customer accepts 4.0 in for the summer, which puts the mow-before height on the route note at 6.0 in, and the trench goes to the office as a fall topdressing quote.

Step 6 rotates the heading 90 degrees and moves the turn point off the ridge. Step 7 restores the machine: lead reconnected, deflector on, blades stopping in about 4 seconds, which passes this ride-on against its 5-second limit and would fail a walk-behind's 3. Step 8 flags the strip, excludes it for two visits, and sets regrowth on an intact crown in active growth at two to three weekly visits, with a check on the third.

References

• The machine's operator and service manual, source of the tire pressure, spindle play limit, roller gap and deck rake used in steps 2, 3 and 7
• 29 CFR 1910.133 for the eye and face protection worn at the tire work in step 3, with equipment to ANSI Z87.1
• 16 CFR 1205.5, the CPSC walk-behind power mower regulation, source of the 3-second blade-stop time in steps 1 and 7; and ANSI/OPEI B71.1, a voluntary consensus standard binding the manufacturer rather than a regulation, in the edition the machine was built to, for the 5-second ride-on time
• Cooperative extension guidance for your region on species mowing-height floors, and the one-third leaf removal rule that sets the mow-before height computed at step 5
• See related: the weekly mowing route service standard for the routine cut and the card HOC, and the turf disease identification and response visit for a boundary following neither contour nor wheel line