A Cut Above

Every good superintendent and golf course equipment manager knows keeping cutting reels and blades sharp is an important aspect for proper turfgrass mowing.

The reason? Dull blades damage leaf tissue, and when you damage leaf tissue, the plants respond in a physiological sense, says Van Kline, former senior agronomist at Toro. “You get more dieback on the leaf, which results in browning and it takes longer to recover. Sharper blades give you greener turf. Continually mowing with dull cutting units or dull blades will cause the turf to thin out more.”

But, even with so much on the line, keeping reels and blades in optimum cutting condition is sometimes overlooked.

“We find that many technicians learn ‘maintenance by tradition,’” says Greg Turner, gobal sales manager for Foley United. “Many people come from an automotive or agriculture background where the basic concepts of engines are similar, hydraulic systems are similar, but the reel cutting unit adds a whole new level of knowledge and expertise that makes their jobs more complicated.”

Some individuals may, in fact, learn reel maintenance without a full understanding of why they’re doing what they do, Turner says. “This is why the more educated the market is on why the manufacturers design units the way they do and the benefits of maintaining reels the way they bought them, the less potential for issues,” he adds.

A daily inspection by equipment managers and/or superintendents of each mowing unit’s quality of cut is not out of the question, says Scott Bjortomt, equipment manager at Crooked Stick Golf Club in Carmel, Ind. So, know your height of cut and what has been put on your turf. For example, if you topdressed yesterday and you mow greens at one-tenth-of-an-inch, then it’s going to have an effect, If your mowing at one inch and you topdressed yesterday, it probably won’t have an impact.

“You need communication with the operators, because chances are if they hit something, they would hear it or know it,” Bjortomt says. “That can help everyone, so it doesn’t get hit again the next time it goes out.” Also, pay attention to the after appearance of the cut. It can help find issues that may not be obvious in the shop. “And, grind and back lap, do it when it’s needed,” he says.

“When you consider investing $60,000 on a fairway mower, you quickly realize you’ve spent a tremendous amount of money to make five cutting heads cut grass, Turner says. “When it comes down to it, it’s the cutting head that does all the work and performs the cut, so the maintenance of these cutting units is critical,” he says.

Turner believes the keys to keeping mowers in proper cutting condition are grinding, adjustment, backlapping, and facing bedknives. “All of the factors noted above are ‘tools in the tool bag’ that maximize quality-of-cut and performance,” he says.

Marvin Doerksen, turf equipment manager at Breezy Bend Golf Club in Manitoba, Canada, believes reel cutting units should be “checked for square” and have a fresh grind, spin or relief/spin at the start of the season. “Each cutting unit needs to be set up so the distance between the reel and bedknife is at its maximum distance but still cuts .005-inch paper clean with no jagged edges,” he says. “Grind as often as needed, your check is with .005-inch paper, if it doesn't cut clean, it’s time to grind.”

It’s imperative the cutting units get “verified” daily for their function, Doerksen says. This also allows the superintendent — or foreman in charge of mowing — the opportunity to give the front/rear rollers, reel bearings and all swivel joints a shot of grease to purge any water or debris after the clean and wash.

“To ensure the accuracy of both your height of cut and quality of cut, a prism gauge can be used immediately after the turf is cut, daily, to see both the quality of cut and the effective height of cut,” Doerksen says. “Take a picture of the prism placed on all surfaces being cut and then download it onto your computer. You can generally blow up the picture to have a good look to see how many stragglers didn't get cut. The effective height of cut can be confirmed to within a couple thousands-of-an-inch.”

When grinding reels and bedknives, stick to the guidelines set forth by the manufactures. Remember, these are guidelines. “Experience and good communication with the superintendent will dictate any deviations from that guideline. “Don't think you're saving a lot of money by using aftermarket replacement parts, you're not,” Doerksen says. “Negotiate better pricing from your OEM. When you have any type of issue with your equipment or quality of cut, go to your OEM. They will help you with all your problems and help find solutions. Also, ensure that at day’s end all equipment is properly blown/washed and cleaned. All the checks and adjustments that are required can be made in a timely fashion.”

Rotary blades are normally ground at a 30- to 35-degree angle and should be balanced after each grind or there may be premature bearing failures. The edge of the cutting surface should have a .010 to .015 finish. This can be attained with a side grinder. The same applies to all rotary cutting mowers; each time they go out to cut, touch up the cutting surface.

“First and foremost, keep the cutting units clean,” says Wade Borthwick, equipment technician at Uplands Golf Club in British Columbia, Canada. “Washing a mower after use will remove grass clippings and residue. Grass is acidic in nature, along with fertilizers, which are almost all salts, and will add to the corrosion of the mower.”

For reel mowers, it is important to pay attention to both the reel and bedknife, says Bill Stone, John Deere Golf territory customer support manager. The reel can contain between five to 14 blades arranged in a helix and spins next to the bedknife, which is stationary, but together they work in a scissor type motion to create a precise, consistent cut. Proper maintenance is crucial, he says.

To ensure mower blades are kept in top cutting condition, Stone recommends before performing any maintenance on a reel blade or bedknife, it is important to clean the cutting unit, removing any “crud” or debris that has built up over time. This ensures any damage can be clearly seen.

Likewise, when performing routine maintenance on the mower reel, Stone recommends inspecting the reel blades and bedknife for visible damage. If there is any, the reel and bedknife may need to be reground or replaced.

Stone suggests greasing bearings with a quality waterproof lubricant but cautions not to overgrease. Any grease that is purged should be cleaned off the cutting unit to prevent damage to the turf. By properly maintaining bearings, equipment managers can ensure that there is minimal play in the reels, resulting in longer life of the cutting unit and its parts.

Both backlapping and grinding can sharpen the reel and bedknife. While grinding removes more material from the blades or bedknife, backlapping is more subtle and ideal for restoring an edge that isn’t too far gone. A decent relief grind needs to exist for backlapping to be effective. The relief grind is a secondary grind that creates a “shelf” to hold the grit or backlapping compound for backlapping to be effective. While backlapping may be more cost effective on some courses that don’t have grinders readily available or lack manpower, grinding will “true up” a reel and bedknife more accurately, Stone says.

Due to the helix nature of a reel-type cutting units, technicians are urged to monitor for cone of the reel. This helix nature means that processed grass spins from one side of the reel to the other and can be processed many more times between the reel and bedknife (right to left), so one end of the reel gets smaller in a quicker time span than the other. Cone is corrected by proper grinding. If cone is not properly corrected, then achieving the scissor effect between reel and bedknife becomes nearly impossible, which leads to poor cut quality.

“If using a rotary mower, blade maintenance requires the equipment manager to monitor the unit, ensuring the blade is sharp and balanced,” Stone say. “If needed, the blade should be sharpened or replaced to maintain a high-quality cut, and the balance should be checked each time it is sharpened.”

As a general rule, rotary blades can be used to 60 percent of their original dimension, Borthwick says. “If the sail is excessively worn or any other parts appear close to breakage, the blade should be replaced if there is a difference in the length from center to end between the two sides,” he says.

Keep a spare sharp blade or two on hand so staff is not using productive time to sharpen blades, Borthwick adds. All reel mowers have a specific wear limit for the cylinder as well as the bedknife and these can be obtained from the manufacturer. Exceeding these wear limits will result in poor after cut appearance or other quality of cut issues.

“The damage and cost associated with improperly maintained cutting heads runs a full gambit, from using more fuel because of requiring more horsepower, more wear and tear on the engine and hydraulic systems, and extra money spent on chemicals and water,” Turner says. “It will add up in short order.”

John Torsiello is a turf writer based in Torrington, Conn., and a frequent GCI contributor.