Staying Sharp

Reel maintenance has finally evolved to the “high tech” arena. Aside from using micro chips to monitor engines, drive lines and hydraulic systems, reel and bed knife sharpeners offer the equipment technician more options and control over reel mower performance than ever before. With the demands placed on turf managers to achieve and maintain superior quality turf, the equipment tech is challenged to provide properly sharpened and adjusted cutting machines to help meet those demands. Board members and greens committee members now understand the relationship between quality turf and quality turf equipment. Thousands of dollars and countless man-hours can be poured into an effort to grow grass, only to see those efforts destroyed with one pass of a poorly maintained mower.


It wasn't too long ago when it was impossible to service a reel mower back to the same condition it was when it was brand new. Some of you might be able to recall the time when back lapping was the only method available to an end user. This process was time consuming, messy and produced less than perfect results. With the introduction of the single-blade reel grinder, names like Peerless and Ideal made it possible to regrind reels and bed knives to an acceptable condition. The finished results and the accuracy of grinding the units rested in the experience and patience of the individual who was operating the grinder. The next generation of grinders addressed set up and alignment issues; names like Foley Belsaw and BRL began to appear in the turf market, but even those models required a concentrated effort on the part of the operator. When the “spin” grinder entered the picture in the 1970s, MMM, Leader, Jupiter, Atterton & Ellis, Neary and Foley were some of the pioneers. This process made it easier to produce a sharp reel that was, at the time, more than adequate for cutting in most turf conditions.

However, golfers were starting to demand and expect tournament conditions year round. Heights of cut were getting dangerously low — levels lower than anyone would have previously believed could have been maintained. Researchers and scientists were beginning to develop dwarf varieties and later ultradwarfs. Soon grounds care professionals were being challenged to maintain a quality of cut equal to the expectations of the new varieties of turf. Manufacturers of mowing equipment responded by improving their mower designs and paying close attention to improving the tolerances on their reels, bedknives and even rollers. Terms that were being used to describe distances and spaces were in thousandths of an inch and then changed to be described in microns. Dial indicators, micrometers and feeler gauges became an essential part of the tools of trade for the technician. Reel sharpener manufacturers responded with advances in technology, making it possible to return a reel to OEM specifications with the “touch of a button.” The introduction of the reel mower for use in professional turf maintenance resulted in all reels coming from the manufacturer with the added advantages of the relief grind. Developers and engineers of the reel mowers recognized the advantages and increased performance of reels that incorporated relief, and that hasn't changed in all these years.


The most advanced reel sharpeners offer features and methods to accomplish a complete regrind that includes single blade relief and spin functions. Others cannot, so the debate between spin grinding only and spin plus relief has emerged as a hot topic — as is the comparison of “scything” vs. “scissor” actions. Spin grinding alone produces a sharp cutting edge and is often compared to a scythe, which produces a good quality of cut as long as it remains sharp. Keeping the reel sharp can require the time-consuming task of regrinding during the busy periods of summer. If the reel blades are not maintained to a sharp edge, then the bed knife must be kept sharp by facing or filing the front edge of the bedknife. With no relief, the reel blade thickness could cause increased drag as debris is brought between the reel and bed knife. A gap of one to two thousandths of an inch is recommended between the reel and bed knife when you spin grind alone.

On the other side of the debate, if you add a relief grind or grind the back side of the reel blade off as to produce a very thin land area, you can adjust the reel to the bed knife with virtually zero clearance between the two. With new varieties of ultradwarf turf and heights of cut well below 0.100 of an inch, you can measure the amount of leaf tissue being removed only in microns.

A scissor action is attained when the reel in conjunction with the bed knife creates a shearing type action. Just like a pair of scissors, the two blades must be maintained extremely close to each other, so close that measuring would be impractical. The natural juices in the grass blades act as a lubricant and actually keep the reel blade and bed knife at near zero contact. If you want to have increased performance, you can do so by making the reel blades thinner by relief grinding, that is, by grinding away the backside of the blades.

If you have relief grinded your units, a two- to three-minute back lapping replaces the tedious and time-consuming task of removing cutting units and regrinding. Also, doing so will help you maintain a much more precise relationship between the reel and bed knife than front facing the bed knife in an attempt to keep the units cutting properly. This is a very valuable asset in the busy mowing months. By keeping the reels properly adjusted to the bed knife, you ensure that a consistent sharp edge is always maintained. The key to keeping a reel mower cutting properly is in keeping it adjusted. A reel mower is often considered a self-sharpening instrument that will stay sharp if the gap between reel and bed knife is kept intact at “zero” clearance; however, if you allow the reel to become dull due to lack of adjustment, it will not resharpen itself.


Safety is also an important issue in relation to reel mowers. Sharpening reels and dealing with the dust and sparks is not only potentially hazardous to the operator, but to also those in and around the grinding area. Grinding stones and turning reels often invite potentially dangerous working conditions. Some of the more advanced sharpeners protect the operator by being fully enclosed with safety switches that are designed to turn the machine off if unauthorized activity or improper operations are not observed and practiced. Once the machines are fully enclosed, many models use water to help eliminate dust during the grinding process. Water or coolant also helps produce a more accurate grinding job, in much the same way as the coolant used in milling or lathe work. Water also has the honing effects of a whet rock, keeping the stones clean thus allowing them to work more effectively and efficiently.

With improvements now offered in reel and bed knife sharpeners, almost any shop that operates reel mowers can afford to own its own reel sharpeners. The new breed of reel sharpeners can often exceed OEM specifications for reel and bed knife sharpness. These advancements in cutting units and reel grinders make it possible to achieve a pristine cut delivered from a reel that has been relief grinded at 10 to 15 degrees until each blade is to a “point.” A “slither' of a land area no more than 0.0001-inch wide can be achieved through a spin grind that ensures an absolute perfect cylinder and allows the grinding stone to spark out. By adjusting the reel to a whisper to the bed knife so the purposely-achieved texture of the land area can polish itself against the bed knife surface and properly “seat” to the bed knife, a brilliant and perfectly matched result is achieved with only the natural lubricants of the grass separating the two.

Don Cotton is the vice president and general manager of Locke Turf Inc. (Opp, Ala.). You can contact him at

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