How to get a reely sharp mower
Reel-type mowers are precision cutting instruments. Proper care and setup will result in a clean cut, whereas improper setup and sharpening will tear or bruise the grass. An extra few minutes in the shop will result in many extra hours until the next sharpening and adjustment is necessary.
Sharpening reel-type mowing equipment requires specialized equipment: at a minimum, a bedknife grinder plus a reel grinder. Putting this equipment to its best use requires that you pay close attention to several factors.
Examining the parts to be sharpened will allow you to determine the amount of material you need to remove to provide a clean, sharp edge. It's important to do this properly, because grinding more than needed will shorten overall life (not as many sharpenings before replacement are necessary). However, too little material removal will result in an edge that will quickly break down, resulting in poor mower performance. I recommend using a magnifying glass to study the edge before, during and after grinding.
Proper setup is critical. Reels need to be true, end-to-end, relative to their mounting. Thus, the axis of the mounting system must be parallel to the travel of the grinding wheel. This ensures you have a true cylinder. Then, sharpen and relief-grind the reel to factory specs (see top photo, left).
Setup also is critical with bedknives. However, this setup starts at the bench. The following steps will help ensure success:
Always start with clean parts; remove all old residue and debris.
Determine if a replacement is needed or resharpening will suffice. For this discussion, we'll assume you'll install a new bedknife.
Inspect the bed bar; look for damage to the mounting surface. Check that the mounting surface is flat and straight (I recommend using a flat bar and 0.0015 feeler gauge). Use a flat stone on the surface to remove minor high spots and nicks. If the bed bar is bent or twisted, replace it.
Mount the new bedknife using new screws only. Start at the middle hole and work your way out to the ends alternating side to side (see middle photo, left). Old screws often are deformed or damaged, which prevents the bedknife from proper seating on the bed bar.
Confirm that the bedknife is drawn down tightly onto the bed bar. Use a 0.0015 feeler gauge to determine proper seating.
When grinding both top and face, make sure the surfaces are parallel to the bed-bar mounting face and mounting axis (see bottom photo, left).
Remount the bed-bar/bedknife assembly in the mowing unit and adjust to factory specs. A properly ground reel and knife will require minimal backlapping, if any.
Glen Rising is a product manager at Kondex Corporation (Lomira, Wis.). Special thanks to Rusty Boldrey of J.W. Turf (Horicon, Wis.) for allowing the use of their facilities and grinding for this article.
A clean (dressed) wheel is a must for a sharp edge.
Heat from grinding must not be transferred to the reel or bedknife. If this occurs, it could temper the blade material, reducing its life.
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