Saturday, January 21, 2017

Grinding Reels

One of the many jobs golf course maintenance departments perform over the winter is reconditioning and sharpening mowers. Reel mower cutting units require a lot of maintenance to get through a year, and over the winter we try to get them back to "factory specs" -- or as close as possible.  It is a time-consuming job, but very necessary to keep the machines cutting through the growing season.

At Sugar Creek, our grinders are very old and "low tech" but they get the job done. As near as I can tell, the maintenance department has spent a grand total of $800 on used grinding equipment over the last 40 years. We have a Neary 500 spin-grinder from the 1980's and a Neary bedknife grinder from the same period. In addition, we have a Peerless 1300 sharpener from probably the 1960's. We normally relief grind with the Peerless, then spin grind with the Neary 500.

Peerless 1300 Manual
Our John Deere manual contains this relief grinding diagram:

From John Deere 2500B Manual

A perfect "double relief grind" as in this diagram is difficult to achieve with our equipment, so we use the Toro specification of a 30 degree single relief grind. Either one performs just as well. In the European literature, they often use the term "blade thinning" interchangeably with "relief grinding," and I think that describes perfectly the main benefit of relief grinding. According to the research, specifically Toro's, the best quality of cut results from sharp edges with "light contact" between the bed knife and reel blade. Light contact is much easier to achieve with less surface area making contact. Relief grinding, or blade thinning, achieves this and also makes keeping the edges sharp through backlapping much more effective.

This year, we tried something new: a Bernhard Rapid Relief grinder. As you can see from the manual cover above, the Peerless sharpener takes up a lot of floor space. With space at a premium in the shop, I wanted to see if a smaller tool could replace the old Peerless grinder. It turns out, the short answer for us, a 9-hole golf course with a total of 17 reels to grind, is "yes;" the long answer is "yes -- but it is quite a bit slower and a little less precise than a full size relief grinder." I'm still not sure if I will get rid of the old Peerless, but this little tool has me thinking about it.

Here is the Rapid Relief:

Berhard Rapid Relief

The rail attaches to the bedknife with strong magnets. On some reels, the front roller has to be taken off. On these reels, we had to remove the groomer to make space for the wheel. This was an extra step but the groomer gear boxes needed inspection and cleaning any way. Once you have the setup parallel and adjusted correctly, you have to get the feel down.

It takes some practice to get consistent results. The first reels we did were fairway reels and they did not come out "perfect" but they were completely adequate. Once we got to the greens mower reels, though, the results were just about as good as we could achieve with the old Peerless grinder -- but quite a bit slower. It took dozens of passes with the abrasive wheel to take off the required material. These greens mower reels took about 45 minutes each. I did take off a lot of material because they had lost almost all of their relief from the previous year. This unit is not really intended to be a shop's only relief grinder. It is more meant to touch up or restore relief to blades during the season. For a small shop like ours, though, it can get the job done.

Bernhard Rapid Relief in action

After the restoring relief to the blade, the spin grinder is used to sharpen the reel and ensure that it is a perfect cylinder. It would be nice if this Neary spin grinder had a relief grinder attachment, but it is a spin-grind only model that we purchased used about 15 years ago. It is in good shape and works perfectly but it is a single purpose grinder at this point. I would love to find a used relief head that could be retrofitted to this unit.

Neary 500 spin grinder

Here is a close-up of the spin-grinding process:

See Time to Grind and Reel Grinding Complete for more on reel grinding.

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