Technical “
created as the knife travels across the face of the bottom blade. By using multiple blades, this provides several contact points across the face of the bottom blade, ensuring an even and consistent cut.
Adjustment
The two blades, or knives, have to be set very close to each other in order to achieve the above mentioned scything cut. There is some variance between manufacturers over the actual dimensions but, again, the principles are the same; it is essential that the cylinder can freely turn after it is set ‘on cut’. If there is anything more than the very lightest of contact, then the friction between the two surfaces will generate heat and expansion, leading to heavier contact and greater heat build-up.
The effect of this heat build-up is not fully appreciated by the layman. The cylinder blades
blades. With the gap set, double the paper and spin the cylinder to check the cut, freshly ground units will cut both pieces cleanly; used units which are still sharp enough will cut one, and crease one. A unit that will not cut a piece of paper cleanly, simply will not cut grass cleanly.
Top tip: do not use newspaper as it is too thin for setting cylinders; business cards are too thick for setting fine turf units. Photocopier or printer paper is ideal for the task.
and the bottom blades are carefully heat treated in the factory during manufacture. Heavy contact causes friction, which heats the components again, and then letting them cool naturally removes the hardness gained during manufacture, and they go ‘soft’.
Soft blades lose their edge quickly, and so will not stay on cut, regardless of grinding or backlapping. If this process is continued, it is not just the bottom blades which are effected. The cylinder blades can also be affected; and replacing them is an expensive business, so let’s avoid it by starting to set our cutting units more carefully.
Mind the gap
There must be a gap between the blades, to avoid the above issues of friction and heat. So what should the gap be? Well, that depends on the turf your cutting and the conditions you are working in. The operator’s instruction manual supplied with your mower will give the manufacturer’s advice, and the following works for all cutting units.
A piece of paper (setting strips or photocopier quality paper) is the ideal way to set the gap; you can use feeler gauges or shim steel, but you’ll very soon cut the ends off if the cylinders are sharp, so a sacrificial piece of paper is best!
Use the paper as a feeler gauge and slowly reduce the gap at either end of the unit, until the paper will just slide between the two
of the sports surface you are preparing will be adversely effected should you fail to set your units correctly.
If you have set the gap correctly, but the paper is not cleanly cut, but torn or gets jammed between the blades, then the units needs to be sharpened by either backlapping or grinding. Backlapping is acceptable for a quick fix but, to get the unit back to its best, both the bottom blade and the cylinder should be ground.
Click Adjust Units
All modern manufacturers now offer greens units with audible clicker adjusters to aid setting the units on cut. The adjustments are now made from the top of the units, making this even easier to do. However, making it easier has not made it any less important!
PC FEBRUARY/MARCH 2015 I 119
The message here is that the cylinder and bottom blade both have to be sharp and correctly set in order to cut cleanly and efficiently. The health, quality and appearance
Do not use newspaper as it’s too thin for setting cylinders; business cards are too thick for setting fine turf units. Photocopier or printer paper is ideal
Please don’t go round the machine and give every unit “a couple of clicks” without using setting paper to get the correct setting, as this may not be the same on all units. As with any precise adjustment, this requires care and consideration, if you are going to do it correctly.
Facilities
Yes, of course you should have a heated, well lit and fully equipped workshop where you can carry out this essential adjustment, and all the other essential maintenance tasks associated with running a modern machinery fleet.
But we appreciate that many of you simply do not have these type of facilities available to you. So what are the basics?
Well, cold and wet hands are no good for setting and adjustments! After using the machine, it must be washed off and allowed to dry before attempting any maintenance. You also need to be comfortable enough to concentrate on the task, and to do it safely and do it well.
Safety
You’ll need a clean, level floor to work on and sufficient light to see what you are doing, as well as having the right tools to hand. The operator’s handbook should be available, so you can check actual settings as you go.
Gloves should be worn, and use a spanner (or a suitable length of wood) to turn the cylinder, not your fingers! Too many of us have had fingers nipped in cutting units over the years and, unfortunately, many of you will know someone who has lost a finger, so be careful, always use the right tools, and please be aware that you can’t set the unit on the machine; get it on the bench!
You should always complete a risk assessment for such essential maintenance tasks, and use this to ensure that your club or business gets you the facilities you need to complete this work correctly and safely.
Hopefully, this short piece will give you the confidence and ability to carry out this most important of tasks. However, if you’re still unsure how to do this, or would like some additional guidance, ask your supplying dealer for some training, or approach a professional training organisation who will be able to show how to set and adjust your units correctly. Your turf deserves it!
Watch the How To ' Workshop - Cutting Unit Set-Up’ video here
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