OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers scott bonnar 45 mower

Hi Steve, mate, I'm sorry to hear that you have had probs with setting up the cylinder reel, if it has been professionally sharpened and the reel and bottom knife blade ground and lapped together as they should have been, it should be relatively easy (with a bit of practice) to set it up.
Could you please answer the following:

(1) Does the engineering workshop that sharpened them for you do cylinder reels for Bowling Clubs or Golf greens mowers?

(2) Has the bottom blade been ground, your pics don't show the 'top' of the blade?

(3) Are the bearings true and servicable?

all you have to do is adjust each side of the blade by eye until it looks like the entire blade just brushes the bottom blade when you turn it by hand. Then get your newspaper and fine tune the adjustment untill it slices that paper the entire length

{1} he specializes in queens for bowling greens...

{2} The bottom blade has been ground and brand new

{3} New bearings have been fitted deejay and the bearing hangers/bearing cutter housings are in serviceable condition snugg fit anyway i phoned the fellow who undertook the sharpening for me and has suggested to see how it cuts and if need be come back and see him so i guess thats a fair call thanks deejay/tezza

Hi Tezza, you're correct there, in theory, that's what should happen, but as you will see, in practice, you will do the fine tuning, and all is fine.....paper is cutting nicely from one end to the other, so you then tighten the locking nuts.....
All of a sudden, the reel is too tight on the bottom blade! So you back off the locking nuts and start again!! It takes a bit of practice, but you can get it right.

That is assuming that the reel blades have been ground 'square' (ie.) the reel is placed correctly in the lathe and is spinning; and the rotating grind stone is perfectly square to it, (and in itself exactly square); as the stone moves across the face, each blade should be exactly the same height and perfectly flat (from left to right....The thing to remember here, is that the reel is a helix spiral (ie.) the blade curves around the spiral.
If for any reason the reel is not 'square'to itself or all of the blades are not exactly the same height, NO fine tuning adjustments will correct the problem.

This is what I feel has happened in Steve's case, the reel has been ground slightly "off square".
The solution; re-grind the reel and lap it to the bottom blade.

The main problem is the same one that occurs adjusting tappets on OHV engines. When you tighten the lock-nut, it pulls the central screw through the fixed nut until it is hard up against the upper side of the thread of the fixed nut. This always changes the adjustment from what seemed right when the lock-nut was loose or only slightly firm. The problem gets worse as the machine gets older, because there is more wear on the threads, resulting in more slack.

You need to understand which way the adjustment will shift when you tighten the lock-nut, and allow for it. You should also make your initial tests with the lock-nut moderately firm, and don't over-tighten it when you finish the adjustment - over-tightening accelerates the wear on the thread and makes it harder to adjust next time.

ok all thank you for your help ...

is there a chance that over time and a few ajustments to the cutter reel that it could fime tune a little better thanks again steve...

There are two issues here: first, how well the reel and the fixed blade fit each other, if perfectly aligned; and second, how well you align them. The first is a sharpening issue, and the second is an adjustment issue. You can't fix faults in one by doing additional work on the other.

In my limited experience the biggest problem in most cases is amateur adjustments that damage the blade or cylinder. Once that happens it doesn't matter how well you adjust it, the parts no longer fit each other. Hence I suggest after professional sharpening you should never run the reel under power until you have achieved a perfect result turning it by hand. A perfect result means there is almost no force required to rotate the reel, and no sound except a sort of very slight hiss as the reel blades pass the fixed blade. When you put a sheet of paper between reel and fixed blade, it should cut smoothly right across the width of the reel, and sound like using a pair of scissors to cut paper (only a bit smoother - most scissors are not very well made).

Hi Steve, if the cylinder reel is, as I suspect, slightly out of square, you will find it will wear un-evenly.

However you now have plenty of meat on your new bottom blade and plenty on the reel, so just set it through fine tuning as best you can, or better still, take the whole machine to the chap who did the sharpening for you, and get him to fine tune it....That way he can see the prob and may do a re-grind free of charge for you, if he can't set it up correctly.

Hi Grumpy, you're spot on there, mate, and good advice.
When I first started tinkering with reel mowers, I didn't have a clue on how to set the cutter clearances correctly, so I enlisted the help of the head greenskeeper at my local Bowling Club. He suggested I bring the complete machine down to his workshop, and very patiently guided me through the set-up. My SB, at that time, was very much in need of a sharpen, so he got me to remove the reel and bottom blade complete with it's holder and oganised to have it sharpened. We replaced the bearings as well and (under instruction) got me to do the final adjustments.
Grumpy, you're right about the sound, my machine just humms when it is set correctly.
The advice of that chap has been invaluable over the years, and I am indebted to him for his knowledge and patience.

great help chaps i think going back to the place of sharpening will be the go thanks again....

No probs Steve, please let us know how you get on.

g day well i took a trip to the guy who sharpend my cylinder blades he gave em anther quick relief grind it seems i was not ajusting the cylinder cutter down enough thats about the size of it what i did work out for myself was that by folding a piece of newspaper in two so to make it thicker to resemble a blade of grass it was spot on good sissor action i think what im trying to say is it will come out in the wash regards chaps steve.....

deviosi,

If the cylinder is set correctly it should cut thin paper. I have set cylinders to cut tissue paper in the past for bowling clubs and they cut all the way through the cylinder.

The trick is not to have the cylinder to tight against the bottom blade and when it is running it should sound like it is humming with no ticking noise or clanging.

Good to see that you got it all sorted out.

thx bruce can u tell me what is the diff between a relief grind and a full grind from what i saw the relief grind is done by hand moving the cylinder cutter left and right whilst a cutting wheel sharpens it. and the other is a bit more involved and automatic once set up and takes some time but i think more precise anyways regards steve...

Hi Steve, if I could wade in at this point, there seems to be a bit of debate on the point of full grinding (or "Spin" grinding as it is known) and relief grinding.
Here is some information I have found....It relates more to the tolerances required when cutting the dwarf type grasses found on golf greens and possibly bowling greens.

SPIN GRINDING VS. RELIEF GRINDING

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.
Hoping that this might be of interest, Steve.

Steve, here is a little more on the topic.

Myths about Spin Grinding

There are a lot of myths out there about grinding. In this issue we tackle two common myths with Express Dual and Anglemaster user Peter Fletcher, owner of PMG Consulting Services in Alicante, Spain.

The self-confessed �miserable old codger� is anything but miserable or old. Peter has been travelling the world recently helping to prepare some of the world's best golf courses for major tournaments.

In May and June of 2007, Peter has travelled around the world providing tournament support at the Volvo China Open, the BMW Asian Open, The Celtic Manor Resort Wales Open, the Open de France and the Italian Open. Along with an impressive amount of air miles, Peter has a tremendous amount of experience using spin grinders and here he helps us set the record straight.

Myth: Blade thinning keeps blades sharper, longer.

Fact: �Blade thinning, or relief grinding as it is commonly referred to, has no effect on sharpness at all. Relief grinding is carried out on the back edge of the blade and serves only to �relieve� the drag caused by contact between cylinder and bedknife. It is the front edge of the blade where cutting takes place.�

Myth: Quality of cut is guaranteed with a sharp reel and bedknife.

Fact: �The most important element to ensuring quality of cut is a sharp bedknife. A sharp bedknife (faced bedknife) will cut grass cleaner with mediocre sharp reel blades vs. a rounded edge bedknife and very sharp reel blades.�

well deejay the sharpening plot thickens thanks for your reply's it serves as good infomation as bruce said he has cut tissue paper for me to acheive that the contact would be to heavy so ill be m,aking sure the ajustment is giving that very slight tickety tick thanks all steve.....

all i have a question for cylinder mower capabilities to keep a nice edge around my gardens i use a spade to keep the edge strait what im getting at is when i use my brushcutter to nick the grass that has grown at the edge it throws some of the tea tree mulch onto the lawn what i want to know is how much can the cylinder cutter cut/chomp without damage dont get me wrong im carefull about the area that is to be cut running my eye the lawn which i have been bettering for some time now i think it goes with the terain using a cylinder mower and the look u can acheive cheers steve...

The mower can cut clean, thin bark without harm but it should not be asked to cut thick bark, let alone woodchips. It especially must not cut sand or grit. If you look at the stuff that you call tea tree mulch by the time it gets whippersnipped and thrown across the lawn, you'll probably find it contains lots of sand and grit, and very likely some woodchips as well. There might even be a few paperclips, kids' toys and loose mower-parts included.

I suggest you look closely at it, then think about whether it is suitable for mowing.