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

Hi again. Had my 14 inch sharpened a couple if weeks ago at a local mower shop. At the same time they replaced the bottom blade.
In my opinion the roller doesn't seem to be very sharp. How sharp should it be? Should it be capable of cutting my finger like a knife would?
Should the bottom blade have any sort of edge ground on it ?
Cheers Tony.

Hi Toeknee,

I have always been of the understanding that after a Reel (not roller)has been sharpened one should bee very careful in handling it as the edge of the blades should easily cut skin if you run your fingers along it, now not for one moment am I endorsing that this is the way to see if its sharp but I'm sure you get the general idea from my suggestion.

I hope that I've shed some light on what you've asked.

Cheers,
BB

Not to keen to run my finger over the blade to test it just in case but I still suspect it is not as sharp as it should be. Just finished mowing the lawn and it seems to be tearing rather than cutting. I'm really quite disappointed considering how much it all cost to get sharpened. Think I'll give the mower shop a call and see what they say.
Cheers Tony.

Hi Tony,

After having another look at you photo of the bed knife and the reel it looks like there's a bit of a gap between the two parts due to the dark shadow I can see where the coming together of the two components meet. I think that the reel should be a tad closer to the bed knife. I would adjust it until the two make contact then back it off just enough until the reel no longer touches the bed knife.

Cheers,
BB.

Hello Toeknee, BB and ODK members and Guests,

This is an interesting subject of some importance nowadays.
I don't want to take away from the excellent observations that Bonnar Bloke has made.

I do want to broaden the topic about reel mower maintenance in general,
and help Toeknee form an informed view. The issues here are not so simple.

Since the rotary revolution of the 1950s, reel mowers have been in the decline.
The concern that I have is that skilled people and the use of appropriate
machinery is more so in decline. This topic is about consumer awareness.

The first thing is that reels will not cut your finger "like a knife would" after
even just a few weeks of service. Once the burrs are gone, the keenness of the
reel is maintained by the quality of the steel and, most importantly, its being a precision
cylindrical piece (precision grinding). Whether that precision is maintained is dependant
on the quality of the 'set' - the gap between the reel and bottom blade.



CONSUMER AWARENESS
Toeknee, like all reel mower users, should 'do their homework'.
The first thing I would ask a repairer would be about their credentials: do they know
what they are doing; do they have the right equipment.

I have evidence that repairers are not using specialised reel grinding equipment at all,
but make-shift lathes and grinders. They also have no knowledge of the relief angles
on reel blades (spirals) and bottom blades. This is not a good idea.

Reels require the right relief angle and direction of grind. Second, the fitting of a
new bottom blade without further preparatory grinding of it is not good practice. This is because
the bottom block (sole plate) may no longer be within specification. The fitting of a new
blade on a rusted block alone will cause distortions.

New bottom blades, like worn ones, should have their front and top face ground at
the correct angles. These angles are agreed to be about 3 - 5 degrees relief.

The setting of reel mowers seems to have developed a mythology of its own.
This is not necessary. On professional equipment a feel gauge may be used to ensure
there is the smallest of a gap between reel and blade.

In practice, most setters - professional and amateur - set by sound and feel.
A slight pressure and 'scissor-sound' is all that is needed. The popular test is to use
a standard 80 gram piece of paper for testing. If the paper cuts cleanly, the set is a good one.

If the set is too tight, the reel will bind more easily. I have seen professional
gang mowers of 15 feet width, hydraulically powered, bind and labour because the
set was too tight when set cold. When the reel and blade gain temperature, particularly
when these components are not cooled by cutting grass and forward momentum, the
reel will bind, and cause unnecessary wear.

When the set is too loose, the reel cutting face will degrade more quickly and
back lapping will be necessary more often.

BACK LAPPING
Toeknee, my advice is to get acquainted with back lapping.
Traditionally, this was well-understood and practised. the professionals use it,
but domestic users remain largely ignorant of it these days.

When done well, your machine will cut nicely for many seasons before it will
require grinding. Currently, the price of reel grinding in Australia is way-too-expensive,
largely due to the reasons I have said: ignorance and incorrect machinery.

I hope this helps answer your question.
-----------------------------------------------------
JACK.

Hi CyberJack, Toeknee, and ODK members,

My caution regarding cutting ones fingers was merely a caution as I'm not aware as to how long ago the reels was sharpened. When I get my reels back from sharpening they will slice skin open without any effort, but once used for a while there's not any chance of that. Like I mentioned it was basically a caution as we don't want to have any of our members harmed in any way.

Now as far as this whole scenario of reel adjustment is concerned there have always been two schools of thought and that is "to touch or not to touch" if you watch DeeJay's video's you'll see his method is "not to touch". I was always of the belief that the reel was meant to cut paper like a scissor after sharpening when placed between the reel and bed knife when the reel was rotated, thus cutting the grass, but I have been since advised by quite a few members here on the ODK that grass is not like paper and that the most minute clearance between the two components is the correct method.

So from both these ideologies I see merit, but it seems that there is more than one school of thought regarding this matter. Who's right and who's wrong is the age old question in this field of work.


Cheers,
BB

Hi BB,

Great words. I am, as always, in total agreement with you. You comments about
caution were simply sensible mate.

With respect to the 'two schools of thought'
Yeah, I understand that is the case here. In my view, schools of thought become
entrenched, people are 'set' (pun intended) in their views, with little chance of resolution.

This does not prevent friendly debate, based on rational argument and evidence.

My personal view is that, when in doubt, always defer, and refer to the manufacturer's instructions.
I think my views are consistent with the view that was held by that great company, Scott Bonnar.

All very sharp.
-----------------------------------
JACK.



Mower Maintenance - Early 20th Century

Hi Cyber Jack and BB,

Thank you very much for your input. Very interesting and informative. You have certainly helped to increase my knowledge. The shop that sharpened my blades is happy to have another look at the mower and now I feel more confident talking to them thanks to you.

It appears that the new bottom blade needs some work. The reel is touching the blade at each end but clearing it in the middle. My straight edge also indicates it has a hump in it.

If all else fails I will try to find someone with the right credentials.

Once again thanks for the help.

Cheers Tony.

Hi Tony,

Glad to have been of help.

Cheers,
BB

Just a quick one on this subject, I'm wondering if the blade was sharpened off the sole plate then fitted back onto to it, thus this would most certainly explain the bow in the blade.

The Bedknife should always be sharpened while firmly mounted on to the soleplate assembly, then fitted back into the mower.


Cheers,
BB.

Hi BB,
I don't think the bottom blade was sharpened at all. Just put straight on to the soleplate which no doubt is not straight anymore. Anyway I dropped it back at the mower shop yesterday. Hopefully they will get it right this time. I'll let you know how I get on.

Cheers Tony.

They sound like complete amateurs to me and are just into taking money under false pretences.

Hi Toeknee, CyberJack, BB and ODK members and Guests,
Toeknee, wishing you a warm welcome to the forum. It's always nice having another Scott Bonnar Model 45 owner on board.
From what I can see the cylinder reel does not look like it has been sharpened at all...the new bottom blade (bedknife) still has new paint on it and has not been faced and ground...and the new bedknife screws have not been counter-sunk correctly and are sitting proud of the bedknife which is unacceptable...all round, very shoddy work mate.
We can help you get it sorted, without taking it to a workshop, if you wish....you can do it yourself with our help.
All food for thought.
Once again, to OutdoorKing.

Hi all,
Got the mower back today. Fair to say nothing has really changed. He said he Made a few adjustments and that he got it cutting ok. I gave it a quick run tonight and yes it is cutting better however I'm still not satisfied. There has been no change to the bottom knife as shown in the photo above. Unfortunately I think I'm going to have to take this one on the chin and learn from my mistake.
Deejay, thanks for your input. I would love to sort it out myself as much as possible with your help. Unfortunately at this time of the year time is my biggest obstacle. Do you think it is a big job?
Cheers Tony.

Hi again Toeknee,
No mate, it is not a huge job, it will need you to source reputable engineer to sharpen your reel.Try asking at your local Bowls Club...speak to the greenkeeper and ask who sharpens their cylinder reels.

For the instructions for the removal of the cylinder reel and soleplate (complete with the bedknife still attached) for sharpening, please see the video Joe and I did, Click HERE

Then take both components to the engineer.

See the Fitting and Adjustment Guide: HERE for the replacement of your now sharp reel and bedknife.

Thanks Deejay. Can you remove the cutter sprocket without a gear puller?
Cheers Tony.

Hi Tony,

Sometimes you can be lucky as they don't generally don't require too much of an effort, it's just the initial movement that starts the process off.

Cheers,
BB

Hi Tony,
BB is on the money...some will almost fall off ...but equally (remembering some Scotties are nearing 40+ years old) and may not been sharpened in a long while, things tend to get a little tight with surface rust on the reel spindle and the inside surfaces of the sprocket may be hard to get off easily.

But my advice would be to remove the sprocket nut and get some penetrating oil (Penetrene) down the center of the shaft and let it soak in, and, as the sprocket is clagged, use a large screwdriver in behind the sprocket central ferrule to try and get it to move....

Remember, chinese 3 leg gear pullers are cheap, and you will use it time after time as they do come in handy and are the best method of sprocket removal.
Remember to safely store the key from the spindle keyway after sprocket removal.
Hoping it comes off easily for you...