Repairs what angle to put on front edge of blade

woolyhead

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The fixed blade of a reel mower passes over the ground at a set height and the rotary cutters push the grass up against it, just missing the blade and passing over it very close so as to cut the grass. What is the ideal angle to grind on to the fixed blade at its front edge when reconditioning it? I realise the obvious fact that one should use the same angle as the blade had when it was new but unfortunately that doesn't answer the question. So could anyone tell me what this angle should be please? Should it be at right angles to the ground or something else? And how does the newly ground front face slope; away from the direction of travel on its top edge or towards it?
 

bertsmobile1

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The blade angle depends on the diameter of the reel.
It should be in the owners handbook and they should be available free on line , consummer law that is worldwide, nice to agree on something.
 

tom3

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My dad was a millman in a railroad repair yard, part of his job was sharpening stuff. His theory on mower blades was based on how it is used. Nice smooth yard with nice grass, a more acute (thinner) angle, a rough yard, maybe some rocks, and roots, tough grass, you'd want a more blunt angle so when the cutting edge hits something tough there's some steel to back it up. Thinner angle might use less power and cut a bit better? And a good balance job is critical for nice operation.
 

woolyhead

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The blade angle depends on the diameter of the reel.
It should be in the owners handbook and they should be available free on line , consummer law that is worldwide, nice to agree on something.

I can't find the handbook for my mower, a Qualcast Concorde 35. I'm not interested in finding the absolutely and theoretically perfect angle, only the approx. angle for a small, neat back garden with no bricks or sticks etc on the lawn. The related question is about how the angle is positioned relative to the bottom of the fixed blade. Is the bottom of this blade ground to the angle or is it the top of it that's ground? I've been given a definition of the angle as being relative to the ground but it depends whether it's the top surface or the bottom one that's referred to that's ground to this angle. One post said it's the angle between the upper surface and the lower one as if it didn't matter whether it means grinding metal off the bottom of the blade or the top. This must be wrong. Anyone help me a bit more. please?
 

tom3

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Never seen a mower blade that wasn't flat on the bottom of the cutting edge. The angle is on the upper side. I'd guess grinding some off the bottom is a short cut to get a sharp edge.
 

woolyhead

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Never seen a mower blade that wasn't flat on the bottom of the cutting edge. The angle is on the upper side. I'd guess grinding some off the bottom is a short cut to get a sharp edge.
Great news Tom. Thanks for that information. I was previously told that the angle is measured relative to the ground but there are two meanings which can be attached to that. A little thought will make my point clear. Your post has removed my doubt however.
 
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woolyhead

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I spoke with the supplier to Silverline Tools about their 270952 blade sharpener and they told me it isn't suitable for the fixed blade of a reel mower. They said I would need a flat bed grinder for that. In other words it seems that the top face of this fixed blade needs to be flat. If the front edge was at 90 degrees to that face the corner between the two would be sort of sharp. I think the blade system works like this:- The rotary blades first push the grass stems on to the front edge of the fixed blade which stops them moving back any further. The rotary blades then slice through the stems. Does anyone agree with this idea?
 

tom3

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Never seen a mower blade that wasn't flat on the bottom of the cutting edge. The angle is on the upper side. I'd guess grinding some off the bottom is a short cut to get a sharp edge.

Reel Mower? How did I miss that? Throw out my response, probably wrong for type of machine. Sorry for the confusion.
 

woolyhead

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Reel Mower? How did I miss that? Throw out my response, probably wrong for type of machine. Sorry for the confusion.
Don't apologise Tom3. Your replies have sorted the problem out for me. And you were right about the sharpening needing to be on the top surface of the fixed blade. When that surface is lapped to suit the fixed blade we have two ground surfaces sliding past each other with a perfect fit between them at the point of contact. My comment about having the front edge of the lower blade at right angles to its bottom surface was wrong because when the grinding is done the two ground surfaces are virtually parallel to each other at the point where contact is made. This is not like those cutting points in scissors where it is the unground surfaces that slide past each other. It has been an interesting discussion so thank you again.
 
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