Sharpening hedge shears

U

Ultradianguy

Joined
Jan 1, 2020
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Hi all - I started trying to sharpen my dad's old hedge trimming shears which seem pretty well made. I noticed that as I slowly close the blades, they meet at the tip and the heel but in the middle (longitudinally) there is a gap. Is this how they're designed or do I have bent blades? Not sure if I should attempt to take that out. To be clear, the hollow is along the length - not across the width of the blade.
 
Ultradianguy said:
Hi all - I started trying to sharpen my dad's old hedge trimming shears which seem pretty well made. I noticed that as I slowly close the blades, they meet at the tip and the heel but in the middle (longitudinally) there is a gap. Is this how they're designed or do I have bent blades? Not sure if I should attempt to take that out. To be clear, the hollow is along the length - not across the width of the blade.
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Yes this is to ensure a single point of contact between the blades in use. The contact point should move from the heel to tip as the blades are closed. This is known as the "ride" of the blade.
 
FortyTwoBlades said:
Yes this is to ensure a single point of contact between the blades in use. The contact point should move from the heel to tip as the blades are closed. This is known as the "ride" of the blade.
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Sorry - so you're saying it's okay that when they're closed the blades don't meet in the middle section? I shouldn't expect to see them contacting each other along the whole length? Should I check to see that as the blades close that there is only one point of contact at any moment? They're not cutting well right now but they may just need better sharpening than I did on my first rough attempt.
 
Ultradianguy said:
Sorry - so you're saying it's okay that when they're closed the blades don't meet in the middle section? I shouldn't expect to see them contacting each other along the whole length? Should I check to see that as the blades close that there is only one point of contact at any moment? They're not cutting well right now but they may just need better sharpening than I did on my first rough attempt.
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Correct. The gap is deliberate. Open the blades and watch the point of contact between the edges as you slowly close them. It should move from the base of the blades towards the tip as they close. When fully closed, the tips should meet.
 
Sometimes, if the pivot gets too loose, you may not have adequate single-point contact from heel to tip. So it's good to check if there's too much sideways play or 'slop' in the pivot as you open & close the blades. That can really impede cutting too, even if they're well-sharpened. Happens a lot with well-used trimmers & scissors.
 
It does indeed. Be gentle when tightening the riveted ones, it’s easy to tap them too tight and a lot of work to correct.

The screwed ones, many are peened. The challenge is turning the screw without stripping either the threads or the head. However, there’s always the option of drilling out the screw and riveting…

Parker
 
Actually mine are quite old - probably 50+ years - the pivot is solid and easily adjusted. But that wasn't the issue. There was apparently a little bit of a bend in the blade. After cleaning, sharpening and tightening, there was a section in the middle that seemed to not make any contact through the closing stroke. I put them in a vise and gently bent in a few places - very small changes - and now they seem to be making good contact. Tested them out and they cut well! Very pleased to be able to recover them rather than toss and buy some Fiskars that probably wouldn't have lasted long. Plus it's nice to use something that my Dad used decades ago when I was a kid. I doubt my kids will feel that way in another 20 or 30 years - but who knows. :)
 
If no material is removed from the area of the pivot screw the blades just keep getting further apart as we sharpen the bevel. On some shears that area around the pivot is hollow ground just like the rest of the blade, it's part of the ride line.
It's possible to touch up shears without reestablishing the ride line but at some point it needs done. I do it every time I sharpen, judiciously.
 
Ah this is interesting. So you would remove material where the blades contact each other right around the screw? I'll have to look at that next time i sharpen them
 
Basically any maintenance that's done on the backside of the blades should include that area. HOWEVER, this rarely needs to be done, and if done incorrectly can screw up the shears pretty badly. So any work on the interior faces is not to be undertaken lightly. Make sure you fully understand how they function before attempting.
 
catspa said:
However, there’s always the option of drilling out the screw and riveting…

Parker
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I like to use nylok nuts on my pivot bolts.

Great info in this thread. First time I noticed that gap I was also perplexed
 
Here is a video of a professional fixing an improperly sharpened grooming shear. They can't be fixed without addressing the inside of the blades.
No need to be afraid to touch the inside of a blade just understand that the ride line should be minimal.

 
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