Sharp secateurs

[Tiger]

Dear all,

Have a pair of good quality secateurs that can be disassembled. They had been a little blunt and struggled to cut anything more than about 10 mm thick, so I took them apart and first I tried a stone to sharpen them. Didn't get much benefit out of that so I took the blade and very carefully sharpened them on a bench grinder without taking any metal off. Now they're a lot sharper, but still they don't cut much better:mad: . Any advice from people who have sharpened these things would be appreciated.

[atregent]

When you sharpen the blade piece, make sure you only sharpen the one side, it needs to have one flat side against the other bit (that's a really technical term, but it is Sunday morning after all!).

With mine, the nut that tightens them occasionally works its way loose too, which means the blade doesn't have a good cutting action against the other bit. Of course, tighten it too much and the things wont open.

I'm not sure if that helps, depends on if your secataurs are made in a similar way to mine, but I've had mine for quite a number of years and take them apart to clean and sharpen them quite often.

Cheers,
Anthony

[macca2]

What Anthony said but also the other bit needs to have a clean angle for the blade to cut against, so you need to touch up both sides.
The adjustment of the blade nut is important to get the 2 pieces as close as possible without being too tight to use.
Oil all pieces before you reassemble.
Having said that some I have had are poor quality and can never be set up satifactory.

Cheers Macca

[scooter]

Anthony is on the money, only sharpen one side of the blade, kinda like scissors. Sandvik (Bahco) recommend along these lines, with just a light pass along the flat side to debur.

The process is basically the same as sharpening anything else, just a little trickier with the curved blade.

You want to create an edge, where two planes intersect. One plane is the flat side of the blade, the other plane is the bevel you sharpen. Try to keep the angle of the bevel about the same as what the manufacturer intended, that will most likely give you the best combination of sharpness and durablity.

Using your grinder will create this bevel, but it will have "micro serrations" due to the coarse nature of the grindstone (not to mention overheating the edge if you're not careful). Unless the secateurs are in really bad shape, you shouldn't really need to do this, it is a little heavy handed and will eat up the blade pretty quickly.

You want to refine this bevel by using one or more progressively finer sharpening mediums, ie. some form of sharpening stone (oil or waterstone), sandpaper (wet & dry), or whatever you have to hand that will abrade/sharpen the edge.

The difficult part you'll find is sharpening at a consistent angle on the curved blade.

You may find it easier to sharpen half of the length of the edge first, then proceed to the remaining half. What you want to do is abrade the blade at the bevel angle until you create a tiny burr that you can feel with your finger on the opposite side of the edge, ie. the flat side.

Only when you create this burr will you have ensured that the bevel you've created extends right to the very edge. Continue to do the same on the remaining length of the edge, until you can feel the tiny burr right along the edge.

If you want to use a finer stone, do the same process now on it.

To "back off", or remove this burr, lay the other side of the blade flat on the sharpening stone, raise the back of the blade very slightly (only a mil or so) and make 1 or 2 light passes on that side of the edge. This will remove the burr.

Bit of WD40 or kero to keep rust away (do this after each use).

If you still struggle and want some sort of sharpening aid, your hardware will sell a secateur & lopper sharpening jig by Muliti-sharp; shouldn't really need this though as it is only something you need to do occasionally and just takes a bit of perseverance.

Put up any questions if not clear.


Cheers..............Sean

[Tiger]

Thanks guys for your responses.

I actually flattened the flat side with wet and dry sandpaper, took it to 2000 grit and it was really polished. I didn't do the same on the bevelled side because as has been said it's a lot harder to retain the edge with that curved blade, good idea to do one half and then the other half so thanks for that Scooter.

I think the blade is sharp, it will cut paper no problems. As has already been pointed out, the way the blades meet up could be the problem. I notice on mine that it sort of twists the branch before cutting, but do the nut up tight and you can't open it properly.

By the way, what diameter do you go up to when using these things, can yours cut more than 1/2 inch?

[Sturdee]

By the way, what diameter do you go up to when using these things, can yours cut more than 1/2 inch?

Depending on the type of tree/shrub between 15 - 20mm with secateurs, 20mm - 30mm with the longer handled loppers and above that with a chainsaw.

BTW it is also a good idea to regularly wipe the blades with a kero soaked rag to avoid gum buildup which makes it harder to cut.


Peter.

[Tiger]

Depending on the type of tree/shrub between 15 - 20mm with secateurs, 20mm - 30mm with the longer handled loppers and above that with a chainsaw.


Peter.

We've mainly got roses and there's no way we would be able to cut 15 to 20 mm with the current secateurs. Interestingly, I borrowed a neigbour's set of secateurs and they were a cheaper brand but the sharpened angle was a lot shallower, probably around the 10 to 15 degrees mark and they left a cleaner cut. Mine will crush the stems before cutting them even though they are fairly sharp:confused: .

[scooter]

Small tip, orient the bypass-type secateurs when cutting so that the sharp blade is on the trunk side of the cut, thereby confining any damage to the waste piece.


Cheers....................Sean

[Sturdee]

We've mainly got roses and there's no way we would be able to cut 15 to 20 mm with the current secateurs.

If you have trouble cutting thicker branches you could always get an extra cheap pair of ratchet secateurs.

Bunnings have them and if the branch is to thick to cut at once the ratchet mechanism will help to assist cutting.


Peter.

[soundman]

Dont forget to lap the face of the other blade too.
It dosn't cut but it is cut against.

I have wizzed the bevel side of the sharp blade on the grinder before & stoned the flat.
They don't need to be real sharp to work but the geometry has to be right and the adjustment has to be good.

cheers

[BobL]

If you have trouble cutting thicker branches you could always get an extra cheap pair of ratchet secateurs.

Bunnings have them and if the branch is to thick to cut at once the ratchet mechanism will help to assist cutting.


Peter.

I gave my 80 year old mother a pair of those ratchet ones last year for mothers day - she's now hacking at everything in sight and instead of having to cut things for her I now have to pick the clippings up!

[MrFixIt]

Hi

I actually flattened the flat side with wet and dry sandpaper, took it to 2000 grit and it was really polished.

That's a "bit over the top"
You DON'T need a polished edge for the tool to cut. In fact you need a slight serration for the cut to improve. Basically think of the edge(s) as a VERY fine saw blade eg with almost invisible saw teeth.

When you grind the blade and have that rough edge on the other side of the blade, that is the kind of edge that cuts.

You do not need to back off that rough edge as the first few cuts with the tool will remove most of that surface.

It may be that any hollow grind in the back of the blade has been removed (or reduced) and this can lessen the quality of the cut and increase the effort required to use the tool.

One other point is to have the blades CROSS each other. So if you view the blades (edge on) when the secateurs are open, at least one blade should have a slight bend in it. When you view the blades when the secateurs are closed then the tips should touch and there should be a "slight" gap at the base of the blade (near the handle).

This bend ensures that the edges cut as they pass each other and helps prevent the urge to twist the item being cut.

[Tiger]

Thanks, Peter, what you've said makes sense. I was applying woodworking knowledge to the secateurs in regards to the polishing of the back of the blade. What it produced was a razor edge that cuts thin stuff, say 10 mm or less very clean, however it struggles with anything over 10 mm. I've noticed that the cheaper versions have a thinner blade which perhaps aids when cutting the thicker stuff. My secateurs are rated to cut up to 1 inch but have a much thicker blade which I've added an angle of about 25 degrees to.

Regarding the slight bend in the blades, if there is none as I think is the case with mine, can you bend slightly in the vise or would that damage the secateurs?

[MrFixIt]

Hi Tiger

My appologies for the late reply.

My secateurs are rated to cut up to 1 inch but have a much thicker blade which I've added an angle of about 25 degrees to.

I think you will find that thicker branches cannot be "cut" per se, thicker branches are sheared. In the case of "shearing" the requirement is more pressure than a slice of a thin blade. Perhaps the 25º angle you have on the blade is "preventing" the correct shearing action from taking place?

I know that my garden shears, that are used for thick branches (when I am ultimately coerced into doing some gardening ) have a 6mm thick, almost "flat" edge to them. The blades are very short and fat whilst the handles are very long to impart the pressure to shear the thick branch.

Regarding the slight bend in the blades, if there is none as I think is the case with mine, can you bend slightly in the vise or would that damage the secateurs?

I think you could bend them slightly in the vice. Obviously take care in what you do. The bend has only to be slight so that the tips cross when viewed "edge on". I have done such bending operations on my own (oops, correction, SWMBO's secateurs) and similar bending on her hedge/grass timming shears. In each case this has improved the cutting performance.

BTW this "technique" was imparted to me during my engineering apprenticeship when being shown how to sharpen tinsnips

[Tiger]

Thanks, Peter.