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need info on sharpening small scissors
- Thread starter fudo
- Start date
Esav Benyamin
MidniteSuperMod
- Joined
- Apr 6, 2000
- Messages
- 90,915
Have you tried the Sharpmaker? I've sharpened scissors, nailclippers, and old potato peelers with mine. It comes with instructions for this, and even has a hole in the end of the base for scissors.
- Joined
- Apr 27, 1999
- Messages
- 6,117
Let me explane the terms that I use. The two blades of the scissors slide past each other with their sides touching. The side surfaces that touch are what I call the sheering surfaces. As the blades close the front surfaces that slide past each other I will call the cutting bevels. The angle between a blade's cutting bevel and its sheering surface is its cutting edge angle. On a single-ground knife blade the cutting edge angle might be 20 degrees. On a pair of scissors it may be as high as 80 degrees (getting close to the 90 degrees of a right angle).
You sharpen scissors by honing the cutting bevels and you must not hone the sheering surfaces (except for just a touch of deburring). The Sharpmakers have a place to stick a rod that holds it at 12.5 degrees from level. When you hold the scissor blade verticle and stroke sideways it hones the cutting bevel at 77.5 degrees. This will work pretty well for touching up a pair of scissors ground ate 77.5 to 80 degrees. I would use the medium grit rods for this. If the surface is very narrow you may not be able to feel it. In that case color the surface with a permanent ink marker so that you can see what you are doing. Tilt the blade back from vertical to something that you guess is 80 degrees instead of 90 (vertical). Do a light honing stroke and see if you remove ink closer to the sheer line (indicating you need to tilt the blade back more) or if you remove ink closer to the back side of the blade (indicating that you need to hone closer to verticle). Reink adjust your technique and try again. You don't need to be perfect to improve the performance of your scissors.
If you hone your scissors by hand you will need to press the cutting bevel flat on a hone and feel for the correct angle (the angle where the hone is flat on the old cutting bevel surface). Then you carefully stroke the blade on the hone such that the sheering surface is in front as you stroke. This will reduce burr formation at the cutting edge. Do not use an extremely fine hone for this. Scissors need to bite a little into material as they cut or it will tend to slide out of the scissors. Sometimes I even use a smooth file for the job. A fine diamond hone or a medium-fine aluminum oxide hone can work. If the blades of the scissors don't open all the way to 90 degrees you may need a thin or tapered hone to fit between them. You can take something like a popsicle stick and glue some 220 grit Wet or Dry paper on it. This will fit in the gap to do the job. After you hone you might use some very fine abrasive lightly on the sheer line to remove any burr on the edge you just made. Don't let it rap around the edge or work on the cutting bevel since you want to protect your edge and the surface roughness on the cutting bevel.
Another thing to know about is that fine scissor blades are bent in a slight curve so that the blades press against each other when they are closed and curve across the sheer line (across each other) when the blades are partially open. This curvature causes a the cutting edges to press against each other under spring tension as the scissors are used. This curvature is call "set". There are special gadgets to bend the blades and adjust this. If the tips of fine scissors don't cut it is often that the set has been lost (usually by cutting things that are too tough for the scissors). Tightening the scissor pivot screw and sharpening won't help this problem. You can try and rig some blocks and use a vice or something to restore the set, but you are very likely to break the blades when you try. You need the gadget or a lot of skill to restore set on your own.
The pivot screws for scissors are often self locking types. They are oversized for the holes they are in or something else has been done to make the screw bind in its threaded hole. It can be very hard to tighten these screws without slipping and damaging the slots. I have taken short screw drivers and drilled holes across the handles to alow me to insert a rod to use as a lever. Then I insert the screwdriver blade in the screw slot and clamp the scissors and the screwdriver together lightly in a vice. This prevents the driver from backing out of the slot. Then I use a rod through the screwdriver handle to twist the driver a bit. This is something I did when I had a lot of other people's scissors to work on. For my own scissors I would start be using a good hard screwdriver that matched the slot and just lean hard on it as I turn the screw.
You sharpen scissors by honing the cutting bevels and you must not hone the sheering surfaces (except for just a touch of deburring). The Sharpmakers have a place to stick a rod that holds it at 12.5 degrees from level. When you hold the scissor blade verticle and stroke sideways it hones the cutting bevel at 77.5 degrees. This will work pretty well for touching up a pair of scissors ground ate 77.5 to 80 degrees. I would use the medium grit rods for this. If the surface is very narrow you may not be able to feel it. In that case color the surface with a permanent ink marker so that you can see what you are doing. Tilt the blade back from vertical to something that you guess is 80 degrees instead of 90 (vertical). Do a light honing stroke and see if you remove ink closer to the sheer line (indicating you need to tilt the blade back more) or if you remove ink closer to the back side of the blade (indicating that you need to hone closer to verticle). Reink adjust your technique and try again. You don't need to be perfect to improve the performance of your scissors.
If you hone your scissors by hand you will need to press the cutting bevel flat on a hone and feel for the correct angle (the angle where the hone is flat on the old cutting bevel surface). Then you carefully stroke the blade on the hone such that the sheering surface is in front as you stroke. This will reduce burr formation at the cutting edge. Do not use an extremely fine hone for this. Scissors need to bite a little into material as they cut or it will tend to slide out of the scissors. Sometimes I even use a smooth file for the job. A fine diamond hone or a medium-fine aluminum oxide hone can work. If the blades of the scissors don't open all the way to 90 degrees you may need a thin or tapered hone to fit between them. You can take something like a popsicle stick and glue some 220 grit Wet or Dry paper on it. This will fit in the gap to do the job. After you hone you might use some very fine abrasive lightly on the sheer line to remove any burr on the edge you just made. Don't let it rap around the edge or work on the cutting bevel since you want to protect your edge and the surface roughness on the cutting bevel.
Another thing to know about is that fine scissor blades are bent in a slight curve so that the blades press against each other when they are closed and curve across the sheer line (across each other) when the blades are partially open. This curvature causes a the cutting edges to press against each other under spring tension as the scissors are used. This curvature is call "set". There are special gadgets to bend the blades and adjust this. If the tips of fine scissors don't cut it is often that the set has been lost (usually by cutting things that are too tough for the scissors). Tightening the scissor pivot screw and sharpening won't help this problem. You can try and rig some blocks and use a vice or something to restore the set, but you are very likely to break the blades when you try. You need the gadget or a lot of skill to restore set on your own.
The pivot screws for scissors are often self locking types. They are oversized for the holes they are in or something else has been done to make the screw bind in its threaded hole. It can be very hard to tighten these screws without slipping and damaging the slots. I have taken short screw drivers and drilled holes across the handles to alow me to insert a rod to use as a lever. Then I insert the screwdriver blade in the screw slot and clamp the scissors and the screwdriver together lightly in a vice. This prevents the driver from backing out of the slot. Then I use a rod through the screwdriver handle to twist the driver a bit. This is something I did when I had a lot of other people's scissors to work on. For my own scissors I would start be using a good hard screwdriver that matched the slot and just lean hard on it as I turn the screw.
Are we talking 1.5" blade surgical small, or like .5" blade periodontist small?
You'll want them razor sharp. I really love DMT's stuff, because it cuts fast and the Green (extra fine) stuff will get you just about where you need to be for everything, probably including scalpel sharp. This probably includes scissors. Their diasharp line is nice (no holes inbetween diamond surface), get something in green and you'll really like it, I think.
Depending on how sharp you need it though, you'll probably also like ceramic stuff at REALLY high grit levels. Spyderco makes some ceramic rods at pretty fine grits, IIRC.
What you buy depends on if you're sharpening lots of various items, or a specialized few.
Hope that helps.
_z
You'll want them razor sharp. I really love DMT's stuff, because it cuts fast and the Green (extra fine) stuff will get you just about where you need to be for everything, probably including scalpel sharp. This probably includes scissors. Their diasharp line is nice (no holes inbetween diamond surface), get something in green and you'll really like it, I think.
Depending on how sharp you need it though, you'll probably also like ceramic stuff at REALLY high grit levels. Spyderco makes some ceramic rods at pretty fine grits, IIRC.
What you buy depends on if you're sharpening lots of various items, or a specialized few.
Hope that helps.
_z