messed up my edge

TheSnakeman

TheSnakeman

Joined
Dec 27, 2012
Messages
810
hey guys
so here is what happened: i went and did some fishing and forgot to clean my rodent 3 as it is made of a carbon steel it rusted. so i took a bit of sandpaper and took the rust off but the blade is dull now i tired stropping it back to original sharpness (shaving sharp) but i cant seem to get it there
any help or suggestions would be greatly appreciated
 
TheSnakeman said:
hey guys
so here is what happened: i went and did some fishing and forgot to clean my rodent 3 as it is made of a carbon steel it rusted. so i took a bit of sandpaper and took the rust off but the blade is dull now i tired stropping it back to original sharpness (shaving sharp) but i cant seem to get it there
any help or suggestions would be greatly appreciated
Click to expand...

What are you currently using to sharpen the knife, besides your strop?

Depending on what type/grit sandpaper you used (what is it?), you might be able to just 'strop' the blade on the sandpaper. Same technique, but using the paper's grit to your advantage when a plain strop won't be aggressive enough. For most knives, any wet/dry-type sandpaper in the 320 - 2000 grit range can work well, depending on how much repair is needed and desired finishing grit (from coarse/toothy to more highly-polished).

The sandpaper will work better on a firmer backing, like thin/hard leather or wood, or even on glass (this is how I use it now). I originally used one of my strop blocks (leather on oak; see pics below) as the backing for sandpaper. Produced some good convex edges this way. A harder backing will reduce the amount of convex, and will also help protect the edge from being rounded off, as might happen when the backing is too soft and compressible.

David
 
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I am going to say I am not a big fan of stropping to sharpness on sandpaper. It can be done and can produce some really mean convex edges, but I would much rather just use a more "traditional" free hand sharpening method, and you can still convex on a stone. If you are set on using sandpaper it is a cheap yet functional method and Obsessed with edges is right, you need to "firm up" the sandpaper by backing it on something. A good way is to staple/tape/glue some paper to a piece of 4X4. One side for coarse grit, and then the subsequent sides for higher and finer grits. Then just work the edge until you reach your desired sharpness. Another bit of advice is to not switch grits until you make the blade sharp on that grit. So start with a pretty coarse grit, 250-320, then work the edge until it is sharp. You can get an edge to slice paper cleanly or pop hairs even at this grit. Once you have it sharp on that grit move to a finer one ensuring the edge stays sharp throughout. If you have lost sharpness that means you have rounded off your edge. This is easy to do with sandpaper sharpening methods. Also watch your burr formation. If you have developed a burr strop it off on a piece of leather, or stroke it through some soft wood.

As far as technique goes I will share my freehand counting method: If I have dings, dents, or chips, or just want to reprofile. I am going to stroke the knife a number of times on one side before switching. Reducing the number of strokes as I go so I do not grind one edge more than the other. Also I use a double stroke and count it as one. IE: Stroke away like you are cutting, then pull in like you are stropping and thats one stroke. Do that 7, to 10, to 15, to 20 times each side then reduce the number. So if I did a 20 stroke then next set will be 15, then 10, then 7, then 5. Then I go in a cutting stroke switching sides up to the number I started with. Then check the edge. Switch grits, repeat. Strop on leather. I know this may sound silly or complicated, but I have been doing this for awhile and it works well for me. Everyone is going to tell you a different method, and they are all about the same, just find a rhythm that works for you. If you cant do it... go to bed and try again tomorrow. You might just figure it out in your sleep. The trick is to not force it, but to be relaxed and comfortable.

Dont know if that helps, but... Thats what I have for you.... :D
 
I use sandpaper to actually sharpen.

Take 400 grit or 600 grit and use it like a strop. Edge trailing. Light touch. Match the angle. Once you get it feeling sharp like that, then move on to a higher grit if you are so inclined.

You should be able to go from a 600 to strop and have hair jumping sharp.

I have gone up as high as 3000 grit before the strop, but that is not needed.
 
i have 1000, 1500, 2000 and 25000 grit sandpaper on hand will that work?
also how do i figure out i am rolling the edge visually if there is a way because even under the magnifying glass the edge looks like it would be sharp...
thanks for the responses i will try what you have suggested
 
TheSnakeman said:
i have 1000, 1500, 2000 and 25000 grit sandpaper on hand will that work?
also how do i figure out i am rolling the edge visually if there is a way because even under the magnifying glass the edge looks like it would be sharp...
thanks for the responses i will try what you have suggested
Click to expand...

Sounds like you have a decent assortment for starting out. I'd likely start at 2000 grit or less; if stropping wasn't quite able to fix it, I'm not sure the super-fine 25000 (or is it 2500?) would be aggressive enough. Depending on how damaged the edge is, if the 2000 doesn't seem to be working well enough, take a step down to 1500 and try that, then down again if need be. More often than not, with simple carbon steel such as in your knife, it doesn't take long to tune-up the edge again. You might find the finish from the 1000+ grits to be finer than what was the factory edge. If you'd ideally like a somewhat coarser/toothy edge, going down to 220-600 grit should get it in the ballpark. But that's optional.

Cutting tests will be the best indication of how the edge is shaping up. Even when the edge 'looks like' it should be sharp, oftentimes small burrs will get in the way of smooth cutting. Or, the edge may not be fully apexed, in which case the edge will just slide over the material being cut. I like to use phonebook paper to test for either condition (burrs or incomplete apex). Burrs, chips or dents will snag in the paper, and a less-than-sharp edge will just slide over without cutting it.

The stropping technique with sandpaper is pretty easy. I think it's the easiest, in fact, and it's how I usually tune up my edges when stropping isn't quite enough (doing some this afternoon, BTW). Keep pressure light, and keep the angle conservatively low, to avoid blunting or rounding off the apex. This is another good reason to start relatively high in grit, when practicing. If the technique is a bit off, less damage is done while figuring it out. And while learning, check the edge very frequently (include cutting paper), every 3-5 passes, to see how it is changing as you work. Checking frequently will keep you from going too far astray with the edge condition, if technique needs adjusting.


David
 
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Used 1500 and taped the sandpaper over the strop and worked my way up and then used the strop itself
 
TheSnakeman said:
another question... how do i know that i am done with one grit?
Click to expand...

A lot of that comes down to deciding if you like how the edge is performing. If it's fully apexed and all the burrs/wires are cleaned up, and it's cutting well, you don't necessarily have to keep going up the grit chain.

If you're pursuing a highly-polished edge, it becomes more important to make sure all the scratches from coarser grits are erased by the current grit, before moving to the next grit. Best way to make sure, is to inspect the bevels & apex under magnification at each grit stage.

With wet/dry sandpaper, it tends to break down with use and become less aggressive. So, even if sticking with one piece of paper, the more it gets used, the finer it will tend to work. This is more noticeable in the medium & finer grits (maybe above 400/600 or so), and the grits above 1000 will produce a higher polish with more use, to near mirror polish.

David
 
ok... i have made a mirror polished edge but that does not really matter because the edge is still not shaving hair or cutting paper cleanly... i am fairly positive i have not apexed the edge yet but i do not know
this is my main EDC and small wilderness blade so that will give you an idea what i am cutting. do i just work one side tile i work up a burrs and then go to the strop or what?
thanks again for the help
Thomas
 
TheSnakeman said:
ok... i have made a mirror polished edge but that does not really matter because the edge is still not shaving hair or cutting paper cleanly... i am fairly positive i have not apexed the edge yet but i do not know
this is my main EDC and small wilderness blade so that will give you an idea what i am cutting. do i just work one side tile i work up a burrs and then go to the strop or what?
thanks again for the help
Thomas
Click to expand...

Agreed, it sounds like the edge isn't quite there (apexed) yet. Make absolutely sure you form a burr along the full length of the cutting edge, then start working to reduce/remove it. Go about that lightly (light pressure); can do at least some on the sandpaper if you wish; otherwise use the strop. In fact, use the strop first. If some of the burr is too stiff or stubborn to remove on the strop, then 'stropping' on the sandpaper at feather-light pressure can help to clean it up.

If your edge angle is a little too wide (obtuse), that will also impact how well the edge might shave, at least. If it's also not apexed, it likely won't cut well at all. Focus primarily on getting it to cut paper cleanly and repeatedly; if you can make it shave beyond that, it's gravy. Also don't worry too much about the polish on the bevels. Make it cut well first, then you can focus on making it look prettier after that. :)


David
 
You should be shaving sharp or at least able to cleanly slice paper from the first grit used, after that each following grit should make it sharper. If this is not happening then something is not being done correctly.
 
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