$7 Period of Instruction

Idaho Jarhead

Idaho Jarhead

Joined
Nov 2, 2007
Messages
1,415
I have been wanting to learn how to convex sharpen for a while now, but wasn't quite sure how to go about it. So last night, while walking through the hardware store I saw a display with some cheapo fixed blades. I grabbed one of those and a few sheets of sandpaper and I was set.

A couple of things I learned is that the 220 takes off metal quick! I don't know what kind of steel this knife is, but it went down fast. Another thing is that I may have been holding the blade at too sharp of an angle. It seemed that it wasn't convexing as much as it was just sharpening at a V.

One frustration is that I didn't feel as though the blade got very sharp. Out of the box it wouldn't even cut paper. I was able to get it respectably sharp, but it still couldn't shave hair. I stropped a little with 220, 400, and finished at 600 because that is all that store had in stock.

So I will show a few pictures to go with my story and if anyone has any pointers I certainly appreciate the feedback.

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Try less pressure and a softer backing.
 
Should I go back to a courser grit or stay at the 600? How fine a grit should I go before I enter the realm of obsessive?
 
I'm no guru on sharpening :foot:, but I can usually get a convex edge to shave (badly) at 600 grit and by 1200 grit it shaves fairly cleanly. I use an old computer mouse mat (about 1/4 inch thick or less) as my backing. It is a very soft backing so it deforms+ and I therefore lay the knife relatively 'flat' (lifting the spine maybe 1/4 - 1/8 of an inch at most, but that depends on the height/width of the blade) and use fairly light pressure - at finer grits I apply almost no pressure to the knife - just concentrating on holding it at the correct angle consistently. Eventually the law of diminishing returns kicks in... I then usually strop on leather loaded with chromium oxide :D.

I'm a slow learner so it took me a couple of hours of practice to get in the groove. Now it takes only a few swipes to freshen up a blade but still >30 mins to covert a v-grind.

You will get it - hopefully faster than me! Good luck :thumbup:

PS - try finer grit, if still no results, back you go :D;)
 
Hey there, it looks like youre getting the hang of convex sharpening.

I use the lower (less than 1000 grit) for reprofiling a V-ground edge, and then move on to 1200, 1500, and 2000 grits for the final sharpening before stropping....

I have learned that using the sandpaper over my leather strop gives me the most consistant results. I used to use a mousepad, but it was too soft and I found myself ending up with butterknife edges rather than razor blades......

The most important thing to remember is that the bevel should be shaped like the nose of a fighter plane or a rifle round....... It takes time and patience to get a gentle curve to the edge. Make sure that you wait until there is NO drag on the blade before you go up in grit. If you dont, it takes much longer at the higher grit to remove the scratches you missed at a lower grit.

Look for a consistant light dispersion on the bevel (it should be even from the base of the bevel to the edge), to make sure that you are hitting the bevel evenly on your strokes.....

The best place to get your sandpaper is from an auto parts store, as the higher grits are used for polishing metal, a task not common to Home Depot or Lowe's.

It doesnt matter how thick or thin the blade is, once you get convexing down, you will never go back to a V-edge again...

The Battle Mistress (combat grade) is 1/4" thick...
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This Game warden is over .3" thick!!!!!
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Here's a link to the video I watched before trying:

Link

I then tried this with a small folder. Its edge doesn't look anything like the beautiful polish rangerover got on his knives.
 
Thanks for the pointers, gents. I think this thing is coming around alright. I worked the 600 grit over a mousepad for quite a while last night. I think I am about as sharp as I can get with my current supplies, so have to get down to the autoparts store to re-supply and take it to the next level.

One thing I have noticed is that I am scratching up my blade a bit about mid-height. I am assuming this is normal due to the angle at which I am sharpening. But is there a way around this?
 
You can cheat and use masking tape on the top 1/2 of the blade. :D

I found that when I have scratched high on the blade I had either had a momentary lapse of concentration and dropped the angle too much or (more usually) applied too much pressure on a too soft backing. The latter is easy to pick because the knife seems to get blunt again as the pad wraps around the edge.
 
Hey Idaho Jarhead, thanks for pointing me over here from my sharpening thread. Have you watched the sharpening videos from knivesshipfree? Check them out, a lot of good info. You seem to be at the same stage I am figuring this whole convex sharpening out, the videos really help.

Rangerover_95, good idea with using the leather rather than a mouse pad. I will give that a shot too and see if my results are different. Awesome pics by the way!

Convex Sharpening Videos:
http://www.knivesshipfree.com/pages.php?pID=4&CDpath=0
 
If you need help, or a more involved answer, feel free to PM/Email me....... This goes for anyone:thumbup::thumbup::thumbup::thumbup:

I have really just been practicing for the last year or so, but I attribute it to a slight case of OCD (and a good deal of boredom at times) that I strive for perfect edges on my knives. I started freehand with stones, and just liked the edges much better after convexing them.... I fully convexed a Busse Skinny ASH, all by hand!

It took 15 hrs from strip to finish IIRC(damn INFI dimples ;)), but she is a beauty now!!!!
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OT-----I see your from Central Ore? Whereabouts??? I have been trying to get some So./Cen. Oregon hikes and fun things like that organized this Summer!!! I would love to finally meet some of the fellow BF'ers!!!!

Back on topic......

The high polish will come with time, just make sure you are finished with one grit before switching....dont be impatient!!!!! The stropping is the key to mirror edges!!!
 
Let me second a few things here.
I have found that as rangrover_95 says convexing on a strope works great and mouse pad I find is a little too soft. Make sure you are getting a bur!! I start at 320grit wet/dry paper then progress through: 400, 600, 1000, 1500, 1800, 2400, 4000 then loaded strope and then bare strope. I have a love/hate relationship with D2 I .love the edge holding, I hate when its gets dull and I have to bring it back to hair popping sharp. The above works great for me on the kitchen knives and my EDC’s and especially my axes and machete’s.
 
rangerover_95 said:
OT-----I see your from Central Ore? Whereabouts??? I have been trying to get some So./Cen. Oregon hikes and fun things like that organized this Summer!!! I would love to finally meet some of the fellow BF'ers!!!!
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rangerover, I'm in Bend. Yes, it would be great to organize a hike or something this summer. Shoot me an email at this username at hotmail dot com and let's figure out a trip! Maybe Thielsen or somewhere around Williammette Pass.

Back OT, I have never really gotten a burr with convex sharpening -- the maybe it's the steel (A2, 12C27, and 1095), or the fact that most of my convex blades are already pretty sharp and I'm just touching them up.
 
How important is it to raise the burr? Could a guy just alternate strokes until the beast is sharp? If no, why not?

I ask because this burr is a mythical object to me. I can sharpen a knife so-so but have no idea if I have ever raised a burr.
 
Good question! I really only get a burr on the belt sander. I can't imagine how you'd raise a burr on a Sharpmaker, for example.
 
tradja said:
Good question! I really only get a burr on the belt sander. I can't imagine how you'd raise a burr on a Sharpmaker, for example.
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The same way, just slower. :D

Thanks for this thread, I've recently started using a strop and have been thinking about convex edges. The first thing I learned it that if you press too hard you get a beautiful smooth round... butterknife.
 
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