View Full Version : Convex problems
Hi to you all
I have been following the threads on BCUK for many months but this is my first ever post so fingers crossed I don't mess it up!.
I currently own a Falkniven F1 and a WS Woodlore. I love both knives but I am able to get a much better edge on the WS. I believe that this is because I can get an initial wire edge on the WS when sharpening. I have followed all the advice on this forum about sharpening convex edges using mouse mats, wet/dry paper and strop etc, but still fail to achieve the same results as I can using WS on the stones. My question is this.
When using a mousemat on a convex edge should I concentrate on sharpening one side of the blade until I manage to raise a burr, or is it not possible to raise a burr on a convex edge. If not, how do you know when you have removed enough metal and the edge is ready to polish?
I apologise if this subject has been covered but having just ordered a Northstar I would appreciate some guidance.
Cheers
Nick
When i sharpen a convex edge, i either follow the guidlines in a tutorial that i have forgotten the link to (someone?? its the convex edge guide thingy) or i use a piece of wet'n'dry on some cardboard, i do say 5 strokes on each side until the damage has gone. If the blade isnt damaged then go for aStarkie Sharp (http://www.axminster.co.uk/default.asp?part=180010)
Its a versatile little leathe pad and honing paste that really makes convex edge sharpening a doddle, gives a high polish, razor edge.
:biggthump
Try this link for sharpening convex edges...
link to convex sharpen guide (http://home.nycap.rr.com/sosak/convex.htm)
Keep at it, convex edges just need a bit more getting used to. Don't roll the edges and do plenty of stropping after sharpening. Preferably never sharpen and just strop, but if you have damaged the knife you will have to.
If I am not mistaken the Woodlore is high carbon steel and the F1 is VG10. High carbon should be easier to get really sharp.
Good luck! I too am awaiting no less than 2 Northstars....
DUCky
Colin KC
20-09-2004, 22:14
Nick,
The main thing about sharpening a convex edge, is to be aware of what is achully on the edge itself (in other words, don't worry about the finish on the sides, they'll get scratched up with use anyway, start shallow & gradually raise the spine) Try using a marker pen on the edge first & try to leave a slight black line at the edge, after you are comfortable with this, then go for the full monty;)
Hope that helps
Col
That was the link i was thinking of! :biggthump
after you are comfortable with this, then go for the full monty;)
Colin..... just because you like to sharpen in the nude doesn't mean you have to tell everyone else that, that is the way to do it :nana:
Thanks for your replies
Judging from the replies, would I be right in assuming that it is not possible or necessary to aquire a wire edge on a convex blade?.
The more I think about it, the more I wonder if I am trying over complicate what should be a simple procedure! Although I still feel I should be able to achieve as good an edge on the F1 as I can on my WS. I will keep trying on my F1 and hopefully get the hang of it before the Northstar arrives.
With regards to Colin sharpening in the nude, maybe he has just ran out of hair on his arms! :rolmao:
Cheers
Nick
I've moved onto my hands :roll: I've left the top bit of my arms so i dont look like a girl!
Paganwolf
21-09-2004, 12:42
:rolmao: its the wig and dress that realy makes you look twice not the shaved arms :rolmao: :rolmao: :rolmao: :You_Rock_
Just a quick note, you dont want to be raising a wire every time you sharpen, your knives wont last long that way. Get youyr initial edge and then maintain it. You can keep a good edge going for months with just a strop or a ceramic. Raising a wire is pretty heavy duty sharpening.
Thanks to you all
As you can tell I am a newbie to all of this! I hadn't realised that you do not need to raise a burr each time you sharpen a blade (DUH :?: ). I think I will order the starkie strop and try again with my F1.
I stated earlier that I am able to get a much better edge on a scandi blade than a convex. This leads me onto another question.
Is there any members who find they can get a better edge on a convex blade than a scandi?
Cheers
Nick
ME! Now that i have a starkie :wink:
Thanks to you all
As you can tell I am a newbie to all of this! I hadn't realised that you do not need to raise a burr each time you sharpen a blade (DUH :?: ). I think I will order the starkie strop and try again with my F1.
I stated earlier that I am able to get a much better edge on a scandi blade than a convex. This leads me onto another question.
Is there any members who find they can get a better edge on a convex blade than a scandi?
Cheers
Nick
Nick, I use both types of grind, I also have the H1 which is also VG10 (which is the same steel as the F1), a Gene Ingram #30 in D2 which has just been reprofiled to a convex grind, to be honest the only difference in thier sharpness is minimal to that of a Brusletto flat ground knife.
I think the steel makes a difference, as one of the guys here already mentioned, a high carbon steel would be easier to sharpen than one of the super stainless steels. Your WS Woodlore is made from 01 tool steel, if I am not mistaken and that is a high carbon tool steel, from talks with Martyn on this site and BB the stainless is generally a lot harder and this can make them very difficult to sharpen. I hope this helps :wave:
OldJimbo
24-09-2004, 05:47
Is there any members who find they can get a better edge on a convex blade than a scandi?
There shouldn't be if both edges are ground at the same angle, and the steel similar - same the other way around. The problem with the F1 is simply the obtuse bevel - lots of us have done extensive grinding to change that as we prefer knives that cut to having the utmost in robustness of edge. Once set up, though, the Falknivens will slice the thinnest cigarette paper as well as anything else. You just won't get a straight cut because of the blade thickness.
You have to get a burr in initial sharpening - if you don't, then you aren't touching the edge.
There are advantages to the convex grind in actual cutting and the best way to see them is not to start with a convex ground knife at all, but rather a Scandi ground Mora. Round off the TOP shoulder of the bevel and cutting will go easier with less drag. Use a Hoodoo hone on the edge and you can see some increase in edge holding and robustness - with a slight decrease in sharpness because you are making the edge slightly more obtuse. There's always trade offs. Many of us also fully convexed Moras to see how they worked out, and they do extremely well for bush work. It's a heck of a job, though!
Hi OldJimbo
Interesting reply!
Reading your reply leads me to believe that in theory there should be no difference between the two profiles, but in practice the scandi would be the sharper of the two blade profiles? (Please correct me if I have misunderstood :?: ).
You also mentioned that some of the members have done extensive grinding to increase the cutting edge of the F1. Is this a job for a newbie? if so, could you explain how to do it?
I do hope the Northstar will have a slightly narrower blade width if it means a sharper edge!
Here's another question to throw open to the members. I wonder how many of you bushcrafters would choose a convex blade over a scandi, if they were only allowed one knife for a week out in the woods?
Nick
Nick, I think that you'll find that both grinds will be just as sharp. What OldJimbo was getting at would more be to do with re-profiling the convex grind on the F1 to be shallower, this will give it a better cutting profile, but still retain some of the added strength that a convex grind has.
The ease and difficulty of re-profiling an edge depends on the experience of the person doing it and the sharpening/grinding system that they use. I grind using waterstones in various grades before going onto a leather strop, others may use specific sharpening systems (the likes of Lansky come to mind) that will allow them to maintain a specific angle whilst grinding and then they would go onto using a strop.
Once an edge has been re-profiled to your satisfaction maintaining it using your chosen system is a lot easier and takes a far shorter amount of time. :-)
I have had good luck maintaining the sharpness of convex edges by simply stropping them on cardboard and few strokes per side after each serious session of use. This has worked on Fallknivens (all VG 10 and laminated), Bark Rivers (A-2 high alloy tool steel), and a couple of knives I converted to convex edges via mousepad and sandpaper (S30V and 0-1, respectively).
Seems to me when I was a Scout they encouraged you NOT to get a wire edge ("tinned edge") on your knife.
racquette
25-09-2004, 13:12
Once I have a convex edge sharp,all I do is strop it regularly. Just a few strokes each side is all it takes. I like the green honing compound on leather.
Dale
If you have a starkie, then thr more you strop, the sharper it becomes, even once you have a razor edge...long live the starkie.
Nice one Jake
My Starkie arrived yesterday, so last night I went to town on my F1. What am amazing piece of kit!. It's the sharpest it has ever been.
I am still struggling to come to terms with the fact that a soft piece of leather, will sharpen a piece of VG10 steel (answers on a postcard please?). However, it does work and thats good enough for me.
One question springs to mind. The block of paste that comes with the strop seems really hard and when you rub it onto the leather, and hardly any of the paste comes off. Is this normal or should I be doing something to make the paste softer?
Thanks again to all the members for there input.
Nick
Ps: Can't wait for the Northstar now!
Nick from what I have seen of them that is the same as any of the polishing compunds, so it sounds pretty much normal.
YEAH! Another fan, well, that another for the tally. It is an amazing piece of kit. And the customer service i got from starkie was very good.
Its a perfect convex sharpener, but if you put it on a flat serface, then you can sharpen scandi's and pretty much anything else!
OldJimbo
03-10-2004, 05:14
Normally when I use buffing compound on leather, I use neatsfoot oil on the leather first. It then takes the buffing compound nicely. I usually use bore lapping compound on leather, though. It's just carburundum powder in oil, and fine valve grinding compound from the local garage would do as well. The larger abrasive particles sink into the leather so that one can get a good finish. I normally use green buffing compound on cardboard from cereal boxes - and fine stuf it is!
The Northstar should meet all expectations of sharpness,as it's a full convex from back to front and it's a well tested design.
Sharpness as in real world cutting rather than just slicing some paper or rope is a complex thing. Mostly, though it comes down to uniformity of grind.
If a person takes a $10 Mora - well most will slice paper and even shave hair. Use it on wood, though and the edge goes fast. Now take the same knife and lay the bevels flat on a LARGE sheet of emery on a flat surface and rub away and - well you'll see that the wire edge comes off like saw teeth at first. Keep going until you have a uniform wire edge and then work through finer grits and eventually you'll have an edge that will slice the thinnest cigarette paper or just as tough toilet tissue of the softest kind. How well it works on wood will relate to the acuteness of the bevel.
The strangest thing is that wood carvers need the blade to be as sharp as possible for all cuts, so they strop the bevels on cardboard with green buffing compound. This of course soon makes the bevels convex - slight though it might be. Much the same happens for us Scandi lovers who come in from the bush and strop the Mora sharp again. With most of my Moras and Scandis in general - I often can't remember the last time I actually sharpened them. And I do lots of cutting.
Round the top shoulders of the bevels - again on a large flat abrasive surface, and a person has a good idea of what a good convex will do. People like nice grind lines, but uniformly convexing the shoulders really does help in slicing fuzzies in difficult conditions. If a person wants to experiment with more convex on the bevels, then they just have to use some rubber under some emery paper. It'll work well IF the bevels are very uniform to begin with.
The thing about minor convexing of a Mora is that it'll show how much uniformity of grind counts - if you have some damp knotty wood to have to whittle fuzzies out of.