sharpening questions

[Tye Possum]

Ok so I've been trying to sharpen my mora 510 today and yesterday, got it shaving sharp yesterday but wanted to see if I could polish the bevel a bit today, as it was looking very scratched. I ended up dulling it a bit because I still suck at sharpening but that's not really what this thread is about.

When I was sharpening it, I started by pushing the knife back and forth in a stabbing action because it's easier to keep the bevel flat on the stone like that, and it was getting fairly smooth looking, no more grind marks from factory sharpening, not a mirror finish but not bad. That was with my DC4 stone, the diamond side, which is course I believe, then I switched to my new two sided diamond plate from ragweedforge, it has a 600 grit side and a 1200 grit side, but when I used that it seemed to do more harm than good as it left some weird kind of brown colour on the knife, possibly the coating holding the diamond grit on and it left quite a few scratches, so the knife seemed less smooth than after the coarse stone, plus had some gunk on it that isn't coming off. I'm pretty sure that gunk is from the diamond plate but there's a chance it's from my finishing stone which is the "viking whetstone" from ragweedforge again but I think it was probably from the diamond plate.

So first of all, has anyone else had that problem with the brownish colour left on the blade from a diamond plate and if so does it go away after a while? Second, do you think the system I've come up with is a good one or am I missing a step, as in 250(I think), 600, 1200 grit diamond plates and then finish with a super fine natural stone (jasper). Is it possible to get a mirror finish with that process do you think, or are mirror finishes reserved for expensive japanese waterstones? I guess I don't need a mirror finish but a fairly smooth one would be nice.

 

[Shewie]

It sounds like you're just missing that final strop Tye.

 

[Tye Possum]

Ya a strop would help too I guess. Been using my belt on a table for that but haven't been doing it too much. I was impressed with how much it did to my swiss army knife, never had it that sharp before the strop.

So has no one had the problem with the brown gunk? Maybe I was just using the stones too hard or something...

 

[forestwalker]

Agreed on the strop. Glue an old belt (say a 20 cm piece) to a chunk of plywood (I prefer flesh side up) and rub some Autosol into it.

 

[slammer187]

A strop with a bit of metal polish on it will get rid of your brown gunk!

 

[FGYT]

possible your pulling out old rusted metal from previous sharpenings

ATB

Duncan

 

[Tye Possum]

possible your pulling out old rusted metal from previous sharpenings

Well it does look like rust kind of but the thing is, this is a brand new stone (and new knife), just got it, and that was the first time using it. The stone kind of looks discoloured now near the middle, pretty weird... Might end up asking Ragnar about it.

I did get all the gunk off with the ceramic side of my DC4 today and got it back to shaving sharp, might just be getting the hang of this sharpening thing... but not quite there.

Oh and it didn't have the gunk on it after the DC4 diamond side, just after the new stone.

 

[Traper]

Diamond side of DC4 is about 600 grit.

You shouldn't put too much pressure on diamond stones (actually you should use just the weight of the blade) - maybe you are tearing diamond bits out and the brown stuff may be some kind of coating?

 

[Ogri the trog]

You shouldn't put too much pressure on diamond stones (actually you should use just the weight of the blade) - maybe you are tearing diamond bits out and the brown stuff may be some kind of coating?

Amen to this little nugget,
I once destroyed a diamond stone when trying to sharpen an axe - got the geometry of the strokes wrong and tore a strip of stone clean of the diamond abrasive. By pushing the blade in a stabbing action, you can get teh edge under the cutting surface and tear out the diamonds like I did.
Tye, there are plenty of videos on Youtube etc about sharpening - check out a good handfull of them before jumping in.
Sharpening is a skill that takes time to learn and there are few shortcuts to long-term success.

ATB

Ogri the trog

 

[Tye Possum]

Diamond side of DC4 is about 600 grit.

It's 600? I thought it was courser than that... It says 25 micron or something on the site so I wasn't sure though.

You shouldn't put too much pressure on diamond stones (actually you should use just the weight of the blade) - maybe you are tearing diamond bits out and the brown stuff may be some kind of coating?

Oops... Didn't know that. I mean a metal plate covered in diamonds sounds like a pretty tough stone so I just assumed it would be fine... Well that's not good.

Amen to this little nugget,
I once destroyed a diamond stone when trying to sharpen an axe - got the geometry of the strokes wrong and tore a strip of stone clean of the diamond abrasive. By pushing the blade in a stabbing action, you can get teh edge under the cutting surface and tear out the diamonds like I did.
Tye, there are plenty of videos on Youtube etc about sharpening - check out a good handfull of them before jumping in.
Sharpening is a skill that takes time to learn and there are few shortcuts to long-term success.

Interesting, I didn't think that would happen, I read the "Reestablishing a Scandinavian Grind" thing on ragweed forge and thought that stabbing action thing would help me keep the bevel flat on the stone, which it did but I guess that's not the best method... I have seen plenty of videos of sharpening knives and read alot about it but all that stuff seems to be about using bench stones which I'm not because I'd prefer to be able to sharpen my knives in the field rather than waiting to get home, plus bench stones are expensive. This wasn't my first try at sharpening knives either, just first time with this stone, knife, and technique. I've switched back to the taking slices off the stone kinda method since, although it's a little trickier with the smaller stones but like I said, I managed to get it shaving sharp with a micro bevel but I still need to work on it a bit more.

So I guess we've found the problem, thanks for all your help, and I'll be a little more gentle on diamond stones in the future.

 

[spamel]

First, search for the 5 pound sharpening kit on these forums and you'll have something comparable to bench stones at a fraction of the price and light weight to boot. Look at hoodoo hones, you can use them without a mouse mat backing so that it will also be like a bench stone and one block with various sheets of wet and dry will do the job.

Sharpening a knife is all about keeping the angle consistent throughout, apart from on convex blades! I also use the small jasper stone you have, I take just that with me when I go out and about, you need nothing more if you have a true scandinavian ground knife. If you have a flat bevel, then it ain't a scandi grind I'm afraid. To be a scandi grind, you need to have that micro bevel on the edge.

 

[Tye Possum]

Ya I've seen that 5 pound sharpening kit thread and thought about doing that. One question though (if you or anyone else who happens to read this uses it), how long does the wet and dry sandpaper last for sharpening a knife? I'd imagine it wouldn't last too long and you'd end up needing to buy a lot of wet and dry which is what put me off the idea of using this system.

Good to know someone else uses the viking whetstone too, and my knife has a true scandi grind I guess because it has a micro bevel.

 

[Urban_Dreamer]

how long does the wet and dry sandpaper last for sharpening a knife? I'd imagine it wouldn't last too long and you'd end up needing to buy a lot of wet and dry which is what put me off the idea of using this system.

It depends

In simple terms the courser grades last well. The fine stuff seems very difficult to clean and you wind up replacing it often. If you're mad, like I went, you wind up with insanely fine stuff that lasts seconds.

Please understand that what I now say is my personal opinion.
Course, medium and "fine" stones (or diamond plates) will get you a sharp nice edge, with fine scratches that act as serrations. If you want a more impressive edge then you are in the realm of polishing. At that point you are not creating a edge but changing the surface and refining the edge.

A strop with fine abrasive will polish out the scratches but even the wooden backed ones are that flexible that they tend to follow the surface rather than attempt to mold it (though try and avoid faults in a home made strop). Remember what it is that you are sharpening. The requirements for a knife, carving or otherwise, are quite different from a woodworking plane. A edge that's sharper but is not totally flat is the norm, rather than a anathema.

Ps I too have destroyed diamond plates by cutting into them. According to research sharpening with a cutting action is slightly better, but obviously impossible with a strop. However after my experiences I no longer use that method on diamonds plates. Instead I drag away from the cutting edge, accepting the burr on the reverse and clean the micro-burrs up as another operation.

 

[Tye Possum]

Hmm well maybe I'll just stick with diamond plates, all I really need is a working edge, nothing fancy.

Ps I too have destroyed diamond plates by cutting into them. According to research sharpening with a cutting action is slightly better, but obviously impossible with a strop. However after my experiences I no longer use that method on diamonds plates. Instead I drag away from the cutting edge, accepting the burr on the reverse and clean the micro-burrs up as another operation.

So where exactly does the burr appear when you use this method? Also when you strop it, do you lift the spine of the knife to strop just the micro bevel or do you lay the large bevel on the strop which because of the give in the leather also ends up stropping the micro bevel?

 

[robin wood]

So now I am interested. You have a knife with a large primary bevel and a micro bevel. Which are you sharpening at the moment? I mean when you lay knife on stone where are you removing metal? from the primary bevel or the secondary? If you are not sure use a marker pen on your bevels then do whatever sharpening you do and look to see where the pen has gone from.

 

[Tye Possum]

That would be the micro bevel now. I started off laying the larg bevel flat on the stone but that was just to smooth it out which didn't turn out quite as expected but it's flatter now I suppose. Then I lifted the spine up a little and did some strokes on the very edge to form or if there was already one there, sharpen the micro bevel, now if I wanted to sharpen my knife I would just sharpen the micro bevel right? Hope that answers that, gotta leave now!

 

[Ogri the trog]

Snip........ Then I lifted the spine up a little and did some strokes on the very edge snip,,,,,,, now if I wanted to sharpen my knife I would just sharpen the micro bevel right?

Well its kind of right.
On the proviso that you can attain the exact same angle that you did when "lifting the spine a little!" If you lift the spine to a little minus a tad, you'll be putting another, shallower micro bevel on it and approaching a convex grind - without actually removing steel from the edge of the blade. If on the other hand you lift to "a little plus a tad" you'll be making the edge more obtuse and therefore gradually removing its ability to cut cleanly.
The skill comes in being able to find this bevel angle or being able to replace any micro-bevel with an overlaying one that cures all the faults of previous sharpening attempts.

ATB

Ogri the trog

 

[oetzi]

These days, the final edge on any knife I get with a two-sided leather strop, first the side with the compound, then the plain leather.
Gives a fantastic edge.
And when done regularly and often, I dont have to use the (much moremessy) waterstones
that often.
Best of all, you can get them used and very cheap, in all kind of styles, at ebay, if you look and wait.
I prefer this style:
http://www.executive-shaving.co.uk/shaving/leather-strops/cyril-r-salter-leather-hand-strop-2052.php

 

[Tye Possum]

The skill comes in being able to find this bevel angle or being able to replace any micro-bevel with an overlaying one that cures all the faults of previous sharpening attempts.

Uhh ok... How do I do that exactly?

I'll tell ya, I've even been thinking of giving up on scandi ground knives and going to something a little less complicated but then it wouldn't cut wood as well anymore and it would kinda be giving up... I was lead to believe that the scandi ground knife was super easy to sharpen but it sure doesn't seem that way anymore. If only it didn't cut so darn well!

 

[Greenbeast]

I've been trying to learn on a blade with a decent sized secondary bevel (as opposed to a microbevel, i don't know the grind names yet) and had to admit temporary defeat.
I've just bought a mora clipper to learn on and hopefully get some success before going back to the other knife.