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Grit Progression

Posted by Bugout Bill 
Grit Progression
December 22, 2014 02:05AM
This is a fairly basic concept that I have somehow failed to understand. In the three step method of sharpening, how does one go about refining the edge on a finer grit stone? Do you need to reapex on the finer grit like the previous one?

Now I came resharpen a blade to a finer finish, but I have never really understood the process involved.

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Bill22252 on YouTube. "See you space cowboy"

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Re: Grit Progression
December 22, 2014 02:41AM
The problem when discussing sharpening, or any method, is that you can't present something which can work as an introduction and as well cover intricate details. The basic method :

-cut off the apex
-reshape
-micro-bevel

Has a bit of a problem if you want to finish with an 8k micro-bevel as this won't work :

-cut off the apex
-reshape on Suehiro 'Chemical'
-micro-bevel on 8000

It will produce a high sharpness sure, but the apex will not be 8000k it will be some inbetween the two finishes. I normally don't run a lot of high polishes but when I do I just add another step, possibly 2 :

-cut off the apex
-reshape on Suehiro 'Chemical'
-grind the edge on a 400 grit Naniwa Superstone
-grind the edge on a 2000 Naniwa Aotoshi
-micro-bevel on 8000

I don't run multiple micro-bevels because if you free hand you will just layer them. Once all the shaping is done and you are just removing the scratches it takes very little time on the other stones, ~30s easily does it unless you are working with very poor grindability steels and even then ~60 s handles a lot of steels.
Re: Grit Progression
December 22, 2014 03:15AM
Cliff: Right, thank you.

So if I am intending to use a Spyderco UF stone, would a jump from DMT 1200 be too much?

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 22, 2014 03:23AM
It won't give an UF finish, the UF is just that, one of the finest benchstones you can get. If I wanted to get just that finish as a micro-bevel I would use the Naniwa Aotoshi and let it get really muddy then rinse it off and use it lightly. The muddy part will remove all damage but it will leave the apex very thick which will make too much work for the UF. Now maybe you can, but for me, if I have to do a lot of work with the UF I am going to take a large risk of deforming the edge. I want the UF to just be a few passes only on a micro-bevel.

Now to be clear, an UF finish which isn't exactly a pure UF isn't a bad thing really. In fact in many cases it is going to be rare you really want a true UF finish because the edge retention in slicing is pretty low.
Re: Grit Progression
December 22, 2014 03:38AM
I might need to pick up a Naniwa superstone for curiosity's sake, but I think the UF should be sufficient, even if I am not getting a pure UF finish.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 22, 2014 12:08PM
Huh, and what I usually did was just bring the edge to nearing the apex on the lower grit stones, then completely apex on the stone with which I want to finish.

This however I would assume is far from optimal on stones like the UF spyderco since they don't cut as well, but for the stones I use it generally produces good results with most if not all the scratches removed.

_______________
Coffee and Blood
Re: Grit Progression
December 26, 2014 07:49PM
So I got a 8 inch Spyderco UF Stone and have had some interesting results so far:

-On Spyderco Tenacious and a Superblue Endura, I polished the edges to a fairly high degree. Not very happy with them; there is little slicing aggression and the edges almost feel duller than when I started. However, they will shave arm hair readily and will push cut through paper with ease.

-I microbeveled an F. Dick chef's knife after shaping the edge with a Norton Coarse India stone and had much better results. The edge now has a decent blend of push cutting ability and slicing aggression.


Interesting results, but I think I might be screwing up something in regards to technique.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 26, 2014 09:29PM
Quote
Bugout Bill
...there is little slicing aggression

What exactly do you mean by this, if you take the knife and try to cut a piece of rope what exactly happens?
Re: Grit Progression
December 26, 2014 09:36PM
Cliff: I'm afraid I don't have any rope around, but on cardboard and paper the edge feels like it just sort of skips over the material on a draw.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 26, 2014 09:57PM
That sounds like the edge is folded over, does it shave cleanly on both sides? How much work are you doing with the UF stone?
Re: Grit Progression
December 26, 2014 10:16PM
The edge is shaving cleanly on both sides. I sharpen using scrubbing passes, with maybe 10 or 15 actual passes before alternating strokes. I spent longer on the UF than the previous stone, maybe 50-60 pps.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 27, 2014 12:06AM
Quote
Bugout Bill
I spent longer on the UF than the previous stone, maybe 50-60 pps.

That is almost guaranteed to degrade the finish. I micro-bevel with them maybe 5-10 pps, if I try to work very high then it is very likely to deform the apex vs grind it plus you have to be past the apex at that point and if I didn't then it wasn't set properly. If you want to try something frustrating, then let knives get dull and try to sharpen them just on that stone, you are almost guaranteed to get deformation more so than anything else.
Re: Grit Progression
December 27, 2014 12:57AM
Cliff: That would make sense then. So if I wanted a highly polished finish, I would need some other stones and work up through their grits?

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 27, 2014 02:23AM
What are you using now, right before the UF.
Re: Grit Progression
December 27, 2014 02:28AM
Following your previous advice:

-Cut the edge off the tenacious.

-Shaped with a DMT fine, did 2 light debuting strokes at a high angle.

-Microbeveled with 10 passes per side on the UF stone.


The results seemed better, but the edge still felt slippery on a draw into paper.

Previously, the edge on the Tenacious was from a Spyderco fine rod using the flats.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.



Edited 1 time(s). Last edit at 12/27/2014 02:29AM by Bugout Bill.
Re: Grit Progression
December 27, 2014 02:58AM
Bill, without some hard numbers it is hard to interpret what is happening, but I don't see it as necessarily a problem with the results.

If I finish an edge on the DMT fine for example and try to cut a piece of rope (or anything on a slice) it will take more force to start a cut than the UF finish, but it will cut deeper with lower force if a long draw is used.

A push cut requires a certain amount of force to make a cut, if you don't use that force the cut just stalls. A slicing cut can make the cut with lower force if you are willing to use a longer draw.
Re: Grit Progression
December 27, 2014 03:30AM
Cliff: I'll play around with it some more and try to get some more exact numbers. I'm thinking this might just be a case of weird expectations for what high polishes do.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
December 27, 2014 02:59PM
Does it slip on tomatoe skin? That's usually a pretty good test of whether the apex has been rounded. I have a spyderco double stuff, and the fine side from the factory had a weird finish on it that would dull my blades when I tried to microbevel on it... It felt like there were very small ridges that the apex was bumping into. I resurfaced it on a DMT plate (huge pain in the butt) and now that's fixed and the finish is much finer as well. I know the straight razor guys have been complaining about the often irregular factory surface on the UF stones for a long time.
Re: Grit Progression
January 04, 2015 07:21PM
What stones do you have available to you? How high of a polish are you looking for? Mirror polished edge?
Re: Grit Progression
January 04, 2015 07:29PM
The highest grit I practically can use is a 1200 DMT. I still need to play around with the UF a bit more to get some idea of what it does and doesn't do.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
January 05, 2015 01:05AM
Achieving a polished edge going from 1200 DMT to Spyderco UF I think is a big leap to polish the edge, usually what happens is what you said, polished edge, no slicing agression. If you have a strop, or a piece of carboard or MFB, try some compound or stone swarf after you take the progression up to the 1200 DMT. Then I'd use the UF for a microbevel.

It's basically the same thing Cliff said at the top of the post, you just need to substitute your sharpening stones for the ones he suggested. Usually the for polised edges, the less grit jumping you do the better. Maybe try some SiC wet/dry sandpaper on a hard backing, with this grit progression, 600, 1000, 1500, 2000. If that is not enough polish, try some green compound to stone swarf.
Re: Grit Progression
January 27, 2015 05:19PM
I had my first real success with the Spyderco UF last night sharpening my Buck 110. After shaping with a oil lubed XC DMT, I raised the angle to about 20 dps and did 5 alternating passes on the UF with the weight of the knife. The edge produced is highly aggressive, but has decent push cutting ability and will pop hairs of the arm with a draw.

Still, if all you have is fairly coarse abrasives and the UF, it becomes a little difficult to justify the stone's cost if all you use it for is microbevels.

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Grit Progression
January 27, 2015 06:53PM
Nice!
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