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Sharpmaker : CBN rods : 400 grit/mesh

Posted by CliffStamp 
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Re: Sharpmaker : CBN rods : 400 grit/mesh
May 15, 2014 01:37AM
As an update :




This is a knife used to cut batt-insulation, it is heavily worn :

-points are rounded off flat
-the first section of the blade (about half an inch is ground down to a 1/16" flat from cutting on cardboard)
-inside the scallops are chipped/dented

The latter damage comes mainly from cutting other things on site, wires and such most likely.

These are just thrown out, however using the corners of the CBN rod on the scallops and the flat on the back in just 25 passes the knife easily slices magazine paper.

The CBN rods some in plastic tubes with end caps so it is trivial to pop one in your pocket, keep it in your glove compartment, etc. . It is aggressive enough to do very quick field repairs and get blades back to cutting.
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 15, 2014 07:23PM
I got a pair of these in the mail today.

Seem very nice. The one came with a very small imperfection in the nickel plating / CBN coating...about 5/32s long and 1mm wide, but it doesn't seem to affect the function as the edge of a knife doesn't catch on it at all.

I sharpened my favorite kitchen knife with one of the rods. Destressed on the edge of a ceramic plate, but then figured that probably just impacted the edge so destressed on a 40 grit Norton stone for dressing wheel grinders.

I get bored and lose track of counting easily, but I would say after about 30-40 pps 65% of the edge was apexed, no longer reflecting light. It took another 30 or so pps to apex the last portion of the blade near the tip. Time wise this is about how long it takes me using the coarse side of a Norton Economy stone, but I use scrubbing motions on that and use a lot more pressure. With these I used very light pressure as the warning that comes with them says to do.

Afterwards I deburred and did 9pps alternating the angel of presentation to the edge. It would shave hair at this point easily, but not as well as I'm used off of a coarse stone...the fine hair on the under side of the arm wasn't shaving easily. So I gave it another 10pps (alternating) and it was where I'm used to.

Finished with 9pps on the brown and then a deburring pass and 4pps on the white. It is as sharp as I have been able to get a blade at this point in my life. Can easily push cut on a 45.

A few thoughts:
The CBN rods do not feel coarse at all...like an emery board for sanding ones nails, finer than a DMT Coarse, but maybe a hair coarse than a DMT 600 off the top of my head.
I like the Economy stone better at this point. It's easier to hold and I can work much faster with the greater surface area but I'm impressed with how quickly these cut given the light pressure I was using and the surface area of the triangles.

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 15, 2014 08:57PM
Collin: Glad to hear that the CBN stones are working out for you.

Cliff: How exactly were you sharpening the serrations? Also, if you were doing draws on the corners, was there any durability concerns?

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 15, 2014 09:08PM
Quote
C Amber

I like the Economy stone better at this point.

In general, if you have the skill it is hard to argue against a benchstone. It would be interesting to see if you saw any difference on very hard/high carbide steels as that is what CBN/diamond make the most sense for.

Quote
Bugout Bill

Cliff: How exactly were you sharpening the serrations? Also, if you were doing draws on the corners, was there any durability concerns?

No the corners, very light, just drawing the hone along the edge, it will naturally fall into the serration pattern, people make this much more complicated than it needs to be.

I use very light force, edge trailing, and the hone is lubricated, no issues with durability.
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 16, 2014 12:15AM
True on the benchstone comments.

The plus is that the nature of the abrasive makes me use lighter force and not get carried away with pressure and time.

I will dig out an Elmax blade and start using it and see if I notice a difference in sharpening between the two with that.

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 19, 2014 03:19PM
OTK EDC : k390/64 HRC : [www.cliffstamp.com]

I have not done any stock with this this yet, just utility/kitchen work. In the kitchen the edge retention was not overly impressive as it didn't take long for the edge to not be able to slice tomatoes or cut meat without slipping, however that could have been issues with corrosion, as it also spotted with orange scale readily right through the forced patina, so now it looks a bit ginger.

I am going to take the edge down to ~10 dps, however I wanted to check the CBN stones first on this type of steel so I used them in the 15 dps setting to reset the edge to a uniform fifteen degrees.

--

As an aside, custom makers at this level of product really need to ask themselves if belt sharpening is the proper service to their clients. This knife was in general < 20 dps on one side, < 15 dps on one side, but a full cm section of the tip was above 20 dps. That is common if the edge hits the side of a belt which can round up over it.

Now I knew this because I had measured the edge and knew what had to be done to fix it, however someone just trying to sharpen this would likely get frustrated by the compound/varying angles with the combination of very high hardness/high carbide steel. In general, even if you ignore over heating, giving this kind of edge to a lot of users will cause frustration when it is sharpened.

Interestingly enough, I have started to see as of late a kind of odd sort of weird almost like respect given to some knives because the first sharpening takes so long, as if the extra work required is some sign of quality. A knife should not be difficult to sharpen, the first time or otherwise, if it is then it isn't made properly.

Fisk has a decent method where he belt sharpens, but he finishes on a stone. This both reduces the tendency for overheating (or at least removes some of the damage) but also makes sure the final edge bevel is flat, even and consistent.

--

On the right side, a quick 25 ps showed that side was < 15 dps as a micro-bevel formed. That is a decent sign as the edge bevel will be taken down to 10 dps after it has been used at 15 dps for awhile if no significant problems happen (none are expected).

On the left side, another quick 25 ds showed the edge cleanly apexing near the choil, but it was just grinding the shoulder through the second half of the blade. After 200 ps, the edge was cleanly apexed on the left side except for a cm of edge which had a strong micro-bevel. It took another 250 ps to minimize this to a few mm in length and complete the apexing in the tip.

--

I attempted to measure the force I am using, however it is very light, it won't even move a bathroom scale so it is << 1 lbs as expected. I will check it on a food scale later.
cKc
Re: Sharpmaker : CBN rods : 400 grit/mesh
May 20, 2014 10:01PM
I belt sharpen under coolant using 400 grit which creates a clean paper cutting edge and then normally clean it up on a fine dmt followed by a few passes on a strop. I find this creates quite a nice utility edge. I'm rarely even going to 1200 any more.

If you make the edge bevel only a couple of thou then a few angle deviations will dissapear very quickly I think.

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Sharpmaker : CBN rods : 400 grit/mesh
June 21, 2014 02:01AM
Update using the CBN rods followed by the fine rods : [www.cliffstamp.com]
Re: Sharpmaker : CBN rods : 400 grit/mesh
June 30, 2014 11:12PM
Update, comparison vs the WE :

- [www.spyderco.com]
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 08, 2014 02:47PM
Cliff: Given the problems that the sharpmaker has been known to cause with ZDP-189, have you tried using the CBN rods on a ZDP delica or such?

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Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 08, 2014 02:51PM
No, but the steels used above are similar in carbide/hardness with no issues. All of my ZDP's are zero ground, however I will be getting some C-X from Bruce which I might be able to edge it on.

The main reason that the Sharpmaker has problems with ZDP-189 is people leaning into the abrasives to speed up the cutting and since ZDP-189 is hard and high carbide it just fractures instead of deforming.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 08, 2014 03:14PM
Cliff: Right. I was under the impression that it had more to do with the corners of the rods fracturing the steel.

---------------------------------------------------------------------------------------------------------------------------------------

Bill22252 on YouTube. "See you space cowboy"

Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 14, 2014 12:46AM
I carry one of the rods and use it to sharpen a lot of utility knives, it isn't the ideal finish for it as it is really coarse however most of the blades are very dull, often damaged so it quickly gets it sharp. I have been asking for feedback and most of it has been really positive but again they are comparing the sharpened blade to a dull one so that doesn't really say much aside from very sharp blades (of any finish) cut better than dull ones.

I got a big bunch of the same cardboard boxes this weekend and decided to do a direct comparison in a simplified data collection/analysis. I have been refining my methods to speed them up but still get decent information :

-1/8" corrugated card stock, cut across the ridges in 30 cm slices
-sharpness tested by slicing bergia spinning thread under a 50 gram load

This was the blade :



It is a very common utility style blade, this is a folding model of the common Stanley. I compared :

-the as-boxed sharpness and edge retention
-the sharpness and edge retention off of the CBN rods at 15 dps

The sharpening was :

-10 pps, light force
-5 pps, very light force (5-10 grams)
-2 pps on the 20 dps side, just barely touching the stones

The CBN rods can easily produce a shaving edge using that method.

I did four runs, a quick check just to see what kind of difference was produced. The initial sharpness (lower number is higher sharpness, it is linear) :

As boxed : 23 (4)

CBN : 18 (2)

No significant difference, this was kind of interesting. I wasn't expecting to produce an edge which may in fact be sharper and is more consistent with the CBN rods.

In regards to edge retention I calculated the lifetime cutting efficiency which is basically the amount of material cut for amount of work you do cutting. The results (higher number is better edge retention) :


As boxed : 40 (3)

CBN : 30 (3)

The CBN edge retention while lower isn't significantly lower (the random spread in the results is large enough to prevent rejecting the null hypothesis that the edge retention is the same).

In short :

-the initial sharpness and edge retention are not significantly different

Now I only did four runs and cardboard is very variable in cutting - but still this is far more controlled than what anyone would see in actual use. This means that that initial sharpness and edge retention in use are likely to be seen as the same. This is kind of interesting when you consider the CBN rods very quickly reset the edge on these utility blades, even just 5-10 pps will get the edge back to cutting very well even when significantly damaged because the rods are so coarse.

After using these for awhile and sharpening many utility knives their usefulness outside the Sharpmaker is proving to be very high, so much so most people will ask "Hey, you got that file?" because of how simple it is to get an edge back shaving and cutting well.

--

Now to clarify something, I am comparing the edges in slicing which is the most favorable way for CBN, if I was push cutting plastics then the results would be expected to be different. I will likely do this later as well as maybe add a couple of more cardboard runs to see if I can see if they will be different if I refine the results a little.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 14, 2014 01:30AM
Have you considered doing a comparison run with the brown ceramic (M) stick? May require a few more passes, but my sense is that you'd see at least a slight increase in both sharpness and edge retention.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 14, 2014 05:43PM
Chad,

Yes, the problem is though that I didn't random sample the cardboard in this case I just used from the same sample. I wanted to see if it would make the runs more consistent, and it did, but it means I can't compare to that unless I find more of the same cardboard. I got it all from a friend who was replacing a floor. I will check to see if they have any more left.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 16, 2014 12:07PM
I found some more cardboard of the same type and did another couple of runs :

As-Boxed :

-IS : 20.8 (2.9)
-TCE : 38.3 (2.5)

CBN :

-IS : 19.0 (1.8)
-TCE : 30.4 (2.1)

No significant difference in the initial sharpness and while I would bet that if I ran more data the edge retention/efficiency would be statistically lower, the random variation is still too large to say that with confidence.

In short, it would seem unlikely that someone would see a difference slicing cardboard with the two finishes in regards to ease of cutting or lifetime. Given at how fast the CBN sharpens those blades that is a fairly useful tool indeed to have on hand.

--

Now here is where it gets interesting.

I had enough cardboard so I did two runs with the medium rods just sharpening the used edge without cutting it off. The edge retention was fairly low (TCE < 20). As the medium rods cut much slower than the CBN rods I thought that I could be seeing the influence of leaving damaged metal on the edge. I then did another run but first ground the edge off . It took 100 pps to reset the edge with the medium rods and while the edge retention was slightly higher (TCE < 25) that many passes increases the chance the edge will be burnished or otherwise deformed.

As a trial I then cut the edge off, reset the edge with the Bester 700 (same as the as-boxed angle) and then micro-beveled with the medium rods at 15 dps (this only takes < 10 very light passes per side). The edge retention exploded (TCE > 100). I have to see if I can get this behavior to repeat and make sure it isn't just a large edge retention spike before I would even make a tentative conclusion.



Edited 5 time(s). Last edit at 07/16/2014 01:28PM by CliffStamp.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 12:23AM
Quote
CliffStamp

I have to see if I can get this behavior to repeat and make sure it isn't just a large edge retention spike before I would even make a tentative conclusion.

It was just a spike, two more runs and while the edge retention is higher than the a-boxed it isn't that much higher. I want to try a few more runs comparing using the medium rods by themselves and comparing it to resetting the edge and then using the medium rods as there appears to be a big difference and it isn't obvious this should be the case if the sharpening is ideal in both cases.

--

As an aside these blades are not easy to sharpen by regrinding the bevel as it is hollow ground (not an issue) and very uneven. As you start to flatten it then parts of the bevel will apex and parts will not. It takes about 300-400 passes per side on the Bester 700 to even out and flatten the bevel. That hollow edge bevel is likely why they are fairly fragile and why they are usually damaged and not just blunted. I think I am going to take the ones I have flattened and give them to a few guys and see if they notice any difference.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 12:45AM
That is crazy the amount of passes to sharpen one. Out of curiosity where to your resharpened blade fit into the world's greatest sharpener testing?

www.theflatearthsociety.org

BIGFOOT FINDS YOU, YOU DON'T FIND BIGFOOT!



IT IS THE E-NEP THROWING BROTHERHOOD
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 01:55PM
Quote
Mark a
That is crazy the amount of passes to sharpen one.

The first sharpening has to completely reset the bevel. The apex is hit almost immediately but the hollow is uneven and I think I was getting an influence from parts of it not being flat and parts of it were. I like the Sharpmaker stones for many things but extended grinding isn't one of them. I have found that as soon as I start doing a lot of work the chance of the edge being deformed vs being cut is high and once the edge is deformed then edge retention/durability suffers significantly.

With the edge reset, the apex will form almost instantly in subsequent sharpening, as in less than 50 pps on the Bester 700.

Quote

Out of curiosity where to your resharpened blade fit into the world's greatest sharpener testing?

It isn't a fair comparison because I sharpen based exactly on the measurements I have developed, other people do differently. It is very likely for example that I would not sharpen a plane blade as well as you do for work you do. You have to keep in mind that I have literally sharpened blades thousands of time in optimizing the sharpness for specific measurements.



Edited 1 time(s). Last edit at 07/17/2014 01:56PM by CliffStamp.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 02:17PM
Fair or not it is an honest question. It also goes towards the abilities of others. Are they equal to or better than your edges?

www.theflatearthsociety.org

BIGFOOT FINDS YOU, YOU DON'T FIND BIGFOOT!



IT IS THE E-NEP THROWING BROTHERHOOD
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 02:38PM
Quote
Mark a
Are they equal to or better than your edges?

Less.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 17, 2014 03:38PM
Work in progress :



The as-boxed is the baseline, all of these I can explain and are understood but I am not that confident in the last two results. I think the order is correct but the magnitude I do not have much confidence in because they are only based on three runs each and cardboard is so random even if it all comes from the same source.

What I think is happening is that the medium rod alone finish is deforming/placing the edge under strain and thus even though it is sharp the deformed edge collapses very readily in use. The edge once reset and finished on the medium rods simply has the optimal edge performance for individual hand sharpened blades. I would expect that to be higher but I think the amount will come down if I can find enough cardboard to double the runs.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 18, 2014 08:39PM
What gives you more satisfaction Cliff, a well designed knife or a well designed experiment? (I'm not poking fun either...just curious as they both seem to get you excited).

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 18, 2014 09:50PM
Quote
C Amber
What gives you more satisfaction Cliff, a well designed knife or a well designed experiment? (I'm not poking fun either...just curious as they both seem to get you excited).

I want to guess on this one...

I think he'll give a vague response that doesn't answer the question, and will say something to the extent that it it depends on several factors.

Then, after some arm twisting, Cliff will choose the well designed experiment... he probably has most beneficial cutlery based design features figured out, sees them often, and incorporates them into the knives that don't have them (ie. thinning the primary, giving greater texture to a slipper handle, etc.)

At heart, Cliff is a scientist, and a well designed experiment probably gives him a great sense of contentment, regardless of it being cutlery related or not.

He may also purposely change his answer just to make my guess incorrect... because he doesn't like guessing spinning smiley sticking its tongue out


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 18, 2014 11:52PM
Quote
Chum

...at heart, Cliff is a scientist

I can appreciate art, I even won regional competitions (mult-town) for watercolor paintings when I was younger, and I grew up with master craftsmen of many kinds (timber, masonry) and so I can well appreciate what it takes to build/make or do something which requires significant skill.

Learning how to fold a piece of polyethylene so that a tight corner is made which prevents having to cut/tear it while installing gyproc is curious and interesting, but seeing a temple in India which was hand built with literally thousands of people is more impressive. But in some kind of pound for pound type of comparison then I would rather do the work to be able to make a knowledge claim.

Most people don't appreciate that fully because they don't actually understand what it means to know because they claim truths all the time without justification. It is actually very hard to know something physically through observation but once you actually know because you did the work then it is a pretty nice feeling - especially if you are a great big nerd.

Feynman said it best : "Physics is like sex: sure, it may give some practical results, but that's not why we do it.”
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 19, 2014 01:06AM
Update :



Summary :

-the CBN and Diamond rods are able to match the performance of the as-boxed edges
-the medium rods alone have high initial sharpness but lower edge retention
-the steeled edge is able to match the initial sharpness but the edge retention is even worse
-the edge reset on a Bester 700 and then finished on the medium rods is superior in both initial sharpness and edge retention

Explanation :

The steeled edge pushes the deformed material on the edge back into place but doesn't actually remove it and thus the edge is left very weak and brittle and it blunts very quickly. The medium rods have a similar effect but since they are abrasive they remove some of the damaged material and have improved edge retention over the steeled edges but are worse than the as-boxed edges in edge retention. The CBN and Diamond rods are abrasive enough to remove the damaged material and thus the edge is on undamaged steel and can match the edge retention of the as-boxed edge.

Now why is the medium rod finish after the edge reset the highest? Two factors :

-all weakened material is removed
-as the draw is very short this is close to a push cut and the ideal finish is likely not the most coarse

A few interesting questions :

-how would the fine rod edge retention be if they were used after the edge reset
-how would the medium rod edge retention be if the edge was first ground with the CBN rods

I would have looked at those as well but after two km of cardboard I ran through all the boxes of that type. I might look at those finishes later.

To clarify this is edge retention on a slice, it can't be extrapolated to edge retention in general. Edge retention on a push cut could very well suffer significantly with the CBN/Diamond rods, I do have some hard plastics to check this on.

As a few points of interest/curiosity :

-these are very cheap blades (less than $0.25 if you buy a large amount of them)
-the optimal finish could cut 500 feet of used/dirty 1/8" ridged cardboard cut across the corrugations and still wet shave arm hair
-the edges had no chips or visible deformation (except the steeled ones)
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 19, 2014 04:23AM
For me, the "why", the analysis is far more important than the numbers themselves.
Could you extrapolate these results to generally avoid rod full sharpening of knives (limit to edge touch ups) in preference to full size bench stones?

Did you run any that were CBN ->medium?
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 19, 2014 12:52PM
Quote
chad234
Could you extrapolate these results to generally avoid rod full sharpening of knives (limit to edge touch ups) in preference to full size bench stones?

I don't generally advocate the kind of "touch up" sharpening that is often popular because it just pushes weakened and damaged steel back into the edge. But we have to keep perspective. The steeled edges could still cut about 15 m of the cardboard and wet shave air hair and were restored with just 2-3 passes on the steel. For many people that is more cutting than would be done in a day or even a week.

For a lot of people then the simple idea of just using a steel or very fine hone on a regular basis works perfectly fine and the fact that you could get 5-10X better edge retention with sharpening has no practical benefit. However in that case just use a basic blade material because since the edge is always in a strained/weakened state it doesn't make much sense to pay a significant amount for a very high performance blade material.

Quote

Did you run any that were CBN ->medium?

I did one however it was problematic to be consistent because replacing at 15 dps CBN grind with a 15 dps medium finish takes a lot of passes and I didn't want to mix in angle influences by jumping to a 20 dps micro-bevel. I did that trial after I had the initial poor results with the medium rods alone. Now I could have used the CBN rods to reset the primary grind instead of the Bester, I just used the Bester out of habit more than anything else and only thought after I had half of the runs done that it would have been more sensible to stay with the CBN rods for the regrind.
Re: Sharpmaker : CBN rods : 400 grit/mesh
July 23, 2014 12:15AM
Video over view of the edge retention comparison :



Re: Sharpmaker : CBN rods : 400 grit/mesh
July 23, 2014 02:33PM
In regards to use of the rods, which can be extended to any multi-surface rod, I number the sides and use them in rotation :

-use #1 until it has worn to the point the aggression is too low (not happened yet)

Then at this point you switch to using #2 for all heavy metal removal and you use #1 for finishing and general sharpening. You repeat this until the same thing happens with #2 and then you switch to the #3 side.

In this way you eventually end up with a coarse, medium and fine grit CBN rod.