I'm impressed... Ken Onion Worksharp.

I have a question for someone who might have the knife grinding attachment. I know it’s not the best heavy duty grinder, especially for making knives from scratch, but would it be up to heavy modification of existing knives. For instance cutting in a a finger choil or reshaping the grip tang. I am especially curious if the portion of the belt above the roller could cut in a choil or would it bog down?
 
The one I have, I would not say you would do a lot of heavy work with it, just not a power house behind the motor, I use the grinding attachment, mainly for larger fixed blade sharpening and the rollers have no rubber on them so you wouldn't want to press anything down onto them. Some one else might have had better luck but, I'd look elsewhere when it comes to grinding much metal away or handle material even.
G2
 
Edge apex overheating is underestimated too often.
New Zealand researchers have shown that using a belt sharpener causes knives blunt 2 times faster (Work Sharp in particular).
Full article can be downloaded from the New Zealand University of Waikato website https://waikato.researchgateway.ac.n...le/10289/10004

Our own research at a meat plant revealed that knives honed on a felt wheel blunt more rapidly, which we also attribute to the edge apex overheating:
http://knifegrinders.com.au/SET/Edge...felt_wheel.pdf
 
UPdate: I've been playing around with the Ken Onion Worksharp sharpener now for a few weeks, and I have to say that I'm more impressed the longer I use it. Obviously it has its limitations, but then, so does every tool. I'm sure I can get a sharper edge if I hand sharpen down to .25mics, but I don't really need to do that very often... if 'need' at all. But for utilitarian sharpening... kitchen knives, EDC knives, hunting and bushcraft knives... this thing is slick! Very fast, very clean, very effective. I have started to dunk the blade in cold water between each pass which slows things up a bit, but not much, and I figure it's worth it for the edge retention.

I live in an apartment and don't have a shop. All my sharpening gets done by taking the supplies out of the closet, setting them up on the kitchen counter, using them, cleaning up, and putting them away. I spend more time with the setting up and putting away than I need to do with the actual sharpening, even when I do a few knives. I'll still sharpen the occasional blade by hand, just because I sometimes enjoy the repetitive, relaxing motion of the task, but if I 'have to sharpen' several knives, it will be done on the KO Worksharp.
 
I've just read specifications of the Work Sharp Ken Onion WSKTS-KO, and at the minimum speed of 1200 SFM it has 3 times less RPM than the standard Work Sharp WSKTS. If you use the Ken Onion version, you are safe, because that research was done on the standard WSKTS running 3600 SFM.
Apologies for confusion
 
To understand what's going on with the WSKO, you sorta need to experience it. I say this because, it's a little toy sized sander. The motor is decently strong. But at the lowest RPMs, it's very very weak. You can almost stop the belt with your hand, or by pressing hard with the blade.

I'm not sure if a study done on any kind of real belt sander would correlate to this small machine. Don't get me wrong; I appreciate new information for sure. I'm just adding some context since I have quite a bit of experience using the WSKO, albeit freehand, as opposed to using the guide.

Brian.
 
Thank you for the details Brian. I've just got an email from a Korean fellow that he always runs his WSKO at the highest speed for similar reasons - at its high speed the KO version may be causing the same edge overheating as the standard.

Anyway, in EDC and home kitchen knives this edge apex weakening won't even be noticed. It matters only where you have to do a serious workload of cutting.
 
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Hi wootzblade,
Thanks for the links, very good, interesting.

wootzblade said:
Our own research at a meat plant revealed that knives honed on a felt wheel blunt more rapidly, which we also attribute to the edge apex overheating:
http://knifegrinders.com.au/SET/Edge_retention_worsening_by_felt_wheel.pdf
Click to expand...

What is low rpm? High rpm would be felt wheel at 2850 RPM ... 8inch or 6inch wheels?


So 2 pairs is 4 knives ... only a single run each?

What sharpening angle?
Have you ruled out angle differences, are you compensating for the felt wheel squish by dropping the the angle you sharpen at, so the actual apex angles are the same?
Or are you doing that already?
Does that explain why The felt wheel is sharper initially than the paper wheels?
Have you ruled out a detectable burr on the felt (make a few cuts into wood , then measure)?



If/For next time, to confirm or rule out overheating as the cause , maybe add an air blower to the felt wheel for cooling .
 
wootzblade said:
I've just read specifications of the Work Sharp Ken Onion WSKTS-KO, and at the minimum speed of 1200 SFM it has 3 times less RPM than the standard Work Sharp WSKTS. If you use the Ken Onion version, you are safe, because that research was done on the standard WSKTS running 3600 SFM.
Apologies for confusion
Click to expand...
Nope :)
You're "safer" but that doesn't mean you're "safe", 1200 SFM is still 20 feet per second (fps), slower than 60fps yes, but still faster than any human hand (ex comfortable average might be 3fps), and as dr roman landes says
Re: Unwanted Tempering Whilst Sharpening

Post by Roman Landes » Wed Sep 07, 2011 5:05 am
And as you probably know Robert, every metallurgical sample preparation works the way, to avoid heat creation whist grinding.

I had a book dedicated to general grinding methods, in this book i found a test application.
A normal steel block apx. 2"x2"x4" that had a large number of highly sensitive thermocouples integrated in the surface.
The block was slit dry by hand over a 1000grit grinding paper.
The peak temps measured, walked up to 2000°C for split seconds in the very surface (some microns).
Of course the block did not melt since the volume fraction of induced heat was to tiny to affect such a large solid piece of steel.
But the effect was there and proofen.
In a edge we just talk about some microns of material, here the effect is solid an clear.
Every manufacturer of razorblades knows this and does excessive cooling whilst grinding and polishing edges, that need to hold an super sharp edge for very long.
It seems just some the magic makers out of the custom knife scene think, the physical principles like this, do not apply to them....
 
I have and use a KO work sharp frequently, and you can add me to the “impressed” camp. I sharpen on the lowest setting and switch sides frequently to avoid overheating, and don’t use the guide while only running the belts away from the edge.
This tool can get you to an insanely sharp edge in a few minutes!
 
I have the KOWS with the Blade Grinder attachment. I run the motor at a bit over half speed, at that speed it isn't getting blades too hot to touch, and with the KOWSBG I am getting knives almost as sharp as I am with my Wicked Edge WE-130.
 
I picked up a KOWS today to help fix an uneven grind on a ZT0452 that was making me lose my mind trying to sharpen with the sharpmaker. Practiced on a few super dull never been sharpened kitchen knives and they were all super sharp in 15 minutes. The ZT took a little longer because of the higher quality steel and the bevels were so uneven on the knife that it took some time to get it down. I’m talking one side was 15 degrees and the other side was probably close to 40 degrees. I was able to get the fat side of the bevel evened out and now she’s shaving sharp. The only downside is now I can see how off primary grind was on the knife. Also I not only didn’t round the tips I was able to restore them on the kitchen knives. Here are a few pictures of the ZT’s tip. I already ordered the blade grinding attachment as I basically just used the angle guide as a visual reference and free handed it.



 
I'm still trying not to round tips on my regular WS. Did a great job freehand on the axe and shovel though.
 
To make and keep sharp tips, you need to sharpen up to the tip, but NOT past it. This means you don't draw the whole blade through. You stop when the tip is touching the belt and then lift off. Freehand, this is pretty easy to see and do. With the guide it's probably a bit harder to see and I'm not sure if you can lift straight off of the belt, but you should be able to do something very similar to this.

Brian.
 
Not to hijack this thread but I just got my blade grinding attachment in....took my 452 from shaving sharp to hair popping sharp with damn near a mirror polish in less than 5 minutes. At this point for me the worksharp is hands down the easiest sharpening system I’ve ever used.
 
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The BGA comes with a pretty good set of belts. I really can’t say how impressed I am with it. I have a sharpmaker and have used an edge pro and for me there’s no comparison. I do hit the blade on a strop maybe 3 strokes per side to help with any burr but including that I can go from dull to shaving in a few minutes and as long as you follow the instructions I can’t see how you’d ever round a tip.
 
It took a while to bite the bullet and order it, but after about 4 months I'm pretty happy with my Ken Onion Worksharp. Before using it I really did my homework, read the do's and don'ts, and understood that you could quickly mess up your blade (e.g. rounded tip). I started on my junk knives and worked my way up to my nice kitchen knives and, after a lot more practice, my prized EDC knives. This is the way to do it, because as I said before, you really can screw up your knife or just take off a lot of metal if you just start grinding away without thinking.

I have to admit it was a lot of fun when it arrived and I was sharpening every knife in my house in a short amount of time. I have a couple young kids and it was difficult finding time to sneak away and sharpen my knives, but for the first few weeks I did just that. A couple times I sharpened knives before heading off for work, I enjoyed it so much. I am one of those people that just don't have a knack for sharpening by hand, so this was a life saver for me. I still strop by hand because of the Zen feeling it gives. I have to admit I was a bit leery about converting all my blades to convex, which means I am basically tied to the Worksharp for sharpening, but I got over it and am happy with the results.
 
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