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Grind Direction
#11
Mr. Jan, what you've done with the Tormek is Amazing! I've never seen anything like that. Indeed, that would be an ideal tool for studying burr formation, and standardizing edges to be compared with the new EOU edge folding machine. I'm definitely going to have to do that to my Tormek. I like it much better than the Tormek jig.

Do you ever use a layer of electrical tape on the spine, to give just enough added angle to make sure you're only hitting the EOTE for finishing? 

I sharpen all of my personal knives on stones. Doesn't matter if it's a folder, kitchen knife, or knives I make. If you have the best stones, and know how to use them, it simply boils down to the best way to manage burrs IMHO. 

Edge leading (EL) vs. edge trailing (ET) makes a big difference to me. The resultant burr is much different.

I don't use Edge Following strokes ("A" direction), very much, since it produces no scratch pattern, but there is a legitimate use for EF strokes on stones. Some folks use EF to remove large burrs.     

I admit it's easier to sharpen a sword edge following, but I don't use my sword much anymore. Edges that held up to chopping through bone were more practical than toothy edges in my gladiator days.  

Axes don't benefit from tooth either, which is why ax stones are round. They are meant to be held in hand, and used with circular (scrubbing) motion for forming the edge or removing damage, and edge following strokes for finishing  

For long kitchen knives, scrubbing EL-ET at about 90° to the stone, working from heel to toe is preferable for sharpening in traditional Japanese fashion, then diagonal ET to finish. This is due to the perception that if you are ET, the edge would more or less ride over a larger grit particle, where if you were EL, a grit particle could more or less dent the fine edge.

I tend to favor ET when I want a refined edge, but I go EL when finishing for maximum tooth.    

Finishing ET diagonally is enhanced by honing from heel to toe, then toe to heel, for a "perfect" "X" scratch pattern. Especially with straight razors, because straight razors are special, and the more complication the better.

I would describe the difference between an ET and El burr like this; 
An ET burr Tapers, from the edge of the blade outward. If you over sharpen, you get tinsel, but there is a more significant burr at the base of the burr, and you will discover it if you cut the burr off with an EL stroke on a stone. All the tinsel will come off immediately, and you will have a small "shiny line" at the Edge Of The Edge (EOTE), but it's small and super easy to flip because it's so flimsy.

An EL burr is much more substantial. The burr "piles up" on the burr side. It actually doesn't flip. When you try to flip it, something different happens. What happens is basically like a "double burr". You will get a new burr off the piled up burr, going back to the other side of the edge. You can feel the burr on the other side long before you've eliminated the base of the piled up burr.

I know this is true, because I have been studying this with significant determination, and hard stainless steel, which magnifies burr properties.
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#12
(01-30-2018, 09:12 PM)Mark Reich Wrote: Mr. Jan, what you've done with the Tormek is Amazing! I've never seen anything like that. Indeed, that would be an ideal tool for studying burr formation, and standardizing edges to be compared with the new EOU edge folding machine. I'm definitely going to have to do that to my Tormek. I like it much better than the Tormek jig.

Do you ever use a layer of electrical tape on the spine, to give just enough added angle to make sure you're only hitting the EOTE for finishing? 

Mr. Mark, your interest pleases me! Some more info you can find here https://www.tormek.com/forum/index.php?t...5#msg13625


As you know it is not easy to mount the blade correctly into the knife jig so, that bevel angles on both sides are the same. For this reason I add angle by shortening the protrusion by the black collar of the jig.


Jan


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#13
That looks like an awesome thread, Mr. Jan!

Now I'm going to have to register on the Tormek Forum too, if they'll allow me.

Since you and Mr. KG are doing so well sharpening knives on the Tormek, I want to get in on that.
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#14
Mark,

I believe the Tormek forum would allow you to be a member.

Ken
Moderator, Tormek Forum

Smile
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#15
Jan,
As you know, I hope, I make sharpening tool as a hobby. I do not know if you have seen my homepage, http://www.edgepal.com visit and study my tools please.

My tools are precision tools. My tools Chef can be adjusted down to 1/100 part of 1 degree as you can see on this picture:

[Image: 2d7g0sh.jpg]

I have make the scratches diagonal in different directions so it is possible to se both angles.
I used a Norton diamond sharpener on 25 micron to make this - you can se the scrathes.
Look also at the backbevel that have a perfect line.

Chef can also make multipel bevels one edge - and go forward and back between the bevels.

Now, to my question Smile

Chef fix the blades in postion on the grinding table so that they cannnot move. This are done with strong magnets, 7 kilo power each, and Chef can use 3 magnets if wanted - 21 kilo magnetic power. The angle are fixed and the guide rod are 5 mm stainless steel.

I can clearly se with the help by a 3 X magnifying glas that there is a sifferent in angle between moving the sharpener forwards and backwards - we are now talking some singel parts of ?/1000 parts of 1 degree. How many parts it is I cannot meassure... My question is - can you?

The reason i ask you is what you have constructed to your Tormek. Amazing! I Love that construction!

becouse of your construction I rhink that you have seen the same thing I have seen on small variations in angle depending on what direction the sharpener is moving across the edge. I like to know, and understand, why this happen Smile

Thomas
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#16
Mr. Thomas, thanks for your kind words and also for your confidence I could answer your question. Smile 

I know your precision sharpening equipment quite well. I admire your beautiful handmade instrumentation.

What concerns the claimed precision 0.01°, this is geometrically well possible, but it would require to set the height of the pivot with an accuracy better than 0.05 mm, which is not impossible, but quite challenging. (0.05 mm = 0.002" = 50 microns is a the thickness of human hair)

The other factor influencing the bevel angle accuracy is the distance between the pivot and the point where the edge meet the grindstone. When this distance is not constant along the edge, then also the bevel angle is not constant. 2 mm (0.08") increase in distance between the pivot and the edge will decrease the bevel angle by more than 0.10°. (This is below the limit of resolution for most knife grinders.)

I know that you are aware of it, your custom made Chef overcomes this problem and enables to sharpen "per partes (by parts)" the same bevel angle along very long blades also. Simple, but really very significant improvement, congrats! 

   

In my understanding your instrument works perfectly when the grindstone axis is oriented perpendicularly to the edge. For curved blade sabre it may be true for almost the whole blade while for straight blade the bevel angle gradually slightly decreases towards the tip and towards the heel.

   

Some role in the answer to your observation may be attributed to mechanical plays in the pivot and other components also.

My laser goniometer, in its current state, measures with an accuracy of some 0.25 to 0.50° only. So to measure several hundredth of a degree is far beyond my possibilities.

Jan

P.S.: It would be interesting to know what happens with the burr when one pass is edge leading while the other edge trailing. Lansky, for example, recommends edge leading direction only.


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#17
Jan,
I have choose to use screws instead of blank rods to hold up the bar the pivot sits on. Those screws are made of stainless steel and hold high quality. Where other sharpening tools slide up and down, Chef adjustment in height are made by screws.

1 full turn gives 7/100 part if 1 degree = 1/7 part of a full turn gives 1/100 part of 1 degree. It is very simple. I cannot meassure this if cause - but all meassuring tools are based on the same type of mathematic.

To fix the bar in position i use 2 screws. Thise screws are real stainless steel if veey high quality. They press the bar between them. The upper one have a marking on the upper side. With the help of this mark it is possible to move this screw dor example exact 1 full turn. I have also a wider screw, real wide. With this acrew it US very simple to move exactly 1/7 of a full turn = change the angle 1/100 part if 1 degree.
The screw on downside the har have also a marking on its upper side. This markings was there allready on my first Chef. The wider screw are extra equipment.

Now, to make a change of the edge angle with 1/100 part of 1 degree have no practical use what so ever. But - i can adjust an edge exactly 0,25 degrees if I like to, or 0,5 degrees. the main function of this possibilitie is that when I test two different steelqualities i can grind their edges exactly the same before testing them. Both edges need to have exactly the same edge when testing them.

Chef have markings on the guide rods for 28 cm distance between the cutting edge and the pivot point.
The slide make it possible to veey easy adjust Chef for different blade width. That incloudes also for example that you can asjust for deep recurved edges inthe same way, if you like to do that.

Chef have, if I remember correct, 16 new functions for sharpening tools. The fixed distance, allways 28 cm, was necesarry to give Chef a built in protractor (the first sharpning tool that have this) this was possible thru the slide and 2D pivot point (up and down, forward and back). Later, I made tye Rail that give a 3D pivot point (sideways, up and down, forward and back).

Other new functions was magnetic grindingtables, angled guide rods that grind convex edges in wanted degrees and in wanted convex spheres (with the help of the two stop nuts on the guide rod that give wanted distance for the sharpener to move). The adjustble sharpener holder that can use sharpeners and strops up to 23 cm in length. Two grinding tables as standard, one dor short blades, one for long blades.
Adjustble knife neck support tyat gives support also for curved knifenecks - and so on...

Other things:
Chef are made i massive aluminum, 15 mm thick, and brass. No platsic. Hand made in all parts, no other tools needed to clamp knifes ore adjust Chef in any way.

So, Chef are a very advanced sharpening tool in al aspects. When I show Chef for the first time there was only one other bench tool on the market, EdgePro. All other bench tools come later.

Next step is a extra equipment for Chef that make it possible to grind in Zero degrees - and 90 degrees in both directions from zero degrees, a scissor sharpening equipment, axe sharpening equipment for small axes, a chissel sharpening equipment, and much moore... Smile
Chef will be the base of a complete sharpening system that can grind and sharpen most edged tools there are.

So, yes, Chef can be adjusted down to 1/100 part if 1 degree - and when that is done, i can go between those two angles ans hit their surfaces perfect. No other tools can do that.ä

I am not a person that walk thru life beeing proud of things - but sometimes I am proud of Chef Smile

My most advanced shatpening tool are: IcePal. IcePal sharpens ice drills and augers, all of them.
Most people have "problems" to get a knife edge sharp. Knife edges have only 1 dimension. Ice drill edges have 3 different dimensions and are probebly the hardest edges in the world to sharpen becouse of this.

IcePal sharpens all three dimensions at the same time. The best thing with this are that no one can have a personal opinion about this, only the ice can tell the quality of the edge. A ice drill drills a hole in the ice - or dont drill at all, tye edge just slides on the ice.

If 1 mm if the edge is not oerfect, the drive deill will not function at all. Smile That is wonderful. By a IcePal from me, sharpen your ice drill, if the drill dont work send IcePal back to me and I send you your money back. I have not get any IcePal back yet Smile

The edges on a ice drill have 3 dimensions, 1 the edge hold 40 degrees in ine end and 20 degrees innthe other end. 2 the edge is concave, 3 the edge is screwed.
IcePal sharpens all three dimensions at the same tine - and do not change any angle, and IcePal can repeat it any time you need to sharpen your ice drill.

Ok, sorry that you cannot give me an answer about this small change of the angle. I shall try to make a video of this small change later on.

Thomas
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#18
Mr. Thomas, thanks for your additional explanations. I have no doubts that your sharpening instrumentation belongs to the most accurate tools currently offered to knife grinders.

Please continue to post here. Your ancient picture showing the oval grindstone was perfect foot for thought. Smile


Jan


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#19
Gentlemen, your thoughts on the oval grindstone, please? 

Many simple things seem impossible, like balancing the wheel, truing the surface, and holding the work piece at a consistent angle.

It boggles my mind to think how much more difficult that would make everything, from making the wheel to using it. 

I can't see any purpose. What am I missing?
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#20
Mark,
I can clearly se many different functions that a oval grinding wheel can give. One of them are convex edges with wanted degrees on the cutting edge, easy to do and easy to maintain.

As I see it, the oval grinding wheel with diamond surface would be nice becose it so not change its diameter. Think a fixed guide rod with a knife fasten on its end. When the grinding wheel turns the knife will then move a little up and down in height (gives the convex edge becouse the distance on the oval wheel from the center to its grinding surface change). Depending on where on the oval wheel i have the edge decide how many degrees the edge will get. It is simple to make a protractor for this.

If I was a producer of a watercoled sharpening tool based on a round turning wheel - I would be interested of a oval grinding wheel as extra equipment - but that is me... I like presision and quality edges.

The important thing is that a oval grinding wheel is a old innovation, no patent are involved = it is an idéa anyone can use and develop and combine with todays tecnuiqe and knowledge. For example, I think it is possible to construct a grinding machine knife producers can use to get identical convex edges on complete serias of knifes. (Today all knifes are produced with flat edges - ans they are later, by hand, made convex. This means that there is nit Two knifes that have the same convex sphere or the same degrees on their cutting edges). I am not updated what happen innthe production chain during the last years - but I so not think that there have been any change about this.

My point is that our forefathers, that use knifes and other edges rools a lot more then we do today and use a softer steel, they made a lot of innovations that we can learn from today - and develop with tidays knowledge and tecnuiqe.

Thoma
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