a more critical eye

[Ken S]

I have two paring knives. The one I use almost all of the time is longer and slender. It came with my original set. The second knife, shorter and fuller was purchased when Henckel had them on sale for ten dollars. (I bought several for gifts; ten bucks for a top of the line Henckel.)

This morning I used that knife to open a can of McCann's Irish Oatmeal, my one culinary splurge. I noticed that the bevel was slightly wider on one side. The bevel angles are the same. I had sharpened it using the regular Tormek knife jig. The knife is sharp; it is just not quite symmetrical. Since I rarely use it, it is not sharpened very often.

The slight asymmetry probably reflects my level of skill at the time. I returned it to the block as is. It will be a reminder to help keep me humble, and, at the same time, a pleasant reminder that my eye is becoming more critical.

Ken

[Jan]

Ken, small asymmetry is not a serious problem, I have encountered it also.
I see two possible explanations:

a)   The bevel angles are slightly different (this happens when the blade is not properly centred in the knife jig).

b)   You have spent more time sharpening one side of the blade than the other (this shifts the edge out of the plane of symmetry).

I am trying to do the same number of passes for each side. I do not wait until the burr forms on the upper side but flip the sides after some three passes. In the final stage I turn the jig upside down after each pass. I am convinced that this approach removes less steel and consumes less grindstone.

Jan

[Ken S]

Good comments, Jan. I do not remember exactly; I believe the knife was straight in the jig. However, that is a possibility, and I will be more diligent about checking in the future.

I will also be more diligent about counting passes.

I do not feel my sharpening job with that knife was badly done. I do believe it can be done better in the future. (and will be)

Ken

[Rem]

More importantly, how was the Irish oatmeal ??    What is the difference between that and Canadian oatmeal ??   R

[Ken S]

Rem,

As always, the McCann's Irish Oatmeal, the real deal slow cooking variety, was outstanding. I have taught my granddaughter how to make it.

With NAFTA, I would need a passport to eat Canadian oatmeal    

Back to the original topic, if anyone asks, I was experimenting with a 60/40 grind. 

Ken

[Exact Blade]

The newer your jig (or 3050 adjustable stop and 3560 o-ring replacement parts) the better results you get.  2 reasons that each side of a two bevel blade may feel different.

1) There is play in  the threads of the Adjustable Stop on the Jig Shaft.  When you press on the Support Arm, the jig shaft tilts inside the Adjustable stop (slight angle bend), when you switch hands to do the other side, it's doubtful you are replicating the pressure of your other hand. 
2) Secondly, it is doubtful that the knife center-line itself will be perfectly parallel to the center line of the jig shaft.  The jig clamp has two elements- a fixed piece and a smaller piece that tightens.  It would be mathematically impossible to tighten the clamp while keeping your knife's vertical center line exactly parallel to the jig center line. 

So until Tormek makes a all stainless steel  forged machine threaded jig and adjustable stop,  you have to compensate with feel through experience practice.
I solve these small mathematical errors through feel.  Of course I sharpen for a living,  about 4000 knives per month.  There are a number of small tricks I use to keep bevels even(i can share these techniques in another thread).  I got really good at this because stones, machines and jig wear out, so I was forced to sharpen on new or old equipment (new T8 with a 250 mm stone or a worn out T7 with 185 mm and a worn out jig.)  One thing i do is order replacement parts for jigs- the brass threaded bushings (M6), new knob screws and o rings. 

One tip.  Don't over sharpen.  Do your knife and check it.  If it seems good, turn the knob once, fine stone grade the stone for just a revolution or two and make three more passes each side to finish your edge.  make sure to hone at the same angle you sharpened at.

Sorry, but math is overrated for perfect results because the machines, stones and jigs are not as "fixed" perfect as you think.  Understand the math first, then just get better with experience.  I can close my eyes, listen to you sharpen and tell you if a fine German or Japanese knife is in the jig or a cheap steel form China.   

Dan
www.exactblade.com

[Lape]

The newer your jig (or 3050 adjustable stop and 3560 o-ring replacement parts) the better results you get.  2 reasons that each side of a two bevel blade may feel different.

1) There is play in  the threads of the Adjustable Stop on the Jig Shaft.  When you press on the Support Arm, the jig shaft tilts inside the Adjustable stop (slight angle bend), when you switch hands to do the other side, it's doubtful you are replicating the pressure of your other hand. 
2) Secondly, it is doubtful that the knife center-line itself will be perfectly parallel to the center line of the jig shaft.  The jig clamp has two elements- a fixed piece and a smaller piece that tightens.  It would be mathematically impossible to tighten the clamp while keeping your knife's vertical center line exactly parallel to the jig center line. 

So until Tormek makes a all stainless steel  forged machine threaded jig and adjustable stop,  you have to compensate with feel through experience practice.
I solve these small mathematical errors through feel.  Of course I sharpen for a living,  about 4000 knives per month.  There are a number of small tricks I use to keep bevels even(i can share these techniques in another thread).  I got really good at this because stones, machines and jig wear out, so I was forced to sharpen on new or old equipment (new T8 with a 250 mm stone or a worn out T7 with 185 mm and a worn out jig.)  One thing i do is order replacement parts for jigs- the brass threaded bushings (M6), new knob screws and o rings. 

One tip.  Don't over sharpen.  Do your knife and check it.  If it seems good, turn the knob once, fine stone grade the stone for just a revolution or two and make three more passes each side to finish your edge.  make sure to hone at the same angle you sharpened at.

Sorry, but math is overrated for perfect results because the machines, stones and jigs are not as "fixed" perfect as you think.  Understand the math first, then just get better with experience.  I can close my eyes, listen to you sharpen and tell you if a fine German or Japanese knife is in the jig or a cheap steel form China.   

Dan
www.exactblade.com

If you sharpen about 4000 knifes a month, I guess you don't use Tormek only?

[Ken S]

Interesting post, Dan. I like the new knife jig
. In fact, the newer jigs I have seen machined of zinc all seem improved. That stated, in my opinion, there is room for a higher level of precision. Such precision would come with a much higher price. I think this cost and precision would appeal to a much smaller user group. As unfortunate as this might be, I feel it is a business truth. Hopefully the bright engineers at Tormek will strike a good balance and design the next incarnations of the knife jigs with higher precision and only a modest increase in price. Tormek has done this before, more than once. The last model of the gouge jig, the SVD-185, was the state of the art. The latest version, the SVD-186 is a major improvement in several areas, at around the same cost. The former square edge jig, the SE-76 was an improvement over its predecessor. The latest version, the SE-77 is a quantum leap more versatile. It incorporates adjustable camber control. The TT-50 is a far more precise truing tool than its predecessor. Again, both of these were done at around the same cost.

Knife sharpening is a major marketing area for Tormek, especially in Europe. I have no inside knowledge. All I have is a gut feeling that Tormek will continue its innovation, and that really stellar knife jigs are probably high on the priority list.

In the meantime, I suggest getting to know a good machinist. If I sharpened as many knives as you do, I would certainly have several modified or custom machined jigs.

Ken

[Jan]

Exact blade, thank you for your very interesting post. 

Please keep us posted about "the small tricks you use to keep the bevels even".

When sharpening 4000 knives per month, you have to sharpen some 20 knives per hour on average. Do you sharpen freehand or do you mount each knife into the knife jig?

What is the lifetime of your Tormek grindstone?

Jan

[Lape]

Exact blade, thank you for your very interesting post. 

Please keep us posted about "the small tricks you use to keep the bevels even".

When sharpening 4000 knives per month, you have to sharpen some 20 knives per hour on average. Do you sharpen freehand or do you mount each knife into the knife jig?

What is the lifetime of your Tormek grindstone?

Jan

That sounds impossible, free hand or not. That is 3 minutes per knife. I have used Tormek quite a lot and although there are people faster than me offcourse, some knifes have a very hard steel and needs to be grinded millimeters to get rid of minor damage, and this takes time.

[bisonbladesharpening]

Exact Blade,
Thank you for one of the most succinct and realistic assessments of sharpening
knives on the Tormek for professional sharpeners.  I wish I was 1/4 as busy as you
but I am a mobile operation and still growing.  I don't doubt your volume, as I visited you website
and educated myself.  I assume that you have more than one machine and probably some help.
Best Wishes,
Tim

[cbwx34]

I'm guessing the "devil is in the details"... on the 4000 knives/month part.

I'm all for tips!  Smoke 'em.... errrr..... post 'em if you got 'em!