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Started by mannofiron, October 14, 2016, 03:04:38 PM

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mannofiron

All,

Finally found a used Tormek at a great price and started sharpening some knives.  The first results were rough, but I've come around pretty well over the past few days.  I now have some knives that are definitely sharp enough to catch my thumbnail, but don't quite push-cut paper or shave my arm hair.  I'm thinking maybe it's a burr issue?  Additionally, these are fairly cheap knives so I don't know what kind of edge to expect.  That leads me to two basic questions, which I've seen somewhat answered elsewhere on the forum but can't seem to find now that I need help.

1) When I'm grading the stone, I've been told you should put quite a bit of pressure on it for a good deal of time.  I have gotten a pretty glassy finish when aiming for 1000 grit, so that seems okay.  The issue is that when I press down, it's not uncommon for the wheel to slow or even stop and the holding nut to loosen.  I take it this is not what is supposed to occur.  Maybe some maintenance is in order?

2) I've yet to figure out how much time should be spent on each step of the process.  I have been told you should always use 220 first, even if it's just really quick, but also heard that you don't really need to do that unless your edge is really lousy or nicked.  Then, I've heard that you need to really spend time on the 1000 grit (after spending a lot of time grading it), but others say that stropping on the leather wheel is often overlooked.  I know it's not a formula, but should I be spending the majority of the time on one or the other?

Thanks in advance--fun forum!  I have the planer/jointer jig and will eventually tackle those once I do some more knives and some handplanes/chisels.

Cheers,
Ben

SharpenADullWitt

1.  Sometimes the drive wheel will harden slightly, and people recommend hitting it with light sandpaper to cause it not to stick.
http://forum.tormek.com/index.php?topic=241.msg702#msg702


2.  I have taken restaurant grade (NSF approved) inexpensive starter chef's knives ($6 to $50), from no edge to paper cutting edge with just the 1000 grit and polishing.  Cheap knives probably won't last as well as good knives, but price doesn't always equate to quality.  I have yet to use 220 on one, but also haven't dealt with a chipped one yet.  You could cut well off the stone, but I think you really need the honing step to cut paper.
Favorite line, from a post here:
Quote from: Rob on February 24, 2013, 06:11:44 PM
8)

Yeah you know Tormek have reached sharpening nirvana when you get a prosthetic hand as part of the standard package :/)

Ken S

Welcome to the form, Ben. The first thing you should do is register your Tormek. You can find the registration button on tormek.com , the same website as this forum. Whether or not you get any warranty by registering, you can download the latest edition of the handbook. The basic handbook has not changed, so it will help you with whatever model you have.

Do an online search for tormek videos. Pay particular attention to the videos by Jeff Farris. They are an excellent path to get you up and running. Stumpy Nubs' interview with Stig is an outstanding introduction to the Tormek.

Light sanding of the rubber drive wheel is the standard approved method of preventing slippage.

The handbook describes how to tap the grinding wheel a bit tighter. Once you download the handbook, fill an insulated mug with coffee and carefully read through it. If you happen to have a printed copy, use it as a working reference.

Start out by using the stone grader more than you think you need to. You can feel the difference in the wheel with your fingers. You can also hear the difference.

Don't hesitate to post questions; that's why we are here.

Ken

grepper

#3
"...but don't quite push-cut paper or shave my arm hair.  I'm thinking maybe it's a burr issue?"

It's amazing how any remaining burr can make a blade seem dull.  Generally you can feel a burr by pulling your fingertip away from the edge.  Same thing by very gently pulling your fingernail over the blade and away from the edge.

Use a loupe and examine the edge under a good light.  If there is a burr, you will probably be able to see it.

Drag a cotton ball or some gauze along the edge.  A burr will catch the material.

Very, very, VERY gently drag the tip of your fingernail along the length of the blade.   You will be able to feel any imperfections.

Get a piece of soft wood like pine and gently drag the blade over (like you are cutting into it) the edge of a cut end.  This will tear off or bend down any burr that might be sticking straight out from the blade.  Then hone the blade again.  If the blade suddenly gets sharp then you know that your honing process is not completely removing burr.  It's an interesting experiment to try if you think that there is a burr issue.

"I have been told you should always use 220 first..."

220 grit is very aggressive, may well not be necessary, and removes a lot of steel quickly.  It could remove more metal than you need to.  It really just depends on how hard the steel is and how dull the blade is to start with.  This can vary from blade to blade.  This will take a little experience, but you will get the hang of it before you know it.

Here's some really good advice:
Second hand stores like Salvation Army, etc., often have lots of crap (and sometimes good) knives for really cheap.  Like $0.25 - $0.50 per knife.    Buy some and have at it.  See how the different types of steel are more or less hard to sharpen.  Grind the edge off a knife and then sharpen it.  Use 220 grit and 1000 grit.  Try in between grits by just not using the stone grader for so long.  Press hard at 220 grit and watch what happens.  Press gently a 220 grit and see what happens.  Do the same at 1000 grit.  Start with 1000 grit and see how long it takes to grind the scallops off part of a junker serrated knife.  Then switch to 220 grit and see the difference on another section of the blade.  Stuff like that. 

After about 5 knives, you will pretty much have a grip on it.  It really does not take that long to catch on to what's going on.  You don't need to overthink this just because it's a Tormek.  When you consider it, in many ways it's just a super slow bench grinder with different grit wheels.

Just think of it like sandpaper on wood.  You would not use 80 grit sandpaper between applications of poly on a table top for example.   Similarly, you don't need 220 grit to touch up a mostly sharp blade or a blade with softer steel, etc.

If you are not sure, start with a finer grit and then move to a rougher wheel if you need to because it's taking forever, or if you want to remove a bunch of metal quickly.  A 220 grit wheel can turn a pocket knife blade into a toothpick in no time!

Personally, I have yet to find a way to put steel back on a blade.

Hope that helps.  :)


Ken S

Good thoughts, Grepper (as always).

We should never think of removing the burr as an after thought. It is an important part of the sharpening operation.

What good is the fine technology of jigs for repeatable sharpening with minimal steel removal if a coarse stone reduces the tool to a toothpick?

Jeff Farris mentioned that most knife sharpening is best done without using the coarse grading of the SG-250. (In his knife sharpening youtube) I am convinced the same logic would apply with other tools, such as carving tools. However, the handbook is strangely silent on this issue. I would like to see this covered in some depth in a Tormek video.

Ken

SharpenADullWitt

Quote from: Ken S on October 15, 2016, 09:43:24 PM
However, the handbook is strangely silent on this issue. I would like to see this covered in some depth in a Tormek video.

Ken

Personally, I expect this not to be an oversite, but a thought that what a butcher might do, is different from a chef, or someone who cooks at home, to someone who just abuses knifes.  Varies too much and better to learn from experience.
Favorite line, from a post here:
Quote from: Rob on February 24, 2013, 06:11:44 PM
8)

Yeah you know Tormek have reached sharpening nirvana when you get a prosthetic hand as part of the standard package :/)

Ken S

I would lean toward an oversite. Torgny Jansson wrote a comprehensive handbook. I believe the scope of the Tormek expanded more rapidly than the rewrite time.

I'm not interested in throwing stones. I would just like to see the handbook include some things which were not included in the original. Yes, we all learn from experience. I like to give experience a good start.

Ken

mannofiron

Excellent advice from everyone.  I have a few knives sitting around that I don't care too much about and will be testing the tool on.  I think I've come to see that the 220 grit is a bit much and that I can do better with the 1000, generally.  I plan on doing some maintenance later today to hopefully prevent slippage.  I'll keep looking for videos too.

I still am struggling to know how many honing passes I need on the stropping wheel.  A few of the videos I've found seem to show them just doing a few quick strokes on each side.  Other posts I read on here suggest that people neglect this step too frequently, only doing a couple passes when they should be spending more time.  I'll keep experimenting, but would love to know what folks here generally do for knives.

I have registered (thanks for that!) and have the handbook.  Actually, I have a printed copy from the guy I bought the Tormek from, it's nice, but there are some updates in the digital copy I'm reading, I think.  One area where I'm becoming confused is proper use of the angle setter.  Trying to measure my own blades' angles has me confused.  The picture implies that for some, you can set it directly to the angle, but for others you should be setting it at half, and it has to with blade thickness?  I have just been sharpening at 20 degrees on each side, hopefully that's okay.

Thanks again for your thoughts and any more to follow,
Ben

Jan

Quote from: mannofiron on October 16, 2016, 05:54:02 PM

I still am struggling to know how many honing passes I need on the stropping wheel.


Ben, I hone the edge slowly applying quite big pressure. After some three or four passes on each side I test the edge sharpness using the paper test. When the paper is cut cleanly by just pressing the knife down I stop the intensive honing and add several light passes to improve the finish of the edge.

Quote from: mannofiron on October 16, 2016, 05:54:02 PM

One area where I'm becoming confused is proper use of the angle setter.  Trying to measure my own blades' angles has me confused.  The picture implies that for some, you can set it directly to the angle, but for others you should be setting it at half, and it has to with blade thickness?  I have just been sharpening at 20 degrees on each side, hopefully that's okay.


Correct use of the AngleMaster is challenging not only for you.  :) You can easily check if your angle setup was correct by measuring the sharpened edge angle using the grooves of the AngleMaster.

Later you can test the kenjig concept or the Wootz approach, which are immune to blade tapering issues and provide quick and very accurate angle setup.  ;)

Be careful when sharpening very thin or very thick knives. The knife jig works flawlessly for blade thicknesses between 2 and 3 mm.  ;)

Jan

Ken S

Don't forget the black marker. It is a must have and use tool.

Ken

Herman Trivilino

Quote from: grepper on October 15, 2016, 05:01:36 AM
It's amazing how any remaining burr can make a blade seem dull.  Generally you can feel a burr by pulling your fingertip away from the edge.  Same thing by very gently pulling your fingernail over the blade and away from the edge.

I like to drag the blade across an old cloth towel, in the direction opposite to the direction you'd move the knife to cut something. Then examine the edge under a magnifying glass with good light. Threads snagged off the towel will be visible if there's a burr.

I agree that getting rid of the burr is essential if you want to shave hair or slice paper.
Origin: Big Bang

SharpenADullWitt

Quote from: mannofiron on October 16, 2016, 05:54:02 PM
  One area where I'm becoming confused is proper use of the angle setter.  Trying to measure my own blades' angles has me confused.  The picture implies that for some, you can set it directly to the angle, but for others you should be setting it at half, and it has to with blade thickness?  I have just been sharpening at 20 degrees on each side, hopefully that's okay.

Thanks again for your thoughts and any more to follow,
Ben

The angle setter is for multiple tools.  Most of the kitchen knives in the USA and Europe, are western style, two sided.  Eastern style (namely Japanese) may have the blade only on one side.  Chinese style I have been told, tends to use more a cleaver (giant knife for all).  I don't remember what my Korean neighbors did when I was a kid, I got out of there when I smelled something horrible (spelling, Kim Chee?).
So two sided knives, divide in half.  Single sided, don't.  Then you have Chisels and plane blades, which are one sided and don't get divided.
Blade thickness, is more about trying to get a uniform bevel.  The first time you do one and see the bevel more on one side then the other, you will get that.
Buffing for me depends on the knife.  I spend more time buffing a serrated edge knife, then I do a Chef's knife that isn't completely edge less. (wore down to nothing but a lettuce knife)  The towel trick is good as well as the fingernail trick, and the pen test, trick.
https://www.youtube.com/watch?v=rzWdpjyDZKM
Now, IMHO, part of the stropping discrepancy, is how often do you sharpen your knives?  If often, then it will not take as much to get back to sharp (less burr), if infrequent, I expect you would get a bigger burr, and need to hone longer.
Favorite line, from a post here:
Quote from: Rob on February 24, 2013, 06:11:44 PM
8)

Yeah you know Tormek have reached sharpening nirvana when you get a prosthetic hand as part of the standard package :/)

grepper

Quote from: Herman Trivilino on October 16, 2016, 11:21:49 PM
I agree that getting rid of the burr is essential if you want to shave hair or slice paper.

Herman is correct.  Burr removal is absolutely necessary.

From personal experience, you can grind away and a blade just won't get sharp even though from the sharpening process it just has to be.  But for some reason, it is not.  Then... remove the burr and suddenly, almost magically, it's hair splitting sharp!

Why is this?  Because a burr is a pile of metal on the edge of the blade.  If you don't get rid of it, the burr material will get smashed down over the edge and "hide" the sharp edge under the burr.

Burrs vary in both amount metal forming the burr and type of burr.  Some are true "wire edge" burrs many times thicker than the edge.  Others are sparse or stick directly out from the edge. 

When an edge is honed on leather, the burr material is bent from side to side until it fractures from metal fatigue and breaks off, or catches on the leather directly and is torn from the edge revealing the sharp edge under the burr material.

Viewing a burr, it's pretty easy to imagine what happens if you drag a burred edge gently across the edge of soft wood.  Much of the burr gets torn off, and the rest gets smushed (technical term) down and bent over the edge making it easily removed by honing because it is more easily caught up in the leather honing wheel than if the burr is extending straight out from the edge.

As Herman suggests, you can detect a burr because it will catch on cotton or gauze material if you drag a blade across it, or just use a good loupe and a good light or microscope to examine the blade. 

If you don't completely remove the burr one of two things will happen:
1.   The burr material will get bent over the edge and the blade will never get sharp.
2.   If you are lucky ??? :), the blade will magically get sharper as you use it because the burr material will be torn off and lodge itself in you evening's broccoli.

Here are some images that I have taken of various burrs that are useful in understanding what's happening:







Jan

Really nice description and photos, Grepper, appreciated!  :)

Jan

Ken S

This topic illustrates the need for both knowledge of the Tormek and sharpening theory. The sharpening theory is so important that Steve Bottorff devoted a whole chapter to it in his Sharpening School DVD. I do not mean to be an infomercial for Steve, however, I know of no other video source as informative.

I will also add another recommendation for my favorite reference book by Leonard Lee.

Good sharpening is a combination of technical skill and knowledge.

Ken