Idea for measuring "honing pressure" in order to communicate it ...

Hi All,

One of the most difficult things for me to learn as new straight razor honer was operationalizing the concept of "pressure". I watched a lot of videos and read a lot of posts - I kept hearing things like: "I'm applying a little bit of pressure here...", "I'm using little to no pressure on these X-strokes...", "This is just very light pressure.. enough to keep the razor flat on the hone...", "Too much pressure will flex the blade...", "Very light pressure here guys...". It's pretty hard to translate that into feelings in my hand and down to the blade across the hone. I have an intuitive understanding of it now but still struggle to explain it to anyone. I have a working idea to perhaps tackle this - so just spit-balling here but let me know what you think.

Let's make some early assumptions to get the conversation going - before digging into the details that could potentially make it happen. So let's assume I could build a device upon which we could place a hone. The device would be able to be zeroed like a scale with the hone on it perhaps loaded with slurry or water. The base of the device is or contains a pressure sensor and a digital readout - let's skip the math for now on pressure, force and area. Let's assume I could get some folks like Glenn, Jimmy and Lynn to volunteer to do some honing using the device and record their readings and a narrative about what they were doing (bevel set, touch up, 1K, 4K, 8K what type of hone the surface area of the hone, what type of razor etc etc.) - along with a completely subjective assessment of whether they are using light pressure, no pressure etc.

Then let's assume we can analyze the data paired with the narrative and come up with some equivalent analogous metrics for what light pressure, no-pressure, etc mean in terms people could recreate at home. So let's say we find that generally "light pressure" across several honers on a Norton 8K with a Dovo 5/8 full hollow equates to between 4 and 8psi (I'm totally making that up - I have absolutely no idea...) and that we search around the house and find that it generally takes between 4 and 8psi of pressure to click a mouse button or move a business card across clean glass with the tip of a pencil eraser. Things I can do at home to get a feel for how much 4 to 8psi actually is in terms of downward pressure without having to have the fancy device. Better yet - if we can find things to do with the spine of the straight razor that have an effect that can be seen when 4-8psi pressure is applied. Like lift the eraser end of 6inch long pencil by pressing the tip of the razor onto the sharpened tip of lead. We need consistent, repeatable results in order to start training muscle memory.

What if all that was possible? What do you think?

Adam

Sorry, but I think you are over-thinking this, and the device already exists. Several of us already have done these measurements with postal and kitchen scales. I know that it CAN be made more complicated, but I'm doubtful of the necessity or benefit.

I saw a video somewhere (I want to say it was a Dr Matt video), where the fellow noted how much pressure he was putting on the blade by placing his finger on his arm. His version of light pressure - fingers will make no indent (or a very slight one) on the arm. Moderate pressure would make a noticeable impression. Very handy reference, imo.

Here is something that might help with a mental picture and muscle memory on how much pressure to use . :rofl2: Place your index finger that you push the razor with on your work bench and smack it with a hammer. Smack it good! So that the finger nail is turned up in the back and the front of the nail is the color of an over ripened blue berry. Now use that throbbing finger to slowly guide your razor across the hone. That finger will teach you just how much pressure to use. :roflmao I am kidding about the hammer, but I hope the mental picture of how much pressure to use is there.

You actually just have to practice

There are two separate and distinct forces at play here, that most people only mention the first..

Downward force or Pressure

Twisting force toward the edge or Torque

You have too always keep the edge of the razor in contact with the hone this is easily observed by watching the tiny ripple of Water/Oil/Slurry at the front of the edge.. If it slips under the edge you are not using enough pressure in conjunction with torque, it is either at the front of the edge or riding on top of the blade face to be working correctly ..
The Sharper the razor gets, actually adjusts the pressure for you automatically if you are riding the wave, as the edge gets sharper it take less pressure and torque to undercut the wave

The reality of honing

"The more you hone the better you get"

There is no shortcut, there is no "formula" there is only practice..



ps; Just when you think you have it all figured out, there will be a razor that crosses your hones that scoffs at your knowledge :p


pps: I honed 7 razors yesterday the difference in pressure between the PITA Wedge Restore and the Sweet Hollow Henckels on the bevel set was HUGE :D so trying to quantify that on a scale is simply a waste of time ...
Once the bevel is set is all evens out and gets quite easy

ppps: The Stroke: When I am at the meets one of the most common corrections I make when helping new guys hone is to adjust the elbow up, so that the Edge stays in complete contact with the hone evenly and equally across the entire stroke..

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Originally Posted by AlienEdge

Here is something that might help with a mental picture and muscle memory on how much pressure to use . :rofl2: Place your index finger that you push the razor with on your work bench and smack it with a hammer. Smack it good! So that the finger nail is turned up in the back and the front of the nail is the color of an over ripened blue berry. Now use that throbbing finger to slowly guide your razor across the hone. That finger will teach you just how much pressure to use. :roflmao I am kidding about the hammer, but I hope the mental picture of how much pressure to use is there.

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I tried this and the blood on my hone made it hard to follow the swarf in front of the blade...

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Originally Posted by gssixgun

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ps; Just when you think you have it all figured out, there will be a razor that crosses your hones that scoffs at your knowledge :p

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I know - then I send them to you!

What I'm after is not to eliminate the "experience" and "practice" factor. That's obviously the only lasting teacher. As an educator for most of my life, I do find it valuable to provide learning aids that assist the learner in understanding a particular concept. There is the conceptual leap in learning - I understand the ideas behind the series of skills I am learning. There are most certainly faster/better ways of learning. I won't go as far as saying they are "short cuts" as that has a negative connotation. But we do know how people learn abstract concepts like "pressure" and "torque" - it's through making the abstract more concrete and building scaffolding up to the concept. The term "pressure" is so variable with no reference points that are concrete that it makes it difficult thing to apply. Over time - you'll understand it through trial and error (that's the concrete part). If we can help people understand and apply the concepts as they practice the skills with less trial and error - then that makes the learning process more efficient/better.

Torque on the blade is a great example of the subtle forces that would be great to be able to explain in more concrete terms. I've learned it over time when working through a "rough" spot on a blade. But not too much torque or you flex the blade and don't hone all the way to the edge...

Adam

Thing is, it's hard to set an absolute definition on any of these pressures, since for every razor it can be different. Thinner grind razors will flex easier resulting in the apex coming up from the stone, while heavy grinds can take some pressure. One way to get a ballpark idea on thinner grind razors is just to set the razor flat on a piece of wood or something and press down while watching for it to flex. Whatever the grind, use an amount of pressure and torque that doesn't flex the razor - especially at the end stages of each stone and the finishing stage.

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Originally Posted by Utopian

Sorry, but I think you are over-thinking this, and the device already exists. Several of us already have done these measurements with postal and kitchen scales. I know that it CAN be made more complicated, but I'm doubtful of the necessity or benefit.

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Ok - fair enough. I'm a scientist so complicating things is kind of what I do...

So how do the measurements translate in something a new honer can understand and apply? What does .5 lbs of pressure feel like? What does 5oz of pressure per square inch feel like? How does one take the measurements several of us have already done and learn from them? It's not the measurements that have the value to me - it's the translation of those hard data points into transferrable knowledge.

Adam

The really is an egg head way to do it is find a honing mentor and let him show you! Make a trip to Randy's house of honing and he'll show you a very scientific measure, you place your finger on the stone, then he puts his finger on yours and applies pressure, there you go! Ok all fun aside, one on one will show you where to start the rest will be practice. In July I,m getting another one on one with the mountain man, he might use the hammer theory. , Tc

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Originally Posted by aalbina

Ok - fair enough. I'm a scientist so complicating things is kind of what I do...

So how do the measurements translate in something a new honer can understand and apply? What does .5 lbs of pressure feel like? What does 5oz of pressure per square inch feel like? How does one take the measurements several of us have already done and learn from them? It's not the measurements that have the value to me - it's the translation of those hard data points into transferrable knowledge.

Adam

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I work in science too, but I consider my goal to be simplification. I choose not to complicate things for people who don't have the same level of understanding. A razor, a hone, and a postal or kitchen scale are the tools readily available to most people, so pressure measurements probably should not be complicated beyond their use.

Let's imagine the bevel setting (heavy) pressure is 5 lbs, sharpening (light) pressure is 1 lb, and no (weight of the blade) pressure is just a couple ounces. Then all a beginner needs is a thumb and a scale to get a sense of the appropriate pressures at each step.

That said, if you can come up with something more elaborate that can better help beginners, I'm all for it.

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Originally Posted by aalbina

Ok - fair enough. I'm a scientist so complicating things is kind of what I do...

So how do the measurements translate in something a new honer can understand and apply? What does .5 lbs of pressure feel like? What does 5oz of pressure per square inch feel like? How does one take the measurements several of us have already done and learn from them? It's not the measurements that have the value to me - it's the translation of those hard data points into transferrable knowledge.

Adam

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There really are just too many variables at work to set hard and fast rules on pressure and torque used in honing. The variables are which grind are you honing and then there is the individual razor which may or may not need more or less pressure/torque than the same grind razor you just did. Then there is dealing with warps and twists in the blade and so on.

It would be great if you could put a blade in a jig to apply the correct pressure and torque required, then turn the machine on for a predetermined number of strokes for the particular grit hone you are using at that stage in the process. You would have to have perfect blade to do this and that perfection must be in every blade to be honed. That is not likely to happen.

In the end it is down to trial and error till you most of the time get it right with enough experience.

Bob

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Originally Posted by Utopian

I work in science too, but I consider my goal to be simplification. I choose not to complicate things for people who don't have the same level of understanding. A razor, a hone, and a postal or kitchen scale are the tools readily available to most people, so pressure measurements probably should not be complicated beyond their use.

Let's imagine the bevel setting (heavy) pressure is 5 lbs, sharpening (light) pressure is 1 lb, and no (weight of the blade) pressure is just a couple ounces. Then all a beginner needs is a thumb and a scale to get a sense of the appropriate pressures at each step.

That said, if you can come up with something more elaborate that can better help beginners, I'm all for it.

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Of course, I was just kidding about purposefully complicating things as a scientist. I'm also an educator - as I posted in response to Glenn's excellent feedback.

As other's have pointed out (BobH, eKtretz and Glenn), and I suspect they are correct - there are likely too many variables to the process that will make the simple measurement of pressure an ineffective metric to explain that portion of the process. The hone, the condition of the blade, the experience of the honer will all translate to uncontrollable variables. If I created a "pressure guide" it would invariably be used incorrectly with a blade for which it was not intended, on a hone for which it was not intended, and a condition for which it was not appropriate. The end result would likely be higher frustration because a beginner might see it as a silver bullet and expectations would be higher. I could control most of those things in a classroom - but certainly not over the web.

Good discussion - thanks all.

Adam

I think the most helpful would be a "Do Not Ever Exceed This...." with the thinner blades. Of course, depending on how wide the blade is and how thin is thin. That would require much experimentation with a range of blades from different manufacturers.

Plus, ballpark numbers are nice for people to get a sense of what to see at what point in a more translatable fashion.

I have to agree with Glen, and others. Practice makes perfect ........ or thereabouts. Knowing how much pressure in increments is fine if you also know what the results of particular increments on particular blades will be. Hone long enough, with various razors, and you'll intuitively know what is working and what isn't. IME.

Just leaving this here for fun :p


Attachment 238065

Yes it really is an electric SR honing machine

Glen, did you buy that?

It works pretty well!

:w

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Originally Posted by AlienEdge

:roflmao I am kidding about the hammer, but I hope the mental picture of how much pressure to use is there.

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There is some credence to smash finger. In USMC marksmanship training I was taught to bite my trigger finger's nail hard to prevent jerking. By doing so I could not jerk the trigger if I tried. If it hurts you are applying to much pressure to fast. Har!!

I am very heavy handed needless to say. I trashed a few razors in a couple passes in the beginning. Har! In learning to strop I had to bite nails to get a feel for the light touch.

Learning to hone should be comical. I can picture cartoon looking red bulbous pulsating digits.

A new meaning to different strokes for different folks. :roflmao

Adam, I admire your enthusiasm for eliminating variables in this sport. Having been self educated in this myself, with the internet as a resource, I have also had a hard time translating the subjective descriptors. Brush characteristics & lather explanations come to mind.

I have a similar idea of uniform metrics that people could apply to brushes.

I find such intellectual exercises fun & exhilarating.

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Originally Posted by gssixgun

Just leaving this here for fun :p


Attachment 238065

Yes it really is an electric SR honing machine

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Video, or it didn't happen!!!

Ironically, I find that many guys, do not use enough pressure on the bevel set to get the bevel flat. We have drummed in the light pressure, so much that they don’t remove enough material to set a bevel fully.

It isn’t, so much the variables, it is, the target is constantly moving.

The mantra is, “You have to do, what the razor needs, (the moving target).

But first, you have to read the razor, to figure out what that is and that that may change.

The issue with formulaic honing is, none of us have exactly the same stone progression, same razor with the same grind and level of warp or other issue that the guy making the video did, (variables)…

The bottom line is, as Glen said, hone… same advice they give Athletes, Musicians, Writers, and Race Car drivers… seat time.

Or Hands on mentoring.

Can’t tell you how many guys say, “There are so many little things, that you just don’t get, in the videos, no matter how many times you watch.”

It really is about little things, like the elbow, stone prep, cleanliness (grit contamination), stroke and understanding, the adage, “Doing the same thing and expecting a different result, is…

You can, figure it out on your own, it just takes longer. It really is as simple as, Set the bevel, fully set the bevel, then just remove the previous stria with each subsequent stria.

Use some pressure to set the bevel, then do finish laps with lite pressure on your bevel setter. On each subsequent stone, use pressure to remove the stria, then lighten up on pressure, to polish and lay down a new stria pattern. As the grit get finer, you need less pressure.

If you use too much pressure and the edge becomes, ragged or chipping, just joint it, re-set it and move on.

Eventually you will get to where you understand what is needed and you can remove the stria and polish at the same time. Ink and magnification are inexpensive and your best friend, use them.