Thread: 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 . 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. 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


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 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..

Originally Posted by AlienEdge

Here is something that might help with a mental picture and muscle memory on how much pressure to use . 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. I am kidding about the hammer, but I hope the mental picture of how much pressure to use is there.

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

Originally Posted by gssixgun

...

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

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.

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.

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