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.

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

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

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.

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.

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.

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

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

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.