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Micro-convexity and stone hardness

Keep in mind that results with a Jnat vary wildly, depending on the slurry and the nagura used to raise it. Jnat experts are welcome to refute, if their experience says otherwise. I only own one and it is the only one I have ever owned.
They all wary, but they usually give the same charteristic look to the edge. Finding a really good one is not that easy. This particular jnat will not give me that super sharp edge as one of my harder stones. It is fine enough, but it is really fast, and a pleasure to work with. It also works well with just water for finishing. It probably has more potential, the image from the previous post is from finishing on light slurry. I have a harder and finer jnat, but this sees less use.

Everytime I try to understand someting I usually end with more questions then I started with.

I took the 12k Naniwa edge to Crox on balsa, and 0.125 CBN on hard backed leather. I only did about 15 strokes on each. I was expecting the apex to be allot more convexed then it was. The Naniwa edge was OK, but now the edge is definitely sharper.

IPC_2022-06-24.08.05.39.6160.jpg
 

Slash McCoy

I freehand dog rockets
They all wary, but they usually give the same charteristic look to the edge. Finding a really good one is not that easy. This particular jnat will not give me that super sharp edge as one of my harder stones. It is fine enough, but it is really fast, and a pleasure to work with. It also works well with just water for finishing. It probably has more potential, the image from the previous post is from finishing on light slurry. I have a harder and finer jnat, but this sees less use.

Everytime I try to understand someting I usually end with more questions then I started with.

I took the 12k Naniwa edge to Crox on balsa, and 0.125 CBN on hard backed leather. I only did about 15 strokes on each. I was expecting the apex to be allot more convexed then it was. The Naniwa edge was OK, but now the edge is definitely sharper.

View attachment 1477252
With pasted balsa, Less abrasive, rubbed in deeper into well lapped balsa, excess (there is always excess) thoroughly wiped away, yields less micro convexing. Also requires more laps to max out the edge. More abrasive, rolling around on the surface especially of unlapped balsa, gives a little more microconvexing. However this may or may not be a big deal, depending on the razor, honing pressure, (yeah even though it may be spine leading, it is still honing because steel is removed) and how well you timed your exit from the grit in question.
 
how well you timed your exit from the grit in question.
Unbelievably correct.

I ran a Sunnen Hone for decades to finish precision holes and achieve mirror finishes on materials ranging from soft to heat treated steel, bronze and aluminum. Timing the release of pressure is critical. You are the first person on this forum I have ever heard to make that statement.

~doug~
 
Unbelievably correct.

I ran a Sunnen Hone for decades to finish precision holes and achieve mirror finishes on materials ranging from soft to heat treated steel, bronze and aluminum. Timing the release of pressure is critical. You are the first person on this forum I have ever heard to make that statement.

~doug~
"Timing the release of pressure is critical."
Please explain what this means, and how it applies to honing.
With your background there is probably allot you can add relating to honing.
It is really a mystery to me how the same stone can yield different results on different steel.
 
"Timing the release of pressure is critical."
Please explain what this means, and how it applies to honing.
With your background there is probably allot you can add relating to honing.
It is really a mystery to me how the same stone can yield different results on different steel.

Let me start by giving a brief overview of a Sunnen Hone, and I will try and explain the basics of how stone make-up relates to materials being honed. I will try and keep it simple without putting you to sleep.
:popc:
SunnenHoneDetails.jpg

We will start with the White arrow pointing at the foot pedal. Think of it as a gas pedal, it is what applies the pressure as you push it to the floor.
Yellow arrow is the mandrel that holds the stone and where the honing happens.
Light green arrow is the light honing pressure knob adjuster.
Dark green arrow is the high honing pressure knob adjuster.
Black arrow is the knob that advances the stone to account for wear.
Red arrow is a dial indicator that shows how the stone is wearing and the amount of pressure being applied.
Blue is the box of commonly used honing stones. There are literally hundreds of stones in those drawers. Maybe thousands, some of the stones are very tiny.

Lots of stuff going on with a MANUAL honing machine, but the main thing to consider here is how much attention is put on controlling the amount of pressure being applied.

According to the instructions written on the tags on the Sunnen Hone "Use the lightest pressure that gives the fastest cutting action".


So, you ask, How does this apply to honing a SR, and how do different stones react to different materials? Right?

The basic rule of thumb is this, and it is a very simple rule---> As the material gets harder, a softer stone is required to maintain the same cutting action.

Simple right?

Hard material will dull and reduce the cutting action of the stone, so a soft binder(the binder is the material that holds everything together) is needed to release the worn stones and introduce fresh stones and provide new cutting action. That means a coarse and soft stone for hard material.

Soft material will clog the pores between the cutting stones and reduce the cutting action, so finer and harder stones for soft material.

What this boils down to is that a honing stone that works just great with a razor made from hard steel, will not perform the same with a razor made from softer steel, and vise-versa.

You NEED to match the stone to the steel. Simple. Just get a few thousand stones. Lol

~doug~
 
Let me start by giving a brief overview of a Sunnen Hone, and I will try and explain the basics of how stone make-up relates to materials being honed. I will try and keep it simple without putting you to sleep.
:popc:
View attachment 1485894
We will start with the White arrow pointing at the foot pedal. Think of it as a gas pedal, it is what applies the pressure as you push it to the floor.
Yellow arrow is the mandrel that holds the stone and where the honing happens.
Light green arrow is the light honing pressure knob adjuster.
Dark green arrow is the high honing pressure knob adjuster.
Black arrow is the knob that advances the stone to account for wear.
Red arrow is a dial indicator that shows how the stone is wearing and the amount of pressure being applied.
Blue is the box of commonly used honing stones. There are literally hundreds of stones in those drawers. Maybe thousands, some of the stones are very tiny.

Lots of stuff going on with a MANUAL honing machine, but the main thing to consider here is how much attention is put on controlling the amount of pressure being applied.

According to the instructions written on the tags on the Sunnen Hone "Use the lightest pressure that gives the fastest cutting action".


So, you ask, How does this apply to honing a SR, and how do different stones react to different materials? Right?

The basic rule of thumb is this, and it is a very simple rule---> As the material gets harder, a softer stone is required to maintain the same cutting action.

Simple right?

Hard material will dull and reduce the cutting action of the stone, so a soft binder(the binder is the material that holds everything together) is needed to release the worn stones and introduce fresh stones and provide new cutting action. That means a coarse and soft stone for hard material.

Soft material will clog the pores between the cutting stones and reduce the cutting action, so finer and harder stones for soft material.

What this boils down to is that a honing stone that works just great with a razor made from hard steel, will not perform the same with a razor made from softer steel, and vise-versa.

You NEED to match the stone to the steel. Simple. Just get a few thousand stones. Lol

~doug~
Now my head hurts:)
It seems like it is easier to stick with just a few basic steel types and razors. I am struggling a little with hard O1 tool steel, but C135 high carbon works really well. Just an excuse to get more French razors.

What happened to just rubbing steel on a rock 🪨?
 
Now my head hurts:)
It seems like it is easier to stick with just a few basic steel types and razors. I am struggling a little with hard O1 tool steel, but C135 high carbon works really well. Just an excuse to get more French razors.

What happened to just rubbing steel on a rock 🪨?
Our ancestors found better rocks to rub steel on!
 
Our ancestors found better rocks to rub steel on!
They also probably had allot more patience. If you just work with what you have long enough, you will eventually get good results. Maybe it was also quite common to send your razor out the "rock rubber" or go to your local barber.
There is not allot of professional rock rubbers where I live:)
 
Have you tried using a Belgian Blue to raise the slurry on a coticule for the finishing phase?

~doug~
I don't have any Belgian Blue. I usually don't use any slurry with my coticules. I just take it to a 6k or 8k shapton and finish on water. I have a few that is really fast and some that are slow but finer. So they are also used more as a proression depending on how much work they need to do.
I do not need a coticule to be a one stone solution.
The slurry stone is used to rough up the surface to speed up some stones.
 
I don't have any Belgian Blue. I usually don't use any slurry with my coticules. I just take it to a 6k or 8k shapton and finish on water. I have a few that is really fast and some that are slow but finer. So they are also used more as a proression depending on how much work they need to do.
I do not need a coticule to be a one stone solution.
The slurry stone is used to rough up the surface to speed up some stones.
The reason I mentioned using a BBS to raise a slurry when finishing an edge on a coticule, is because the garnets are finer and polish more than they cut. I have used the back slate of a coticule like a slurry stone to just color the water and have gotten some surprisingly good edges.

Just a little food for thought.

~doug~
 
The reason I mentioned using a BBS to raise a slurry when finishing an edge on a coticule, is because the garnets are finer and polish more than they cut. I have used the back slate of a coticule like a slurry stone to just color the water and have gotten some surprisingly good edges.

Just a little food for thought.

~doug~
Interesting. I have used a Turingian and a La Lune slurry stone on coticules. They seem to play well together. I always finished with water. It might be worth trying to finish with light slate slurry on the coticule. Slate slurry on a Les La hybrid takes away a little of that glassy feel. I am not sure if it does anything good to the edge.
The problem with most of the coticules is that you kick up some of the garnets from the base stone, which limits the finishing capability.
I think Les Lat hybrids are capable of more then just the final finish. With La Lune slurry stone they cut reasonably well. I am not sure how well, or if this slurry brakes down any.
The hard finishing stone needs to make up for the preceeding softer stone and "damage" from the slurry. It is a difficult balance.
 
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