Sunday, August 09, 2020

More on Unicorn Profile

 I'm still crippling around on a bad wheel so not much is happening in the shop even sharpening is too much some days. There have been a few days where whisky and a elevated foot was all I could do. On one of the good days I did install a stitched cotton wheel on the grinder and have taken a couple of my old Freud Chrome Vanadium chisels (BTW, they were the first "good" chisels I bought from the Garret Wade catalog many years ago) and ground a Unicorn profile then buffed on the buffing wheel with green stuff. 

 


First go, David Weaver may be on to something. First it is very quick, grind a bevel on the grinder, hone a secondary with a Washita, Medium India or other quick 1000 grit or so stone. Use whatever you have handy, then maybe 15 to 30 seconds on the buffing wheel. The chisel comes out very sharp and the edge is long lasting, maybe longer lasting and sharper than off a polishing stone.

That's the good news, the process seems to work, it is very quick, and the equipment is inexpensive. That may also be the bad news. What do I do with the tens of thousands USDs I have in sharpening stones when to get a sharper, longer lasting edge all you need is a grinder with a buffing wheel, a little green stuff, and a $30 USD India stone. Also maybe a meal or two of crow.

Check out the Unicorn profile posts on Wood Central, wear your masks and stay safe,

ken

Thursday, July 30, 2020

New JNAT

The new Ohira Range Suita arrived today. It is a pretty stone with a good feel. As you can see it cuts fast but leaves a nice finish. It should be a goto polishing stone.

One more:


In this last image you can really see the swarf.

ken

Loo Is Now a USA Citizen

At 1500 CDT she took the oath.


Wish I could have been there.

ken

Wednesday, July 29, 2020

Wood Central

There are some interesting sharpening discussions going on on Wood Central dealing with bevel angles, shape, buffing and stropping your cutters. Look for the Unicorn threads by David Weaver. David was one of the  leaders several years ago in the change of understanding the role of the cap iron in tear out control. Pretty sharp guy.

I may have more on it it as I explore their finding but bottom line Paul Sellers may be smarter than some give him credit.

ken

Monday, July 27, 2020

Danger of JNATs

Because the best use of a JNAT is as a polishing stone if you are honest with yourself you need at most a couple of stones. Like with my Arkansas polishing stones I have three, a translucent, and two Hard Surgical Black stones. While there are very slight differences in feel of the stones there is little difference in performance and in reality I could get rid of any two with no problem.

JNATs are different in each stone is unique and because of their beauty acquiring JNATs can be addicting even approaching a sickness. as an example: Last night in answering a question I linked to a web site and to a stone that would be a good one to start with. Here is the link: Ohra Range Suita .

If you click the link you will see the stone is no longer available because it is on its way to Tucson. It is a sickness.

ken

   

Sunday, July 26, 2020

Shine Does Not Indicate Sharp

The job of the grinding and honing stages is to shape the bevel so it is a flat plane that meets the also flat plane of the back at your chosen angle. The goal of the polishing stage is to remove the scratches that are left from the grinding and honing stages without adding more.

During all three stages both feel and sight are very important. Clean cutting stones like Arkansas stones will form a burr that can be seen as a black/dark line and felt with your fingers. If your stone forms a surry, that surry can interfere with burr formation and you may not be able to feel a burr when polishing on harder JNAT stones and some WaterStones. In those cases you must rely on sight alone to judge if the cutter is sharp. BTW, shine does not indicate a good long lasting usable edge.

Maximum light reflection requires a flat surface to reflect light, if the surface is rounded the light rays are scattered. Here come the weeds.

The cutting particles of Arkansas stones do not detach in any great amount and those that do are irregular. Another factor is the cutting surface of the stone is also random. A cutter polished on a Hard Black or Translucent Arkansas oil stone will have random shallow scratches with rounded edges. It will not appear as shiny as a bevel polished on a WaterStone but if looked at with a very high power scope the saw teeth on the cutting edge are smaller, smoother and will last as a working edge longer.

The cutting particles of synthetic WaterStones are more or less cubic that break free of the stone's substrate but do not break down. Because there are always new abrasive particles WaterStones cut very fast but, and there is always a but, leave a more or less ordered scratch pattern of relatively deep and straight sided scratches. They are great for shine but not so good at cleaning up the saw teeth on the cutting edge. To the unaided eye the bevel looks great but it is not as smooth cutting or will it last as long as a cutting edge formed by a natural stone.

JNATs abrade by forming a surry of small flattish abrasive particles that will break down, mostly in thickness, as the tool is being abraded/polished. JNATs benefit from the use of a nagura in two ways, the nagura used correctly will help keep the stone flat and it will help form the surry.  The scratch pattern from a JNAT is much like that of the Arkansas stone, random, shallow, with rounded sloping sides. A bevel polished with a medium hard JNAT may appear cloudy, which is highly prized. When looked at with 10X or more magnification the surface will have a matte appearance with no deep or ordered scratches and the cutting edge will be much smoother that the edge of a cutter polished with a WaterStone.

I hate to say it, but more to come,

ken           


The JNAT Journey

Sharpening woodworking chisels and plane cutters is a three step process of grinding to shape the cutting edge, honing to remove and refine the scratches left by the grinding step, and last polishing to farther remove the scratches and smooth the saw tooth like cutting edge.

While there are many ways to do those three steps I'm going to limit myself to three major types of sharpening "stones" with a couple of subsets. The first division is between natural stones and man made or synthetic stones and those two can be farther divided by what substance is used to remove swarf, either oil or water. There are many natural stones but I will limit this to Arkansas oil stones and Japanese natural waterstones. The synthetic stones for my purpose can also be divided into Norton India stones and Water Stones mostly from Japan. The Water Stones come in a mind numbing number of substrates and grits.

Some of my JNATs:


Notice the shop safety toes at the bottom of the image. The stone on the left side is a soft stone that is good for honing. The stone on the right side is the hardest and can give a fine polish. The four stones in the middle are all mid level hard and very good polishing stones that leave a kasumi (hazy) finish.

Because in today's woodworking world synthetic waterstones are the most used we have come to think in terms of the stones "grit". That is the wrong way to look at natural stones. For Arkansas oil stones the Specific Gravity, how dense is the stone will, within a general range, tell you if the stone is good for honing or polishing. Another factor that makes choosing a Arkansas stone easier is they all come from the same geological formation and a soft Arkansas is pretty much like any other soft Arkansas. For JNATs it ain't that simple. They come from many geological formations each different but whatever the mine, the stones hardness will help determine its best use.

The simple fact that there is not a "grit" classification with JNATs is the first major hurdle to learning to buy and use. Another is because they are natural stones, each stone is different, much more so than Arkansas stones. The only way to find if stone works for you is to learn and use the stone. There is the potential for kissing a lot of frogs if you do not work with a dealer you can trust.

All this begs the question; why bother. To answer I have to get into the weeds of polishing, what is the difference between the cutting edge of a natural stone polished cutter and one polished with synthetic Water Stones.

In the end there could still be the question; why bother?

More next time or whenever the mood strikes. 

ken

Thursday, July 23, 2020

The Gods Are Messing With Me

Sometimes you just have to laugh and wonder what you did to piss the gods off. I've been being a good boy with my ankle and it has responded well. Yesterday I did walk a little on it using a cane and it seemed ok until I went to bed last night. At that point my foot was hurting enough I couldn't sleep and finally around 0200 I took a couple of pain pills and got a few hours sleep. I figured I had over done the walking.

When I got out of bed and put some weight on my foot I noticed it didn't hurt at the strained ankle but instead at the great toe. A quick glance told the story, the great toe is swollen, hot, red, and tender. For the first time in almost four years I have a gout attack. It could be worse, the gout could have been on the left foot.

I've enough colcrys to run a course, miserable stuff but by tomorrow or earlier the gout will be gone. and maybe, just maybe I can stand at the sharpening bench and play with my stones. I need it, the last couple of days have been miserable. I do not get bored very often, I can almost always find a book or article to read but I'm at the point reading ain't doing the job. I need to do something.

Enough kvetching maybe time for a post about the beauty of JNATs or the difference in technique between JNATs and synthetic stones. Nothing like getting into the weeds on a sharpening post😏.

ken

Friday, July 17, 2020

Gimp

With retirement I've been looking at money leaks and damn there are a lot of them. None are big, most under $10 USD a month  but when all are put together there is enough to buy several BF of lumber every month. One of the biggest single is the Adobe subscription. I have the full Creative Suite, it is a great set of programs and back in the day a needed set. Today not so much, over the next few months I'll be learning "Gimp", instead of $30 USD a month it is free.

Speaking of gimp, I am one. Yesterday morning I got out of bed a little quickly and lost blood pressure to my brain. While I did not lose consciousness I lost control of my balance and fell on my right ankle. After a visit to the local Urgent Care I know the ankle is not broken but there is a bad strain and holly hell it hurts when I put any weight on it. That's the bad news, the good is my office chair will roll thru all the doors and down the halls. It's not as good as a wheel chair but close. The other good/bad news is MsBubba is still in Oregon. It would be nice to have a helping hand and she would but she is a slave driver. As it is, it is just Sweet Maggie Dog and myself and the only thing I need to do is reach for the doggie treats and feel sorry for myself.

I doubt there will be much wood working for the next few weeks, other than maybe a lot of cutter sharpening once I can stand up. By that time I will likely go back to work for a few months. MsBubba will not return to Tucson until October at the earliest so I might as well get a couple or three paychecks. I kinda want to get a new bandsaw before all the money goes away and a new dust collector would be nice as well. I had planed on retiring at the end of the year before the current unpleasantness came along, I may stick to that schedule. 

Be careful out there, wear you mask and don't stand up too quickly,

ken