Earlier this week, I had dinner with two old Tormek hands. This is a very rare treat for me. Among the various discussion topics was hollow grinding. We had at least three points of view on this. While trying to be fair to the other points, please be aware that this post will probably favor my thoughts.
The traditional Tormek view is that adding a secondary or micro bevel is unnecessary. Grinding with the Tormek is efficient that the labor saving micro bevel is not needed. In general, I agree with this.
Another viewpoint is using the Tormek to establish the bevel and then switching to flat bench stones to create the keener micro bevel, usually to 8000 grit.
A third view is to establish the primary bevel with the Tormek SG grinding wheel and then add a micro bevel using the Tormek SJ polishing wheel.
In my opinion, establishing the two reference points with a hollow grind to allow alignment of the blade on a flat stone does not reflect Tormek thinking. It can produce very sharp edges, and I have no doubt that many use this method. I think it also reflects both a lack of confidence in one's ability with the leather honing wheel and an addiction to grit numbers.
I am old enough to have been a charter subscriber to Fine Woodworking magazine in the early 1970s. One of the hot topics back then was hollow grinding. The majority of home shop grinders were six inch. A few were 1725 RPM. I recall a very few might have been seven inch. At the time, I purchased my set of three bench planes, lovely 1909 vintage Stanley Bedrocks, from an elderly carpenter who was the original owner. He proudly showed me how he had hollow ground the blades so that he could touch up the edges with a file.
Things have changed since then. I now sharpen plane blades with a Tormek with either 200 or 250mm wheel. This produces a hollow grind which is much less hollow than smaller diameter wheels. I do believe that much of today's thinking about hollow grinding is leftover from the small diameter dry grinding days decades ago. It does not reflect larger diameter Tormek grinding.
What about switching to bench stones for final finishing? Two experiences make me think this is unnecessary. The first occurred during one of my knife tests. I really leaned on the fine side of the stone grader with the SG-250 for a long time. To my surprise, the wheel felt smoother than ever before. It also cut very slowly. I had inadvertently been using a middle grit before.
The second experience was reading a post by Stig saying that he routinely used a very light touch for the finishing passes. I believe that if a sharpener used these two techniques, the need to use bench stones would be minimal. Combined with disciplined use of the leather honing wheel, I believe Tormek only edges can rival bench stones. I hope to purchase a USB microscope this summer to document these ideas. I presently have around eight 3/4" Irwin Blue Chip chisels for the tests. (I also have a set of Norton water stones from my pre-Tormek days.)
As I become very proficient with this technique and can document it better, I will compare it with finishing with the SJ-250.
Two factors to consider is the thickness of today's premium plane blades and the newer steels. All of my blades are old Stanley carbon steel. I hope others with experience with today's thicker blades will join in and post.
Ken
Good points, Ken. The only thing I would add is that micro bevels are needed by folks who desire sharp edges and don't own a Tormek. These people may hire a sharpener to establish a hollow grind bevel using a Tormek, but then need to tune up the edges on a bench plane when necessary. This is rather like using a steel to tune up our kitchen knives in between Tormek sharpening sessions. I use my steel just about every time I reach for a kitchen knife, especially if the edge doesn't pass the fingernail test.
Can you tell us who your dinner companions were? I'm jealous!
I remember those days (decades), Herman. I had a high speed dry grinder, however, I usually did all my sharpening with oil or water stones. (That was before flat diamond plates were available to restore India and Arkansas stones.) I welcomed micro bevels, although I welcomed the Tormek even more. I never paid anyone to sharpen to sharpen my chisels or planes.
I really like my ceramic "steel" for kitchen knives.
I suppose I am allowed to post the names of my two dinner companions. Rich Colvin, of our forum, lives in a suburb of Columbus. We have enjoyed "Tormek afternoons" a couple times. The other diner was a guy from Sweden who was in town for a Woodcraft meeting. He said his name was Stig. He knows a lot about Tormek. It was a great evening.
Ken
Lucky duck!
I've actually used the hollow grind / microbevel that way myself, mostly because I can. Give that edge just a couple more super-light passes on a high-grit waterstone (8k Snow White for me) and it puts an extra little bit of pop into the edge with basically no more effort at all.
Do I need to? Nah, that edge off the honing wheel is already sharp enough for any use short of eye surgery. Do I do it anyway? Heck yeah!
Hand touch-ups are indeed a nice complement to sharpening with a Tormek. But only in some cases. Tools like chisels and mower blades,perhaps. But knives, not for me.
Herman, I am pleased you have not forgotten your framing carpenter heritage. Perfection is nice, but so is being done by quitting time. :)
Ken
Quote from: Komitadjie on June 10, 2017, 06:02:29 PM
Lucky duck!
I've actually used the hollow grind / microbevel that way myself, mostly because I can. Give that edge just a couple more super-light passes on a high-grit waterstone (8k Snow White for me) and it puts an extra little bit of pop into the edge with basically no more effort at all.
Do I need to? Nah, that edge off the honing wheel is already sharp enough for any use short of eye surgery. Do I do it anyway? Heck yeah!
Komitadjie,
I applaud your willingness to go the extra mile with sharp edges. I have had similar thoughts. With me, in the back of my mind, I keep wondering whether my limitations with the Tormek are due to the machine itself or with my own level of technical skill. The old saying,"It's a poor craftsman who blames his tools" conyinues to haunt me.
Like many of us, I have studied the videos Jeff Farris made many years ago. Jeff demonstrated the Tormek for many years and became very skilled with it. My thought is if Jeff could do it, so can I, if I am willing to work hard enough.
Some Tormek skills have only developed with considerable effort for me. Case in point is using the truing tool. Like most new users, I delayed using it, not wanting to waste "my precious, expensive grinding wheel". I became very frustrated with the blackstone glazing while reshaping a turning gouge. I resorted to very frequent retruing (restoring) the wheel. I had to do enough of it to become fluent with the truing tool. I have since become a believer in frequent, light retruing. Those of you who, like I did, have not retrued your grinding wheel, or do so infrequently, may not realize the cutting potential of your Tormek.
I had a similar experience with the stone grader. These experiences have bumped my technique closer to full proficiency with the Tormek. This growth is ongoing.
Hang in there; do not settle for less than you can be.
Ken
I really would like a SEM or something similar so I could properly evaluate the edge! Technically, given the way I understand the SB stone to work, there *is* no way it can reach a scratch pattern as fine as an 8K stone by nature of the abrasive. Now, that being said, I'm as far as possible from an expert with the stone and its structure!
Certainly, for all working purposes, the edge straight off the honing wheel is sufficient for basically any use you'd put it to at all. It gets into the "how do you define sharp" arguement, I think. Are we talking perfection of edge linearity? Minimum scratch pattern? Minimum apex? Easiest cutting of a given material? I've heard that argument run around about a million times. I generally base my personal comparisons on the result of BESS testing, just for a baseline. I should really get some numbers for my Tormek edges, come to think of it!
You can create a perfect edge that gets a high score, has a polished bevel, and cuts through paper to impress observers. But as soon you you start using that knife it quickly becomes dull. Sometimes you need a more blunt edge angle so it'll stand up to everyday use, or a toothy edge to slice tomatoes.
The nice thing about a Tormek is you can adjust all these variables to your liking so that each of your knives suits your own purposes and preferences.
Oh, I've played with the variables, and still do! I just like the BESS as a basic way to compare one edge to another in my own sharpening. Nothing like a standard to test to! :)
I tend to go highly polished edges, with as acute of a bevel as the knife can hold. I've had fine luck with tomatoes and a polished edge, as long as I've got the edge polished and acute ENOUGH.
Another vote for BESS standardization of sharpness measurement. I think measuring edge sharpness is the first part. The hard (and interesting) part is in developing a feel for interpreting those numbers for your own use.
Keep on exploring!
Ken
Well, and then determining the factors that make that particular blade work the best in the *exact* use you are sharpening it for. Pure sharpness means nothing if the edge won't withstand the abuse you throw at it, etc. :)
Plus 1 for the BESS sharpness standard.
The first instrument that I purchased to help me to understand sharpening was a USB microscope. There is nothing like being able to get a good look at the edge of a blade to see burrs and the scratch pattern of different abrasive grits.
Then I got a PT50B (BESS) sharpness tester. The two instruments combined are amazing. If a blade is for some reason not testing as sharp as I think it should be or is super sharp for that matter, I can check it under the microscope and see why. With the sharpness tester I not only know how sharp a blade is but can also put a standardized number on the level of sharpness that can be communicated to others. With a microscope I can understand why. Very cool stuff!
I'd love to have a nice tabletop SEM, but it would stress my discretionary income just a bit. ::)
Good points, gentlemen. I'm an old chisel guy. I first bought my Tormek to sharpen chisels. They remain my favorite tool to sharpen. I believe learning to sharpen chisels is "the great teacher" in learning to use the Tormek. Sharpening the straight, good sized single bevel is easy enough in itself to allow "the veriest tyro" ( I love that old British term for beginner) to be aware of the sound and feel of using the Tormek.
In my opinion, getting the bevel sharp with the grinding wheel graded coarse is both the labor intensive and easiest part. The last few light strokes with a 4000 or 8000 grit stone or wheel graded fine and then the leather honing wheel are the less physically demanding part.
In my case, I was content to remain in the comfort of continuing to finish with Arkansas stones or water stones. These were decades long friends. I was almost content, but I felt I had made this decision with bias. To decide fairly, I should have had equal skill with either method. I felt I had not fully learned how to finish with the Tormek. I took the time to practice finishing until I became proficient. Now I am equally comfortable with either method. I generally finish with the Tormek. I would feel just as at home with my water or oil stones.
I do not advocate one method over the other. You should use whichever technique is more comfortable for you, or a combination. I do believe that we owe it to ourselves to make that decision based on being skilled with all choices.
Grepper, as you and the forum know, I have been excited about using BESS testing for some time. It quantifies sharpness with repeatable numbers. I am stepping things up a notch. Sometime this very day, my mail carrier will deliver the Celestron 5mp Pro USB microscope I ordered on your suggestion (badgering? :) :) ) [like yours] I procrastinated too long. I will use it in conjunction with my 10x LED handheld magnifier, another suggestion from a friend.
This may seem like overkill, however, I believe it will intensify my visual acuity with examining my edges, my actual edges, and deepen my knowledge of sharpening. With coaching and encouragement from you, plus some trial and error work, I am finally comfortable posting photos on the forum.
I look forward to future dialogue; we have some new and useful tools.
Ken
ps
My original intent is purchasing the USB microscope was to donate it to my grandchildren's school. It is a delightful learning environment that operates on a shoestring budget. I could borrow the microscope on weekends.
I believe that plan will change very soon. The school will still have the microscope, however, the next time my budget refills I suspect I will be ordering a second unit for my shop. I watched a video of a guy who incorporated it into the flow of his sharpening. He would grind and look, then grind again if necessary. This seems a more efficient work method to me than just having a post work inspection area. Rich Colvin has a tablet in place on the wall next to his Tormek. He is compiling a sharpening handbook which will be a vsluable reference. Pairing this tablet and reference with a USB microscope would be a powerful and efficient combination.
I look forward to future posdibilities.
Ken
I've not thought of including a microscope into my sharpening routine. Sounds like a worthwhile idea.
Question : what magnification should I buy ?
Quote from: Ken S on July 05, 2017, 01:53:59 PMRich Colvin is compiling a sharpening handbook which will be a vsluable reference. Pairing this tablet and reference with a USB microscope would be a powerful and efficient combination.
Hey, if you get some great pictures, I will be happy to incorporate them into the online reference guide (www.SharpeningHandbook.info).
I've already gotten feedback from one person regarding the sharpening of the Termite End Grain Tool, and it has been incorporated.
That is the idea : to capture the wisdom of those who do the work and pull it together in one place, providing it to all for free. I am not seeking funding or advertisers; rather I am funding this myself. That way it is simply a good reference tool. Nothing more; nothing less.
I know there are many sages on this site, and would love to incorporate their wisdom. If you would rather send it via eMail, a link is on the site for that purpose.
Kind regards,
Rich
Quote from: RichColvin on July 05, 2017, 11:52:34 PM
I've not thought of including a microscope into my sharpening routine. Sounds like a worthwhile idea.
Question : what magnification should I buy ?
I have a 200 X optical magnification USB microscope that I have found works well. Look for the optical magnification spec. Ignore the digital magnification stuff. It's meaningless.
Here's a link to some images that I've taken with the microscope:
http://bessex.com/forum/showthread.php?tid=68&pid=510#pid510
Rich and Grepper,
My Celestron 5mp Pro USB microscope arrived yesterday. At this point, I have all the expertise and experience with it as the guys who shoot videos of their first unboxing of the Tormek. However, I would like to mention that after researching the issue, I don't think these things work with tablets. The software program works with Mac OS or Windows. I have not found a version for Ios or Android. That seems really unfortunate to me; tablet use would be a great match for students (and sharpeners).
I have a learning curve to work through before I become fluent with the process. I loaded the software on my laptop;it seems to work fine. Having switched to Mac nine years ago, I no longer have a clue about Windows. I downloaded the instruction manual on my ipad in ibooks, which I recommend doing. Being able to read the manual or search with the ipad while using the program on another computer is really convenient. The manual suggests saving the operating software on the desktop for quicker access.
Copying the digital photos from the macbook to the ipadshould not be a problem, wirelessly or perhaps wired.
The included software can do lots of tricks, which I will learn someday. The adding text and drawing features look promising for forum photos. For the present, I will concentrate on my hit or miss focusing technique.
Rich, I think well done photos from these microscopes would be an excellent inclusion for your handbook. At one point in the last millenium I knew the difference between microphotography and photomicrography.
These little microscopes are inexpensive (under a hundred dollars US). Kids know how to use them intuitively; seniors take a little more effort.
Sadly, I doubt my old faithful Micro Nikor 105mm set up will get much use with edge photos in the future, and the really nice PB6 bellows I recently purchased used may never get used. That's progress.
Ken
ps If anyone knows how to use these microscopes with an ipad, please post.
Ken, the big issue with a USB microscope and a tablet is POWER.
I would recommend a powered hub, which you could then both charge your tablet from, or from a different usb port, control what is plugged into it.
The software that comes for things like this, is basically dummy software (allows use from the get go). These should be like a usb camera, and allow streaming without the software. (can find video's of microscopes and tablets on Youtube, but different languages, and I have neither to play/learn from)
Things like browsers, and players like VLC should be able to stream and even capture images from them.
Interesting and informative post, SADW. Apple sells several different adaptor cords with their lightning connection (the new Apple charging port for the ipad) and various other ends (SD, UBS, Video, etc) on the other end. I have used the SD adaptor with good results. Among the collection is an adaptor with both a USB connection and another lightning port to provide power. I would think that would cover the power issue.
I do not understand the possible software issue. The ipad imports photos and video directly from its camera. In my case, I can use my Macbook and transfer microscope photos. It would be convenient enough for schools and other uses to be able to bypass the laptop. It seems strange to me that someone has not figured out how to do that.
Ken
I don't have a Mac or know its software, so I have no way of knowing how to adjust settings. (why I say issues, in case there is other id hardware for their software, in the way they have hard drives)
SADW,
This reply may surprise you. I was a die hard Mac fanatic for years. I have used several Macs over the years and, despite some MacQuirks, have been very satisfied. In fairness to Windows PCs, I must admit that much of my prejudice stems from having several PCs with not enough hard drive and memory when Microsoft decided that larger operating systems were "better". I learned this lesson and have overbuilt with Mac, with good results.
Two things have given me pause with my MacFanaticism:
First, a friend showed me his basic Chromebook. I was impressed with the amount of firepower the Chromebook had for very little money.
Second: My grandson bought a Raspberry Pi. (actually two, a Pi 3 and a tiny Pi 0) These little things are amazing. The basic zero model costs only ten dollars. Kids (even older adults) can assemble components as needed. They are incredibly inexpensive. For basic email, web surfing, and even things like basic forum photography (including an 8mp camera!) the provide yoeman service.
I think I could get by nicely with a Radpberry Pi, with the MacbookPro for its intended purpose, replacing my darkroom. Check out the Raspberry Pi. They are inexpensive, versatile, and fun!
Ken
Ken,
This is funny : I have an unused Raspberry Pi 3 that I was just recently thinking of setting up in my shop. The Raspberry Pi runs a variation of BSD Linux (called Raspbian, if I remember correctly).
But what is equally a good solution in this realm is LinuxCNC. This runs on really old PCs and is easier to manage & maintain. Response times are similar from what I've experienced. And LinuxCNC is also a variant of BSD Linux.
So the question truly is : does the scope software run on Linux. If so, this would be a REALLY cheap solution!
Kind regards,
Rich
The only Mac I know I might have access to, is the first Bondi Blue mac, sitting in a closet, that was sent to a friends company, after they shut down their mac clone production (one of three authorized companies that Apple then shutdown, remember that?).
I have a couple Windows machines; one for gaming, and one for some work stuff (low powered laptop/netbook thing for special text files). Otherwise my choice OS is Linux (and I own SEVERAL Raspberry PI's).
Raspbian is based on Debian Linux, and Linux is a kernel that with other pieces is a sister os to, and developed because of the whole Unix/BSD license and lawsuit. Linux and BSD are not the same.
The software written for Windows will not by default run on Linux. There are some emulators, but they are problematic, and typically require more horsepower then something like a PI will give.
SADW,
Have you tried LinuxCNC ?
Kind regards,
Rich
No, WAY way way, too many other projects.
At this point, I probably have 10 years worth as is.
"The lyfe so short, the craft so hard to learn".
I agree, SADW. I have had an ongoing program of self study in sharpening for many years, with much still to learn. Add to that trying to increase my knowledge of digital photography and computer skills, including now video. And the forum. This all must fit in the context of being a husband and caregiver to two grandchildren, and very active in their school.
At sixty seven, I still have fond hope of rereading Don Quixote in Spanish in my mature years. I have missed the "at fifty" target. I would like to learn other computer languages, but when?
Ken
Quote from: Ken S on July 06, 2017, 10:50:18 PM
I do not understand the possible software issue. The ipad imports photos and video directly from its camera. In my case, I can use my Macbook and transfer microscope photos. It would be convenient enough for schools and other uses to be able to bypass the laptop. It seems strange to me that someone has not figured out how to do that.
I think what SADW is telling you is that it may so simple as to not need documentation. You just connect the scope to the tablet. A bit of video player software, something plain vanilla like VLC, and you're done.
Interesting thought, Herman. I may be overthinking this. I just placed an order for a USB-Lightning adaptor for my ipad. Sometimes the next logical step is just to try it. :)
Ken
Herman,
I just downloaded VLC for ios (ipad) from the app store, a free app. My USB to lightning adaptor for my ipad should arrive early next week. I will post my results. It would be convenient for me and very convenient for the school if the usb microscope would work with ipads. It can be removed from the stand and used handheld, if desired. The school has a nice greenhouse which is part of the curriculum.
Ken