Re: The Tormek BGM100 and grinding bliss

Re: The Tormek BGM100 and grinding bliss

John Aniano in central NJ

Eliot,

When Derek stated "...Otherwise, the grind is cool enough to take to the (leading) edge of the bevel..." I'm pretty sure he is referring to the difference between a regular high speed grinding wheel that would burn the fine pointed edge of a blade vs. the BN wheel, also running dry, not doing the same thing. Obviously, the usual aluminum oxide Tormek wheel running with water doesn't remove the temper or burn the edge because of the water coolant. BN wheels are strongly recommended to be use dry, not with water as a coolant. But the BN wheels cut with so little heat, they won't burn the edge, so "the grind is cool enough to take to the edge of the bevel"...

For many high speed steel tools, burning the edge isn't much of a concern due to the steel being air hardening. For carbon steel tools, burning the edge is the enemy.

John

Re: The Tormek BGM100 and grinding bliss

eliot feldman

I see what you mean. I was confused because I have always ground all the way to the sharp , fine, edge of the bevel with these CBN wheels when I used them on my turning tools. And it never occurred to me NOT to do the same thing on plane blades and bench chisels -- now that Derek put me on to sharpening such tools as well my turning tools. Now, my go-to method for sharpening bench chisels and plane blades is to grind on the CBN first and then finish up on my two Spyderco ceramic stones-- one fine and one super fine (blue and black cases.) Although today I tried finishing up on my Veritas MKII Power Sharpening horizontal system with the 4 micron wheel. I haven't decided which method for the last steps I like best yet. There's lots of control with the machine, but I find their set-up jig too finicky. It's so easy to just use the ceramic stones. What I haven't decided yet is which method gives me a better surface when I plane the face of a board.

Re: The Tormek BGM100 and grinding bliss

Steve D, in CT

Hi Eliot,

There would be two reasons for not grinding all the way to the edge. As already mentioned, the thermal buildup in a small amount of metal can cause loss of temper.

Another reason could be that there can be damage to the metal from coarse grits on the edge that doesn't help in the sharpening process. By hollow grinding to achieve an easier way to freehand sharpen there is no need to go to the edge and raise a burr on a grinder. A finer stone can be used to raise the burr with only a small amount of metal to remove. As this process is repeated the hollow shrinks and can be refreshed by going almost to the edge again.

Here is an article about the edge damage:

https://scienceofsharp.com/2019/10/02/grit-scratches-and-sub-surface-damage-part-1/

Re: The Tormek BGM100 and grinding bliss

eliot feldman

Apparently, there are refinements that I haven't dreamed of! Does all this mean that I should avoid grinding to the leading edge-- even with the CBN wheels? How about using the CBN ALMOST to the edge and finishing on the 4 micron Veritas MKII horizontal wheel? I also have flat Shapton stones and Japanese stones of very fine grit. How about finishing by hand with these? How about some extremely fine diamond films that I have attached to an extremely flat special stone block that I bought years ago but haven't used for a long while? I think I'm over my head! It's your fault, so help me out!

Re: The Tormek BGM100 and grinding bliss

Steve D, in CT

I didn't mean to gum up the works.

If you have a chipped iron you would of course have go to to the edge with a coarse abrasive. Because of the burn risk I would still stay away from the edge with a wheel and use a coarse stone to repair damage.

The hollow grind makes it much easier to hone the edge because the metal in the middle of the bevel isn't touching the stone.

Whatever you have been happy with should be fine for finishing edges.

Re: The Tormek BGM100 and grinding bliss

eliot feldman

I would have to say, though, that with the CBN wheels there is no burning at the edge. I do it a lot now, and I just don't see the slightest burning. This was Derek's point , now that I understand what he meant by "grinding up to the edge". (But now that I just looked it up, he said "close to the leading edge".) Could there be burning that i don't see? AndI have been grind turning tools all the way to the leading edge for years on the CBN wheels -- and even before CBN (for better or worse) with the old wheels. Turners can't possibly take the time every when they sharpen to play around with anything but grind and get back to turning.

I still would like to hear your opinion on what would be best for the final stages of the sharpening process. Even if it's just between super fine ceramic stones and the 4 micron Veritas horizontal disk. And how do you sharpen?

I still get get over that article! I'll have to really study it to see how it applies to planing a board.

Re: The Tormek BGM100 and grinding bliss

Steve D, CT

Turning tools are often HSS and don't lose temper as readily as non-HSS tools.

Taking them off the grinder should be fine and they aren't expected or required to be hair shaving sharp (disclaimer: extremely limited turning experience). For the sharpness obsessed the subsurface damage may be of interest but should be removed by the time the tools is touched up a few times.

I have and use waterstones already so I would use them. If I were to buy another piece of sharpening equipment, the Tormek looks most interesting but I have a dry grinder and plenty of stones so I'll probably stick with those.

Re: The Tormek BGM100 and grinding bliss

eliot feldman

Turning is what I have the most experience with. Your right, turners don't worry about hair shaving sharpness. If one bothered to sharpen a turning tool like that, say with a Tormeck, it would get slightly dull right away because of the huge amount of wood that's cut at the fast-spinning lathe.

I have a Tormek for plane blades and chisels, but I stopped using it in favor of the CBN wheels ever since Derek passed on his methods of sharpening these tools. I find it fast and excellent. But, as I said, I still have questions about the best way to proceed after the initial sharpening with the CBN. Derek uses ceramic stones(Spyderco) , and so do I. But I am wondering if there may be something even better -- such as my Veritas MKII 4 micron horizontal disk. Or perhaps some sort of very fine diamond material.

As far as getting sort of crazy about all this sharpening, I thought you were one of those because of the scientific article you linked.

Re: The Tormek BGM100 and grinding bliss

Steve D, in CT

I get edges that I am happy with and I don't know how much better they can be. I've handled tools at Bob van Dyke's school here in CT and he keeps those very sharp.

I've stumbled on that site and read the articles and enjoy seeing what is happening on the microscopic level. Since I don't have an electron microscope of my own or have access there is no way to see how well or poorly I am doing.

I'm happy with my results and never consider myself at the top of the heap so I am open to ideas and reasons for doing things as you are. I think I need more improvement with technique than equipment right now.

There is, or at least was, a ton of info with high magnification of edges depicting different sharpening media and different steels. If you are interested in adding to your abrasive toolkit it is worth looking at. For ease of use a set of Spydercos and some Windex could be just the ticket.

Re: The Tormek BGM100 and grinding bliss

eliot feldman

A simple question: Do you regularly remove the grey color that comes from the steel particles that accumulate on your Spydeercos? And if so, what do you clean it with? I am presuming, but don't really know, that you have to get a fresh surface for the stones to work properly.

Re: Spyderco cleaning

Steve D, in CT

That is a good question. I only have the one shaped stone that gets little use and is black. I haven't cleaned it yet.

That is the reason I don't have the urge to buy more. I'm not sure how popular they are with woodworker because they are reputed to be out of flat and extremely hard to flatten. I think Derek Cohen uses them, maybe he has a method.

Re: Spyderco cleaning

Derek Cohen (in Perth, Australia)

Two ways I keep Spyderco clean:

1. To lubricate the stones, I spritz a little soapy water. This tends to keep them clean and prevent the surface becoming clogged.

2. Every 6 months, I take a coarse diamond stone to the surface to check it is still flat. They are always flat, but this also refreshes the surface.

If this was not enough, what I would do is use a little scouring powder and scrubbing brush.

Regards from Perth

Derek

Re: Spyderco cleaning

eliot feldman

Instead of a coarse diamond stone, would the stone designed to flatted Shapton stones work all right?

Re: Spyderco cleaning

Derek Cohen (in Perth, Australia)

Eliot, I do not know of a special stone for flattening the Spyderco. I used a coarse (250 grit) followed by a fine (600) Eze-lap diamond stone.

Regards from Perth

Derek

Re: Spyderco cleaning

eliot feldman

So Derek, am I correct that you start at the CBN wheel(s) and go directly to the Spyderco stone(s)? Following you, because I already had the CBN wheels for my lathe tools , and also had the Spyderco stones, it was easy for me to began sharpening this way. And, also taking your advice, I began flattening the Spyderco's with a coarse(red) DMT diamond plate.( But as far as I could tell, the Spyderco stones were already flat.) The process is extremely fast and easy, and my tools seem sharp. Would you be good enough to tell me what do you do about the backs of your plane irons and chisels?