CBN grinding wheels?

[john lucas]

Well considering David turns mostly spalted wood that I'm sure has problems, and has for more years than most of us have been turning I would take his opinion. Besides he's just a plain nice guy and certainly doesn't act like a god.
My first every demo at the AAW symposium was on Photography. The first person to walk in the room was David Ellsworth. To say I was nervous would be an understatement. The video equipment was not working properly and I had not seen that equipment before. David very nicely came up and helped to get it all working. He will stop and talk to any turner just like you and I would chat.
There still are disputes among even the top turners as to whether you need to hone. If you look at the results Stewart Batty and Jimmy Clewes get right off the grinder it's awfully hard to believe. Some feel the saw tooth edge actually cuts green wood better.

 

[Bill Boehme]

From my experience, I have no doubt that the rougher edge cuts green and dry wood more easily -- perhaps not quite as smoothly, but not much of a difference. I have an unverified hypothesis that a more refined edge lasts longer, but I am not really interested in verifying that hunch since I go both ways when sharpening.

 

[Brian McInturff]

So someone other than Odie explain to
me the "big" benefit to honing for anything other than a finish cut, or on a really, really difficult wood. Seems the objection is to remove wood and get the general shape. Then you hone for the finish cut. Obviously I've touched up an edge just so I don't have to go resharpen but that's when I feel it getting a little dull and don't want to stop the lathe. Do you hone after each and every sharpening? I'm trying to understand the logic but my analytical way of thinking tells me it's not needed if the tool is sharpened correctly and used correctly.

Now a question for Odie: wouldn't a 180 grit wheel be better than an 80 grit wheel for honing?
An 80 grit leaves a pretty jagged edge when you look at it magnified as compared to a 180 grit. So the honing process is less on a 180 as opposed to an 80. As for the CBN wheels a sharpened 180 looks a lot closer to a 600 under magnification than it does a 120. That could be because the wheels are so true and uniform when compared to a friable wheel. The CBN's when properly installed run truer than any friable/matrix wheel I've seen, in any shop.

 

[Matt Lewis]

I may have misunderstood, but you can not compare CBN grits to friable in a one to one manner. A 180 in CBN terms is close to an 80 grit in friable terms and an 80 grit in CBN is close to 46 in friable.....two different identification standards. Sorry to interrupt the conversation, but just wanted to ensure apples are being compared to apples.

Best regards,

Matt

 

[Bill Boehme]

Brian, there was an article in AW by Alan Lacer one or two years ago and I believe the conclusion was that a honed edge is usable for a longer interval between sharpenings.

 

[Odie]

You might want to read what he says about this, I did..

http://www.ellsworthstudios.com/interviews/interviewDavidEllsworth.pdf

Thanks for this, Steve......

It doesn't surprise me that David Ellsworth took a concept that was already being experimented with and modified it. That was innovation at work.....and, a bit of "vision"!

ooc

 

[Odie]

Odie a question?

WHO DO YOU THINK HAS CONTRIBUTED THE MOST THE STATE OF WOODTURNING IN AMERICA

Al......

That would be a question subjective in scope. I believe if you took a poll of knowledgeable turners, David Ellsworth would be among the top of that list.......and, that's where I'd put him.

ooc

 

[Odie]

I believe I've made a few mistakes in this thread......

First of all, is to assume the point would not be completely lost, and irretrievable on so many here. My assumption was incorrect the average age of those on this forum meant there would be a higher level of wisdom in seeing that point. I failed to see the degree of hero-worship, sainthood, adoration, etc., there is.....and, it's probably deeper than I thought! This is human nature I suppose, and we all do need our heroes. I have my own heroes, too! In the world of woodturning, David Ellsworth is a very good choice IF someone needed a hero that can do no wrong.......for the rest of us, including me, he is someone to admire and learn what I can, from what he has to offer......but, his place is somewhere less than sainthood status in everything he does. I'm sure Ellsworth realizes this about himself, but there are those who put him far above how he sees himself......and THAT is the point.

Another mistake I've made is to not make the point absolutely clear, and therefore avoiding those who thought I was attacking David Ellsworth himself. I was attacking the "larger than life" status he has among some (many) turners.....and, not him personally.

ooc

 

[hockenbery]

Odie,

do not confuse admiration and respect with deification and beatification.

I have a deep respect and admiration for David.

Al

 

[MichaelMouse]

For most turning I find honing a waste of time. But when I need that really sharp edge I 500 grit diamond hone then go to a pulley belt with tripoli on it. Thats shaving sharp. But last for just a few cuts. Which is what i want.

You shave with the blade broadside to the whiskers, right? Don't pull that blade longwise on your flesh. Hopefully, you only go broadside into the wood when you absolutely MUST while turning. The edge analogy I suggest is a comb. When you look at it wide, it's pretty ragged looking. The standard pocket comb usually even has two spacings (grits) to reinforce the point. Now sight along the edge. Not only can you not see where the coarse and wide are, it looks sharp, too. Presentation trumps grit,as I see it.

Couple thoughts. The edge goes bad because it rolls its own burr, not because it chips out. Change analogies to a saw, where the teeth have set in them. Only you don't hammer them out, you abrade them away. That's why honing, where the steel is amenable and the damage caused by something besides sand in the bark (guilty!) works to make a good edge again. Or turning a new one with your burnisher, where the metal is malleable enough.

Or, the edge goes bad because it is rounded by extremely fine abrasive in the wood itself. The kind that makes your 600 stone look like a 60. A few passes with that heavy 600 grit makes a chamfer out of a roundover, and off we go again.

I personally don't know whether Ellsworth knows more about metal and edges than Doug Thompson, Ron Hock, or even Charlie Potatoes down the block. But I do know that the Halo effect can be misleading. http://www.wisegeek.com/what-are-halo-effects.htm

 

[Gretch Flo]

interrupting to sharpen

" Obviously I've touched up an edge just so I don't have to go resharpen but that's when I feel it getting a little dull and don't want to stop the lathe."
Brian
Brian-I hate interruptions. So I have five 5/8" ellsworth/Jamieson gouges that I number. I sharpen 5 at once. When I use #1 for roughing and I want a final cut I go to #2. #1 may still be good and I got back to #1. Then use #2 for more roughing and #3 to final cut, etc. Even if you had 3 of the same gouges it would save time, Gretch

 

[Thomas Stegall]

To hone or not to hone?

At the 25th AAW symposium I had the privaledge to do video for the demos including Dale Nish's demo on turning a bowl from green wood. One of the attendees asked about Dale's view on the value of honing turning tools. His response was to say that it has great value in woodworking hand tools like a traditional chisel. However, since the average turning tool will cut more wood in an hour of turning than a chisel will likely cut in an entire lifetime, he did not see the value in honing after each sharpening. He estimated that on american hardwoods the honing sharpness probably had a life of 5 seconds during stock removal. (I would imagine that duration would depend on which turning tool and what type of cut was being done, but his point was well made).

He went on to say that he had asked Richard Raffan if it was possible to produce a noticably better surface on wood with a honed tool. Richard said "absolutely". Dale then asked "So do you hone your tools?", Richard replied "No" Dale asked "Well why not" Richard said "Because I am a woodturner, not a tool sharper, its a waste of time, unless you plan to only turn for five seconds."

By the way in, the course of this discussion I think two things have gotten confused at least by some participants. 1) Honing a scraper and burnishing a scraper are two very different processes with two different results. 2) (Regardless of our opinion of David) Odie's critcism of individuals who in his terms "worship" David, is not the same as being critical of David himself. His words could have been better chosen as he has acknowledged, but it seems the intent of his comments was directed at "hero worshipers", not the hero (David) himself.

While you may see things very differently from Odie, the element of hero worship or the "halo effect" that he was attempting to address, is alive and well within the AAW. And its certainly not limited to the admiration of David. Since our club has been able to bring in world class demonstrators for club demos I see it all the time, even among my friends. Sixty year old men anxiously waiting for an autograph and conversation from a demonstrator not all too differently than when they were teenagers at a rock concert.

Binh was just telling me last week that another friend we have in common has coined a term he calls the "Binh Effect" because our friend often gives Binh some cash to make a purchase for our friend's collection when Binh travels to various symposia. The "effect" is that when Binh attempts to make this proxy purchase for our friend, the artist who five minutes ago was asking $1200 for a piece, refuses to let Binh pay for it at all once Binh has expressed an interest in buying the piece. They assume Binh is buying it for his own collection and they refuse payment for it. Binh then has to explain that it is a proxy purchase in order to get them to accept payment for the piece. I'm sure this "effect" is not unique to Binh, and is evidence of our tendency towards hero worship.

 

[KellyDunn]

Thomas, almost made me laugh. When I go to major events I get a bit of the hero thing. Since I dont teach as much as I used to it takes me by suprise as I am not used to it. They find out real quick I am human. But I am active in our local club. Not only no hero worship But when discussions of bringing in demo folks with certain talents come up and I say we the talent right in this room. And Its not just me I am talking about as we have some world class folks in our club. Well, they dont see me as having any talent at all I guess. Yet alone wanting an autograph or saying let me buy you a beer. Sometimes coming back from a major event has me feeling pretty good about my hat size. Then I go to a club meeting and that hat falls over my ears.

 

[John Sheets]

I have a CBN wheel from D-Way and I like it, but I see only two significant advantages:

1) Most importantly it doesn't need to be dressed, which I find to be a major PITA
2) It definitely is nicely trued and balanced

But remember that "doesn't need to be dressed" also means "can't be dressed".
So be sure that your grinder shaft has little or no runout, because once the wheel is in position on the shaft, that's pretty much it. No truing, rounding, etc. can be done.

 

[Steve Worcester]

I have a CBN wheel from D-Way and I like it, but I see only two significant advantages:

1) Most importantly it doesn't need to be dressed, which I find to be a major PITA
2) It definitely is nicely trued and balanced

But remember that "doesn't need to be dressed" also means "can't be dressed".
So be sure that your grinder shaft has little or no runout, because once the wheel is in position on the shaft, that's pretty much it. No truing, rounding, etc. can be done.

I had mine on a woodcraft grinder initially, and put blue painters tape on the face of the wheel and put a dial indicator on it. With a bit of measurement and moving the wheel adapters around, you can take some of any runout related to the shafts out.

 

[John Giem]

It is interesting to read all of the opinions about what is the best method of sharpening our lathe tools. Everyting so far has been subjective, no actual measurements of sharpness have been made or how long the edges last. The cutlery industry has a set of standardized tests for knives that measure, with numbers, how sharp an edge is and how it degrades with usage. Until we have an equivalent standardized set of tests for sharpness and durability, we will continue to express opinions and perferences. Without repeatable measurements yielding numbers that can be compared, this type of discussion will never estasblish the 'best' sharpening methods or types of tool steels. I will admit that reading about the different OPINIONS is interesting and instructive but this approach is unlikely to arrive at a solid defendable conclusion.

 

[Odie]

It is interesting to read all of the opinions about what is the best method of sharpening our lathe tools. Everyting so far has been subjective, no actual measurements of sharpness have been made or how long the edges last. The cutlery industry has a set of standardized tests for knives that measure, with numbers, how sharp an edge is and how it degrades with usage. Until we have an equivalent standardized set of tests for sharpness and durability, we will continue to express opinions and perferences. Without repeatable measurements yielding numbers that can be compared, this type of discussion will never estasblish the 'best' sharpening methods or types of tool steels. I will admit that reading about the different OPINIONS is interesting and instructive but this approach is unlikely to arrive at a solid defendable conclusion.

Well......not really.

Practical application is the best way to see what works, or not.

I hone, because I've tested honed and unhoned edges on the same piece of wood at the same time. The better results were from the honed edge. It's easy to do this test any ol' time, and the honed edge (presumably the sharper edge) always wins with the more difficult to turn woods.

We ALWAYS have a diverse set of opinions among turners, and there rarely is any subject where experienced turners universally agree.......so, the best thing to do is do what works for you, because there will always be those who will agree and those who disagree with the way you do what you do......

ooc

 

[MichaelMouse]

It is interesting to read all of the opinions about what is the best method of sharpening our lathe tools. Everyting so far has been subjective, no actual measurements of sharpness have been made or how long the edges last.

Can only refer back to the comb analogy. A guy who tries to push the tool broadly into the work will have an entirely different result than the guy who lets the wood cut itself by sliding along the edge. This guy has an interesting take on the matter - it's the steel. Also has an aside for the honers as to why it seems to work. http://www.woodturnersamerica.com/i...-little-time&catid=99:jerry-wright&Itemid=149

One final thought. I'm sure we're all familiar with the "steel" used on carving knives, and what it does? Takes the "set" out of the teeth, right?

 

[hockenbery]

It is interesting to read all of the opinions about what is the best method of sharpening our lathe tools. Everyting so far has been subjective, no actual measurements of sharpness have been made or how long the edges last. The cutlery industry has a set of standardized tests for knives that measure, with numbers, how sharp an edge is and how it degrades with usage. Until we have an equivalent standardized set of tests for sharpness and durability, we will continue to express opinions and perferences. Without repeatable measurements yielding numbers that can be compared, this type of discussion will never estasblish the 'best' sharpening methods or types of tool steels. I will admit that reading about the different OPINIONS is interesting and instructive but this approach is unlikely to arrive at a solid defendable conclusion.

John,
Sharpening seems to be the one area where turners disagree the most.
And much of it is undoubtedly due to a lack of science.
And even if you were to design experiment it is a large multidimensional space with lots of value for each variable



Steel type x flute shapes x grind types x wheel composition x wheel grit x wheel diameter x honing tool X honing method x materials to turn
4 x. 4. X. 6. x. 4. X 4. X. 4. X. 3. X. 3. X. Hundreds. =. One heck of big problem to find the best answer. If you do each combination in 20 minutes on a piece of clear white pine that would take about 8 person years.
Then do it for hard maple, cherry, cocobolo...

Professional bowl turners I know are about 100% on using a side ground bowl gouge, then they split on preferred steel, preferred flute and on specifics of the grind.
Most are now using a course 60 grit wheel for sharpening.. 15 years ago most were using a 100 or 120 grit wheel. Most use 8" wheels and I don't know any who honey heir bowl gouge.

They got there through trial and error and having mentors.
What is clear to them all is that they can turn more bowls with side-ground bowl gouge. So they all use it.

Next they deviate of the finishing tools. Smaller gouges, scrapers, side-ground bowl gouge

Science is great if it can be applied in a meaningful way.

It's a big problem...
Al

 

[Jim Carroll]

Optigrind CBN Wheels

Has anyone tried or does anyone use these CBN grinding wheels?...... What do you think of them, are they worth the money?


http://www.d-waytools.com/tools-diamond-grinding-wheels.html

Getting back to the original question, I use the CBN wheels from Optigrind, yes I have a vested interest in them as I sell them as well here in Australia.

Yes I do like them I think they are fantastic, they give a great edge right of the wheel. They are best used on a slow grinder but can still be easily used on a normal bench grinder.
I use mine on a 6" Cruesen slow speed grinder 1400rpm and it runs a lot cooler than the white aluminium oxide wheels. You can still generate a bit of heat but the downside of that is you grind away a lot of steel.
I also advocate the use of grinding jigs as this gives you more control and less time at the wheel trying to get the edge right.
With a jig you can hold the tool securily and only use gentle pressure so less heat is generated.
We had a turnaround in Wagga a little while ago and resharpened about 30 different tools, all were impressed by how easy they were to use and the edge straight of the wheel, and a longer lasting edge. As some of you know we have some really hard timbers here in Aus so the guys were happy not to have to resharpen so often.
The wheels are not cheap but the biggest advantage is that once you set your jigs for different tools you will not have to do that again as the wheel is not dressed so angles will not change with reduction in diameter of white wheels.

I have never found the need to hone my tools I leave that for my carving chisels where I am the motor and need that extra keen edge.
As others have indicated a honed edge does not help your turning only wastes time from your turning.
Get in ther sharpen your tools and keep turning.

 

[robo hippy]

I don't understand the part about jigs saving steel because you can control pressure better, and spend less time at the wheel. This is not a matter of one method being better than the other, which in this case would be jig vs. platform/free hand grinding. It is a matter of how well you know what you are doing. The only thing that makes platform sharpening faster is that you do not have to set up a jig. Kind of like 'which holds better, a tenon or a mortice?" Of course the answer is they both work fine, when made properly.

robo hippy

 

[Odie]

I don't understand the part about jigs saving steel because you can control pressure better, and spend less time at the wheel. This is not a matter of one method being better than the other, which in this case would be jig vs. platform/free hand grinding. It is a matter of how well you know what you are doing. The only thing that makes platform sharpening faster is that you do not have to set up a jig. Kind of like 'which holds better, a tenon or a mortice?" Of course the answer is they both work fine, when made properly.

robo hippy

There is a lot of insight and truth to what Robo Hippy is telling us, here......

The old saying about "there's more than one way to skin a cat" holds true!

For myself, I did freehand grind, but it's been 20+ years since I have with any regularity. I was never that good at it, but if I had stuck with it, I have no doubt I would have learned to use freehand as well as some of the other turners do.......but........around 1990, or so, I purchased a Wolverine, and have been using it ever since.

Like Robo indicates......learn to use what you got, and you'll make it work as well as the alternative.

I will say this, though........ Jigs do make the less experienced turner get results easier than freehand, but freehand will get the same end result with a little perseverance and practice.

His point about less set-up time is to be considered.......

ooc

 

[Jim Carroll]

granted jigs take time to set up but so does regrinding because you have not got the correct hold on the tool or the angle was not just right and there is an extra facet there where there should not be.

For most turners it is basically seconds to put the tool in the jig and know that a couple of wipes later you are back at the lathe . Not having another go because you did not get what you wanted.

 

[MichaelMouse]

As Roy says, the tool is its own jig. Lay it on the wheel and follow. Just like turning, if you think about it. Not to say someone couldn't wreck anything, but grinding a "facet" of any significance beyond optical would take some extra effort.

I use three-five different gouges in different applications on the average bowl, each of which would require a reset of the jig. Too easy to do it freehand to spend time with a jig.

 

[robo hippy]

My stance on free hand grinding/sharpening is that you have all the skills you need to do it, and have developed them by turning. ABC: anchor the tool on the tool rest (I use a platform, not really free hand) rub the bevel and cut. You move with your body. Learning this is no more difficult than learning jigs, it is just a mental thing.

robo hippy

 

[Matt Lewis]

"It is also my opinion that if you could survey the best of the best turners......they ALL would be honing their tools to perfection!"

Now there is a statement I wouldn't put money on being accurate. Mostly because nobody would ever agree on the so called "best of the best turners."

Back to the technical discussion...have we considered speed and feed in this equation? Isn't it an incomplete argument one way or the other without consideration of those two items?

This discussion reminds me of when I bought a really capable/fancy rack stereo over twenty years ago because I wanted the best system I could afford. Later I realized that the system was much more capable than my ears and required far more input from me to tweak it to its full potential. Consequently, I spent a lot of money and lugged the thing around the world for many years and never pushed it to its full potential. Lesson learned is that something smaller and less capable would have done the trick sufficiently and although a "better" more capable system was in my hands I never really needed it. I guess I am trying to say that the "best" of something is really only a useful term if you are comparing like things and like requirements. And I think it only matters if you can detect the difference or care to. Can the folks buying your objects detect the difference and if they can do they care to? Besides, it all ends up being a matter of opinion...just like if a turner is really good or not. Everybody has their favorites I suppose.........

 

[wnnelson]

Honing wastes time?

I have never found the need to hone my tools I leave that for my carving chisels where I am the motor and need that extra keen edge.
As others have indicated a honed edge does not help your turning only wastes time from your turning.

At a demonstration by Allan Batty he honed his tools all the time. He kept a slip stone in his apron and constantly used it as he turned. I don't remember him going to the grinder once. If you know his history he was a English trained production turner. He stated that they were taught to sharpen their tools with a grinder once a day at the end of their shifts. The whole next day of turning was done with only using the hone to get a good cutting edge. What do you think is faster, honing for a good edge or going to the grinder? Time was money for him but I'm sure that quality also counted in the finished product. True they did not have the sharpening jigs that are so prevalent today but I think the way they were taught the jigs would have wasted their time not improved their work. So to say that honing is a waste of time is a extreme leap in thinking and definitely not true for all turners.

PS
At this time Mr Batty is not doing very well and is very ill. I wish him and his family well.

 

[Brian McInturff]

I'm a believer that honing is a waste of time for removing waste wood down to the finish cut. Then, it depends on how the wood reacts to my finish cut if I hone. So what this boils down to does the removal of the waste wood benefit any from honing. Maybe would be the likely answer. Maybe, if you only use one gouge. Like many others , I use several tools when I'm turning and rarely have to resharpen before I get to the finish cut.

So, let's go one step further. Does honing speed up the removal of wood? I'd say "MAYBE" but probably not enough for me to notice.

Disclaimer: finish cuts are excluded.

And where do you stop with honing? 600? 1200? 3000? Diamond paste honing? If you are a honer then why stop at one of these grits? If you really want that sharp, keen edge then why not take it to the limit? Maybe it's because you think it's sharp enough....

 

[Odie]

I'm a believer that honing is a waste of time for removing waste wood down to the finish cut. Then, it depends on how the wood reacts to my finish cut if I hone. So what this boils down to does the removal of the waste wood benefit any from honing. Maybe would be the likely answer. Maybe, if you only use one gouge. Like many others , I use several tools when I'm turning and rarely have to resharpen before I get to the finish cut.

So, let's go one step further. Does honing speed up the removal of wood? I'd say "MAYBE" but probably not enough for me to notice.

Disclaimer: finish cuts are excluded.

And where do you stop with honing? 600? 1200? 3000? Diamond paste honing? If you are a honer then why stop at one of these grits? If you really want that sharp, keen edge then why not take it to the limit? Maybe it's because you think it's sharp enough....

One thing to consider, here, Brian.......is the less clean the cut, the deeper into the wood the wood fibers will be effected. For a roughing cut, I agree that this doesn't make that much difference, but the closer you get to the final shape, and especially the finish cut, sharpness does make a difference in the quality of surface finish that can be achieved with minimal sanding required.

Sharpness doesn't mean you can remove more wood.......only the cut will be cleaner. As MM continually points out (.....and, he is absolutely right!), a turner needs to let the tool cut the wood as it wishes to be cut. I know exactly what he means by that, but I suspect there are a few here whom that advice is completely lost on. No matter how sharp the tool is, it can be forced to cut more aggressively, deeper, and faster......but, this should not be the main focus. The focus should be to get the best cleanest cut, no matter at what stage of completion his turning is at the moment. Sharp tools accomplish that objective, but there is much more to it than that. The turner must learn how to best manipulate the tool through the cut, not to mention use of the best tool for that particular cut.

The exception would be when removing a lot of wood, just to get rid of it......like the bulk of the interior of a bowl. Here, I'm not too worried about the quality of the cut, but more interested in getting rid of the bulk. However, once anywhere near the final shape, the focus returns to getting the best cut. When there is wood to get rid of, I often find myself practicing, practicing, and more practicing getting a fine cut with nice smooth body movement, even though this isn't absolutely necessary in the evolution of any particular bowl. Every piece of wood has it's own characteristics, and lots of practice getting that fine clean cut adds to the knowledge base and skill level.....and this is also good for the soul!



ooc

 

[idahohay]

My contribution to he information overload, and in a way inspired by M.M.

"A turner needs to let the grinder grind the tool as it wishes to be ground"

 

[Thomas Stegall]

Brian brings up an excellent point regarding the principle of diminishing returns. At what point do you stop honing and why at that point? It seems that the argument to stop at a given grit could be used to stop at the grinder before honing?

In reference to production turners I believe their motivation for honing might be to minimize grinding away the tool because they do so much stock removal? Or because in a demo its hard to face the audience and talk to them while you are grinding? Or because a honing stone is easier to travel with when you can't rely on every place to have the same grinding jigs? It is a mistake to think that everything a pro does during the demo is exactly how they do it in their shop.

In either case I have heard nothing but good feedback about CBN grinding wheels, so I will give them a try, but with their cost, probably won't replace my white stones until they need it. The one thing I am unclear about is the issue of grit on CBN vs. White stones and which CBN grit would be more desirable for routine sharpening (before I hone of course).

 

[robo hippy]

The CBN wheels from D Way come in two grits, 80, and 180. The one from Acu Grind comes in 200 or 220 grit. When the D Way wheels are new, they are very aggressive, with the 80 grit cutting like 40 grit, and the 180 cutting more like 80 grit. They do break in, and the 180 is closer to standard 180 grit wheels. I haven't seen the Acu Grind yet, and will check them out in San Jose. I have both wheels. I use the 80 on my scrapers as they produce an excellent heavy duty burr for roughing out bowls with. I do sharpen my bottom feeder type gouges on that side as well because the platform is already set to that angle. Some times I sharpen them on the fine wheel as well, and don't notice any real difference in how they cut. So, 80 is more for roughing and shaping, though, not as fast as the belt sander at my saw sharpening service shop. 180 for most others.

robo hippy

 

[Odie]

Brian brings up an excellent point regarding the principle of diminishing returns. At what point do you stop honing and why at that point? It seems that the argument to stop at a given grit could be used to stop at the grinder before honing?

In reference to production turners I believe their motivation for honing might be to minimize grinding away the tool because they do so much stock removal? Or because in a demo its hard to face the audience and talk to them while you are grinding? Or because a honing stone is easier to travel with when you can't rely on every place to have the same grinding jigs? It is a mistake to think that everything a pro does during the demo is exactly how they do it in their shop.

In either case I have heard nothing but good feedback about CBN grinding wheels, so I will give them a try, but with their cost, probably won't replace my white stones until they need it. The one thing I am unclear about is the issue of grit on CBN vs. White stones and which CBN grit would be more desirable for routine sharpening (before I hone of course).

If anyone is interested, I see that Woodcraft is now offering an 8" CBN wheel in 120 grit. Here's a link:
http://www.woodcraft.com/Product/2021136/25960/WoodRiver-Diamond-Grinding-Wheel-8-120grit.aspx

================================

Thomas.....

Yes, this is a good point about the "diminishing returns" for honing. I think you and Brian are right that it's a valid consideration.....and, there has to be some point where it's not worth it to hone at any finer of grit. I regularly hone my gouges at 600 grit, and that works out well for my purposes. It's been a few years since I started honing with the diamond plates, but my next jump up is to 1200 grit. I did some testing with the 1200 grit, but felt I wasn't getting any better quality of surface cut with that high a grit. Since that initial test, I've stayed with the 600 grit for all gouges. From my perspective, I guess the "diminishing returns" point was at 600 grit. I haven't purchased every grit I can get, so my findings aren't too scientific.........but, the proof is in the surface quality I'm achieving on my bowls. This, I'm feeling satisfied with, so I've stayed with what works for me.........

ooc

 

[TJ Hamilton]

Odie, the Woodcraft link goes to a diamond wheel; I thought we established that CBN and Diamond were different? Help!

Tom, in D'Ville, confused.

 

[Brian McInturff]

I think 600 would be the choice of those that hone. I have a 1200 plate and think it "can" provide a little sharper edge but not worth the time. I have some diamond paste that goes to I think 4,000 or 8,000 that is packed up with some of my old flat work days. Never tried it with turning tools though, again not worth my time. The whole premise of my last post was to get across the fact that the reason that those that don't hone is because they found the results off the grinder was sufficient. And like wise those that religiously hone do so because that's what they feel works for them. Neither one is right or wrong and for anyone to state that one doesn't want a sharper tool(or however it was worded) didn't take into account that unless they hone theirs to the infinite grit then theirs isn't as sharp either. We all find what we are comfortable with and what gives us the best result we are comfortable with. I'd venture to say that no one could tell a piece off the lathe was turned with a tool honed or just from a grind. Tool control and presentation has a lot more to do with it.

This has been a very interesting thread.

 

[Brian McInturff]

T.J.
CBN wheels are a lot different than Diamond wheels. I didn't look back through the older posts in this thread but The differences have been posted, probably by Robo Hippy. He seems to have the best knowledge and explanation of the 2.

 

[Odie]

Odie, the Woodcraft link goes to a diamond wheel; I thought we established that CBN and Diamond were different? Help!

Tom, in D'Ville, confused.

TJ.......

My mistake........yes, you are correct..... there is a difference.

I ran a search and found the CBN to be a synthetic substance slightly less hard than diamond.

Here's that link......scroll down to see the difference between CBN and diamond.

http://www.riegger-diamant.com/grundlagen/aufbau-schleifscheibe.php

 

[Matt Lewis]

....... They do break in, and the 180 is closer to standard 180 grit wheels." robo hippy

Not sure I understand how the CBN wheels can go from one grit to another by "breaking in" as you can't change the fundamental properties of the material just by grinding to my knowledge. Isn't that the point of a grit specification? Help me understand. I have attached a primer on CBN wheels. The important points are the grit equivalence chart and recommended surface speed per minute on page 35.

Regards,

Matt

 

[Ian Robertson]

I have 3 CBN wheels, 2 from D-way and one Optigrind.

The 2 (80 & 180#) from D-way are 8" wheels mounted on a normal (2850 RPM) speed grinder, and a 6" (80#) Optigrind mounted on a slow speed grinder (1440 RPM).

I have had them for just over 6 months to see if they outlast white wheels. So far they are still performing as good as new. They have to last longer than 12 months to be a viable economic proposition.

For over 20 years I have freehand sharpened and then honed my skews because that is what I was taught to do but about 15 years ago I found that it was quicker to skip it as the finish off the wheel was sufficently sharp to do the job.

Gouges I have always polished the flutes on them but rarely honed after grinding unless it was soft timber that suffered tear out.

About 12 months ago we did a test on honing v's grinder sharpening and found that it is not worth the extra 10 seconds turning time you gain. The results are on another Forum.

In nearly all cases you are sanding the job anyway to remove to remove burnishing from the bevel. Polishers don't like burnishing because the finish won't key in.

I now use jigs to sharpen most of my tools for a very good reason.

The CBN wheels particularly on the low speed grinder have little or very few sparks so it very hard to tell where the edge is and whether you have "full" bevel shape.

On the point of Diamond v CBN this might help:

Diamond wheels deteriorate fairly quickly when used to grind steel.

The reason is, that the carbon of which diamond consists reacts at already quite low temperatures with the carbon which is in every steel and the wheel gets destroyed.

This does not happen if you use a diamond lap, as there are no great forces and speeds at work, consequently low temperatures.

The grinding grain to use for hardened steels is CBN, originally developed by GE. I was fortunate to learn about it many years ago at an SME conference.
Dietmar Holzer
OptiGrind Ltd.

As some raised the point of production turners only sharpening once a day then honing the rest of the day it is a matter of logistics.

In some of those works there may have been upwards of 20 turners working. There was generally only 1 grinder for the whole place. Could you imagine the queue at the grinder? Much easier and quicker to hone.

Timber was green and generally the imported exotics like mahogany etc were soft, much easier on tools so hence less sharpening.

In the final melt down it is what works for you and the quality of the product you produce.

 

[KellyDunn]

This is for Thomas and Brian, This subject seems to be important as it has really gotten large. The largess means things are getting repeated as its a long thread to read each post. It would seem the grinding wheels are a real hit with those that have them. So much so that when my white wheels wear down I will shell out the bucks for these. Then the thread got off on honing. in a yes or no way. Allan Batty and Alan Lacer are I think the only two turners I have seen who hone constantly. Allan Batty even uses a leather strop. The strop is a hand version of when I say I put compound on a pulley belt after hitting a tool with Alan Lacers 500 grit diamond hone and get a real sharp edge. But I am a production full time turner. I only do that when I need a very fine cut. And make no mistake, honing and polishing that edge will give you a fine fine surface. But it last a few seconds. Those few seconds are what I want at the moment for a given wood and cut. Straight off a 120 grit wheel and I tend to be a happy camper. For me when I hone and polish it alters the bevel. Its subtle but I have thousands of hours standing at the lathe. That slight difference I can feel. It actually changes the cutting contact surface. For me depending on the cut I am making it can be a distraction. If so I walk to the grinder and take the honing and polish right off. But I did use the polished grind to do what was needed.