honing

[Fred Belknap]

There has been a bit of conversation about CBN grinding wheels and what grit to buy and I see the term honing use quite a bit. Seems like the term honing is used to mean to sharpen after sharpening on a CBN. My question; what do you use to hone?? Another use I have seen is to hone off a burr from the grinding wheel prior to putting a burr back on with a burring tool. I have a rag buffing wheel from LeeValley and use green goop on it to hone. I also use a small diamond card to hone. Sometimes I don't hone and the tools still seem to work pretty good. Am I missing something???

[John Keeton]

Fred, there seem to be two schools of thought - those that do and those that don’t. Personally, I don’t see the benefit. The new steels won’t take as keen an edge as high quality carbon steel, and even if they did that edge would deteriorate quickly given the “mileage” covered with a gouge compared to a handplane. The quality of the cut might be smoother, but I suspect that difference disappears quickly when the sandpaper hits the wood. The time and effort spent honing just doesn’t seem worth it.

I am certain others will disagree on this issue.

[Reed Gray]

I have a 1000 grit CBN wheel. If I sharpen a skew on it and go straight to the wood, it will cut fine in one direction, but not the other. If I use a fine card hone on the burr side/side that won't cut, then it cuts fine from that side. To hone the burr off, I use my Tormek leather wheel with some buffing compound on it (emery stick from big box store) and hone both sides. So, before this type of honing, it is a NRS (negative rake scraper) because even a 1000 grit CBN wheel will leave a burr. That burr is soon gone. Most interesting demo I saw with a skew was Eric Loffstrom who started by tapping the edge of his skew on the lathe bed, then took it to a 60 grit CBN wheel, then honed on a leather strop, no intermediate steps. Wicked sharp edge... He uses a peeling cut for his finish cut.... Maybe not a 320 grit surface, but there are no tool marks like most of us mere skew mortals leave...

I use a 600 grit and 1000 grit wheel on my gouges once in a while as they do produce a much finer edge which can be really helpful for punky woods, or woods that are prone to tear out. That edge is lousy for any serious heavy roughing. I haven't noticed any advantage to honing the flutes.

My primary tool for shear scraping is a scraper (I have a shear scraping video on You Tube). The best edge I can get for the cleanest cuts is a burnished burr. The burrs from the 600 and 1000 grit wheels produce a very nice burr, but they go dull very quickly. In trying to figure out which way to get the best burnished burr, I do think that when I take the scraper to the leather wheel and hone off the grinder burr both on the top and on the bevel, I get a slightly better burr. If I use the finer wheel, then I can burnish the grinder burr down, which seems to break it off, and then burnish one back up. Not positive on that because when I burnish down there is still a small burr. Need 1000X photos of them. With the coarser wheels, I get pretty much the same results, though it does help to burnish off the grinder burr down and up at least once. The burnished burr can be barely noticeable, but it does cut very well, and holds a good edge longer than the grinder burrs. I can hand hone a burr on with a fine diamond hone, and still get a burr, but the wheels are much easier. I have been surprised on how good and clean of a cut I can get with a scraper where the burr has been totally honed off.

robo hippy

[John K Jordan]

There has been a bit of conversation about CBN grinding wheels and what grit to buy and I see the term honing use quite a bit. Seems like the term honing is used to mean to sharpen after sharpening on a CBN. My question; what do you use to hone?? Another use I have seen is to hone off a burr from the grinding wheel prior to putting a burr back on with a burring tool. I have a rag buffing wheel from LeeValley and use green goop on it to hone. I also use a small diamond card to hone. Sometimes I don't hone and the tools still seem to work pretty good. Am I missing something???

Fred,

Perhaps describe the kinds of things you are turning and the kinds of wood. Small spindles (finials and such) from dry hard woods like ebony and cocobolo? Small things from dry coarser woods such as walnut, cherry, or hickory? Larger things such as bowls and platters from dry wood? Larger things such as bowls and hollow forms from green wood?

I almost always turn dry wood, large or small, some of it quite hard. I always knock the burr from the grinding wheel off tools but I do it different ways, "depending." None of what I describe here applies specifically to green wood, often so soft (in my experience) it cut well with almost any kind of edge.

I often turn small things from hard, fine-grained exotic woods using primarily spindle gouges and skews. I like my spindle gouges to have a nearly polished edge which, for me, cuts better and stays sharper longer. I sharpen them on a 1200 grit CBN wheel on a Tormek then use the Tormek leather honing/stropping wheel with their compound. I do hone the inside of the flute with the leather profiled wheel but if I feel any burr I remove it with either a round tapered hone with very fine diamond grit or a curved ceramic hone. After using the gouge a while I'll hone the inside of the flute again and if needed hone the outside of the flute with an Eze-Lap extra fine diamond paddle hone as well (the blue one). I find this little hone easy to control on the curved outer edge. After a few honings the geometry of the tip changes a bit making the tool less effective for very delicate cuts so I put it aside for resharpening and grab another one. This may sound extreme but it is what I found works best for me for spindles with small diameters. The difference (to me) between preparing the gouges this way compared to using them straight from the grinding wheel is considerable, whether I grind with 220 or 600 grit CBN.

Note that a few seconds on the honing wheel does not leave a mirror polish on the entire bevel. If I wanted that I might try a hard MDF polishing wheel with compound - intuition suggests this would not degrade the edge like a softer buffing wheel.

I sharpen the skews by hand (without a jig) on a bench grinder with a 600 grit CBN wheel. Then I hone by alternating dragging both sides across a piece of MDF smeared with honing/polish compound. The surface of the MDF is too smooth to be effective so I resawed the piece on the bandsaw to expose a less smooth surface which works well. I like this method better than either the leather wheel or a flat leather strop I used to use since it has no chance of rounding over the edge like the softer surface. This gives me a near polished and extremely sharp edge which I like for thin spindles.

When turning larger things like bowls and platters and especially with green wood I sharpen with the 600 grit and remove the burr inside the flue and don't bother polishing the outside.

For conventional scrapers I have always, since I started turning about 15 or so years ago, used a carbide burnisher to raise a cutting burr, not bothering to remove the grinding burr. I don't use these much any more except for the small hollowing bits. I've ground most of my scrapers into negative rake scrapers.

For negative rake scrapers I use the extra fine paddle hone to lightly knock off the burr from the grinder then raise a smooth burr with the carbide burnishing rod. The burnished burr lasts longer than the ragged ground burr and leaves a smoother surface. When this edge starts to wear out I remove it the same way, sharpening the edge a bit, then burnish a new burr. I repeat this several times until the included angle of the edge increases enough to need more force on the burnisher so I stop and regrind.

As for polishing: I have a hard cloth polishing wheel I bought from a woodcarving shop, the same one I watched them use to polish carving tools. I don't use it on turning tools (or my carving knives) since I'm afraid it will round the edge over too much. When needed I sharpen and polish the carving tools the same way I do my chip carving knives - with ceramic stones then successively finer grits of wet sandpaper, from 15 micron down to 3 micron, then finish on a hard leather stropping board. (Unlike turning tools, carving tools in normal use get so little abuse from the wood that the edge is usually refreshed with just honing compound) BTW, from my reading even using a hard leather stropping board is controversial among the chip carving experts for fear of rounding the edge ever so slightly. The chip carving blades are and have to be the sharpest and thinnest edges in the shop. (They wouldn't hold up to turning for even a few seconds)

Just curious - what is the green goop you use and where do you find it? I'd like some kind of goop to use on my MDF stropping board instead of rubbing it with a stick of polishing compound.

JKJ

[John K Jordan]

...If I use the finer wheel, then I can burnish the grinder burr down, which seems to break it off, and then burnish one back up. Not positive on that because when I burnish down there is still a small burr. Need 1000X photos of them...

Reed, I have clinical microscopes and am not afraid to use them. I've sent you a note - maybe we can do some checking.

JKJ

[Fred Belknap]

JKJ I got this from Lee Valley http://www.leevalley.com/us/wood/pag...84&cat=1,43072 It seems to work pretty good, I use it mostly on some wood chisels and sometimes on some turning tools. I have a felt wheel mounted an old motor I had in the barn and it does a good job.

[John Keeton]

You guys are starting to sound like the Neander debates on the microscopic characteristics of edges using different sharpening methods.😄😄 There are folks that just enjoy the process of sharpening and the challenge of getting the ultimate edge and I enjoy the discussion!

[John K Jordan]

JKJ I got this from Lee Valley http://www.leevalley.com/us/wood/pag...84&cat=1,43072 It seems to work pretty good, I use it mostly on some wood chisels and sometimes on some turning tools. I have a felt wheel mounted an old motor I had in the barn and it does a good job.

Thanks, I actually have a bar of that (and some others). When you mentioned "goop" I imagined a tube of compound similar to the tube the Tormek sells. Theirs is great but it's apparently targeted towards the wealthy.

I suppose I could pulverize a bar of compound and mix it with some mineral oil or something. I wonder if my wife would let me use the blender...

JKJ

[Thom Sturgill]

One thing the discussion makes me wonder about - is there a confusion between what is a burr and what is a wire edge? Grinders will often create a wire edge which breaks off quickly or rolls the wrong way. You may feel it with your finger and think you have a nice burr. A shaped burr is "stouter" I think, as you do not move anywhere near as much metal, and thus lasts longer as it wears off.

I am in the camp that honed regularly before I got my CBN wheels. Honing with a diamond card produced a far superior edge as the AO wheel did not sharpen the carbides, but rather removed them. I could turn longer with a few simple passes of the hone occasionally. With CBN which does sharpen the carbides, I have not felt the need except possibly for that final pass (and my skews). I reserve the buffer and green paste for my wife's high-carbon carving knives and the kitchen utensils.

[Perry Hilbert Jr]

When I first started turning, back in the dark ages, we sharpened on an coarse oil stone and then honed on a fine oil stone. Grinders were used when the blade angle had changed too much and then both stones were used again. I use a fine grit grind stone and then hone with a stone or a diamond plate. HSS doesn't not sharpen to the same keen edge as carbon steel , but certainly hss edges last longer.

I have a piece of Tantung G here on my desk to be fastened to a bar for use as a scraper. I understand the edges hold up longer than with carbide with the added benefit that they can be sharpened at home on a grinder. I just don't have the torch to do the silver soldering.

[Reed Gray]

I have a friend who is a very accomplished spoon carver. His honing stick has 4 sides and 4 colors of buffing/polishing compound. He was complaining about a burr on one of his blades, and I couldn't feel it.

As for burr vs. wire edge, I think a third category could be added, and that is the CBN wheel burr. I really can't even remember what a standard grinding wheel burr was like. Last time I used one I was not even using scrapers the way I use them now. I do remember that there is a huge difference in the cutting edge from the standard wheel and the CBN wheels, with the CBN wheels being far superior. A long lasting cutting burr. I can rough out a couple of personal sized bowls without having to refresh the edge.

Perry, the Tantung G does not hold an edge as long as carbide, but it does sharpen well on standard grinding wheels. It has a coarse texture, not at all like the micro grained carbide that is available now. I was very surprised to find out that it responds well to honing for a more refined edge and cleaner cuts, and that I could burnish a burr on it. It is brittle, but a gentle brush with a burnishing rod does a nice job.

I do not burnish the burr edges on my skew type (30/30) NRS tools. I can hear the metal fracturing with minimal pressure. The more blunt ones like 70/30 take a nice burr.

This is the emmory compound I use:
https://www.amazon.com/Enkay-140-BL-...shing+compound
One site had 5 different colored sticks all for about the same price...

robo hippy

[John K Jordan]

You guys are starting to sound like the Neander debates on the microscopic characteristics of edges using different sharpening methods.😄😄 There are folks that just enjoy the process of sharpening and the challenge of getting the ultimate edge and I enjoy the discussion!

John,

I for one hate sharpening and the challenge and not the least interested in bragging rights. What I do love is how much better the tools cut now compared to how I used to sharpen! John Lucas has just finished a lathe tool sharpening analysis and has written an article for More Woodturning. (Doesn't yet know when it will be published.) I loaned him a sharpness testing device to try to get some objective comparisons. I've always wanted to be able to compare sharpening methods and be able to say something more than "Wow, that skew sure is sharp!"

One thing the discussion makes me wonder about - is there a confusion between what is a burr and what is a wire edge? Grinders will often create a wire edge which breaks off quickly or rolls the wrong way. You may feel it with your finger and think you have a nice burr. A shaped burr is "stouter" I think, as you do not move anywhere near as much metal, and thus lasts longer as it wears off.

....I reserve the buffer and green paste for my wife's high-carbon carving knives and the kitchen utensils.

Thom,

I think you hit the nail on the head. I think the "burr" from a grinder close what the knife makers call a wire edge but perhaps stronger since the grinding forces and heat are probably much higher. Under magnification the grinding burr is quite rough but scrapes very well for a short time. However, the surface from the scraping usually looks scratched to me. I've read people say they have to go back to the grinder to refresh the burr every few minutes. Yikes.

The Science of Sharp has some interesting stuff on the definition of a burr along with some great photos: https://scienceofsharp.wordpress.com...hat-is-a-burr/

I suspect the edge is actually formed by the steel becoming plastic and flowing under force and seems stronger than the wire edge I see half way through a knife sharpening session.

The burnished burr is smooth deformed metal, rolled up to make a smooth, sharp edge. The size and amount of roll can be controlled by the pressure used, the diameter of the contact edge with the carbide, and the angle of the rod. This burnished cutting edge is the same as furniture makers have been puttting on their card scrapers for ages although the usual instruction there is to burnish first in the reverse direction, then forward. The other day I was reading a book by Tage Frid from the '70s and found he burnishes hand scrapers the same as I do. I use a lot of hand/card scrapers in my turnings, for example on platters and the bottoms of bowls. This will flatten or dish the bottoms and take out any ripples or irregularities and save a LOT of sanding.

What, does your wife like sharp kitchen knives too?! I have a knife sharpening machine and I have to be careful not to let the kitchen knives go too long before sharpening. If I do, I have to put a sign up with "Sharp knives!" or she will draw blood every time.

JKJ

[robert baccus]

I sharpen with an 180 grit grinder and touch up the edge with a grinder and 6" lapidary discs in 180 & 1600 Grit when a need arises like a finish cut ect. Been using this for several years and planning to buy a 220 grit? CBN whether I need it or not! Just like a new gouge yeah.