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+--- Thread: Deburring for a Toothy Edge (/showthread.php?tid=573)
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Deburring for a Toothy Edge - danforth - 03-03-2021
For you belt guys, I'm looking for recommendations on my final stropping/deburring.
Here is my typical progression:
1. Cubitrion II 120 grit
2. Trizact A30
3. Leather belt (smooth side) with green buffing compound
It gives a very sharp edge, but I find even with feather pressure, the green compound, while it assists it removing the burr quickly, polishes the apex of the edge. I'd like to preserve the tooth as much as possible.
I'm looking for input and discussion on options for step 3 above (or possibly adding a fourth step). Here are some I've thought about
Changing a step:
3. Use a leather belt (or other belt) loaded with CBN or diamond compound to maintain the tooth and assist in deburring without polishing action. Any suggestions on brands or micron size?
3. Use a finer or coarser buffing bar to control the rate of polishing action. Any recommendations on types? I think I am going to abandon the honing compound, personally. At least as far as tooth preservation is concerned.
3. Use a different speed SFPM for the final step so the polishing action is not occurring as rapidly. Could this reduce the effectiveness of the burr removal?
Adding a step:
+ 4. additional trailing pass on each side using a medium ceramic rod or ultra fine diamond rod. This works very well to restore tooth to the polished part of the edge. But really it is just undoing what has been done.
3/4. use scotch brite to deburr followed by plain or coarse side leather. I take it this is the approach many are using right now, and perhaps it is also the best. No compound and just use a two-belt deburr process.
I'd love to hear from those using CBN or diamond compounds for deburring and also those using scotch brite or felt belts do deburr. The SB I find gives fairly rapid burr removal. Felt I find has not produced quick or consistent removal.
RE: Deburring for a Toothy Edge - grepper - 03-03-2021
Welcome to the Exchange!
FWIW, here’s what I do. Not saying it’s the best way, but it works for me.
99% of the time I use 3 belts; Cuitron 150, VF Scotch-Brite and the rough side of a leather belt with no compound. I prefer not to use compound because, as you mention, it removes tooth. You mention slower SFPM so it sounds like you have a variable speed grinder. I use a Kalamazoo 1SM (Kally), non-variable 1800 SFPM, https://kalamazooind.com/products/belt-sanders/1sm-1-x-42-inch-industrial-belt-sander/ and a Kallyrest angle guide; https://www.mechusa.com
The biggest trick that requires the most practice is using the Scotch-Brite belt. It requires an extremely light touch to remove burr but not damage the edge. I’ve learned through a lot of experimentation to see what works. Now… This seems bizarre, but sometimes I’ll just barely tickle the edge against the Scotch-Brite at 45 degrees, just barely touching the edge just enough to chew up the burr a bit. Gotta be careful doing that and practice to see how far you can go, but it can be done.
I’ll also press the blade at 45 degrees to the leather belt. It’s surprising how much of that the edge can take, but then the edge is steel and the belt cow. Steel is much harder than cow.
The idea of the 45 degree thing is to bend the burr as much as possible in hope of stress fracturing it from the edge due to metal fatigue. Some burrs can bend back and forth forever as if they were made of gold, while others fracture quite quickly,
The last step is leather at sharpening angle to straighten up the edge. Without compound I’ve found that the edge can take pretty good belt/blade pressure and not remove tooth.
Admittedly, that process is a bit of an art form and requires practice. It also varies from edge to edge and how pesky the burr is to remove. Sometimes it’s easy, other times it can be a bit frustrating. Polishing an edge with compound to remove burr is generally quick and easy. For me at least a nice toothy edge is worth the extra effort of not using compound.
You mention your belt progression: 120 grit, A30 (800 grit). I’ve found 120 grit is more gnarly than necessary for general sharpening. It makes a toothy edge alright, but that coarse a belt is not necessary for a toothy edge. 150 grit is perfectly adequate. Additionally, 150 grit produces an edge that is toothy enough to stand up to a lot of leather belt work and pressure and still maintain tooth,
If the edge was super dull 120 grit would remove metal quickly but if hogging off lots of steel quickly is not the goal that coarse does not seem necessary. 150 grit removes plenty of steel and does not require much pressure to do it.
If you then do much grinding at all with the Trizact A30, the result will be an 800 grit edge, so unless a lot of lot of metal needs to be removed, what’s the point of the 120 belt? To me, an 800 grit edge is not toothy at all. If you start with an 800 grit edge and then use compound, it’s no wonder why the end result is a polished, not toothy edge.
Maybe try a 150 grit and skip the A30. Then try several of methods of deburring with/without compound and see how that works for you. The point is that 150 grit produces enough tooth to stand up to deburring on leather and still have “teeth” remaining after the deburring process. With an A30 grind, there is almost no tooth to start with and any additional work, especially with compound, will produce a polished edge.
Anyway, that’s what comes to mind. Hopefully it’s helpful. The key is to think about what you are doing and why. Then experiment to find a method that works best for you.
RE: Deburring for a Toothy Edge - danforth - 03-04-2021
Thanks for taking the time to write. Sounds like you have a very well thought out process. I have a few restaurant clients who complain that the knives aren't sharp when I use leather with compound, hence my trying to seek a toothier edge. One commercial account in particular is requesting an 800 grit finish, but with enough bite to grab a tomato skin, so that's why I've been using the A30 Trizact. Even when I can preserve the grind pattern, any use of compound is buffing off the teeth from the very apex. The only saving grace is how fast the burr removal action is. So I think for now I will move to no-compound finishing. For clients who are not requesting a specific grit, I will give your suggestion of 150 grit a shot.
I find unloaded leather alone is not enough to remove the burr, but sounds like a scotch brite can do it! There is also a white felt polishing belt made by 3M that does not have abrasive on it, but I also find that it's not quite enough to remove the burr. I'll experiment with the scotch brite some more. Sometimes I still see a burr under magnification following the felt or scotch brite belt. Do you think this is incomplete removal of the existing burr, or perhaps a new burr created by the belt? Then I guess plain leather might be enough to finsih the edge!
What kind of BESS reading are you getting with a 150 grit edge? I know perhaps it's not the right test for the application, but just curious.
Cheers!
RE: Deburring for a Toothy Edge - danforth - 03-04-2021
Here's a thought. The Scotch-Brite belts have abrasive in them, and the ultra-fine are about 400-600 grit depending on who is ranking them. Perhaps the edge you are creating is actually a 150 grit edge refined and deburred by the SB, and then finally honed by bare leather.
I spent some quality time deburring using scotch brite and found the best success with alternating high angle passes at almost no pressure (almost 45º as you say) followed by two at-angle passes (at the sharpening angle) with medium pressure. That alone will almost completely eliminate the burr and provide a very usable edge. One more pass with light to medium pressure on coarse-side, unloaded leather refines the edge so that it will push through newsprint paper but also split a tomato skin with ease.
Curiously, the coarser the edge, the better it worked. I suppose that's due to bigger saw teeth on the edge. Now if these edges are more functional for real world cutting, what's with the obsession with ever finer grits and mirror polish?
I do think that perhaps with water stones and hand sharpening, the teeth are never really polished off and the burr refined and then flipped back and forth until it severs; there's no real equivalent to leather honing with compound. Even when a hand strop is used with compound, the rate of polishing is magnitudes smaller than when done by hand.
I'll wait until I get some diamond compound and report back on how that compares.
RE: Deburring for a Toothy Edge - grepper - 03-04-2021
Okay… Here are some IMHO thoughts.
I have a few restaurant clients who complain that the knives aren't sharp when I use leather with compound, hence my trying to seek a toothier edge. One commercial account in particular is requesting an 800 grit finish, but with enough bite to grab a tomato skin, so that's why I've been using the A30 Trizact. Even when I can preserve the grind pattern, any use of compound is buffing off the teeth from the very apex.
Edge finish has little to do with sharpness as far as cutlery goes. Razor blades yes, cutlery no. Both a highly polished edge and a toothy edge can be very sharp. More than sharp enough to easly melt through tomato skin. A 150 polished edge and a 150 toothy will slice tomatoes easily. The problem I have found through experimentation is that when a polished edge dulls even slightly the smooth rolled edge rides on tomato skin, while the toothy edge keeps cutting.
It seems strange that your customers are complaining about an 800 grit edge. What sharpness readings do you get with the 800 grit edge? It seems that the edges you are producing must not be very sharp. When an edge is not sharp, my first thought is always remaining burr. But… Burr is rough with a very uneven surface. Burr generally cuts tomato skin quite well because it breaks the skin. It won’t last long because burr is crap metal, but right off the grinder I would think that it would.
So I am left puzzled. Again, what sharpness readings do you get with the 800 grit edge?
Even when I can preserve the grind pattern, any use of compound is buffing off the teeth from the very apex.
The grind pattern you see on the bevel may or may not be indicative of what is happening at the edge. You need a microscope to see if the grind pattern follows through to the edge. The apex is very thin and even if you can see scratching on the bevel the edge may still be polished with little “toothiness”. Additionally, to me at least, 800 grit produces a polished edge, not toothy. Compound applied to an 800 grit edge will no doubt produce an edge far more polished than toothy.
What kind of BESS reading are you getting with a 150 grit edge?
Generally greater than 80 and less than 150. Anything in that range works for cutlery. Not overly sharp so it dulls quickly, but sharp enough to work very well.
Curiously, the coarser the edge, the better it worked.
Yup. That is my finding as well. Toothy edges grab surfaces, break fibers and cut. Polished edges, unless extremely sharp, tend to ride on surfaces. Polished edges are good for push cutting, toothy edges like a miniature version of a serrated, edge work much better for slicing. When polished edges roll the roll is a long smooth surface, When toothy edges roll the roll is still a rough surface so it tends to keep cutting better when slicing.
do think that perhaps with water stones…
The sharpening method does not matter other than powered, and higher speed systems make it all happen much faster and with greater effect. In other words, the same results can be achieved with both powered and hand systems. By hand is just a LOT slower.
As you mention, Scotch-Brite (SB) is an abrasive and will produce burr. That seems paradoxical. The purpose of using SB is to grab and break the burr and base of the burr so that it can be removed with leather. SB must be used judicially or it defeats its purpose.
A toothy edge is created when a coarse abrasive cuts the apex leaving an uneven cut or “teeth”. The idea of using 150 grit is that it produces an edge that is toothy enough to withstand deburring and not get smooth during the process. How I do it, 150 grit seems to work well for that. If you use other deburring methods, like compound or grinding the burr with a finer abrasive then maybe a coarser abrasive like 120 grit might work better for your method. It’s a matter of creating an edge that it toothy enough so that when the burr is removed there is still remaining tooth.
Maybe you will find this interesting:
http://bessex.com/forum/showthread.php?tid=68&highlight=duplicating+the+lasting
RE: Deburring for a Toothy Edge - MaxtheKnife - 03-07-2021
interesting post so far, very interesting.
few months before covid i picked up a local butcher shop as a new exchange customer. he had been using the other sharpener for many years on a weekly exchange........(blades appeared to have been sharpened by hand on grinding wheel)......good meat cutting edge for 3 to 4 days and then dull.........priced very low...........been around maybe 70 years here locally........they work many trucks and many exchanges probably cover 500 mile radius.........restaurants, chicken houses, super markets, etc........knives and scissors for cutting meat - a very big outfit.
i was just a customer of the butcher, he did not know i even sharpened knives until i got my first van with the signs on it, so he asked me to sharpen a few of their knives that had gotten dull...........i did like 4 the first time.............probably guessing around 600 grit edge. butcher said they were pretty good..............few weeks go by and he calls me again and needs a couple more sharpened to get him through the weekend and wants to know if i can make them sharper............boners and butcher knives are the only 2 he used, so he gives me like 4 each this time.
i stop at A16 with leather and compound.............deliver
this process continues for a few months with me helping him out with their knives just to get him through certain periods when they dull rapidly and he needs fast for mostly weekend business after the 3 days of original edge dulls...............i am now doing a great deal of edge experiments on their knives for him and he always wants sharper if possible.....................i'll get to the end now.
he turns in all their knives and i buy him 8 Lasting Cut Boners and 8 Lasting Cut Butchers and i sharpen to A6 and light strop with old leather belt................he calls me every 2 to 3 weeks now for exchange...............i did sharpen to A3, but i can not find them any longer and he likes the A6 edge better................now days i use all 2" wide belts on commercial knives and the butcher i still finish on 2" A6.......i am not overly fond of the 2" after A30..............1" is much nicer............my opinion.
keep in mind he cuts only meat and a lot of it.
comments welcomed
.
RE: Deburring for a Toothy Edge - MaxtheKnife - 03-07-2021
during the winter months and thru this months i work only 2 farmers markets once a month, but starting in april they all go to every saturday or wed and thur. depending the the market.
here i pretty much follow the grepper plan on most knives...........120...180...or 220..........depending on the knife and its origin........scotchbrite and leather with compound.
some knives i go to 600 or A30 and no scotchbrite.
this blue scotchbrite ticket is one fine belt when broken in and used correctly..........my opinion again............
thank you mr Grepper and Gentry for your great post on here..............i enjoy reading and learning and trying to improve the edge.
remember they judge us on tomatoes.
RE: Deburring for a Toothy Edge - danforth - 03-07-2021
Thank you both for the interesting discussion. I do not have a BESS tester, but I do have a Wifi microscope capable of looking at the edge.
I have found that while the compound-loaded leather belt removes the burr very quickly, it also polishes the apex, so that even with feather pressure, the very tip of the edge is polished. Even if the teeth along the edge are preserved, the apex remains polished and can have a tendency to ride on tomato skin. If enough force is applied when cutting to allow the knife to sink in past that polished area, the teeth left by the scratch pattern grab immediately. some call this a polished toothy edge. I have been finishing this way for years, but have recently had complaints regarding tomatoes so this led me to more research and now this discussion.
As for the restaurant client complaining about the edge, I observed the edges under microscope and they were indeed apexed and "sharp." I can only assume when they complained about the sharpness they were actually complaining about toothiness.
As far as deburring, I was not getting good results at first with the scotch brite, but a little bit of practice and time with the microscope and I am well on my way. I find the microscope really helps close and shorten the feedback loop so that one can verify results against performance and physical feel of the edge and cutting.
My clients are very pleased now and I have no complaints at all.
Curiously, I had a look at a Richmond Artifex Knife, bd1n steel, which is purported to be made by lamson. This is a hybrid edge. On the left side of the blade the grind pattern extends to the apex, and on the right side of the blade, the outermost edge is polished. This is an interesting approach, best of both worlds perhaps? I have recreated this edge by using a scotch brite deburr followed by unloaded leather one side and loaded leather on the other side and it is great for tomatoes as well as push cutting newsprint or shaving arm hair. The aggressiveness is understandably less on tomatoes, but that is made up for by increased smoothness in the newsprint and shaving tests. If it's a right handed knife, I wonder if the polished bevel is deliberately on the right side.
I have an order of cubitron 150 belts on the way and will give those a shot.
Lastly, I tried a 28 micron diamond compound on a linen belt and this also provides good result with a nice cutting edge. The difficulty here is that the compound is still sufficiently aggressive to provide abrasive effect on the edge and induce a new burr when one is trying to deburr. will experiment more and report back.
Max: what kind of 2" grinder are you using? And what difference on the 2" vs 1" A30 are you noticing?
RE: Deburring for a Toothy Edge - grepper - 03-07-2021
As MaxtheKnife mentions, SB belts work best when they are worn in. They get much softer. When new they are pretty gnarly and aggressive. The break in period can be hastened by grindind a bolt head or some other chunk of steel with a bit of pressure for 30 seconds to a minute. That will break the bigger chunks of abrasive embedded glue in the fibers of the belt. It helps a lot. Just be sure to hold the belt or whatever with pliers because it will get hot quickly.
Mr. danforth – Get a PT50B (or an “A” if you wish) edge tester! You’ll never look back. I learned more in the first month of having one than I had in years of sharpening before. Then you will actually know how sharp edges are and be able to put a number to it you can share with others. When you say and edge was 175, everybody knows exactly what that means. It’s like saying its 33º instead of saying it feels a bit chilly today. Multiple measurements can be taken along the edge and will show presence of probable burr. I think it’s a necessity for anyone serious about sharpening.
I much prefer a 1” belt over a wider one because it allows working on a smaller section of blade. For example the area right at the heel can be sharpened without having to grind in the center of the blade too. This becomes really obvious with a 3” or even 5” blade. A thinner belt gives more options. That’s just IMHO, of course.
RE: Deburring for a Toothy Edge - danforth - 03-09-2021
@maxtheknife
About your butcher friend. Perhaps since he is cutting meat he is looking for that surgical edge! What do you think? Same way a scalpel would work, that’s why the A6 + compound deburr I
Works well for him.