Microbevels

[Blues]

At Lowes they sell a device for $10 that you can put on your stone that is propped up and it tells you what angle your stone is sitting at relative to the countertop. I set my stones in a rubber stoneholder and set the end of it on top of other stones or objects until I reach the desired angle from the counter. I hold the knife parallel to the counter letting the propped up stone hold my angle for me, picture a 1 sided sharpmaker tilted 90 degrees. It works well enough for me at keeping my angles where I want them. It is kind of like training wheels freehanding that I probably don't need at this point, but that is what I have been doing for years and I am a creature of habit.

Mike

http://www.amazon.com/Johnson-Level-Tool-700-Magnetic/dp/B00004T807

 

[sodak]

Pic's or it didn't happen

I'm starting to think that I need to invest in a better camera. I got my kids an "Eye Clops" for Christmas, it looks a lot like the other one posted here. If I can figure out a jig to hold things, I can plug it in to the USB port.... Hmmm....

 

[gunmike1]

This is my crappy picture. Even in macro mode my camera (or more like ME) takes terrible pics. The larger pieces are easily seen, but the dust like hair pieces aren't even seen on my 65" DLP TV that I am using as a monitor. I mean, you can't even see most of the timy whittles still left on the hair, let alone on the blade. Only the largest of strands are seen. I need a camera set up like knifenut1013's, in his thread on sharpening the Applegate the resolution and clarityy of those pics are just great. Oh well, it does show at least some ability to whittle hair. Now I need to get my back better (I can finally start physical therapy next week, being 6 weeks after surgery, and may get back to work within a couple months) so I can get back in practice.

I also would like to try the Aligner for no other reason than to get a beautiful looking edge. Knifenut's edge on that Applegate is great looking, and while most people I know want me to sharpen their knives they strictly forbid me from scratching up their blades. Most of my edges are horrifyingly scratched backbevels with an ultra polished micro, but that is how I get proper cutting performance, at least in my sick mind. A mirrored out full bevel sharpening finished with sub micron diamond spray would be fun to at least try once in my life, and using a jig rather than my caffiened out hand would be nice. Who knows, if the aligner clamp stopped me from having to bend over and saved my back from only being able to go one or two grits at a time before needing rest I may become a convert, though the paper wheels and power sharpening are calling my name as well. It sucks being a gimp, but at least microbevels save my back a lot of time once I have the backbevel set.

Mike

 

[db]

I'm not sure but there are many that know more than me that say the finish of the primary and secondary bevels do effect cutting performance. I can say that more polished back bevels does help the cuttting of sticky things like rubber idems and tapes. I believe what is behind the edge both thickness and finish are as important as the very edge. This is probably why I'm such a convex fan because I really get a mix of all bevels,primary, secondary, and a micro at the same time. Try this some time put your normal edge on a knife now polish the heck out of one side heck just do the secondary bevel and on the other side leave a coarse finish. Now go cut alot of real sticky tape and see if you notice a difference on how much goo is stuck to each side. If your real ambitious use two knives and polish one and not the other keeping your micro bevel finish the same on each you may even notice they are cutting differently.

 

[supasuprab0b]

i am goign to start using a micro bevel on all my blades, jsut got a sharpmaker, and it was practically begging me to have 30* hsoulders with a 40* micro bevel on my blades, so i tried on my blur, and i love it so far, i can actually whittle hair a little bit.

 

[pantina]

In my experience, the micro bevel helps me to achieve a sharpness that I cannot achieve by using a straight bevel. I feel like it comes down to my skill level at holding the knife perfectly up and down in my sharpmaker. When I do a straight bevel, the blade is always less sharp then when I do a microbevel at a more obtuse angle. Perhaps this is because I'm not that good at keeping the edge fully contacting the stones, but since there's less surface area on the microbevel part, it's more forgiving. Anyhow, that's my $0.02.

 

[Jason B.]

I picked up a new camera that goes to 400x and after many many tries I finally got a good pic. Knife is a G10 endura with VG-10 steel, I finished with a spyderco UF ceramic and then a leather strop with 0.5 micron diamond spray. I stropped at a slightly higher angle (something I usually don't do) just to get the burr off as this is my work knife and it does not need a high polished bevel.

After the UF ceramic

After being stropped, now thats a micro bevel

Sorry about the distortion but even my heart beat messes with the taking the picture.

 

[jimmyh]

How thick are the microbevels you guys use?

I've found that using a second microbevel on top of the first microbevel (~10-15um thick and ~50um thick) allows me to get even sharper than using a single microbevel.

If I sharpen it to the edge with the lansky ultra fine and one microbevel, I can whittle hair. If I put a second steeper microbevel on with about 10-20 strokes/side of the lansky UF it loses some sharpness (barely catching armhair above the skin), but after stropping with polishing compound loaded paper at the angle of the first microbevel, it gets sharper than stropping without the second microbevel- It'll instantly catch and whittle hair equally well in both directions of the hair.

I think this is due to the first microbevel taking the pressure so the stropping compound is only lightly dragged across the edge.

My M2 friction folder has a 50um thick 28 degree included microbevel and a ~10-15um thick 40 degree included second microbevel. When looking at the edge under a 400x microscope, I can see many chips that all seem to make it to the first shoulder. Should I make the bevel more obtuse or wider, or just occasionally reset it, as the chips do not seem to make a significant impact on performance?

 

[sodak]

You're better at measuring than I am! I really don't know how wide mine are, I just raise the back so the angle is 2 to 3 deg more, as "guesstimated" sometimes on my edgepro. I agree with the stropping, it really can help my edges also. I've never thought about why it helps the microbevel, your theory sounds as good as any I've ever heard.

 

[jimmyh]

I have a 400x 'toy' microscope that puts the image on a big flat screen TV. I just measured the width of a hair with a micrometer and then compared the sizes on the screen, with a little trigonometry to get thickness from width.

If you've never played around with sharpening and checking the edges on a microscope, you should!

 

[Jason B.]

I have a 400x 'toy' microscope that puts the image on a big flat screen TV. I just measured the width of a hair with a micrometer and then compared the sizes on the screen, with a little trigonometry to get thickness from width.

If you've never played around with sharpening and checking the edges on a microscope, you should!

Have you had any reliable measurements?

 

[jimmyh]

Have you had any reliable measurements?

It depends on how narrow your probability distribution has to be for you to call it "reliable". My 90% confidence interval for bevel thickness is probably +-30%, which isn't terribly narrow, but is certainly enough to be useful.

If I kept more sig figs on the micrometer hair reading, and used an actual ruler to measure the size on screen, I could be more precise.

 

[Broos]

Put together jimmyh's ability to measure edges, and knifenut's camera (to measure sharpness - really guage wear versus cuts), and you could do some jammin' testing. Great job on that guys.

 

[mbhanzo]

since I freehand, the edge is naturally convexed a little, and when I strop, raise the angle & only the very edge is polished. maybe that's micro-stropping?

Whenever you strop a blade you are to a degree establishing a very small convex microbevel on your edge.

 

[Jason B.]

Whenever you strop a blade you are to a degree establishing a very small convex microbevel on your edge.

Only if the edge has been cut by a jig, if its done freehand your just following the natural convex that has already been established by hand sharpening.

 

[mbhanzo]

Only if the edge has been cut by a jig, if its done freehand your just following the natural convex that has already been established by hand sharpening.

Yes and no. I do agree for the most part with you. The very apex of the cutting edge will be abraded and polished more rapidly than the rest of the face of the cutting edge by nature of its smaller mass and overall surface and the inherent deflection of the strop.

 

[kungfucowboy]

you guys realize you don't need any great gadet to get a benchstone at a certian angle right.
Originally Posted by gunmike1 View Post
At Lowes they sell a device for $10 that you can put on your stone that is propped up and it tells you what angle your stone is sitting at relative to the countertop. I set my stones in a rubber stoneholder and set the end of it on top of other stones or objects until I reach the desired angle from the counter. I hold the knife parallel to the counter letting the propped up stone hold my angle for me, picture a 1 sided sharpmaker tilted 90 degrees. It works well enough for me at keeping my angles where I want them. It is kind of like training wheels freehanding that I probably don't need at this point, but that is what I have been doing for years and I am a creature of habit.

Mike

you can save your money and use a ruler and calculator for the same thing. if you don't have a ruler use some notebook paper and measure in number of lines, if you are reading this your computer has a calculator or use one of the many online ones.

measure the length of your stone let's call this L
and then let's call the angle you want A
then let's call the height you need to put your stone at H

sin(a)=H/L or H=L*sin(A)

that means the height you should raise one side of your stone is equal to the length of your stone times the sine of the angle you want to sharpen each side of your knife.

see and you asked your teacher how you could use math in real life didn't you.

 

[pops1]

Great thread, I have often thought about keeping the tip very sharp for skinning and cleaning, but leaving the straight part of the blade with a larger angle for more strength for shaving sticks or what ever you want to do that you wouldn't want to do with a skinning edge. Now you have both a skinning knife as i usually use the tip for skinning and a work knife all in one and don't have to resharpen as often or risk damaging the edge.

 

[berzerker]

I've micro-beveled since I began sharpening, but I've been drawn into stropping to really finish off the burrs. (Nice idea, but half the time, I seemed to be doing more harm than good.) I've got a bunch of sharpening gear, but nothing seemed to fit the bill (even made a pair of slip-over strops for my Sharpmaker).

So, a few weeks ago, I built an angle-adjustable "tray" for bench stones. It worked fine, but it just didn't seem to be the solution--more of a curiosity and play for idle hands.

Last night I rebuilt it to handle stropping (and convexing). Wow, that was the right decision. Just the stropping of the micro-bevel gave very consistent elimation of burrs. At some point, I'll try snapping a few pix to post.

 

[pops1]

If you want to keep your angle the same when sharping use the larger muscles (your legs) not your arms. Place your blade on the stone of choice at the angle of choice and instead of trying to move your arms and keep this angle, use you legs to move your whole body holding your arms and the blade at the proper angle. It's too easy to change angles as you move your arms closer and farther away the angle changes and a flat edge is sharper than a rounded one.