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Glenn

Knife Class Log 107, Sharpening

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Tonight I will talk about sharpening.... 

And of course that is all dependant on the type of steel and how it is heat treated.  Think about a couple of uses for blades. One a machete Other a box cutter blade.  Machete needs to flex and hack and chop.  Box cutter slices,,if you flex it it will break.   You could get both of those from real similar types of blade steel.   But the heat treat would differ a lot,  Same with a straight razor,,real hard,,keeps a real nice edge,,,will break if flexed  I have terms I better cover.

7TZ5Y.jpg?1

The angle of this file to the blade will give what I call a course edge Think machete

gN5iF.jpg?2

Now I have changed the angle a lot so it will do a fine or keen edge.  And you can use a more coarse angle or a finer angle depending on the steel, the heat treat and the intended use  Does that make sense?TMYdu.png?1

This rudimentary drawing is of a cross section of a blade that has been hollow ground so the edges form the cutting edge

3VRpa.png?2

Rich Hale
This is really not the washington monument  It is a cross section of a box cutter blade  See the difference in the final edge? The first hollow ground right down to the edge would have to be completely reground to sharpen it  The box cutter could be just touched up on the angled edges and not move back onto the sides of the blade much at all
BjULG.png?1

This is a convex grind...some call it a appleseed grind  Now we can think about an axe or hatchet edge  Now we can think about an axe or hatchet edge L2KwS.png?1

This is a flat ground blade with a more coarse angle for the edge....Think kitchen knives  i have heard folks in person and on this site say they flat grind a blade so nice that the edges meet and form the cutting  edge

P9KYu.png?1

Like this  So if this gets dull just like the hollow grind we spoke of earlier,,,,it has to be reground from the spine to the edge to renew the cutting edge   But if we put that second angle along the cutting edge like we showed above it is easy to sharpen
Questions before we getmore practical?  thoughts on sharpening with buffing wheel  Does not work

stuarthesmith
with a hollow ground blade, can you sharpen it like a hybrid, just straight beveling just the edge?

garey
a little final angle on a flat grind makes the edge less prone to chipping.

stuarthesmith
and leaving the rest of the blade hollow ground?   in other words, just staight-beveling JUST the edge

Rich Hale
yes,,,that final edge whether on a flat ground or hollow ground will only be to get the angle you want and that is based on the thickness of the blade  Yes    So I grabbed an Axe,,the edge on it is a convex grind

uM0nE.jpg?1

I blackened the edge with a sharpie  Then hit it with a file   The left side I did not touch the black edge,,I shined up the area up the side of the blade,,,  I had the incorrect angle,,,   That is in left side of that pic  In the right side of that pic I only shined up the very edge of the blade,   Niether of them are correct for this tool

EJjGQ.jpg?2

So on the right side of this part of the blade I started with the file so it took metal away from the edge,,,,,the changed  angle as I filed Until I got to the edge  That continues how this edge was made to work,,,no flats,,,and it will work like it did when it was new As soon as I do the rest of this side and the other side Now to the box cutter blade  I use these things almost daily in the shop,,,I dull them And then resharpen,,,,,,,often

65Ykj.jpg?2

The left end of this blackend blade I have shined it up with wet or dry,,  See how I only hit the edge?  The will make a more coarse edge than it came with...   On the right side I never touched the bevel,,  Only shined up the sides of the blade
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There may be some material missing here
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The left end of this blackend blade I have shined it up with wet or dry,,   See how I onlly hit the edge?  The will make a more coarse edge than it came with...
Only shined up the sides of the blade  If I do that enough it will make a really kean edge,,will be sharper and dull faster in the middle I just got all of the bevel  That will restore it to how it was ground when new  Now as you do this,,, Whether you use hand tools

Abrasive papers
Stones
Diamond sharpeners
Ceramics
Belts grinders
Or stone wheel

When you grind the edge down to where it meets the other side  On the back side of the edge it will develop wot is called a wire edge  That is your cue to use a finer abrasive of your choice   if you did that edge with a 120 grit go finer,,,may 220 AThat will eave a smaller wire edge

DRoberts
i was having that exact problem last night, i need to get some finer grain sharpeners

Rich Hale
To feel the wire edge put finger on the back side near the spine and push it light towards the edge,,you will feel or may see a rouigh spot on the edge you can likelly use a thumb and wipe it off Or imbed it in your finge...youir call Then to a finer edge Finer abrasives as called for The axe is all a file  Machete maybe the same  Kitchen knife,,abrasives or stones Same drill on all of them Use a sharpie,,and as I did,,find the angle that it had to begin with Duplicate that angle

Questions?

stuarthesmith
as I understand it, the axe edge is convex, right? ok, so in order to sharpen it correctly, you need to know how to use a file most people have never had lessons using a file

Timothy Miller
you just rub the file around like you are using sand paper LOL

Rich Hale
Yes as I said above start back from the edge and roll over to catch the edge,,,a kind of a rocking motion,,,,,The sharpie
will tell you just where you are removing metal

stuarthesmith
much easier to file if the blade is held stationary in a vise or clamping device

Rich Hale
They just got one....lol indeed  and Wot Tim said is spot on

stuarthesmith
and I was taught to PUSH a file, and never pull it towards me

Rich Hale
Now let’s cover heat treat and kinds of metals again

garey
file= push lift up repeat.

Timothy Miller
I push my vise around all day it just stands there

Rich Hale
If you have a mystery metal And you don’ want to gamble a lot,  Garey Ford has a great way of checking both the metal he has made knife shape And the final outcome of his heat treat  Before he fits a guard, and before he puts handle on  He sharpens the edge to fine finish And then tests it as if it was a aomplete knfe  Then he knows a coule of things real soon It is all good and will be a fine knfe Or he has come up short in heat treat if redoing that is not good He has not got good steel and he will waste no more time on it, Words to work by i use the same few kinds of steel ,,except for the knfe chat knfe,, and I covered how I tested to make sure the coil spring would harden.

garey
if the blade sharpens up ok i cover the edge with duck tape so i dont bleed all over it.

Rich Hale
I buy all my steel new and I file check after hardening,,,,i trust that method based on a lot of using those steels, I finish the knife,,,and the last step before sheathe making is etching my name and then sharpening.  And every edge is tested
Now back to the buffer:

A buffer is a round object with an flexible backing with an abrasive compound applied  It will remove metal, It will round off edge even if they started out flat So if you want the exact same edge that the knife came with, duplicate that edge. That said,,,I sharpen my blades from rough belts to reallllllly fine belts on the belt grinder,,,,,I know the angles for each use of the blades,,,and at the finest belt,,I hit light on a buffer with super fine compound They get realy sharp angle,,,and I am not on buffer long enough to change anles.

On my box cutters:
In between sharpening I hit on both sides with a medium buffer  One time...   Next time I regind back to flat bevels like new Thats it for this eve,,,Questions??

stuarthesmith
you referred earlier to a "wire edge"  is that the same thing as a burr?
Rich Hale
Yes it is  And it is a clue to look for,  Dr did that help with the buffer

DRoberts
somewhat  i've had real bad success at buffer wheel sharpening all but very thin fishing knives  my fishing knife seems to take a very sharp edge from it, nothing else really does tho

garey
stroping Rich?

Rich Hale
Good thought Garey,,,I have stropped a few blades in the past,,,Tandy leather sells a little white rouge stick,,,you rub it on leather and strop the blade Direct it so you are not cutting into the leather

DRoberts
was wondering if it only is applicable for very shallow angles on thin blades

Rich Hale
id do all blades as I described above

garey
there are lots of little "tricks" like slack belt grinding/sharpening to get down to a wire edge.

DRoberts
definitely going to have to make a belt grinder

Rich Hale
The old barbers used a strop hung from one end and they wiped blade up and down it,,,I dont have luck like that I lay the leather flat on bench and keep the angle the same But the barbers made really nice edges  Slack belt is good for the convex grinds


garey
Rich i have a piece of old flat belt from the mill. it has a stiff backing on it. i put some olive oil on it and then rub red rouge into the leather for a strop.

Rich Hale
Just make sure the belt direstion is so the blade does not cut belt

stuarthesmith
when using a sharpening stone, rather than dragging the blade against the stone, can you drag the stone across the blade?

Rich Hale
When I use a stone I like to try and slice the top layer off of the stone,,,hold blade at angle I want,,,Sharpie will show  that also.  We have our allotted hour and will return to the regular chat, this log will be posted in a day or so and you are welcome to post questions in that thread,,,I check now and then and will answer,,unless I already did,,,,lol

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Seems like this forum needs a section on sharpening.  I didn't find it if it already exists.

anyway, every knife, sword, axe, and spear maker and anyone using tools needs to be able to sharpen their edges.

i recently saw a video on the razor sharp system.  

 

,

i bought mine from the local woodcraft store.  Used it several times and I'm very impressed.  Easy and quick and sharper than I ever got before using stones, diamond doodads and belt sander with strop.  

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That looks like a good system.  I like mine better though.  I use a 220 grit belt on my 2" X 72" belt sander.  I have a contact wheel but I prefer to use the slack area of the belt.  When I use gentle pressure I get a slightly convex grind, almost flat.  Then I buff with white diamond rouge on a sewn muslin wheel.  You will note that my system is quite similar.  I find that using the more flexible surfaces gives me more consistent edges that stay sharp longer.  I tend to get too fragile edges with the convex grinds... good for razors but poor for carving hardwoods.  My results are very similar also... but, IMO, subtly better.

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too bad you missed the entire knife making section,  let me relocate this there for you. I dont know of any serious makers that use the stone wheels for shapening, but what ever works for you, this seems to be a long infomercial....

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I too use the 2X72 belt grinder for sharpening knives and woodworking tools and find it superb for the purpose.  I have belts that go to 800 grit, but typically I only go to 400 grit.  I was going to make a holder so I could regulate the bevel to the exact degree I wanted, but find that free handing works so well I did not need to.  If I were grinding a bevel for the first time on a piece of steel I would want a jig.  I can use a belt grinder on many of my gouges as well.    For those of you who don't have or can't afford a large belt grinder, I used a 1X30 Harbor Freight $30 belt grinder for years and was very happy with it and an assortment of belts.

I should point out that sometimes with belts the convex bevel can get away from you which basically means you have rounded over your edge ever so slightly.  When this happens on knives I just start over on the belt grinder, when it happens with a chisel which requires a straight flat back I have a set of diamond plates I use to reestablish the correct surfaces.

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Hi everyone quick question for you all?What kinda belts do you recommend for sharpening? I'm going to try my hand at some knifes and want to know will standard wood sanding belts work or should I get something more hefty? Thanks for any and all help have a great day everyone.

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you can point them in the right direction., but when they wont read the info, its hard to help

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I do not recommend sharpening on a belt sander. I do recommend sharpening on a well made belt grinder.

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So I found a chisel today. The end is pretty well blunt. Was wondering if there is any certain angle I should put in the edge or just sharpen it at the angle it’s at already

E8C6016D-2EA9-4405-8810-44F5BA909018.jpeg

E3CCAFD1-C809-47C9-87B1-A2C6170D75B9.jpeg

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I was going to link a site named, "How to sharpen a cold chisel," then happily I decided to see what they said first. The very first instruction after the obligatory safety directions was to use the side of the grinding wheel. Maybe that's the new norm but using the side of a grinding wheel for anything but sharpening a pencil would get you desk study and test time in any shop class back when. Dad would yell at you and if he caught you doing it again maybe get you 86ed.

So I didn't link that site. After skimming more sites than my dry old left eye was willing to abide I decided to post this instead.

https://images.search.yahoo.com/search/images;_ylt=Awr9JhbzvstbMGwAdZRXNyoA;_ylu=X3oDMTEycTRtaDRhBGNvbG8DZ3ExBHBvcwMxBHZ0aWQDQjU3MDFfMQRzZWMDc2M-?p=Cold+chisle+bevel+angle&fr=crmas

If that link doesn't work, the terms that worked for me were, "What angle to sharpen a cold chisel."

Frosty The Lucky.

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I’ll check it out. I want to get one of those CBN grinding wheels(cubic boron nitride), you can actually use the side of those safely and they last forever. Since I don’t have a good grinding wheel right now though I’m going to use my belt sander to get it close to how I want probably. 

Also do you think that should be a cold chisel or a hot chisel? Or does it matter much. I know a cold one should be hardened. Not sure if this one is since I just found it in the dirt while cleaning up the garage today. 

This one is beveled on both sides as well 

B86DA294-3453-4FD2-85EF-51D442252A3D.jpeg

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1 hour ago, Pr3ssure said:

CBN grinding wheels(cubic boron nitride), you can actually use the side of those safely

Please provide your reference where it is stated that using the side of a CBN wheel is being safe. It is new to me and I want to read up on it.

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I’ve seen it in a few videos and a few articles, I’ll find it though. Give me a sec. they are awesome. But they have the CBN on the top and it goes to the sides a little bit. But they are of solid steel construction so you don’t have to worry about them exploding or anything like that. 

One sec and I’ll link it

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28 minutes ago, Glenn said:

Please provide your reference where it is stated that using the side of a CBN wheel is being safe. It is new to me and I want to read up on it.

 

It depends on the manufacturer, the wheel and typically the grit.  I have CBN wheels in my woodshop to sharpen my HSS lathe tools and would never try to grind on the sides as mine are not designed with any CBN material on the side to speak of.  Optigrind does have CBN wheels that they say are ok.  "All of our standard grit 170/200 wheels come with the CBN coating on the side to enable side grinding.  We do also supply our wheels in other grits.  A coarser grit wheel may be used for reshaping.  Most of our customers would not use the side grind for reshaping.  For that reason and to maintain the consistent prices of our wheels, coarser grit wheels do not come with the CBN coating on the side."

Source:

http://www.optigrind.com/

 http://www.optigrind.com/page_2538178.html 

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^^^this guy. Lol

https://woodturnerswonders.com/products/radius-edge-4-in-1-design-cbn-wheel-package

theres a link to a cool looking one I haven’t seen until just now. Has more on one side than the other with a radiused edge

I can’t find the thing I read before about them that said you could do it. Although like mishless said, you can’t do it on all CBN wheels, I’ve seen some that don’t have any or enough on the sides to use but I have seen a few that have the side specifically in mind with some having a half inch and some with a full inch of CBN on the sides. Watch some YouTube videos if you can, from what I’ve seen with normal and safe use they will never need replaced. At least not for a long long time. They do have a premium price though, between $150-200 usually, seen some for $100 but I wouldn’t trust the quality. I just found out about these the other night and was obsessed finding out about them. 

2 hours ago, MishlessFeat said:

Good quick reasons why to go CBN. Almost forgot they don’t heat much. They pretty much seem perfect from what I’ve read. 

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The reason we ask for references is so we can contact those references and get additional information.

2 hours ago, Pr3ssure said:

Watch some YouTube videos if you can,

I can and do watch youtube videos, and when beer is involved, or safety is not a priority, then you MUST move on. Injuries hurt and some leave scars, missing parts last a lifetime. Dead lasts even longer. 

Several of the hits I found suggest removing the safety guards when using the CBN wheel. Others discount the metal dust produced. Disabling and disregarding safety features is a red flag. 

Thank you for the references. 

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Yeah, I’d always leave my guard on just to catch sparks and the like but you run a slim to no chance of the wheel exploding which is why a lot of people opt out of the guard. Definitely still getting metal dust in the air just no grinder wheel dust. I think I saw the video you’re talking about though. I just want to get one to test myself. They look awesome and I love the idea of no dressing and it never gets smaller. There was one video I thought was really well made. I might find it when I wake up in the morning and I’ll put it up. Either way though I think they seem to be safer and far more efficient. 

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On the topic of grinding wheels and guards, nothing like a reminder of their danger.

A friend works in a workshop where he finishes up cast pieces on a large grinding wheel. He starts at 6 am yet there is another operator that starts earlier, and he is always greeted by the noise of the grinding.  This time there was no noise, the factory was silent but for a soft whirring in the background.

He went to investigate and found the early starter laying on the floor in a puddle of blood with his face missing. The bench grinder was still running without the wheel.

He was operating the grinder without guard.

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Having seen a grinding wheel explode and tear a hole in a sheet metal locker door 5 feet away I doubt the typical perspex guard would do much to save you. Best thing to do is go on a grinding wheen course and learn how to use them correctly before you go near one and then use the guard because it's better than nothing and will protect you from sparks and debris even if it doesn't do much for an exploding wheel. 

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Debatable and depending of the type of guard. The grinder in question is an industrial bench grinder spinning at 1400 rpm, with a 3" thick wheel and the guard is thick pressed steel not perspex. The guard has a quick release to reposition it to allow different areas of the wheel to be uncovered according to the shape of the work. The operator had some 20 years experience doing the same job on the same machine. It is what it is, and there was talk about sabotage from the coroner office since they found a crack on the wheel and some lateral damage to it. I didn't want to ask too many questions but clearly, using the side of a bench grinder is a bad idea and using it without cover, a very dumb one. 

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Don't believe what you see on Youtube without verifying it, talking to the manufacturer is a good idea. Grinding wheels are designed to be used on edge, for the most part anyway. I've seen poorly trained or just unskilled guys get things jammed between the rest and wheel, gouging serious grooves in and across the wheel requiring serious dressing to restore. Jam anything against the side and you'll probably eat wheel. 

One of our club members was grinding a blade at his winter place in Utah. A neighbor who'd stopped and chatted for a couple minutes walking to the store or where ever, heard the grinder running without a load as he walked past the garage on his way home. He stuck his head in to see what was up and found Gordon dead on the floor. The blade had caught and was taken around the guard and driven through his heart. He was probably dead when he started to fall.

Exploding wheels parts grabbed and thrown, etc. these are dangerous tools and there are two cardinal rules. #1. stand OUT OF THE PLANE OF ROTATION! #2. Do NOT experiment where you grid!

Had Gordon or the man Marc refers to been standing out of the plane of rotation they may have gotten off with a good scare or injuries. If you've seen mud slung of a bicycle tire you know what the plane of rotation is. Anything that swings does so in the plane of it's rotation, be it a wire wheel, grinder, belt grinder, chain saw, sledge hammer. Stay out of the plane!

I just got back from the Optigrind page. Thank you for the link. This is nothing like a "normal" grinding wheel and so the basic safety rule of NEVER grind on the side of the wheel may not apply to the specific wheels designed for the task. Looks like a heck of a tool, I'd love to give one a try.

Frosty The Lucky.

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CBN or Cubic Boron Nitride grinding wheels are designed for sharpening high speed steels only and should not be used for other applications.

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