Glenn Posted December 21, 2012 Share Posted December 21, 2012 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. The angle of this file to the blade will give what I call a course edge Think machete 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? This rudimentary drawing is of a cross section of a blade that has been hollow ground so the edges form the cutting edge 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 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 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 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 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 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 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 ------------------------------------------------ There may be some material missing here ========================================= 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 Quote Link to comment Share on other sites More sharing options...
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.