Question about final edge finishing/sharpening

[weo]

(reading post #29 first will clear up any confusion as you read this thread)

Hello all. I hope I'm not beating a dead horse, so to speak, but couldn't find an answer in a search. Also, I feel I need to add some background for my question, so feel free to skip to the end of the post, where the question is.

Seeing as how all my forging equipment is in storage, I thought I'd focus my time in 'perfecting' my sharpening technique. Also, I'm hoping to land a job teaching blacksmithing soon, and I have a feeling they are going to want me to teach knife making as well, so I thought I should have a consistent system in place.

When I was taught how to make/finish a knife by an ABS Master smith, his technique for final edge grinding was to hold the blade parallel to the platen, but using the slack portion of the belt between the top wheel and the platen to get roughly a 10-15 degree (my understanding, not his exact words) primary bevel, then hand finish the edge on water stones.

Up to this point in my knife making career, I haven't been able to do this every day, so I don't yet have the muscle memory to keep a consistent edge angle every pass, so I came up with this as a guide:

Also, up to this point, I have been primarily interested in kitchen cutlery and haven't been too concerned with primary and secondary bevels, but doing a full flat grind getting as thin as practical then sharpening using one bevel. My current system is to establish the bevel as I was taught using a used 400g belt on the grinder, then using 800g-1200g-2000g Japanese water stone progression, finally leather strop with buffing compound to finish the edge.

In researching 'optimal' edge design on hunters/choppers/EDC knives/etc I'm learning the importance of paying attention to primary and secondary bevels.

My question(s): Do you professionals:
(a) use the grinder to establish both primary and secondary bevels, then repeat the process on stones,
(b) use the grinder to establish just the primary bevel, then refine the primary bevel on the stones, then repeat the stone progression for the secondary bevel,
(c) use just the stones to establish both bevels (which would mean adding a rougher grit stone), or
(d) something else?

Thank you and have a good rest of the summer (or winter for those of you in the Southern Hemisphere)

 

[AVigil]

I have tried many many methods to get a repeatable good edge.

What I currently do is tilt my platen to the degree I want the edge and hold the blade perpendicular to the floor and use the space between the wheel and platen to put an edge on the blade, or close to it.

I then move to a guided rod sharpening system, like an edgepro, set the same angle I had at the grind and put the final edge on the blade.

Then I take it to a strop and knock off any burr left.

Then I am left with a sharp edge at an exact angle I want.

 

[HSC ///]

King Japanese Water stones only. 1000 grit and 6000
And or loaded leather strop

Never on the grinder.

This works for me on what I use which is mostly high carbon steels and thin behind the edge.

 

[weo]

Thanks for the replies, guys

Water stones only.

Sorry if I'm being obtuse, Harbeer, but are you saying you use the water stones to set the primary bevel and the secondary bevel on a hunter/edc?

 

[Rhinoknives1]

I grind all full Flat grind knives and eye ball in about 12 -13 degrees on a slack belt 2 x 72” at 1/4 speed or less on my Culinary knives. This is done on a 120 grit belt with several passings at a light pressure then 600 grit & then a 30 micron .. strop on a piece of card board and it’s GTG!

 

[Alex Topfer]

i do the primary bevels on a grinder during general shaping of the blade. i get the edge down to the point i can use it to cut up sandpaper while hand sanding it.
secondary bevel i establish with the grinder on a slack belt at 120-180 grit, then whetstones from 500 to 4,000 grit.
I can't notice 5 degrees difference with these geometries, so i don't sweat it. they are probably around 15 degrees per side? what i notice in use is thickness behind the edge, so that is what i focus on. i mostly make and use kitchen knives

 

[HSC ///]

Thanks for the replies, guys



Sorry if I'm being obtuse, Harbeer, but are you saying you use the water stones to set the primary bevel and the secondary bevel on a hunter/edc?

Better if you explain your definition of primary /secondary bevels first, then I can best answer

Regards

 

[Alex Topfer]

This is the terminology I use (although i do suggest we use tertiary bevel instead of micro-bevel, and explore the possibilities of a quaternary bevels)
From another thread here: https://www.bladeforums.com/threads...nology-primary-secondary-bezel-grind.1109295/

 

[HSC ///]

Since I’m a student of Murray Carter I use his description ... taken from an article about his sharpening :

“the primary edge on a blade is the sharp edge that can cut you. The primary edge initiates a cut. The secondary edge is the V-shape of the blade starting right behind the primary edge which dictates how easy or difficult it is to pass the blade through things. Cutting a string or thin paper is all about the primary edge, whereas trying to cut through acorn squash or thick shoe leather involves more of the secondary edge.”

 

[weo]

deleted

 

[weo]

Better if you explain your definition of primary /secondary bevels first, then I can best answer

Thanks Harbeer. I was using the terminology that Alex described. And I'm a student of other ABS smiths and recently read John Juranitch's book.


Edit: 2 Aug 2019 - My apologies, but I'm actually following Harbeer's terminology, my mistake)

 

[Metalhead0483]

I have been taking my blades down to damned near full sharp (usually, but not always with a slight convex right at the edge) getting them to full sharp on diamond stones, then finishing them on a strop with jeweler's rouge. way more time effective, and makes for a SERIOUSLY sharp edge.

 

[HSC ///]

Thanks for the replies, guys



Sorry if I'm being obtuse, Harbeer, but are you saying you use the water stones to set the primary bevel and the secondary bevel on a hunter/edc?

So I use king Japanese waterstones for the primary edge (cutting edge) for any kind of knife.

 

[Cushing H.]

If I may, I'll chime in here. I have been playing with different ways to sharpen knives for, well... going on 45 years . Assuming that you either have an existing knife (or one you are in the process of making), you have an already defined "secondary bevel" (i.e. not the action-edge/cutting-edge). The task is to create what this thread seems to be calling the "primary bevel" (the cutting edge itself). My experience has been that wet-stones (aka Arkansas stones) are a PITA. Hard to keep a consistent angle, they fill with debris easily (which reduces cutting ability), they go out of flat quickly, and they are not easy to get back in flat.

Out of desperation, I moved on to using a grinder (actually a HF 1x30 sander) sometimes slack-belt, with varying degrees of grit sizes - moving from somewhat coarse to finer to micro-fine to refine the edge - then finish up with leather strop. This works quite well - but only with lower hardness steels (though you still need to be very careful about overheating the edge). When I hit the harder (60-64 rockwell) japanese steels, I was forwarned the belt was a BAD IDEA. Had to try it myself though - and sure enough with these harder steels (and with the carbide content), even with the finest grits the belt just chewed chunks out of the edge.

Hands down the best approach I have found is what I am using now. Not cheap - but very versatile and creates a scary-sharp edge. I invested in a Tormek T-8 water cooled sharpener ( https://www.amazon.com/Tormek-Coole...rds=tormek+t8&qid=1564591630&s=gateway&sr=8-1 )

Allows you to set and keep an angle for the "primary bevel" (i.e. the business cutting edge) very accurately, and maintain it along the entire length of the knife (and for both sides). It also has available several wheels/stones, one of which is a "Blackstone Silicone" wheel that is specifically designed for very hard steels. (they also have a diamond wheel, but I have not played with that one...). Now ... with the very hard steels, the Blackstone wheel will cut the bevel, but still leave a little bit of serration on the edge. I then finish with a true Japanese Waterstone (1000/6000). Only takes literally a few strokes to refine the edge, get rid of the micro-serrations and any burr. This leaves a scary-sharp edge, even in the hardest steels I have tried (something like 64-66 rockwell??).

There is a little bit of a trick to doing the hand finishing on the waterstone - kind of like grinding the secondary bevel, only in reverse, and rock it until you have a very small gap between the stone and the edge. Then rotate until that gap between the stone and the edge just disappears (you have "found the edge"). Then take your strokes keeping the angle constant. Again, the final hand work literally only takes a few strokes.

FWIW. Again, not cheap (but cheaper than a grinder!) ... and the best approach I have found so far.....

 

[scott kozub]

No expert here but when I started, I was leaving my edges way too thick and it took too long to raise a burr on the whet stones so I messed around with a grinder but that seemed too easy to burn the edge, even with water. It was also hard to prevent grinding valleys in the edge. I started grinding my edges much thinner (0.002-0.003"). With a sheet metal gauge, its easy to get a consistent thickness but they only go down to 0.005. Once I started grinding thinner, it only takes a few minutes to raise a burr on a course whet stone. My edges are much better now. I'll sometimes also leave the heel a little thicker for heavier cutting and the tip thinner for finer cutting.

Note that I make mostly kitchen knives in AEB-L so I can get away with thin edges. Once you get below 0.004", the edge starts feeling sharp. Won't slice paper but it will cut very easily.

 

[Rhinoknives1]

If I may, I'll chime in here. I have been playing with different ways to sharpen knives for, well... going on 45 years . Assuming that you either have an existing knife (or one you are in the process of making), you have an already defined "secondary bevel" (i.e. not the action-edge/cutting-edge). The task is to create what this thread seems to be calling the "primary bevel" (the cutting edge itself). My experience has been that wet-stones (aka Arkansas stones) are a PITA. Hard to keep a consistent angle, they fill with debris easily (which reduces cutting ability), they go out of flat quickly, and they are not easy to get back in flat.

Out of desperation, I moved on to using a grinder (actually a HF 1x30 sander) sometimes slack-belt, with varying degrees of grit sizes - moving from somewhat coarse to finer to micro-fine to refine the edge - then finish up with leather strop. This works quite well - but only with lower hardness steels (though you still need to be very careful about overheating the edge). When I hit the harder (60-64 rockwell) japanese steels, I was forwarned the belt was a BAD IDEA. Had to try it myself though - and sure enough with these harder steels (and with the carbide content), even with the finest grits the belt just chewed chunks out of the edge.

Hands down the best approach I have found is what I am using now. Not cheap - but very versatile and creates a scary-sharp edge. I invested in a Tormek T-8 water cooled sharpener ( https://www.amazon.com/Tormek-Coole...rds=tormek+t8&qid=1564591630&s=gateway&sr=8-1 )

Allows you to set and keep an angle for the "primary bevel" (i.e. the business cutting edge) very accurately, and maintain it along the entire length of the knife (and for both sides). It also has available several wheels/stones, one of which is a "Blackstone Silicone" wheel that is specifically designed for very hard steels. (they also have a diamond wheel, but I have not played with that one...). Now ... with the very hard steels, the Blackstone wheel will cut the bevel, but still leave a little bit of serration on the edge. I then finish with a true Japanese Waterstone (1000/6000). Only takes literally a few strokes to refine the edge, get rid of the micro-serrations and any burr. This leaves a scary-sharp edge, even in the hardest steels I have tried (something like 64-66 rockwell??).

There is a little bit of a trick to doing the hand finishing on the waterstone - kind of like grinding the secondary bevel, only in reverse, and rock it until you have a very small gap between the stone and the edge. Then rotate until that gap between the stone and the edge just disappears (you have "found the edge"). Then take your strokes keeping the angle constant. Again, the final hand work literally only takes a few strokes.

FWIW. Again, not cheap (but cheaper than a grinder!) ... and the best approach I have found so far.....

A suggestion for those using Arkansas Stones/oil stones. Ceramics Don’t use oil. It just makes the stone plug up faster. Use Simply Green soap in the spray bottle. Squirt the heck outta the stone and you’ll see the crud float out. With with oil T-shirt or paper towels. Repeat a few times. Then just use simple green as your lube for sharpening. You are making contact with the stone that does the cutting. Works great! Some my Remember old

 

[REK Knives]

Here's how I do it and it's super accurate. Zero the angle cube out on the platen and adjust the bar in /out to exactly where I want it.

 

[Cushing H.]

Here's how I do it and it's super accurate. Zero the angle cube out on the platen and adjust the bar in /out to exactly where I want it.

Cool idea. Where did you get the bracket/brace? Looks exactly like the brace off of the Tormek system....

 

[REK Knives]

Cool idea. Where did you get the bracket/brace? Looks exactly like the brace off of the Tormek system....

It is, I purchased it and adapted it for my grinder

 

[weo]

Hello all. Thanks for the replies and suggestions.

My original question was based on my thought that, on hunters/choppers/EDCs, establishing the primary bevel (referencing Alex's posted diagram above) on the grinder with a 400g belt would allow one to see grinding lines from the 400g belt on this primary bevel compared to the flat of the blade where I use 2000-5000g when hand sanding.

It seems from all your responses that I'm overthinking this.