£300 plus knife ? ?

[Broch]

That being said, I'd be using a dunk bucket every pass just to be safe.

What material do you run on your belt that puts up with getting wet? Mine deteriorates very quickly if I don't wipe dry after dunking.

A lot of tempering soak time is more to do with making sure the whole blade reaches the required temperature though I do accept that a spark generated heat will be very short lived. However, my point really is it's not possible to tell in a dry process what temperature was reached and, as you can't really test the hardness of the very edge, you can't say with any certainty what the hardness is.

If you're trying to convince petrochemicals that the process is sound I just don't think that video will go very far

 

[C_Claycomb]

(tongue firmly in cheek)
TOPS knives...the edges are so thick and obtuse that there is little reason to worry about over heating....they are not after all "thin" parts!

Sparks are a poor indication of the temperature the steel is at. Stainless steel tends to spark less, and seems to get hotter faster. The material being removed takes some of the heat away with it, same as in milling. What really heats a blade is a very fine belt moving fast, throwing almost no sparks and attempting to remove too much material.

Maybe what one thinks comes down to where one falls on accepting risk of over heating an edge, and what one thinks about "sufficient" vs "ultimate".

The risk of over heating vs method of sharpening is a gradient with steps. Anything that is powered, faster than a hands on a stone, has some risk of over heating, but that is usually well understood and steps are taken to mitigate the risk. Managing the heat generated can be done a lot of ways. Have any of you seen the cubic boron nitride wheels made for sharpening with bench grinders? Coolant can be used, flood, spray, mist, or intermittent dunking. A flood or spray coolant system has less risk of error than the dunk, but is much more complex and costly to implement. Skilled craftsmen can achieve great results with apparently limited tools. That should hardly need saying here.

There are many thousands of knives made that are sufficient and more than sufficient that set up the bevel on dry grinders, and there are other makers that use wet grinders, and others still that do it all by hand. The sharpening is just one small part of the knife and its quality can be made or broken on so many other things. One could argue that Rockstead make "ultimate" knives, and they sharpen and polish by hand on yards of wet and dry (could be Micromesh or other cloth backed material). They also get the other aspects right....BUT...you PAY for it!!! They start at around £600 and rapidly add £1000 to that!

Once upon a time I didn't have a grinder so had to form edges in hard steel by hand with a 220 grit water stone brick. A 6 inch camp knife took me five hours to grind down to an edge. Not finish sand, not sharpen, just get it down to a 220 grit burr at the edge, having hardened with a 0.75mm thick edge. That blade was filed by hand, which also took a long time. That experience showed me how much I needed a grinder, that there were key elements in making a good knife that I wasn't able to practice often enough if I was spending so much time filing and sharpening.

 

[0000]

What material do you run on your belt that puts up with getting wet? Mine deteriorates very quickly if I don't wipe dry after dunking.

A lot of tempering soak time is more to do with making sure the whole blade reaches the required temperature though I do accept that a spark generated heat will be very short lived. However, my point really is it's not possible to tell in a dry process what temperature was reached and, as you can't really test the hardness of the very edge, you can't say with any certainty what the hardness is.

If you're trying to convince petrochemicals that the process is sound I just don't think that video will go very far

Yes the times are set to get rid of any retained austenite, and a temper can be ruined quickly, I just don't think that belt sharpening is necessarily always doing that. I think cooling, angles, materials, grit size, belt speed and pass speed all play a big part. My point was that a blanket statement with words in it like "lazy, horrors, and abuse" are un nuanced and poorly thought out. I agree that the supplied video will do nothing for my argument and I agree that belt looks way too fast. You're right that I couldn't use my Rockwell tester to test the edge, or indeed any of the bevel. I suppose one could use rockwell files if they really wanted to know. I think different companies have different r and d and this one presumably has no data to suggest it should sharpen any other way. I personally use a wicked edge and it takes more time and effort but leaves a beautiful edge. I've convexed on a slack belt before though and had no notable edge issues in woodworking. This is even how I sharpen my bushcraft axes.

Oh as for the belts, I use water with all of them. Ceramic, aluminium oxide, trizact, gator belts. All of my bevels are ground post heat treatment so I'm sure you can imagine the job they have! Are you saying the abrasive falls off of yours? Or just wears quicker?

Sent from my SM-A705FN using Tapatalk

 

[0000]

(tongue firmly in cheek)
TOPS knives...the edges are so thick and obtuse that there is little reason to worry about over heating....they are not after all "thin" parts!

Sparks are a poor indication of the temperature the steel is at. Stainless steel tends to spark less, and seems to get hotter faster. The material being removed takes some of the heat away with it, same as in milling. What really heats a blade is a very fine belt moving fast, throwing almost no sparks and attempting to remove too much material.

Maybe what one thinks comes down to where one falls on accepting risk of over heating an edge, and what one thinks about "sufficient" vs "ultimate".

The risk of over heating vs method of sharpening is a gradient with steps. Anything that is powered, faster than a hands on a stone, has some risk of over heating, but that is usually well understood and steps are taken to mitigate the risk. Managing the heat generated can be done a lot of ways. Have any of you seen the cubic boron nitride wheels made for sharpening with bench grinders? Coolant can be used, flood, spray, mist, or intermittent dunking. A flood or spray coolant system has less risk of error than the dunk, but is much more complex and costly to implement. Skilled craftsmen can achieve great results with apparently limited tools. That should hardly need saying here.

There are many thousands of knives made that are sufficient and more than sufficient that set up the bevel on dry grinders, and there are other makers that use wet grinders, and others still that do it all by hand. The sharpening is just one small part of the knife and its quality can be made or broken on so many other things. One could argue that Rockstead make "ultimate" knives, and they sharpen and polish by hand on yards of wet and dry (could be Micromesh or other cloth backed material). They also get the other aspects right....BUT...you PAY for it!!! They start at around £600 and rapidly add £1000 to that!

Once upon a time I didn't have a grinder so had to form edges in hard steel by hand with a 220 grit water stone brick. A 6 inch camp knife took me five hours to grind down to an edge. Not finish sand, not sharpen, just get it down to a 220 grit burr at the edge, having hardened with a 0.75mm thick edge. That blade was filed by hand, which also took a long time. That experience showed me how much I needed a grinder, that there were key elements in making a good knife that I wasn't able to practice often enough if I was spending so much time filing and sharpening.

Well said. I couldn't agree more.

Ps. I can't believe you use a belt grinder. How barbaric. Do you also wear oven mitts and a blindfold when you use it?

Sent from my SM-A705FN using Tapatalk

 

[TLM]

I think that most of the work is done on the parts that are cut off, that work is what gets them hot. Some is retained though.

 

[C_Claycomb]

What material do you run on your belt that puts up with getting wet? Mine deteriorates very quickly if I don't wipe dry after dunking.

A lot of tempering soak time is more to do with making sure the whole blade reaches the required temperature though I do accept that a spark generated heat will be very short lived. However, my point really is it's not possible to tell in a dry process what temperature was reached and, as you can't really test the hardness of the very edge, you can't say with any certainty what the hardness is.

If you're trying to convince petrochemicals that the process is sound I just don't think that video will go very far

Wet, I use Norton Blaze and R984 ceramic belts. I also use Hermes RB515X silicon carbide/cork belts with green polishing compound. I haven't tried my Norax U936 engineered ceramic belt wet, but the backing is meant to be waterproof. I also have 3M micron belts down to 1200grit (15micron)

My Norax AO belts don't like getting wet, cotton backing and the surface gets muddy.

You are right in that if you dry grind you would struggle to prove what hardness you have at the edge, too small to hardness test easily without destroying the knife, but this isn't part of the space shuttle, its a knife, and if the heat hasn't turned the edge blue (often the burr can be seen at the edge, and if that isn't blue, the main blade certainly didn't get that hot) then the chanced of a noticeable, significant change in hardness is minimal. Anything that small is going to get removed on the first or second hand sharpen.

You say that one can't test. However you can test performance, do cutting trials, and take customer feedback. If the process is a problem then this will be highlighted.

Not trying to convince Petrochemical, but I wouldn't want someone new to read his post take it too seriously. Poorly drawn conclusions and biased views shouldn't go unchallenged.

 

[0000]

Wet, I use Norton Blaze and R984 ceramic belts. I also use Hermes RB515X silicon carbide/cork belts with green polishing compound. I haven't tried my Norax U936 engineered ceramic belt wet, but the backing is meant to be waterproof. I also have 3M micron belts down to 1200grit (15micron)

My Norax AO and Gator belts don't like getting wet, cotton backing and the surface gets muddy.

You are right in that if you dry grind you would struggle to prove what hardness you have at the edge, too small to hardness test easily without destroying the knife, but this isn't part of the space shuttle, its a knife, and if the heat hasn't turned the edge blue (often the burr can be seen at the edge, and if that isn't blue, the main blade certainly didn't get that hot) then the chanced of a noticeable, significant change in hardness is minimal. Anything that small is going to get removed on the first or second hand sharpen.

You say that one can't test. However you can test performance, do cutting trials, and take customer feedback. If the process is a problem then this will be highlighted.

Not trying to convince Petrochemical, but I wouldn't want someone new to read his post take it too seriously. Poorly drawn conclusions and biased views shouldn't go unchallenged.

Yup. Again I completely agree. I've not noticed any muddyness personally but I don't keep belts around too long anyway. I've actually stopped using gator belts though. Beautiful finishes when new but the abrasive seems very soft and wears unevenly for me. After 3 blades I start noticing some artifacts in my finish. The inside condition of my belts has radically improved since installing a glass platen, if you're interested.

Sent from my SM-A705FN using Tapatalk

 

[Broch]

Not trying to convince Petrochemical, but I wouldn't want someone new to read his post take it too seriously. Poorly drawn conclusions and biased views shouldn't go unchallenged.

Agreed, and reasoned discussion, which I believe we have now achieved, is always going to be more convincing than just presenting opposing views

 

[TLM]

Edges can't be tested with Rocwell C but they can be tested with micro Vickers tester. Though I just don't see much point.

 

[C_Claycomb]

TLM, if I could like your hardness test post twice, I would

For as long as I can remember I have had an affinity for older craftsmen. At university I got on much better with the crusty, grumpy lab and machine shop technicians than with the professors upstairs. Then when I started work, I found I had a lot of time for the guys on the shop floor. However, I am not blind to some of the short comings of taking their views as holy writ. Some of the experience old boys I have met stopped learning once they had enough to do their job. This wouldn't be apparent until they were asked to do something a little different or new. They would take it on, then it wouldn't work. I suspect there is a warning in that for me and us all!

It was older blade smiths who were happy using their forges or oxy torches for heat treating and extolled the virtue of the forged blade over stock removal, citing idea of "edge packing" to make the blade's edge denser and harder. Better knowledge has won out and the use of newer, electric and electronic controlled ovens and thermal cycles is now the norm. It is now recognised that many stainless steels can take and hold a very good edge, in clear contrast to the older generation whose experience said that stainless wasn't worth spit for a knife. There is quite a lot of debate and discussion about heat treating of tool steels for tools vs for knives, and the widely differing opinions on the use of D2 tool steel for blades being the result of industrial heat treatment producing poor blades, vs knife makers tweaking the process to get what they want from the material.

Over on Blade Forums I have read a number of threads where a "new" knife maker has made fantastically fast progress, only for it to be revealed they are tool makers, or precision machinist. The formal, industrial, training certainly shows, but they have to learn about knife making, and things like ergonomics, aesthetics and the interplay of design features, which are new skills. I have seen the term "engineer's knife" used as an criticism of a very precisely made, but ugly, lumpy and angular knife.

 

[0000]

My dad used to differentially heat treat the knives he made (not a huge number, its true) by heating only the spine. Did at least one on the gas cooker, he told me. Tempered it in the oven.

Interesting. I've never heard of heating a spine only. I know the kami in Nepal differentially heat treat kukris by only water quenching the edge with water from a teapot. The spine cools slower resulting in a softer spine that absorbs shock.

Sent from my SM-A705FN using Tapatalk

 

[TLM]

Differential treatment can be basically be done in any of the three stages, heating, quenching and tempering. The practicalities differ a lot.

 

[0000]

Differential treatment can be basically be done in any of the three stages, heating, quenching and tempering. The practicalities differ a lot.

Yeah it's something I've never dabbled in.

Sent from my SM-A705FN using Tapatalk

 

[TLM]

TLM, if I could like your hardness test post twice, I would

Thx

I can still remember our professor telling us the differences in testing. In this case the problem is the way Rc measures the depth of indentation. Vickers does not care if the measured piece has some flex or not but requires manual measuring from enlarged pic in the old machines.

 

[Broch]

Edges can't be tested with Rocwell C but they can be tested with micro Vickers tester. Though I just don't see much point.

Of course, I should have said most of us do not have the means to test the edge hardness.

However, I am not blind to some of the short comings of taking their views as holy writ. Some of the experience old boys I have met stopped learning once they had enough to do their job.

Agreed, even when I was doing my apprenticeship I would sometimes question the 'old ways'. I did it the other way round - shop floor first followed by uni; I am sure there are advantages both ways

I think your last point is very important - unless a knife is made purely as a functional tool, there is an 'art' in it that some people have and others don't. I have seen plenty of knives that really are ugly but are very serviceable (I've made a few ) and I've seen things of beauty that I wouldn't dream of using in practice. As someone that works with knives most if not every day I tend towards the 'serviceable', but that doesn't stop me enjoying the aesthetic of nicer looking knives even if they wouldn't be suitable for the work I do with them.

 

[petrochemicals]

For more fun, go on one of the US knife forums and post your thoughts. Lots of full time makers and blade smiths....many who are much older than I am

For a more definitive answer go to a university metallurgy dept and enquire, they will have a far more open minded approach than i suspect people who are dead set in their ways.

 

[0000]

For a more definitive answer go to a university metallurgy dept and enquire, they will have a far more open minded approach than i suspect people who are dead set in their ways.

Perhaps you should do that and report back instead of stating as fact, things you clearly don't understand. You addressed none of the points that I brought up with regards to speed, material, size/type of abrasive, cooling, geometry and stock thickness as contributing factors. The Dr Larrin Thomas that I mentioned earlier is a Dr in metallurgy and his speciality is cutlery steel. He is a very active member of blade forums and so perhaps for some advice, one need not enquire at a university. As for you, after the way you've presented yourself, talking about open mindedness and people dead set in their ways, I genuinely laughed. Satire? Irony? Words to live by in any case sir. I think I'm done banging my head against this particular wall and I'll save my professional opinions and experiences for somebody who actually wishes to have a discussion and learn. Toodles.

Sent from my SM-A705FN using Tapatalk

 

[Broch]

For a more definitive answer go to a university metallurgy dept and enquire, they will have a far more open minded approach than i suspect people who are dead set in their ways.

There really is no progress in a discussion if all people can say (from both sides) is "I'm right, go check" - if we want people to believe our stance on these kinds of discussion we should be prepared to quote specific information. So, what research has been carried out that specifically shows that post heat treatment dry/wet shaping on modern belt materials at the right speed does/does not damage the tempering? Don't just say go and find out; if you know it exists quote it.

For some time I was of the same opinion as you. I still believe that a lot of amateur knife makers are dreadfully unaware of the metallurgy and how to control the heat at different stages of knife making; however, they still produce serviceable knives. When I did get off my high horse and look at the materials and speed control of belts I realised there was room to work without damaging the tempering. OK, I don't take a lot of material off after heat treating, my blades are electric kiln treated with a reasonable edge profile on, but I do the last-but-one shaping on a belt with final finish (sharpen, hone, polish) by hand - but I enjoy the Zen of that and I'm not trying to do it commercially.

 

[0000]

There really is no progress in a discussion if all people can say (from both sides) is "I'm right, go check" - if we want people to believe our stance on these kinds of discussion we should be prepared to quote specific information. So, what research has been carried out that specifically shows that post heat treatment dry/wet shaping on modern belt materials at the right speed does/does not damage the tempering? Don't just say go and find out; if you know it exists quote it.

For some time I was of the same opinion as you. I still believe that a lot of amateur knife makers are dreadfully unaware of the metallurgy and how to control the heat at different stages of knife making; however, they still produce serviceable knives. When I did get off my high horse and look at the materials and speed control of belts I realised there was room to work without damaging the tempering. OK, I don't take a lot of material off after heat treating, my blades are electric kiln treated with a reasonable edge profile on, but I do the last-but-one shaping on a belt with final finish (sharpen, hone, polish) by hand - but I enjoy the Zen of that and I'm not trying to do it commercially.

With respect, I don't think it is "from both sides". I have very clearly and politely given the reasons that I believe what I say to be the case. I didn't just say "I'm right, go check". I did say that if he was interested in learning more he should check out a very distinguished person in the field, who's knowledge I have utilised many times. I thought of this as a genuine resource for him and should be considered further reading. Also, I haven't been citing sources because much of my knowledge on this particular topic is from discussions I've held with my peers in this field and from personal experience and testing over the years. I'm sure you would agree that these are anecdotal. If it were a heat treatment graph or something it could be more cut and dry. Ah well, I can only share what I know and if people don't want to pick up what I'm putting down that's fine.

Sent from my SM-A705FN using Tapatalk

 

[TeeDee]

There really is no progress in a discussion if all people can say (from both sides) is "I'm right, go check" - if we want people to believe our stance on these kinds of discussion we should be prepared to quote specific information. So, what research has been carried out that specifically shows that post heat treatment dry/wet shaping on modern belt materials at the right speed does/does not damage the tempering? Don't just say go and find out; if you know it exists quote it.

Completely agree - and its this ' my opinion that trumps Facts ' thats been used elsewhere.

Assertion without any evidence.

Along with the typical 'argument from authority ' response , these are the bane of decent debate.