sharpening?

Stetzan

No one is saying it does not happen

It may be just academic when it comes to real world use on a knife.

Jumping to the conclusion that grinding under a coolant is going to decrease the temperature of a knifes edge enough is just an assumption. How much is that final temperature at the edge? The coolant may have dropped it down from 3632 F (2000 C) but by how much? To assume just using a coolant of water decreased that temperature more then 3232*+ degrees down below 400* F is a big assumption to make.

People are assuming they are decreasing their sharpening temps down over 3232* F at the micron level by using water as their coolant.

What evidence is there that they are decreasing it 3232* + ? They might only be decreasing it 3000* F and that would still leave them with a temperature of 632* F at the edge and far over the temperature of the temper in many cases.

My point is people just might not be doing what they think they are doing when it comes down to the micron level experiments they are quoting.

So the question is "what is the end temperature at the blades edge at 30 microns when sharpening under coolant and is it under 400* F?"
 
The block test referenced earlier also did a wet comparison. The temp with coolant was below 300 F.

Even though Ifully endorse the use of coolant grinding, I think people may be making too much of it. There is no reason to shelve a blade that was sharpened on a dry grinder and had the edge overheated. The depth of damage is small as long as some care is taken. Just resharpen it a couple times and that 30 um of damaged metal should be gone. My S7 blade that showed issues was not having the same trouble after 2 resharpenings on a 1000 water stone.
 
The block test done with coolant would cancel pyrophory, since there would be no access to O2.
Adam, I asked that same question on the forum where this was eagerly discussed, and the answer was, "test it yourself, find a way to measure and post your results" which is perfectly valid but probably not going to happen.
Wet sharpening makes tons of sense, but what I'm not seeing is this (and it may just be my myopia): People are making a claim that wet sharpening is mandatory, without presenting convincing evidence. If you're going to say that thousands are doing it all wrong, there needs to be a weight of proof.
I'll be doing as much as possible of my post ht grinding wet with my new rig, though, since it seems much more efficient- no stopping to dip.
 
AVigil said:
Knives are tools and we have gotten so good at making them some actually have to stick them under a microscope to try to find something wrong with them.

Information is good, but knowing how to apply it and when it does not apply is equally good.
Click to expand...
^^I Like This^^:thumbup: It reminds me of the scientist how they "Know more and more about less and less till they know everything about nothing"
I have nothing to add to this conversation other than that I enjoy reading it, there's merit to this discussion. Personally I believe coolant is a wise move but what does using coolant really give you in actual performance? I have no idea.
DR...
 
Any estimates on how much a cooling set up (like the Kool Mist) cost to actually put into use? Not just the unit itself...but water collection, pumps, etc?

If it's less that $400, as a potential customer of a maker regularly selling $200 plus dollar knives, well, I consider a serious plus, if nothing else as a sign of the makers commitment to quality. I don't believe it makes or breaks the knife, but I think this is a person seriously worried about giving me the most for my dollar. And that makes me more likely to want to do business with them. I hope that's coming off correctly. It just makes me pause to think someone would so easily ignore something that seems to seemingly easy to add as insurance of quality.
 
Camber said:
Any estimates on how much a cooling set up (like the Kool Mist) cost to actually put into use? Not just the unit itself...but water collection, pumps, etc?

If it's less that $400, as a potential customer of a maker regularly selling $200 plus dollar knives, well, I consider a serious plus, if nothing else as a sign of the makers commitment to quality. I don't believe it makes or breaks the knife, but I think this is a person seriously worried about giving me the most for my dollar. And that makes me more likely to want to do business with them. I hope that's coming off correctly. It just makes me pause to think someone would so easily ignore something that seems to seemingly easy to add as insurance of quality.
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$30 pump, some plastic tubing, some sheet metal and two plastic buckets...

and some floor mats

and a ghey looking apron to wear...
 
A water bottle mounted upside down dripping into a sponge dripping onto the belt.

Gravity will do the work and you can control the flow with the size of hold you drill into the cap.

That works well and is on the cheap
 
Camber said:
Any estimates on how much a cooling set up (like the Kool Mist) cost to actually put into use? Not just the unit itself...but water collection, pumps, etc?

If it's less that $400, as a potential customer of a maker regularly selling $200 plus dollar knives, well, I consider a serious plus, if nothing else as a sign of the makers commitment to quality. I don't believe it makes or breaks the knife, but I think this is a person seriously worried about giving me the most for my dollar. And that makes me more likely to want to do business with them. I hope that's coming off correctly. It just makes me pause to think someone would so easily ignore something that seems to seemingly easy to add as insurance of quality.
Click to expand...


My wet grinding set up:

[video=youtube;u0Iu_EEyEIU]https://www.youtube.com/watch?v=u0Iu_EEyEIU[/video]


This gives me a consistent angle, and when coupled with light pressure and low speeds, prevents problems with overheating the edge. I think it's a pretty good way to grind the initial edge on a knife blade. Particularly in materials like Elmax that get hot when you grind them, don't conduct heat well, and have low tempering temperatures so are easily damaged when sharpening.

As you can see, it's extremely difficult, expensive and messy and hardly worth messing with :D

^ *sarcasm*
 
Lol, point made :) I've actually seen a few made with the weed sprayer bottles as well.

As a customer it just really doesn't make sense to me why you wouldn't do it. We can agonize over the steel selection, how the heat treat is done, etc all in the name of performance and yet to not take that little bit of extra, pretty cheap care with the part that represents all that work...well it doesn't make sense to me.

I know a few other makers who use Kool Mist during all grinding as well...really allows for longer faster grinding even pre heat treat, and I do believe it can have big benefits there as you may not accumulate as much stress that can interfere with heat treat and cause warping. Again, none of this is to say it's necessary. But as a customer, I like to see someone who is all about risk minimization with my investment...that and testing their work.
 
Nathan the Machinist said:
My wet grinding set up:

[video=youtube;u0Iu_EEyEIU]https://www.youtube.com/watch?v=u0Iu_EEyEIU[/video]


This gives me a consistent angle, and when coupled with light pressure and low speeds, prevents problems with overheating the edge. I think it's a pretty good way to grind the initial edge on a knife blade. Particularly in materials like Elmax that get hot when you grind them, don't conduct heat well, and have low tempering temperatures so are easily damaged when sharpening.

As you can see, it's extremely difficult, expensive and messy and hardly worth messing with :D

^ *sarcasm*
Click to expand...

I'm interested in your wet grinding rig Nathan. It looks like you aren't getting enough splatter to even warrant a guard or apron. Is this just due to the low belt speed? I imagine even minimal water, in conjunction with the platen chiller makes for a very cool temperature. How did you rig your wet grinding?

Also, as far as the parallelogram is concerned. Did you just hang a aluminum pipe from the ceiling and use a level to true it?
 
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