At what thickness do you…

[J. Hoffman]

HT piece of steel from which you want to make knife ........ceramic belts don t give **** which steel is in question , they will eat it fast !


Clearly, this statement was made by someone that has never ground CPM M4, Magnacut, Elmax or Rex 121. Yes the belts do care!

 

[Taz]

I ground an 18" x 2.3" wide x .110" thick piece of hardened CPM 20CV to make a Shechita post Heat treat. Took a long time! I gotta do 2 more in 18" x 2.5" x .125" CPM S90V post heat treat as well. Not looking forward to those!!!

I've ground CPM S30V (61 rockwell), Elmax (62 rockwell), MagnaCut (63 rockwell), as well as 3V (60 rockwell), all post HT. 5160, 80CRV2, 8670, AEB-L and Nitro V post HT at 62 feel like butter compared to the other steels! Good belts make a difference; 36 grit vsm Actirox/Destroyers work really well. Wide kitchen knives are more of a pain due to the thinness behind the edge and you are removing steel from the whole taller face of the blade compared to a 4" hunting knife. Fillet knives present their own challenges due to the flex in them as well.

I grind everything post heat treating. I dip a sponge and wet the belt frequently, but I want to get a mister system set up.

 

[Crag the Brewer]

I run my compressor between 100-120psi for my mister and it keeps a lot of the mess down. Not sure if that’s the best range but it’s what works for me. Keeps blades completely cool for the entire beveling process.

Sounds interesting....
About how much volume of air and water is being moved?

I only have a pancake air compressor like for nail guns.
Would this thing be running constantly?
It turns on about once per topping off low truck tires, so I bet it will?

I'll have to look in brands of these misters.
I fell in love with hacksaw blades, and their Hardened steel.

 

[Joshua Fisher]

Sounds interesting....
About how much volume of air and water is being moved?

I only have a pancake air compressor like for nail guns.
Would this thing be running constantly?
It turns on about once per topping off low truck tires, so I bet it will?

I'll have to look in brands of these misters.
I fell in love with hacksaw blades, and their Hardened steel.

That small of a compressor won’t work in my opinion. I tried it and found it was an absolute mess because I wasn’t getting enough air volume. I use a 20 gallon compressor and it runs almost nonstop and could really use something bigger. The misting systems move a good amount of air and water. In a 8 hour day of grinding I’ll almost run through a 5 gallon bucket of water. Soon I’ll have to fill and store my water bucket inside or it will start freezing.

 

[Stacy E. Apelt - Bladesmith]

I've been using a Kool Mist knock off for a while now with plain water, not the additive, but I've been wondering about potential long term rust damage to my grinder parts, especially moving parts like bearings. Does the additive help with that? Is this even something I should be concerned about?

Yes, it will help with rust control. It also helps with make a better mist and lubricant.

If the air is high pressure, it will vaporize the water into a cold mist. not a wet spray. It can nearly freeze your fingers sometimes. Gloves are necessary sometimes. 90 PSI will just barely work. 120 works great. Play with the water and air adjustments to get the proper mist. The simplest way is to turn them both to off and then open the air until it has a good jet. Open the water slowly until you start to get a light mist. Open it more until you get a wetter spray, add more air until the mist returns and gets really cold. Go back and forth increasing or decreasing until the mist is pretty dry but very cold. It takes a lot of air, but not much water.

 

[Hubert S.]

Sounds interesting....
About how much volume of air and water is being moved?

I only have a pancake air compressor like for nail guns.
Would this thing be running constantly?
It turns on about once per topping off low truck tires, so I bet it will?

I'll have to look in brands of these misters.
I fell in love with hacksaw blades, and their Hardened steel.

I doubt that a pancake compressor can provide enough air to run a mister efficiently. I run mine off a 60 gallon air compressor and have a water separator and pressure regulator close to the grinder. The air valves on my misters are not really very reliable and I get a lot of variation in the amount of water and droplet size without the separate regulator. Running at tank pressure also produces a lot of variation with the rising and falling pressure and I therefore run my mister at a pressure that is a good bit below the pressure at which the compressor kicks in. This ensures that the pressure is always the same at the mister.

The amount of pressure I use varies a bit, but is normally between 60 and 90 psi. In the current weather conditions, the mister works great and produces a mist that gets uncomfortably cold after a grinding for a few minutes at 80 psi. I measured the coolant consumption when I first got the mister and it was around a quart per hour, IIRC. The consumption varies a good bit though, depending on how you set it up.

 

[Crag the Brewer]

I doubt that a pancake compressor can provide enough air to run a mister efficiently. I run mine off a 60 gallon air compressor and have a water separator and pressure regulator close to the grinder. The air valves on my misters are not really very reliable and I get a lot of variation in the amount of water and droplet size without the separate regulator. Running at tank pressure also produces a lot of variation with the rising and falling pressure and I therefore run my mister at a pressure that is a good bit below the pressure at which the compressor kicks in. This ensures that the pressure is always the same at the mister.

The amount of pressure I use varies a bit, but is normally between 60 and 90 psi. In the current weather conditions, the mister works great and produces a mist that gets uncomfortably cold after a grinding for a few minutes at 80 psi. I measured the coolant consumption when I first got the mister and it was around a quart per hour, IIRC. The consumption varies a good bit though, depending on how you set it up.

Thank you for the very informed post!
Sounds like I need More equipment
*My hands get so cold, now as it is....
I grind in a unheated basement. I can see my breath in winter.....

Isn't a cold ambient temperature good enough when grinding hard M2?
. Damn.

 

[Crag the Brewer]

That small of a compressor won’t work in my opinion. I tried it and found it was an absolute mess because I wasn’t getting enough air volume. I use a 20 gallon compressor and it runs almost nonstop and could really use something bigger. The misting systems move a good amount of air and water. In a 8 hour day of grinding I’ll almost run through a 5 gallon bucket of water. Soon I’ll have to fill and store my water bucket inside or it will start freezing.

Who'd have thunk we'd have mold issues grinding knives? Lol
Wow, five gallons sounds like A lot of moisture.
That much vapor, are you concerned about the additive/lubes being breathed in?

Oak and Iron don't worry me so much as spraying Science all over the place.....

 

[Joshua Fisher]

Who'd have thunk we'd have mold issues grinding knives? Lol
Wow, five gallons sounds like A lot of moisture.
That much vapor, are you concerned about the additive/lubes being breathed in?

Oak and Iron don't worry me so much as spraying Science all over the place.....

I’m only spraying water. I have some of the kool mist additive but haven’t tried it. I’ve found it works great with just water. Honestly I’d be more worried about iron and oak dust than the water vapor/additives.

 

[Stuart Davenport Knives]

I do have a pancake compressor. It really is not enough. I don't use it any longer.

Now I have a water hose fixed above the platen and just let it run through a piece of PVC with a little hole cut in it for pressure. Surprisingly, I don't get that wet, and there is PLENTY of water to keep things cool! Being in San Antonio, there is a sort of blessing to have 100°F heat all summer, and the winters here are like the rest of the country's fall! Slop bucket has to be dumped often tho!

 

[Natlek]

HT piece of steel from which you want to make knife ........ceramic belts don t give **** which steel is in question , they will eat it fast !


Clearly, this statement was made by someone that has never ground CPM M4, Magnacut, Elmax or Rex 121. Yes the belts do care!

I don t know why I can t Qoute your post J. Hoffman ............Well , you are partially right .I never ground M4 ,Magnacut or Rex 121.But so far maybe I make maybe more then 60 , 70 knives from HSS steel like M2 , M35 M42 , and some from T series HSS .All in range from 64 to 68 Hrc . I make two ro three knives from M390 also .....It depends on what you mean by *belts do care * , years ago when I start making some knives with file I read lot here on forum .I remember that one maker write that he worn a few belts to grind one blade from M2 steel ??? Well , I can grind dozen from M2 on 64 HRC with one belt ? I wait for two piece of K390 steel .I expect to receive them next week . I'm really interested to see if my Klingspor belts *care* about that 9% vanadium

 

[Stuart Davenport Knives]

A dozen M2 64HRC blades with ONE belt????? What am I missing here? Are these small paring knives? What Klingspore belt is this?

 

[Natlek]

A dozen M2 64HRC blades with ONE belt????? What am I missing here? Are these small paring knives? What Klingspore belt is this?

Most likely you missing right speed and pressure Knives with blade around 4-5 inch blade.
When you cut steel with angle grinder , when you drill hole in steel there was narrow spot /pressure/where disc/drill bits /belts are most effective in cutting steel less heat generated and less wear on disc/drill bits/ belts . To much pressure and you heat steel and wear disc and slows down cutting speed , with too little pressure you heat steel and you glaze disc and it will not cut .
In one episode on Forged in fire one competitor CAN T cut some inch thick automobile axle with that big Metal Cut off Machine He hung onto it with all his weight and glazed the cutting disc in a few seconds , he struggled for a while not realizing what he had done !!And he canceled from cutting! When you buy new tool you need to LEARN how it need to be used !

Look this steel , it is 7mm thick 52100 .I have no idea how much I can cut with that single disk , but i can bet I will cut lot of it with that disk ! Can you see somewhere on cut sigh of heat ? And i cut that thing fast !

I don t think that anyone is capable to put and KEEP it /which is important / right pressure when freehand grinding steel .Especially on wide and relative thin knives such as kitchen knives..
Now we are deep off topic ....

 

[Stuart Davenport Knives]

What belt???

 

[nmbarta]

15n20 is probably my favorite steel. I use it more than anything else. It does tend to warp a little in the quench. Everything I do is 1/8 or less. It grinds nice post ht. I quench in parks 50 at 1465 for about 8 seconds and then to the plates. They come out straight every time. Any warp from the quench comes out in the plates if you don't let it get to cold in the quench.

I've taken edges down to around .010 pre ht and had my edge warp past repairable. It grinds easy enough post ht that I don't bother with that anymore. If it's a short hunter and you want to take little off pre ht it'll be fine, if it's a longer kitchen knife, I definitely wouldn't.

 

[JoeBusic]

I can grind dozen from M2 on 64 HRC with one belt ?

The "?" is interesting. Are you asking or claiming? If asking, get some rum . If claiming, I am curious about the thickness of those blades and how much do you use the initial belt (percentage of grinding). I use one belt per side of a 12" chopper out of 8mm D6 @ 65HRC. Belt can be used more, but on small things because of the pressure needed to break ceramics. I use 40 grit for 90% then go to 80, 120... Tried a few makers and 40 grit are almost the same. Most advances in belts are in the breakability in ceramics, ergo, less pressure for a break. There is a possibility that our volumes are the same but just the amount of blades seem an exaggeration.

 

[JoeBusic]

To pitch in with an answer to the thread, I use max 10mm steels (majority is D3, D6, M398) and all grinding is post HT. No bending, no trouble with decarb...

 

[Natlek]

The "?" is interesting. Are you asking or claiming? If asking, get some rum . If claiming, I am curious about the thickness of those blades and how much do you use the initial belt (percentage of grinding). I use one belt per side of a 12" chopper out of 8mm D6 @ 65HRC. Belt can be used more, but on small things because of the pressure needed to break ceramics. I use 40 grit for 90% then go to 80, 120... Tried a few makers and 40 grit are almost the same. Most advances in belts are in the breakability in ceramics, ergo, less pressure for a break. There is a possibility that our volumes are the same but just the amount of blades seem an exaggeration.

Most are 3.5mm , some of them 2.5 and some are 5mm thick .Some are full flat some little lover then full flat grind and all are about 4.5 - 5 inch long .
Belt I use is Klingspor CS 910 Y 40 grit . If I grind hollow grind I can grind lot more then dozen blade with one belt ............
I don t understand this ..... how much do you use the initial belt (percentage of grinding) ?

 

[JoeBusic]

I don t understand this ..... how much do you use the initial belt (percentage of grinding) ?

Percentage of grinding. I do 90% with the low grit belt and move to another grit. Some go lower and some all the way to 98%.
By volume we are the same grind amount. So the belts are generally the same at low grits.