Grinding Post HT and kool mist system

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Randydb

Joined
Sep 27, 2014
Messages
1,107
Hi,
I have started grinding AEBL blades post heat treat. I dip in water after every pass and don't war gloves so I can feel the heat and never let it get to a point where my fingers are getting "HOT or burnt." Problem is that I can't push as hard and take off metal as fast as when I ground pre heat treat.

I see these cool mist units that people use. When I looked them up they seem to be around $150-240+usd. But then this was posted in another thread.

https://www.amazon.com/Coolant-Lubr...d=1&keywords=kool+mist&qid=1600260366&sr=8-11
Do I have it right that they work on the bernoulli effect? Basically hook it up to my compressor, put the intake into my liquid and it works?
I have more questions.
1) How much does it help? Will I be able to grind with more pressure and as a result a fair bit faster?
2) Should I be buying the "kool mist" solution or is it pretty good just using water?
3) What am I missing here? Anything else I need besides a container and air hose to get going?

It just seems a bit too good to be true at $10 plus an air hose and container.

Thanks
 
I use a mist setup for grinding post HT and I like it.
Yes, you just need the misting unit, an air compressor and a bottle of liquid.
I do use the Kool Mist solution. You dilute it so it isn't that expensive and it seems to reduce rusting.
It really helps to keep the blade cool.
Downside is that it makes a bit of a mess and not all belts play nicely with water.
It's cheap to set up, so give it a try.
 
I don't know how I can miss at that price.... $10 + some kool mist and a hose.
My garage is more of a mess than tidy, so a bit more mess isn't going to be a problem. There was a thread on belts for wet sanding and I will start buying those. I've decided a couple bucks one way or the other on a belt won't be the end of the world for me.
I'm interested in what is in the kool mist solution that makes it cool so much better than water.
Off to read a bit.
 
I just started using one (I've ground three kitchen knives with it so far) and it has made a big difference for me. The belts seem to cut better for longer, probably because I apply more pressure. I have cut my grinding time in half, but that does not mean very much as I am pretty new to this, so I've gone from four hours to two.

At first I used way too much water and that made a pretty big mess. On Stacy's recommendation, I turned the spray down to barely a mist and that worked well. My clothes barely got wet on the last knife I ground.

My mister is hooked up to a pretty big air compressor and it turns on a good bit. Not sure what the minimum requirement on these misters is for air, but I suspect you won't be able to run them of a small compressor.

I use the kool mist solution, don't know if it is needed or not.

You may need to get a fitting to connect the small diameter hose to the air supply, I don't think that came with my mister. I have a different version from the one you linked that has adjustment screws for air and water on it. The only other thing I can think of that might be nice to have would be a separate pressure regulator. The air adjustment screw on my device is a bit finicky.
 
Randydb said:
I don't know how I can miss at that price.... $10 + some kool mist and a hose.
My garage is more of a mess than tidy, so a bit more mess isn't going to be a problem. There was a thread on belts for wet sanding and I will start buying those. I've decided a couple bucks one way or the other on a belt won't be the end of the world for me.
I'm interested in what is in the kool mist solution that makes it cool so much better than water.
Off to read a bit.
Click to expand...
I don't know if the solution makes it cool better, I thought it was for preventing rust and mold.

I have used mainly VSM ceramic belts in 60 and 120 grit and just last weekend tried the Norax belt in 220 grit. It is a bit pricey, but I am happy with it so far. I hope it lasts as long as the trizacts, we'll see. The only other belts I have used with the mister are cork belts. They seem to do better with a lot of water vs. just a mist.
 
Just a quick search and it seems like this kool mist liquid is hard to find in Canada. By the time I pay shipping I'm paying about $90cdn/gallon for it. Does this seem about right? I get that I can dilute it about 33 to 1. But am I missing something here?
 
Also, is that right...the solution just inhibits rust/mold. Doesn't cool better? I have sort of settled on using stainless steel because I live on the left coast and I work outside every day...often in the rain. So my knives either need to be stainless or else require more care if they aren't.
So if the coolant just stops rust i sort of wonder if it is okay to use water?
 
It is about $42/gallon at McMaster. I had the coolant anyway since I sometimes use a mister on the milling machine, not sure if I would go out and buy it just for use on the grinder. I'm less concerned about rust on the parts I'm milling, but more concerned about rust on the milling machine and other machinery in the vicinity. With my intermittent use, the bucket also sits around for quite a while before it is used up, so the mold inhibitor is a nice feature. I've had a bucket of the solution sitting in the shop for months and there was no mold or odor.

I've read some people use water and dish soap, or add baking soda or borax. The cooling effect is likely the same as long as it is mainly water. The device should work with any fluid that is not too viscous. There are a bunch of posts about it here on bladeforums.

Here is the product description from the McMaster catalog:
Made of synthetic base oil, these coolants have excellent cooling properties to prolong tool life, are long lasting, and prevent corrosion. They inhibit bacteria growth to prevent foul odors. All are chlorine free, for use where chlorine waste disposal is a concern, and sulfur free. Dilute with water.
Click to expand...
 
Randydb said:
Also, is that right...the solution just inhibits rust/mold. Doesn't cool better? I have sort of settled on using stainless steel because I live on the left coast and I work outside every day...often in the rain. So my knives either need to be stainless or else require more care if they aren't.
So if the coolant just stops rust i sort of wonder if it is okay to use water?
Click to expand...
Of course that you can use only water .You deep blade in pure water when you grind without kool mist so what difference will made that solution ? To save grinder from rust ?
 
You want the rust inhibiter as well as the anti-mold property. Wet shops will become musty and mildew easily. Your grinder could develop rust from stray mist and 100% humidity around it. The concentrate is $42a gallon and lasts a long time. The data says it costs $0.03 an hour to mist with it. I am sure there are other brands besides Kool-Mist.
A second reason to use the #77 Kool-Mist concentrate is it is safe and has been tested and approved.
 
I've used Kool Mist for years as a manual machinist, and have one at home for finishing knives. The adjustments at the nozzle and on the block have to be balanced to control air and liquid, and it takes a bit of playing to get it just right.
My only issue on the grinder is that the wheels and platen load up with a mixture of grinding swarf and coolant, making a lumpy, gummy mess. It has to be removed often.
 
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Cut back the water and up the air until it makes a fine mist. Aim it 1/2" above where the blade meets the belt.
 
That's what I use. Make sure you have enough compressor. A pancake one won't cut it. You will have to open and close the mister valve all the time.

I use the cool mist additive. It lasts a long time. I have to replace the cheap mister unit every once and a while. Maybe if I was more fastidious about keeping my coolant holder ( old windshield washer container ) super clean I wouldn't but whatever.

I order like 5 at a time from aliexpress. That takes a while to get to you. I'm using the one you linked right now.
 
Randydb said:
Hi,
I have started grinding AEBL blades post heat treat. I dip in water after every pass and don't war gloves so I can feel the heat and never let it get to a point where my fingers are getting "HOT or burnt." Problem is that I can't push as hard and take off metal as fast as when I ground pre heat treat.

I see these cool mist units that people use. When I looked them up they seem to be around $150-240+usd. But then this was posted in another thread.

https://www.amazon.com/Coolant-Lubr...d=1&keywords=kool+mist&qid=1600260366&sr=8-11
Do I have it right that they work on the bernoulli effect? Basically hook it up to my compressor, put the intake into my liquid and it works?
I have more questions.
1) How much does it help? Will I be able to grind with more pressure and as a result a fair bit faster?
2) Should I be buying the "kool mist" solution or is it pretty good just using water?
3) What am I missing here? Anything else I need besides a container and air hose to get going?

It just seems a bit too good to be true at $10 plus an air hose and container.

Thanks
Click to expand...
You talk about wanting to push harder, and not removing material quickly. By all means get the cooling system if you wish, but I would look at your belts also. A fresh 36 grit ceramic will move material quickly enough for me!
 
If you have a good small pump or connect direct to a tap you can mist a direct water spray. Use a small mister tip, which you can get in the plumbing dept at Home Depot in the plant/irrigation drip system stuff (along with the tubing, fittings, valves, etc.). It won't be the same as the Kool-mist, but it will work. It will be wetter. Using a pump and the Kool-most #77 concentrate would be best.
 
What I've used is just bucket of water and a rag, you dip the rag in the bucket, then put it against the belt. I reapply every few passes or whenever I notice any heat.
 
Richard338 said:
You talk about wanting to push harder, and not removing material quickly. By all means get the cooling system if you wish, but I would look at your belts also. A fresh 36 grit ceramic will move material quickly enough for me!
Click to expand...
Agreed. I start at 60 grit and even that is not a big issue in terms of controlling the heat. The big problem for me is 120 grit and above, I have burned the tip and/or edge on several knives. All thin kitchen knives. It happens so quickly once the edge gets thin enough. So I guess it became a vicious cycle. I'd burn a tip, so I apply less pressure next time, so the belt is not cutting well, so there's more friction and I burn the tip again. The mister seems to have solved my problems, or at least one of them. For a beginner like myself, I think it's really helpful not to have to worry about overheating the blade all the time.
 
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