14" circular metal blade

I’d be very surprised a carbide blade would cut an axel. They are forged I believe and very tough. I’ve cut one with an abrasive saw and it took a while.

Abrasive blades are scary and dangerous for sure and I use them as little as possible but they are ultimate in my bag o tricks when nothing else will dent it.

I’m glad you were armored up Aukai when that blade let go. Abrasive wheels of all types are nothing to take lightly. Being the squimish type I generally away from medical shows but they mentioned a run in with a bench grinder. It was the nightmare I’d always feared working in a big shop full of dumb buba’s where they would break or jam equipment and leave it or the next poor guy.

This guy was in an auto body shop and was using a bench grinder and the wheel exploded. They didn’t say if here was using any safety gear, I think not. A chunk of the wheel hit him between the eyes. It vaporized the bridge of his nose and the center of his brow, shattering his skull. When his brain quit swelling and went back down they had to pull his face back, and take a short rib to replace the bridge of his nose and center of his brow.
 
The trick to abrasive cut-off wheels is HEAT. If you work it until the metal is cherry-red where the abrasive wheel is making contact, it will cut MUCH quicker than simply "grinding" the metal away. I worked a LOT with knife steel, which rapidly work-hardens (such as 1095). It was much quicker than any type of saw I used, and it did not care in the slightest about how Hard the metal was, once it got to cherry hot.

As a sub-note, if you push the wheel hard, be sure to get a good quality wheel, such as a Norton.
 
Yes my Janyce is a metal blade slow RPM.
Does getting the metal cherry red do more hardening? In my project I was back about an inch cutting off a torch cut off, after facing I could see a different texture ring on the outer surface I'm assuming was the depth of the hardening.
 
Aukai said:
Yes my Janyce is a metal blade slow RPM.
Does getting the metal cherry red do more hardening? In my project I was back about an inch cutting off a torch cut off, after facing I could see a different texture ring on the outer surface I'm assuming was the depth of the hardening.
Click to expand...
cherry red usually makes metal softer
the depth of hardening is not usually very deep, you witnessed it in the ring
 
Aukai said:
Yes my Janyce is a metal blade slow RPM.
Does getting the metal cherry red do more hardening? In my project I was back about an inch cutting off a torch cut off, after facing I could see a different texture ring on the outer surface I'm assuming was the depth of the hardening.
Click to expand...
I know you asked a simple question, now let me give an answer.

I have heat treated a lot of knife blades. This includes the hardening phase, and the separate tempering phase. I will not speak to tempering, as it does not apply to the process of the steel being cut in an abrasive Chop Saw.

When you are hardening steel, it is heated to the Curie point (the point where a magnet no longer sticks to it, due to the iron in the steel losing it's regular bonded structure; it no longer understands North and South poles of a magnet (and is no longer attracted).
At this temperature both the Iron, and the Carbon atoms (which is about 1 percent of the total composition) are mobile.
When you rapidly quench a water-hardening steel like 1095, the Iron atoms form regular cubic structures so quickly that the roaming Carbon atoms don't have a chance to escape the forming iron bonded cubic structure. This makes that Cube stiffer and harder to deform (because it has that Carbon atom trapped in it's structure), it makes it HARDER. This is the hardening phase of the heat treatment. However, if the steel cools slowly, the carbon has time to migrate outside of the cube before the door slams shut, and trapping the carbon. The steel is NOT as hard when it slowly cools, as versus when it quickly cools. But yes, some still get trapped and produces some hardness. This can also happen if you are grinding on steel and get it really hot, but not red hot. This latter effect is known as "work hardening".

When using an abrasive hot saw, I would frequently allow about 1/8th of an inch of extra metal at where the knife tip will be. This was also due to the fact that when steel gets cherry hot, some of those mobile carbon atoms are pushed to the surface, or sweated out. Remember, what makes steel hard is the trapped carbon atoms. If the carbon is sweated out, then it is not present to get trapped, to make the steel hard. Only about an 1/8th of an inch is measurably impacted from Hot/Chop saw use. I allowed 1/8th of an inch, so that the tip of the knife would not be notably softer than the rest of the blade. That extra 1/8th inch gets ground away during the process of contouring the knife blade.

Now to the shallow depth of hardening, brought up sensibly by Ulma Doctor. He is spot on. Air only transfers heat at a fraction of the rate of brine water used for quenching. Only the surface cools fast enough in the air to trap those carbon atoms, The rest of the thickness cools slowly enough that the carbon is not trapped and remains in a more amorphous concentration, as versus trapped in the regular cubic structure. Air cooled 1095 steel is not as hard as water hardened 1095. Most of the hardening is ONLY on the surface.

This is not meant to be a tutorial on hardening 1095 steel, and is only given to illustrate the affect of the heat from cutting.
 
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I have (and love) my Makita dry cut saw but it is for this very reason I will NEVER ever part with my abrasive chop saw.




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If I go back to having an abrasive chop saw Dewalt has a discontinued model still available from HD, and Amazon 5.5hp. Any other recommendations?
 
Aukai said:
If I go back to having an abrasive chop saw Dewalt has a discontinued model still available from HD, and Amazon 5.5hp. Any other recommendations?
Click to expand...
Just remember that this saw is rated at 15 Amps of current. There is no way it is actually making a continuous 5.5 hp. It is generally agreed that it takes about 746 watts of electrical power to produce 1 HP of rotational force. This means that the saw has "at best" a steady state of about 2.5 HP. The industry is rife with "specsmanship", where the company that brags the most HP gets the sale. My Milwaukie chop saw makes a similar exaggerated claim... that is typical. Still, even 2.5 HP is a lot to work with.

By the way, read the reviews. They read similar to a lot of chop saws in this price range.
 
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