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M2 steel at 66 69 rockwell

M

masa

Joined
Feb 3, 2005
Messages
191
I was thinking of making a knife out of a m2 at 66 -69. I do not have the steel with me yet. Any idea how it would shape at this hardness on a belt sander and normal sharpening stone / angle grinder? Would m2 be brittle at this hardness and at 2 mm blank thickness?
 
At 65 or so, the only way I have found to reliably cut it is with an angle grinder, and it's slow work. I'm also not a knifemaker, so take what I say with a large grain of salt. I would suspect at the 66 - 69, you'd have to use a fairly thick edge to prevent chipping in tougher media. Others here on this forum have sanded and shaped blades at this hardness, I'll let them chime in.
 
pretty soon i'm going to be making a machete from some and i plan on using a right angle grinder with a mist of water to keep the steel cool. once i get the bevels rough ground i'll switch over to my belt sander to smooth things out. i have my sander set to run really slow but i plan on using a 40 grit belt.
 
I used an 80 grit and was able to shape it fast but this is with another m2 at 60-61. I have no idea how hard or brittle it would be at 66 - 69

I had a 65 hrc at home , it was hard enough that a file could not scratch it.
 
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69 is overkill outside of a small skinner, but I doubt 66 could be much worse than my S125V custom at Rc 64-66 given that M2 is non-stainless and should thus be tougher.

And I was under the impression that all shaping should be done in the annealed state? Reprofiling even ZDP-189 fully hardened doesn't seem that difficult to me, but I suspect attempting to put a grind from a sheet of it at that hardness would be like using 1200 grit sandpaper to sharpen a chip out of an edge.

I believe Farid who works with CPM Rex 121 uses a 36 grit ceramic belt(not sure on the dimensions).
 
I am taking advantage of the ability of M2 to maintain its temper at grinding heat to make it because I lack the skill to HT it. Its actually designed for machining purpose and it is factory treated to be 66 - 69 range. I am simply grinding it.
 
I made a knife from a power hacksaw blade that was 65-66 Hrc. The toughness was impressive at such high hardness. The stock I was working with was already hardened. The standard industrial hardening for M2 gets a hardness around64-66. Your hardness range sounds a little high unless your re/hardening it yourself. Edgeholding and wear resistance are exceptional. It can be worked with an angle grinder and small belt sander, but prepare to spend a lot on belts.
 
I've made a few folders from M2 chop saw blades. The best thing I found was grinding to shape with a white norton grind stone. Then to the belts, and only when you have it as close to finished as possible do you hit the stones. Unless you have much better tools than me you can forget about drilling any holes in it. That stuff is HARD! I originaly put a near-mirror finish on it but found it worked better with some bite.
 
I wonder if the Micro-Mesh diamond belts would be good for this. I'd assume the cost would be prohibitively expensive, maybe above $20 for a single 1" x 42" belt. I would think one problem would be belt life, as using diamonds on steel rather than ceramics tend to have the consequence of having the diamonds torn out of whatever is holding onto it. Though I wonder if steels in the Rc 64+ range would be hard enough to avoid that.
 
I have been wanting to make m2 blades out of folders but this is difficult due to the precision compared to fixed blades.

Its actually not a saw blade but a machining blade so its made a little harder.
 
M2 won't get to RC 69 at any temp. If it's fully hard it's probably RC 66. Then tempered probably it's in the Rc 65-66 range. This steel tempers at around 1000 degrees F so you can do a bunch of grinding on it before you begin to soften the steel. It's designed just for this purpose in fact. That's what the High speed steels are. They are steels designed to take the heat of machine operations and not get soft, or lose their strength. I wouldn't be grinding it until it was glowing red, but it could take a lot higher temps than simple carbon steels before softening/annealing.
 
Greetings from Fiji, I made couple of knives from fully hardened planer blades. I also used an angle grinder, just keep a wet cloth nearby and continuously cool the
steel as you grind. I know for a fact that the steel will remain hard despite reaching temperatures of 1000F.... The grade I used are T - 1. I find that it retains its
edge holding capabilities despite months of cutting meat and vegetables daily....

The planer blade is made by Kanefusa of Japan.

Good luck.

Philip
 
I really like these high speed steels for knives. The only thing about them is that knives don't really need the heat resistance they offer, according to conventional wisdom. I find I disagree with this. When we shape the blades from hardened stock, the heat resistance is very handy. Also, the resistance to softening helps for those of us who like to power sharpen our blades. One steel I'd like to try, just to see if the heat resistance is helpful, is F2 or it's similar alloy, Hitachi Blue Steel. Both are what I'd call tungsten finishing steels, and I've seen more than one source recommend putting them in service at a hardness of HRc 64-66. F2 is no longer made here in the US. Blue steel seems very close and more available. I've used what I think is M2. I would assume T-1 gives similar performance. I've used M2 to cut quite a bit of cardboard, ~300 inches with the same 1 inch section of blade, and it would still catch hair on my arm above the skin. Enjoy those high speed steels. Also, if anyone has tried Blue steel at the higher hardness levels, let us know how it worked.
 
Noctis3880 said:
I wonder if the Micro-Mesh diamond belts would be good for this. I'd assume the cost would be prohibitively expensive, maybe above $20 for a single 1" x 42" belt. I would think one problem would be belt life, as using diamonds on steel rather than ceramics tend to have the consequence of having the diamonds torn out of whatever is holding onto it. Though I wonder if steels in the Rc 64+ range would be hard enough to avoid that.
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Tearout is only part of the problem. At grinding temperature, the carbon that makes up the diamond reacts with the steel and you dissolve the abrasive. Diamonds are often recommended for non-ferrous metals or with to be used with liquid cooling.
 
i finished my machete which was made from a power hacksaw blade. i found out the blade i had was not m2 but m42. it is a chisel grind half convex edge. i did some chopping with it on a skid and it held up great. working it was no problem and i used a right angle grinder to rough out the grind hitting it with a water hose just to make sure i kept it cool. i finished it up on my belt sander and had it ground in just over an hour from start to finish.
 
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