slowly but not so surely

hardheart

hardheart

Joined
Sep 19, 2001
Messages
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these are from two 17 x 1.25 x .062 Lenox mo-speed blades, 10 teeth per inch.

I have to slim down the handles on the top two, and I'm trying to see if I can leave the saw teeth on the spine of the top one. The middle one is just a mess, but will hopefully turn into a mild drop point. Next one will have a curved spine, so I think I'm gonna have to remove the straight section on the edge to keep it looking right. Last one will be a wharnie, had to blunt the tip cause it kept overheating.

If I can finish profiling, and not blow the primary grind, I'll epoxy some wood scales on.

Better tools would help, I'm using a little 3" bench grinder with flexshaft attachment (that loses a lot of grease), 1 x 30 belt sander, and a 4" angle grinder with grinding disc and cutoff wheel.
 
No way for me to do a reasonable hollow, so I was going to flat grind with the belt sander about 7/8" high, the piece is 1 1/8" total height. I might attempt some sort of shallow hollow with the angle grinder on the one in the middle, since I don't know what I want it to look like anyway.

Thickness behind the edge, heck if I know. I might zero it and then put it on the sharpmaker.
 
You can do a hollow grind with the grinder, just take multiple passes, to create the curvature. 1 then 2 then 4 then 8, etc., as you move down the blade. When you are finished then use a sanding block to even out the curvature. Of course I'd likely just do a flat myself as well, Thom however would likely grind a hollow by hand with a benchstone.

-Cliff
 
Grinding the teeth off can be alot of fun and really chew through grinding stones. You can use the wheel of the belt grinder to get a fair hollow grind as well. There is no turning back now your hooked. :)
 
the teeth actually came off pretty easily, that's why I chose the finest tpi ;) I just picked up a few more things. 24, 36, and 50 grit flexible discs, I used to use these without a backing pad when doing body work. The speed of the grinder keeps a good amount of tension in the disc, while not have a pad behind them keeps heat build-up down just a bit. Also got an 80 grit flap disc, to hopefully clean things up before moving back to the higher grits on the belt sander.

And while I was there, and before I've even gotten halfway through these, a 2 pack of 12" hss hand hacksaw blades. This thin stuff should grind a bit quicker. I wonder what Rc they are, they're really flexible, feel like bi-metal.
 




Well, I wasted about half a dozen belts doing stuff I should have been doing with the grinder in the first place. As you can see by the remaining coating, these saw blades aren't precision ground :rolleyes:

If I leave the grind as is (and plan on doing something else with the rest of my life), it should be about .025" at the edge. Finish right now is 320, with a hint of D8XX from trying to flatten out the primary. My little belt sander doesn't have the best platen available to the artisan.

a couple tips for anyone planning on grinding out a blade from hardened M2:

1. don't
2. you apparently skipped number 1, read it
 
I fully flat ground a small D2 blade once, all I did was taken an existing primary grind and basically move it back until it was full to the edge. It took forever, multiple sessions of 1/2 hour. Of course I had to go slow and cool a lot, but still, those high carbide steels are hell to grind. You need to use the grinder, it will tear into M2 like the belt sander eats through wood. Note, you don't water cool M2 by quenching it constantly, if you do get it very hot then you let it air cool.

-Cliff
 
I did use the grinder after the first couple of belts, I'd probably still be going at it if I hadn't. But I did keep going back to the belt sander to clean up and measure my progress. Now that I have a better idea of just how much work it's gonna take, and some better idea of how to hold and grind the blade, it should go faster on the next one. I see that the belts I have aren't going to be at all useful until I'm almost done with the primary. They don't remove enough metal before losing their bite to be worth using early on.

It never got hot enough to cause blisters or burns on my fingertips, but I had a few instances of letting it get a little too hot to hold, near the tip. It didn't even sizzle when I dunked it in water, so I hopefully didn't get it anywhere near hot enough to mess with the temper. I don't know exactly how hot I can let it get, so I'm trying to be very cautious.

One side (top pic) is a little convex, gotta fix that. At least the edge is fairly well centered, I didn't scribe it out on this one.
 
hardheart said:
They don't remove enough metal before losing their bite to be worth using early on.
Click to expand...

What grit?

It never got hot enough to cause blisters or burns on my fingertips, but I had a few instances of letting it get a little too hot to hold, near the tip.
Click to expand...

Anything above 120F is uncomfortable to hold, low carbon steels have tempers of 325F+, most tool steels are 400-600F, some are 950F, HSS are 1000F +.

-Cliff
 
I started with a 60 grit belt, it quit throwing sparks before I had taken it down by .020". Did use it for a little more profile work, so I got use out of it. I can't flat grind 2.5" of hard steel with it, though.

Well, I guess I'm good on the temper, maybe I'll wear gloves an let it run on the grinder a little longer. When I was using the cutoff wheel, I'd get hotspots where the steel would change color. I figured the blue and gold colors were bad news for that small section of steel, so I'd grind it off. Too hot to hold were a few instances of my hand jerking back from the steel, temp really jumps fast as the blade thins out [/captain obvious]
 
Yeah, you might want to ask in the shop talk forum about a higher grade of belt, but in general the angle grinder works so well I would be surprised if a belt sander was efficient for anything beyond finishing.

The colors are a bit tricky, for low alloy steels it is straight forward and pretty much as soon as you see a color you are drawing the temper unless the tool is a spring. However it isn't such as most people imply which is color = dead soft.

Basically what you are doing is just drawing the temper and this is very slight at the light colors, but once you go to blue/black then for those steels you are in the range at which the temper will draw the hardness down to 30 HRC. Plus when you slam it into water you are likely going to crack it apart anyway.

However once you start to put chromium into steels it changes the temperature at which you see the colors. This is about 300+ C in the stainless steels so once they hit straw color they are 500 C, so you can actually burn them without seeing a color change.

You can grind the HSS without seeing a color change, just use light passes and move fast. You can also use a constant water coolant, or at least put the blade on a huge heat sink like a big block of metal which will suck the heat out of the edge very fast and basically make it like you are grinding a machete.

-Cliff
 
This looks really good! I've got a whole bunch of HSS M2 in my garage that I've only just started on. I'm trying to use the angle grinder for everything possible, but I'm nowhere near as far along. This is encouraging, except for those 2 pesky rules.... :D

I hear that it is all worth it when you start using the knife, though!
 


well, this is taking too long :D Any ideas what I can put on the wood? Was thinking of maybe a polyurethane sealer.
 
Sheesh , it's about time you posted pics ! :D

Right on man , you could use tung oil , or similiar to seal it up.
 
yeah, I took a long break from messing with this stuff. Seems I won't be able to use this wood on the Marzitelli, too narrow. But I have some ironwood for that. Really need to get the bugs worked out first, like the cracks between the blade and scales on this one. Should have done a better job fitting it before gluing them down. Also looks like I gotta hand sand out the scratches in the steel. fun times :(
 
I hear ya. I have so many knife mod projects I have planned , and then I buy a new knife or two and get in over my head.
I just got a CRKT Crawford Falcon I am wanting nice wood scales on.
I've got some nice Ironwood but , its so hard to work with.
I'm thinking maybe Shedua or quilted Maple.
 
hardheart said:
yeah, I took a long break from messing with this stuff. Seems I won't be able to use this wood on the Marzitelli, too narrow. But I have some ironwood for that. Really need to get the bugs worked out first, like the cracks between the blade and scales on this one. Should have done a better job fitting it before gluing them down. Also looks like I gotta hand sand out the scratches in the steel. fun times :(
Click to expand...

You might want to try using a cloth belt with a liitle Chromium oxide. I've heard reversing a well worn sanding belt with a cloth backer (like emery cloth), a knife sharpener at a trade show I attended used this method with a stick of the stuff. Not sure if you can find 600-2000 grit belts inexpensive enough to make it worth your while but the cloth belt trick might do the trick.

Good luck!

NJ
 
Very nice work, Hardheart!

I've found that with anger and a fresh 100 grit belt or two, it's easy to make a knife from fully hardened M2 so long as you don't mind buying a new belt-sander soon after.
 
the 36 ceramic belts work much better, putting the blade grind on is still not fast but much better than the 80 grit belts I used before. I don't use belts to profile just for putting the blade grind on it really saves on the belts.
 
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