latest blade (with a picture)

C

chucktilbury

Guest
Here is a picture of my latest blade. http://whistlemaker.com/pics/baladenumber4.JPG

It is made from O1 tool and this is how it looked out of the quench. I quenched in new 10w40 motor oil. My question is: is that texture normal? The blade is also a bit warped because it is pretty thin. I just want to know if I made a mistake.

Thanks,
-=Chuck=-
 
Kind'a hard to tell, Chuck, the file won't come up. If it's a dark cruddy looking surface, you could be looking at fire scale which will clean off if you soak it over night in white vinegar and scrub with a wire brush. It you tempered it with the oil still on the blade, that can cause some crud to build up. That should come off with the fire scale. Not being able to see the warp, I can't say if it's too bad to try cold straightening with or not.

Doug Lester
 
Sorry I spelled it wrong. The correct link is http://whistlemaker.com/pics/bladenumber4.JPG

The picture was taken after I got the fire scale off. I used some 220 grit sand paper on a rubber drum sander. I have been shining it up a bit and getting -all- of the oil off before tempering. The metal has a "funny" texture and I was wondering if that was unusual.
 
At first glance it looks like the steel may have gotten hotter than it should have. If that bumpy/scaley texture is in the steel that's a definate. If not It may be surface residue cooked on from the oil you used or fire scale not removed completely . Hard to tell without actually seeing it physically. The edge was definately too thin. I've never had that happen on any O-1 I've done.
 
At first glance it looks like the steel may have gotten hotter than it should have. If that bumpy/scaley texture is in the steel that's a definate. If not It may be surface residue cooked on from the oil you used or fire scale not removed completely . Hard to tell without actually seeing it physically. The edge was definately too thin. I've never had that happen on any O-1 I've done.

So... ya. That is certainly bare steel. It hardened well in that I could not scratch it with a file. It did warp a lot. The reason for the edge warping is pretty clear. (too hot and too thin) It also seemed to temper well enough. I vised the blade and gave it a little tug and it deflected slightly without snapping. It also took a great edge. I have not tried to drive it through a 2x4 yet, but I plan to.
 
After your testing, if you're up for more, try an angle grinder on the blade and remove the surface down to new bright steel. Then test with a file. It almost looks like you polished heavey scale towards the middle of the blade. You may have been testing the scale with your file. If you break your blade, show us the grain structure in the blade.

Rudy
 
I ground off that pattern after I tempered it. It completely disappeared and the blade surface is bright and does not have any flaws that I did not put there. :) I did not try to scratch it after tempering it. I will post pics when I get it back from the leather guy.

I am planning to use a plastic dead blow hammer to test it with. Does that seem like a good idea? Would a wooden mallet be better? I guess the real purpose of the test is to simulate actual use, right? I am pretty sure the blade won't shatter, but I may roll the edge. If the blade doesn't shatter and the edge doesn't roll, are there any other confidence tests that are good but non-destructive if the blade is OK?
 
I have had problems with the brass rod deflection test. I cut through, or at least into, soft steel wire without chipping or indenting the edge. I would not strike the flat of the blade with anything to test it, unless I'm trying to see how much it takes to break it. I do, however, strike the spine of my blades with with a wood mallet to cut the wire. You can test larger blades by chopping 2X4's to see how well it holds an edge. Smaller blades you can see how many cuts you can make trough cardboard of fiberous rope before they loose their edge. Cutting the hanging end off some 3/4-1" rope tests the blade goemetry. Cutting through water bottles can do the same thing. You will at least want it to be able to cut through one standing bottle. If you leave the bottom standing with water in it, you did real good.

Doug Lester
 
What is the brass rod deflection test? Put it in a vise and bend the blade?
 
The brass rod deflection test is done by pressing the edge of the blade held to a brass rod at an acute angle until the edge deflects slightly. You are trying to bend the edge side ways. If the bend does not return to straight after the pressure is released then the edge is too soft and it needs to be straightened, rehardened and retempered at 25 degrees cooler. If it chips out then the chip needs to be ground out and the blade retempered at about 25 degrees hotter. Adjust the temper temperature in 25 degree incriments until the correct hardness is achieved. The same corrections would need to be done with the wire cutting method that I use, except that in both the cases of being too hard or too soft the blemish in the edge will have to be ground out. Chuck, if you don't have a book on basic knife making I suggest that you get one. My favorite for beginners is Wayne Goddard's "The $50 Knife Shop". Many of the questions that you have been asking are answered there and it will make a good start in a reference library of knife making.

Doug Lester
 
The brass rod deflection test is done by pressing the edge of the blade held to a brass rod at an acute angle until the edge deflects slightly. You are trying to bend the edge side ways. If the bend does not return to straight after the pressure is released then the edge is too soft and it needs to be straightened, rehardened and retempered at 25 degrees cooler. If it chips out then the chip needs to be ground out and the blade retempered at about 25 degrees hotter...

Or more likely the edge geometry needs to be changed for the given hardness, this is why the rod flexing test is not reliable measure of hardness, flexing is always more profoundly effected by cross section than by heat treatment. That is why I also feel your wire cutting exercise is a better edge test Doug, for one it actually uses the edge in an action similar that it will be used for as a knife but more importantly it measures direct forces that would correlate to impact toughness in chopping and overall strength in push cutting, which would more closely resemble a proper hardness test. From where Chuck is at in his progress I would say he may be beyond the $50 Knife Shop, perhaps one of Hrisoulas's books or a very basic metallurgy text would be of more help. Chuck if you want to get a grasp of whats going in inside that blade and the properties involved I highly recommend "Metallurgy Fundamentals" By Daniel Brandt, is a the best entry level metallurgy book out there and I have used it as a textbook in my bladesmithing classes.
 
Well, the wire cutting is not exactlly my method, I got it from Tia Goo. I think it was on Rod Wood's video on primative knife making featuring Tia Goo and Tim Lively. I agree that Chuck needs to build up a library, and the reason is, Chuck, is that you have been asking a lot of basic questions that is covered in that book. But that is only a start. I too recommend Jim Hrisoulas' books, I'm actually waiting for his next book to come out. I might look up "Metallurgy Fundamentals" myself. John Verhoeven's "Steel Metallury for the Non-Metallurgist" is also highly recommended; I refer to it often. A few videos could be handy too, like some of Bill Moran's, if they're still available, or one that Ed Caffrey did.

Doug Lester
 
I am slowly building my library. (the nice folks at Amazon all love me) I have a couple of "you can do it" books. I pretty well burned through them the first day. Now learning some detail on metallurgy is probably a good next step. Clearly, I need a better way to accurately heat metal. I also make small aluminum parts and it would be useful to be able to heat treat them as well. I may try to build the one from plans shown in another thread. Do people ever use an electric oven as a forging furnace? Most of the ones I have seen are gas.
 
Back
Top