Cracked blade from peening - 14C28N?

Scaniaman said:
I also use an anvil, and get better results now compared to when I used a piece of mild steel ,that was a bit off in the surface too. You can get a new 20 kg Kanca anvil on amazon.de for good money. It's what I have.

I use a fairly rounded carbide tip, stuck in a hammer. I never hammer hard, just tap, and the divots are shallow and sand out easily. This is 2 mm 14c28n at 61 hrc on its way to a flat grind. You can see the divots in 2nd pic.

dSOMOGr.jpg

3VKRhVP.jpg
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Is that a pic after straightening? The rest of the warp you ground out?

Yeah, those divots look much less stress inducing then the ones I did with the drill bit.
 
JTknives said:
not sure what experience you have with blade straightening but surface peening is quite common. Its super common in the sawmill industry as that's how the keep their blades straight and I also believe that how the Japanese straighten their blades.
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I'm no expert on whacking things with my peen, but I believe the Japanese peen the softer spine of of the blade, not the hardened edge, and I think its the same with sawmill blades, which are usually hard teeth on a softer disc.

Correct me if I'm wrong there, as I don't work with hardened steel very often.
 
Mecha said:
I'm no expert on whacking things with my peen, but I believe the Japanese peen the softer spine of of the blade, not the hardened edge, and I think its the same with sawmill blades, which are usually hard teeth on a softer disc.

Correct me if I'm wrong there, as I don't work with hardened steel very often.
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The spine isn’t always softer. The homogeneous steel blade could be evenly hardened throughout. Most Japanese blades are laminated steels which are straightened in a completely different manner than carbide peening
 
HSC /// said:
The spine isn’t always softer. The homogeneous steel blade could be evenly hardened throughout. Most Japanese blades are laminated steels which are straightened in a completely different manner than carbide peening
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I know they don't use a carbide peen, but have seen that they do some cold hammering and such. With the exception of the maru or monosteel type which I'm sure was rare before modern copies, they all have a tougher, softer element within them.

ajcWLUL.jpg
 
Mecha said:
I'm no expert on whacking things with my peen, but I believe the Japanese peen the softer spine of of the blade, not the hardened edge, and I think its the same with sawmill blades, which are usually hard teeth on a softer disc.

Correct me if I'm wrong there, as I don't work with hardened steel very often.
Click to expand...
Mecha , they do that .I make so far maybe more then a hundred knives from HSS saw. I have hundreds of them , some broken some of them with worn teeth ..... Back then I was wondering what the hell can make damage like this on HSS steel ???? I know that almost always they work on soft steel with HSS circular saw ... Now I know that was marks from straightening..........and that is on at least 64 HRC steel ....BUT they are not dots ...they are like on FredyCro pictures....marks like it is used chisel...To be honest I never seen marks from straightening on Made in Germany HSS ................like on Wittmann-Komet brand ...
Here is pictures of one of them with I believe they are straightening marks ...............
OeFqnrN.jpg

Z07Fuuf.jpg
 
Mecha said:
I know they don't use a carbide peen, but have seen that they do some cold hammering and such. With the exception of the maru or monosteel type which I'm sure was rare before modern copies, they all have a tougher, softer element within them.

ajcWLUL.jpg
Click to expand...

If you are interested in the different techniques and hammers used for straigtening M Carters video on YT is pretty informative.


Natlek said:
Mecha , they do that .I make so far maybe more then a hundred knives from HSS saw. I have hundreds of them , some broken some of them with worn teeth ..... Back then I was wondering what the hell can make damage like this on HSS steel ???? I know that almost always they work on soft steel with HSS circular saw ... Now I know that was marks from straightening..........and that is on at least 64 HRC steel ....BUT they are not dots ...they are like on FredyCro pictures....marks like it is used chisel...To be honest I never seen marks from straightening on Made in Germany HSS ................like on Wittmann-Komet brand ...
Here is pictures of one of them with I believe they are straightening marks ...............
OeFqnrN.jpg

Z07Fuuf.jpg
Click to expand...
I am checking some Hss saws on local classifieds and also noticed the marks. Do you just cut and a grind the knives or do a new HT? Is additional tempering necessary? I would like to try some small neck/pocket knives and then maybe something larger.
 
FredyCro said:
If you are interested in the different techniques and hammers used for straigtening M Carters video on YT is pretty informative.



I am checking some Hss saws on local classifieds and also noticed the marks. Do you just cut and a grind the knives or do a new HT? Is additional tempering necessary? I would like to try some small neck/pocket knives and then maybe something larger.
Click to expand...
Just cut /shape and grind bevels ..................
 
Natlek said:
Mecha , they do that .I make so far maybe more then a hundred knives from HSS saw. I have hundreds of them , some broken some of them with worn teeth ..... Back then I was wondering what the hell can make damage like this on HSS steel ???? I know that almost always they work on soft steel with HSS circular saw ... Now I know that was marks from straightening..........and that is on at least 64 HRC steel ....BUT they are not dots ...they are like on FredyCro pictures....marks like it is used chisel...To be honest I never seen marks from straightening on Made in Germany HSS ................like on Wittmann-Komet brand ...
Here is pictures of one of them with I believe they are straightening marks ...............
OeFqnrN.jpg

Z07Fuuf.jpg
Click to expand...


Crazy! I thought nowadays saw blades were all about hard teeth on a more tough basic steel body. :eek:
 
If of interest for anyone, I managed to get the 14c28n meat cleaver mostly straight and tempered it down to 59/60 (240°C).

The tile hammer was shit, the carbide insert shattered straight away, I ground it back couple of times but it kept shattering. Still using the massive 14mm masonry bit. I dulled the tip to a round point, the peening marks by a rounded point is marked blue vs a red marked "sharp" bit.
9YFKCRt.jpg
 
Scaniaman said:
I don't think you even have to go that deep. Mine are quite superficial.
eREdR1X.jpg
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Its 4mm thick and 9 cm wide. On thinner stock it goes much faster and easier, today I was grinding 1.5mm 1.4034 that kept moving with each pass left/right. I stopped correcting till I was almost done, corrected at the end with very easy hits, two passes with 120 and they were gone. Probably gonna have to remove 0.2-0.3mm to remove the marks on the cleaver.
 
Yes thinner is easier. I haven't tried thicker than 3.5 mm. Still I don't see the need for a sharp point. Rounder works well, and leaves less to sand away.
 
Scaniaman said:
Yes thinner is easier. I haven't tried thicker than 3.5 mm. Still I don't see the need for a sharp point. Rounder works well, and leaves less to sand away.
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My point was that sharp can cause cracks and that I learned it the hard way :)
 
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