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grinding already heat treated blades
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I purchased a blade made of 154 CM that has already been hardened. It is a bit too big and I would like to change the contours on it. What can I get by with without ruining the heat treat. What should I use to grind it down.

Thanks.
 
Posts: 7090 | Registered: 11 January 2005Reply With Quote
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It's going to be too hard to file down so it's going to be very difficult to change the shape without ruining the temper of the blade. You could try grinding it with a belt grinder but do it very slowly. Grind a little let it cool, grind a little more. Never let it get too hot to handle bare handed.

Even then you might change the emper somewhat but not enough to make it brittle.
 
Posts: 31 | Location: Louisville, KY | Registered: 03 January 2009Reply With Quote
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22WRF,

If it has already been hardened, a file won't touch it.

A grinder is the only real way to approach it. I'd use a 2x72 belt grinder ... and be very careful to keep it cool. Would require constant dunking. Temperatures as low as 400F will impact the heat treat ... making the blade softer. The higher the temp the softer it will get.

I usually draw hardened blades twice for an hour at 425F to get them down to RC 59 as if they are much harder there will be a tendency to chip and they'll be difficult for the average person to sharpen. Big knives are made softer ... as low as RC 55. Most folks would rather a survival knife not break because it is too hard!


Mike

--------------
DRSS, Womper's Club, NRA Life Member/Charter Member NRA Golden Eagles ...
Knifemaker, http://www.mstarling.com
 
Posts: 6197 | Location: Charleston, WV | Registered: 31 August 2002Reply With Quote
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sorry-don't exactly know how to post. anyway,my farrier gave a hoof rasp. anybody make a knife from one? how do you cut and shape? can you temper in oven? just an idea for a project.

thanx,guys
 
Posts: 43 | Registered: 22 April 2006Reply With Quote
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Best way is to dunk the blade and keep it wet, use light pressure against the belt sander and when the blade heats up the water will steam off, use that as your guide that it needs another dunk and then dunk it now, don't think you can get away with another half second of grinding....


for every hour in front of the computer you should have 3 hours outside
 
Posts: 7638 | Location: Between 2 rivers, Middle USA | Registered: 19 August 2000Reply With Quote
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quote:
Originally posted by poppycarroll:
sorry-don't exactly know how to post. anyway,my farrier gave a hoof rasp. anybody make a knife from one? how do you cut and shape? can you temper in oven? just an idea for a project.

thanx,guys


There's a maker on Blade Forums that makes some nice looking knives from mostly new hoof rasps. He leaves the remnants of the rasps on the top part of blade, has a nice antique look. I'm not a maker and don't want to try to tell you how to do it, but you'll need to soften it to shape it and then retemper. And, yes, I think it can be done in an oven.


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Posts: 17099 | Location: Texas USA | Registered: 07 May 2001Reply With Quote
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A lot of good advice has been given!

154CM is very similar to ATS-34.
The good news-You can push the temperature higher than most steels without losing hardness or temper. I have reground several with good results.
The bad news-As mentioned, a file will be a waste of time.
Use a fresh belt, low speed and frequent dunking if possible.
(Might be a good time to deliver a case of beer to a local knifemaker)
If you can touch the edge bare handed (without lingering pain or permanent disfigurement)then you need not worry about damaging the heat treat.

Remember that those strange and or glowing colors are not your friends! (but you might be able to have it re-treated)

Good luck with it!
 
Posts: 44 | Location: Midwestern USA | Registered: 30 November 2006Reply With Quote
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154CM,ATS-34 and some others are sometimes tempered at about 900 F but some are tempered at 400 F.Unless you know which keep it cool !Not a big deal just be patient.
 
Posts: 7636 | Registered: 10 October 2002Reply With Quote
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quote:
Originally posted by SH:
A lot of good advice has been given!

154CM is very similar to ATS-34.
The good news-You can push the temperature higher than most steels without losing hardness or temper. I have reground several with good results.
The bad news-As mentioned, a file will be a waste of time.
Use a fresh belt, low speed and frequent dunking if possible.
(Might be a good time to deliver a case of beer to a local knifemaker)
If you can touch the edge bare handed (without lingering pain or permanent disfigurement)then you need not worry about damaging the heat treat.

Remember that those strange and or glowing colors are not your friends! (but you might be able to have it re-treated)

Good luck with it!


How about if I deliver it and a case of beer to you? Big Grin
 
Posts: 7090 | Registered: 11 January 2005Reply With Quote
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I'm no expert, but I am assuming this is a completed knife?

What about blades? Can a bare blade be
annealed, re-ground and then re-heat treated?

For example. The Enzo "badger" and "camper"
look promising and are made of D-2 steel. But the blades are longer than I would want with a scandi grind.

Can these be annealed, reground to 4" with a flat grind, then re-heat treated?

Anyone out there doing flat grinding?
 
Posts: 1610 | Location: Shelby, Ohio | Registered: 03 November 2005Reply With Quote
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Unfortunately I do not have a "before" picture, but here is a Buck 119 Special that I got with about 1/2" broken off the tip and someone had tried to sharpen it on a bench grinder so it more resembled a Kukri than a hunting knife.

Anyway, first step was to re-profile the blade tip and remove the "belly" that had been ground in. After the profile looked how I wanted it to I reground the false edge on the top of the clip point and got all the curves to blend in together, and then I did a "flat grind" on the blade. If you look you can see the grind lines on it and the hollow grind in between the two, which of course is left over from the original grind.

I was thinking about taking the original hollow grind out to the edge but by the time I got to that point I was already questioning my reasoning behind putting a couple of hours into a garage sale knife! Afterwards I gave it a glass beading to blend all the finishes together.


The other area I worked on was the handle, which was way too thick for my taste in its original form. One thing that I did that I don't think I'd do again is follow the contours of the original finger grooves in the handle. IMHO finger grooves are good when you're fighting pirates but a smooth handle allows for more varied hand positioning when you are actually using the knife to butcher a deer.

Anyway, as I mentioned earlier my technique for regrinding tempered blades is to have a pot (as in cooking pot so it is easy to dunk) of water right next to the grinder and keep the blade wet at all times. Be especially careful when working on the edge as the metal is so thin that there is not much mass to carry away the heat.

Here is an image grabbed off the net to see how much material has been removed:


Regarding the question about tempered D2, yes the way to go about doing it would be to anneal it and then re-temper.


for every hour in front of the computer you should have 3 hours outside
 
Posts: 7638 | Location: Between 2 rivers, Middle USA | Registered: 19 August 2000Reply With Quote
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