First time questions

W

Wiredude

Well-Known Member
I'm getting reasonably close to being ready to ht my first blade. I have a few general question that I'd like some advice on though.
First off, I will be heating with a brake drum (ish) forge, it's what I have, and I know it can work, as long as I do the right things.
1. Should I heat from the spine side of the blade? Obviously the edge is the thinnest part of the knife, and would be the easiest to overheat. I was thinking that heating in that manner could reduce chances of warping, etc.
2. Should I try and get the entire blank to critical temp, or should I really only concern myself with the blade and ricasso areas, not so much the entire tang as well?
3. On the quench, same as 2, do I need to get the entire blank in the quenchant, or really just through the ricasso? I'm trying to find an appropriate vessel, and my overall length is about 12", but only about 7" of blade. Obviously, I want something big enough, but I don't want to go completely overboard either.

Thanks,
Steve
 
Fist things first...... Steel type? That's generally the basis on how each part of your question(s) is/are answered. For my response, I'm going to assume this is a plain carbon steel such as 1095, 1080, etc.

1. Should I heat from the spine side of the blade? Obviously the edge is the thinnest part of the knife, and would be the easiest to overheat. I was thinking that heating in that manner could reduce chances of warping, etc.
Click to expand...

If you're going to fully hardening the blade, then spine up is how I would go. If you intend a differential heat treat (hard edge, soft back), then I would place the edge down.

2. Should I try and get the entire blank to critical temp, or should I really only concern myself with the blade and ricasso areas, not so much the entire tang as well?
Click to expand...

Personally, I prefer not to heat treat tangs, so I would not "heat" the tang. That being said, its going to depend on what you want...... for a fully hardened blade, you want EVERYTHING to critical temp prior to quench. When I differentially heat treat, my goal is to heat ONLY that portion of the blade that I wish to harden.

3. On the quench, same as 2, do I need to get the entire blank in the quenchant, or really just through the ricasso? I'm trying to find an appropriate vessel, and my overall length is about 12", but only about 7" of blade. Obviously, I want something big enough, but I don't want to go completely overboard either.
Click to expand...

If you want the entire blade hardened, then yes, you must quench the entire thing. If you want to differentially heat treat, I only quench that portion of the blade that I wish to harden. Personally, the minimum amount of quenchant I will use is approx. 2 gallons. That is very important for the size of knife/blade you indicated. Generally, anything less then 2 gallons of quenchant, and the temp of the quench shoots too high when the hot blade is introduced, and you don't get full hardening of the steel.
 
Thanks Ed.
I would have included steel type, if I knew. I was stubborn/cheap/stupid, and went mystery steel (actually a flat pry bar from HF), and I find myself regretting it quite often. That said, I also am doing this blade largely as a learning experience, and in that light, I have learned a great deal (much of it things NOT to do again), so it's been successful in that regard.
I've been looking for something suitable as a quench tank, but as of yet, I havn't found anything that I like. I do appreciate the information on volume as well, that's something that has been rolling around my head, but I hadn't asked yet.
 
Wiredude said:
Thanks Ed.
I would have included steel type, if I knew. I was stubborn/cheap/stupid, and went mystery steel (actually a flat pry bar from HF), and I find myself regretting it quite often. That said, I also am doing this blade largely as a learning experience, and in that light, I have learned a great deal (much of it things NOT to do again), so it's been successful in that regard.
I've been looking for something suitable as a quench tank, but as of yet, I havn't found anything that I like. I do appreciate the information on volume as well, that's something that has been rolling around my head, but I hadn't asked yet.
Click to expand...
sorry to say a pry bar is probably not going to have enough carbon to harden. i would go to NJSteel Baron or Alpha Knife Supply and get a piece of 1080+ or 1084. not a huge investment, $20 or so. either make a knife small enough to fit in your brake drum, or look for another heat source. a charcoal grill with a hair dryer for forced air will give you enough heat to harden 1084.
if you have some extra $$, this is what I started with http://www.ebay.com/itm/Kiln-enamel...776134?hash=item43e6032b06:g:x6UAAOSw4UtWRljl a basic kiln like this will work for blades up to 11 inches and has good enough temperature control that you can use it for O1 or 52100.
for quench tank, a big stock pot would work. you want something that holds at least a gallon.
 
Well, you may be right Scott, I hope not, but I'll find out soon. I do know that it has enough carbon to at least partially harden, as it did soften noticeably when I annealed it. Wether on not it will reach knife hardness remains to be seen.
I actually am planning on buying a bar of 1084 for future projects, but I was hoping to get through this one first. I learned my lesson about 'mystery steel' though.
 
Steve, I can share my favorite method for heat treating with a forge, and for it I prefer a coal forge over gas. Get 3 or 4 fire bricks and build a brick tunnel over the coal fire and the reduce the fire until you have a nice blue flame coming out of either end of the tunnel. You now have a heating chamber that has an atmosphere capable of controlling decarb and scale more effectively than almost any method I have tried short of salt baths or an argon purge. The real beauty of this is the selective heating you can now do. I prefer this over a gas forge when I have to demo offsite because the even heat in the gas forge will bring the edge and tip up to temp long before the rest of the blade and thus not evenly. With your enclosed coal fire you can pull heat on the spine first while keeping the tip out of the fire and then choose when to bring the entire blade to temp at once.

I start with this method by first heating the tang and ricasso because the ricasso is nothing but a big heat sink in heating the blade. Then I turn the blade around in my tongs and pull the spine through the fire while keeping the edge and tip out of the heat until things all even out. On the last few pulls through the fire I drag the tip deeper in and allow it to equalize with the blade and when it is up to temp I quench. Due to the enclosed reducing atmosphere and temperature control I normally pull a completely scale free blade from the oil.

The only time I teach how to make a blade bend is in the ABS “Intro to Bladesmithing” course, and for this you just take two of your fire bricks and lay them flat on the fire with a .75” gap between them. Keep the draft low and draw just your edge through that gap until just the edge is up to temp, work the tip in last as before, and then quench.

Although I am known for my high tech heat treating gadgets, the coal forge is still one of my favorite methods for demonstrating heat treatment when I am not at home. While bladesmithing and blacksmithing is thriving in the 21[SUP]st[/SUP] century the proper use of a coal forge is still a dying art worthy of preserving.
 
Well, I performed an experiment today. My forge isn't exactly finished, but it is usable.
So, I grabbed a chunk I cut off the bar I used to make my blade, grabbed the 1/2 bag of charcoal that was kicking around the garage, and got things fired up.
Things learned:
1: definitely need to get some firebrick, and a tunnel like Mr. Cashen described above. Definetly lost a lot of heat out the top.
2: I need to go get me some coal. The cheap charcoal briquettes that I used in this test (because I had them) simply just didn't generate enough heat to even think about heat treating a blade. I hsve a semi-local source for coal, just need to get there.
3: Definetly need to do this in the dark for real I couldn't see the colors for crap, despite it being a gloomy, cloudy day.
4: (And perhaps most important ) The steel does harden! Despite barely managing to get to/past non-magnetic. After a water quench I got a nice ring bouncing it off the driveway, and holding it on my train-track anvil, I snapped a bit off the end, so it certainly appears to have hardened, despite me not getting as good/uniform heat on it as I would want to do a blade.
 
I helped a young guy build his first knife this last year out of a flat-bar (by his choice). It seemed to come out pretty hard. After getting started, I could tell that my annealing process wasn't as effective as it had been in the past. After the annealing, we were having trouble even with grinding, but more so with drilling. So I re-annealed it after getting set up with vermiculite. Prior to that, my red-neck annealing technique amounted to using the coals in my shop-heating wood-burner, and surrounding the hard steels with charcoal briquettes between the steel and the bed of coals. Then I would just let them slowly cool over a period of a day or two. That had worked acceptably before, but is obviously not very consistent. I have used the vermiculite several times since, and it seems to work well.
Anyway, since we weren't very far into the grind process, before saying 'this thing is still too hard!', I re-annealed the flat-bar blank. That brought the hardness down where it should be. I had shown him how to test-quench a scrap of the flat bar, and I don't have a rockwell tester, but it snapped pretty good after hardening. I realize that the carbon content of flat-bars on the market is probably all over the place, but I think he ended up with a pretty decent blade (for an unknown steel). He chose some home-brew ivory card-stock micarta for scales, and was very pleased with the end result. More importantly, he got his feet wet, and is talking about his '"next knife". I realize that unknown steels are likely to give you more trouble and often produce less than optimum results. The very experienced craftsmen here convinced me of that quite awhile back. But I can also see times where using an unknown steel might lend character to a knife or would incorporate some sentimental value into the knife.

I'd say don't give up, and remember the two most important goals:
Enjoy the work of your hands.
Learn from your mistakes.
It's all good from there!
 
Thanks for the thoughts Bill. For me the choice of a flat-bar was because I could get it easily and locally. I thought that, because if the design and intended use ot those bars, that it would likely need to have decent carbon content to not just bend when under reasonable use. I really have no intention of using "mystery steel" again, but I have learned a great deal thus far, and that can be applied as I go further down the path.
 
You must log in or register to reply here.
Back
Top