help with hardening in forge

[Scott Roush]

okay... getting frustrated with quenching. Tonight, for the first time... I had a blade fail my file and brass rod. The edge bent right around that rod! Before getting my forge I was using an old ceramics kiln for hardening... but it took well over an hour to get up to critical temperatures at the highest setting. So I decided to put it away when my forge was built. But now I'm having a hell of a time getting even heating.  Tonight, I was so paranoid about over heating the very thin tip on this blade, that I don't think I got the edge up to critical.... only non-magnetc (I'm using 1075).

I've been playing with a steel tube... and I now have the hardware to make an idle valve so I can bring the heat way down.  It also occured to me that it might be better to use the back of my forge.  My forge is about 17" long... and I have a single venturi burner closer to the front opening to allow room for a second burner (if I ever even need one)... so there is a lot of open space towards the back and a small opening back there to allow air flow... anyway...

So what do all you folks do for your hardening heat? Would I be better off getting my old kiln out? It does have a pyro and thermocouple. But it's old and will die soon.  What about another forge made especially for heat treating???

[beaver#1]

it does take some practice to do it right, and im no pro at it, but i sucessfully hardened blades in my coal forge and have no doubt that i will be able to in my new gas forge.  when using a forge, its best not to just put the blade in and let it sit. learn how to watch the heat move through the steel, the ricosso is going to steal alot of heat because of the mass,  so once you get that and the spine heated you should be able to get the proprer temp, through out the blade.  you kinda have to "hold its hand" to help reach the right heat overall.  i hope this didnt confuse you more.  but some of the pros will be by shortly im sure
dustin parker

[beaver#1]

btw that first knife you forged looked really nice,  heck of alot better than my first.  dont get to frustated, you will get it.

[R H Clark]

I'm no expert either but I have had the help of one and this is what he told me.

You can hold the blade with the tongs the whole time,as beaver said,don't just let it sit especially a small blabe.You can heat the ricasso first by flipping it around and holding the tip.Don't let the tip get too hot.Keep it close to the front while you heat the ricasso then quickly flip it so you are holding the tang with the edge up.Stick the tip out the back hole if it tries to get too hot.

While you are doing all this you are moving the blade to insure you are getting even heat.As soon as you reach temp through out the blade quinch within about 1 sec.

May not be what you hear from everyone but it has been working for me.

[Wampus]

It also doesn't hurt anything to dip the tip in your quench oil a few times to keep it from overheating while you're waiting for the rest of the blade to come up to heat.

[kbaknife]

Scott, I have no experience with the type of forge you are using.
But I do know a couple zillion guys who build and use the vertical forges on a daily basis.
I have two of them and my 12" comes up to welding heat (2300) in a handful of minutes.
The key is the heat entering the bottom of the forge, in addition to the blower, which gives a lot more control and less fuel pressure needed.
Heat entering the bottom totally eliminates the need to be careful of overheating from direct contact with the flame.
Also key is proper insulation. You are heating the blade by radiant heat from the forge - NOT the flame!
A vertical forge is just so much easier to control from all the problems I have seen just like the ones you mention here.
If you can find another forge body and stand it on end and get a small blower, your problems would cease.
I know you've been getting some other advice on the other forum and they mention your kiln.
They have their place as well. I use my heat treat oven  weekly for spherodizing and and austenizing large 5160 blades.
But my forging, damascus making and MOST of my thermal cycling/normalizing/hardening procedures are done in my vertical forges and I am in total control of the out-come.
You already have some of the piping and other supplies needed to build one.
I'd help you in any way that I can.
This is my 12" for Damascus making and larger blades, but I have an 8" that I use for forging and hardening hunter size blades.
They even use LESS fuel pressure than the one you are using now.
I've heard sooooooooooooooo many complaints from users of that type forge, and I have literally never heard complaints about this one.
 

 

 

[Scott Roush]

Thanks guys...  Yeah... I've been holding the blade and moving it around. I did that right off the bat....  My problems yesterday are the blade design...a very narrow, skinny tip.

Karl...  My forge is very well insulated... but I've been using the front of the forge closer to the flame and that has been my major issue.  I might have better luck in the back where I can see that the insulation has a nice even color all around the perimeter and no blast from above.

But... I've been thinking a lot about making a vertical.  The propane forges they were using at Haywood were similar to mine for forging... but they had a vertical with heat from below for heat treating.  I saw them put their blade in that thing and walk away.

I will probably keep the setup I have...and start looking for a body to make a vertical.

I might have to get your advice on some of the fittings Karl... Thanks for the offer of help...

[Jeremy]

Is this your forge, or have you modified since?
 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=110;t=002222#000000

[Scott Roush]

oh... I appreciate the compliment Beaver..

And RH... I will play around with flipping it from tip to tang.  I was trying it by holding the spine and having it parallel to the heat source.

Anyway...  That last hunter I posted was a lot easier to deal with because of the mass in the blade.  This little guy I'm working with right now is just more susceptible to burning at the tip.

Somebody on another forum had the idea of reducing the internal volume of my kiln.  That might be a good solution too...

All good advice... However... it might all come down to getting more stuff.

[DANA HOLMAN]

Scott, i have one kind of like Karls, and it works vert good, about 5 min. of pre heating and about 10 min. of heating treating. I've  used a one brick forge when i started. but the vertical is the way to go
dana

[Jeremy]

Closing off the front opening of your forge would help - you're losing a lot of heat with that big opening.  Redirecting where your flame is coming off your burner to get the heat circulating better would help quite a bit too.
Looking at the pic in the thread though... close off the front opening and turn your burner down.

The vertical forges are real nice, but they aren't a cure-all.  You still need to control how much heat your burner is putting out or you will overheat the tip.

Properly controlled either style of forge will work great.  You just need to get your forge under control.

For thermal cycling and hardening small to medium blades I still use my miniforge precisely because I know can get an even heat in the forge chamber and not risk overheating the steel.

[Scott Roush]

Jeremy... yeah that is the one.  I normally have firebricks stacked up to reduce the opening. I didn't have them there in that picture.  

And good point.. I do NOT have it under control yet. But I'm getting there.  I now at least have an idea about how far I can turn it down and still get a nice flame.  I'm hoping my idle valve set up will make that even better...  I also think it's gonna help a lot when I start using the back of the chamber where it is a bit further from the main blast of the flame. It sure looks like a nice even heat back there...

Thanks again...

[Jeremy]

If you do decide to change over to a vertical forge at some point you can still use the burner you bought from Zoeller.  You can easily run those at 5psi and if you're careful in how you set it up can go lower and still get a good burn.

I don't always have power (done a few demos in random places) so a blower-type forge is out for me.  They should be more efficient, but I'll never be in the position where I'm using it enough that the little bit of fuel saved is going to amount to much.

[osageo]

i took a 7 gal propane tank , lay bown style , cut the whole end of tank off valve end ,put my koa wool in it , cut the valve out for my opening , welded the end of tank back on , mounted a smallest burner i could build on middle side blowing straight down, turn it as low as it would go, it runs very quiet and burns perfect at critical temp, never over heats the point. tested it out at don foggs shop , worked great, don was impressed.