is a charcoal fire fit for heat treating 1084?

[max o' the north]

I'm dipping my toes into knifemaking for the first time, and after reading up decided to go with 1084 steel. I don't feel like buying a propane forge, and I was thinking I could instead use a charcoal fire setup, I have an old washing machine drum that I use as a fire pit. It's got some holes in it for airflow, and I was thinking that if I dumped a bag of charcoal in it, it might get hot enough to treat a relatively small 1084 blade. I could also set it up in a different manner if that's more advisable.

 

[DevinT]

No

Mayday…..Mayday…..Mayday…..

Hoss

 

[gentleman_edc]

If you add a blower, it would probably get hot enough, but why?

 

[Glen Juntunen]

If you insist on using charcoal, I recommend going with hardwood lump instead of briquettes. It will definitely get hot enough with the right amount of air flow. However, you’ll need a quench oil as well to harden the blade.
Heat treating in a forge and judging the temp by the color of the steel isn’t the best way to heat treat, but your blade will get to some degree of hardness.

 

[daily_grind]

Welcome to the forum!
Or coal? Not sure where you're from - I could recommend somewhere if I knew.
I feel like I'm stealing Stacey's thunder by recommending that you fill out your profile a bit. Sometimes there are knifemakers nearby that might be able to help you out more directly.

 

[max o' the north]

If you insist on using charcoal, I recommend going with hardwood lump instead of briquettes. It will definitely get hot enough with the right amount of air flow. However, you’ll need a quench oil as well to harden the blade.
Heat treating in a forge and judging the temp by the color of the steel isn’t the best way to heat treat, but your blade will get to some degree of hardness.

thanks for the advice; I have one of those laser thermometers, so hopefully that'll help. I'll set up a hairdryer and some fans to increase airflow, and I'll definitely look into the hardwood charcoal. I also know there's a coal mine in Fairbanks that I can go to, but I don't know if they sell directly to the public. thanks again.

 

[Stacy E. Apelt - Bladesmith]

Welcome, Max. There are plenty of knifemakers and blacksmiths in the Fairbanks area. Try and find one to help you do the HT. Also, check with larger machine shops. Many have a HT oven and could do 1084.

If you build a proper coal/charcoal forge you can do the HT in it. With no experience the results will be unpredictable, but with some practice you can harden in a simple forge. Practice on some cheap steel bars or scarps.

You need to look at some plans for building a coal/charcoal forge. It seems you don't quite understand how they work. It isn't like a big BBQ.
You need a relatively small pile of burning coals and an air blast directed up through the coals from below to get the heat needed. Do a Google search for "Brake Drum Forge". That will show you how to make the simplest coal/charcoal forge. My first forge was basically one like that.

As mentioned, you want lump charcoal or forging coal ( bituminous).

As an alternative, you can learn to HT a knife with a torch and some firebricks. There are lots of tutorials and such in Shop Talk about that, too. Use the Custom Search Engine in the stickys to find any topic. There is also a HT and metallurgy section in the Stickys.

 

[Daniel Fairly Knives]

You just need a blower/tube setup. You want a pipe running through it blasting air through holes. Look up Tuyere Forge, run it on hardwood and it can get plenty hot. You might get away with an old blow dryer and creative engineering. Now this is more of an advanced setup but you can get it going!

 

[running bird]

If you find an old sink laying around they can make an ok coal forge too. That’s what I made my first forge out of. Was a stainless steel double sink. Blower hooked up to the drain on one side, lined with refractory cement and fire bricks. The drain had a 90° elbow at the bottom so nothing hot would fall into the shop vac hose. And don’t put the coal directly over the drain. I had two bricks meet right over the drain so the air came up between them, then some chicken wire under them to keep it from sinking in. The other side of the sink I filled with water to cool my tongs and punches.

 

[Stacy E. Apelt - Bladesmith]

My first forge, at age 11 in 1961, was an old hibachi (you youngsters will probably have to look that up) with a 90° piece of 4" duct under it and a 3-speed fan blowing into the duct. I burned coal from I picked up the sides of the coal train tracks. Luckily, it was met-coal (but I didn't know the difference back then). It got hot enough to ruin a lot of metal before I learned to close up the draft with a damper. Years later I built a Brake Drum Forge that was actually a pretty good forge. All the parts were scrounged except a bag of fire clay and some pipe fittings.

The biggest mistakes most folks make in building a home brew forge is too much air and no ash dump.

If all you will do is do HT, make a pit forge. It is a piece of 1.5" pipe with 1/4" holes drilled in it in the bottom of a dirt pit (if you have local clay soil, all the better). Use a small shop vac for the air supply, and a PVC valve to control the air blast. Use blocks of hardwood burned down to coals, hardwood charcoal, or blacksmith coal for the fire. Heck, for a simple HT, even chunks of 2X4s will work.
You will have to make some long handles tongs from a pair of HF needle-nose pliers. Do a Google, there are 100's of videos and tutorials on making them online. This simple forge and a strong welding magnet will do HT for most simple carbon steels. 1084 should be brought to non-magnetic and immediately quenched in warm canola or mineral oil.

 

[thebrain]

I remember this from many years ago. There are articles on how to make this type of forge all over the Internet. Tai Goo is pretty famous for this type of stuff.

 

[Bill DeShivs]

The laser thermometer won't work for what you want to do.
You can use a magnet. When the steel gets hot enough that a magnet won't stick to it, it's time to quench the blade.
Then, you have to temper it.

 

[Alex Topfer]

From my understanding 1084 might not be the best steel to start with here. Try 80crv2, very similar but the extra alloying elements make it a little less prone to overheating

Be aware there's a lot more to learn with forge heat treating. A reasonable result requires experience and practice with the specific forge, if you're not interested in learning that then look into heat treatment operations or a kiln

 

[max o' the north]

My first forge, at age 11 in 1961, was an old hibachi (you youngsters will probably have to look that up) with a 90° piece of 4" duct under it and a 3-speed fan blowing into the duct. I burned coal from I picked up the sides of the coal train tracks. Luckily, it was met-coal (but I didn't know the difference back then). It got hot enough to ruin a lot of metal before I learned to close up the draft with a damper. Years later I built a Brake Drum Forge that was actually a pretty good forge. All the parts were scrounged except a bag of fire clay and some pipe fittings.

The biggest mistakes most folks make in building a home brew forge is too much air and no ash dump.

If all you will do is do HT, make a pit forge. It is a piece of 1.5" pipe with 1/4" holes drilled in it in the bottom of a dirt pit (if you have local clay soil, all the better). Use a small shop vac for the air supply, and a PVC valve to control the air blast. Use blocks of hardwood burned down to coals, hardwood charcoal, or blacksmith coal for the fire. Heck, for a simple HT, even chunks of 2X4s will work.
You will have to make some long handles tongs from a pair of HF needle-nose pliers. Do a Google, there are 100's of videos and tutorials on making them online. This simple forge and a strong welding magnet will do HT for most simple carbon steels. 1084 should be brought to non-magnetic and immediately quenched in warm canola or mineral oil.

thanks for all the help; I'll look into building a more advanced setup, and I did find that I can buy a bag of suitable coal from the mine.

 

[Stacy E. Apelt - Bladesmith]

You can set it on some cinderblocks or weld on legs from scrap metal. I saw one where the base was a tire rim with rebar going up to the drum.
A hair dryer from te thrift store of the junk closet will work for the air supply. The biggest problem with most folks is getting the steel too hot and burning it up.

 

[LCoop]

I presently only use SS that I heat treat in a electric kiln I made. Wrapped in SS foil, plate quenched in aluminum then put in DI slurry. Then tempered in a PID tempering oven. Lastly RH tested to ensure every part of the process was perfect!
I STILL get compliments from the simple knives I made when I had a two brick propane forge, a magnet and quenching in Olive oil. 1080,1095 and O1, Yes all the data suggests most of those were horrible for simple heat treat. Did I get the ultimate performance from the steels. Heck NO. But I still to this day get comments that they were the best ever knife they owned. So to all the nay Sayers, go for it You can make a great knife with very little equipment if you just pursue it.

 

[DevinT]

It amazes me that we are making something that is supposed to cut yet we neglect the heat treating, geometry, sharpening and steel selection, the most important things.

Hoss

 

[Deutron]

Hi,

I am using a simple char coal fire for learning heat treatment and making knives/edge hardened axes for myself. I have made a forge from fire resistant bricks and hot air blower. Later version has steel pipe running through the ground for air supply and it is far more effective to heat stuff.
Gauging temp by colors is not easy, while temperature is critical, especially not to overheat the part. So far I have got the best results by quenching immediately(very little hold time, like 1-2 minutes) as temperature is reached. For most carbon steels color will lie between dark to bright red,, depending on hardening temp, lighting etc. It's kind of fun process for me, even though results are not always consistent.

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Regards

 

[J. Doyle]

It amazes me that we are making something that is supposed to cut yet we neglect the heat treating, geometry, sharpening and steel selection, the most important things.

Hoss

It amazes me (but doesn't surprise me) that one of the best makers ever in the knife world, that's also part of/has direct access to the most advanced and up to date metallurgical information, can be the first to respond to this post with an answer (the correct one) and a bunch of people act like he's not even here and go ahead and ignore his post and go on about how to heat treat in a charcoal forge.

This place is LUCKY to have Devin Thomas even here trying to answer questions. Enjoy it while it lasts.

It's a great reminder why I read here infrequently and post here even less frequently.

I'll put on my flame resistant suit and go ahead and see myself back out.

 

[Stacy E. Apelt - Bladesmith]

No need for fire retardant.

Devin is a great guy and has a ton of experience. His son, Larrin, has even more knowledge. They always give the correct answer on the BEST way to HT a knife.

However, everyone does not have their experience, finances, equipment, or resources. Those people have to either never make a knife or make one as good as they can with the things available to them. This is how it has been since man discovered fire and melted metals. Do the best you can and strive to improve. Most all the HT info and equipment used today is less than 100 years old.

I would not be a knifemaker if I had not started on a home brew forge and lesser materials. Looking back from my current knowledge, it was a miracle that I turned out anything useful. It was a long time before I had a propane forge, and longer before I had a HT oven. I started on whatever steel was reliable as high carbon steel, mostly tire irons in the beginning. I studied, improved, practiced, and improved more.

When I advise someone in Shop Talk who asks how they can HT a knife with only the simple things they have around them I give them the answer they need. I always point out that it is not the best way, but with practice and attention to the details it will work.