Thread: Not hot enough

Today I fired up my makeshift forge for the first time.
It's basically a repurposed old bbq, and a small hairdryer for blowing air through the holes.
It was not a big success. I succeeded in flattening the piece I was working on, but imo it was not hot enough. My pieces only got to be slightly red-ish.

The steel had to be hammered very hard in order to get it to do something.
Any suggestions for improving it in order to make it get higher temperatures?
Or is this bad enough that I have to scrap it and make something better?

Hey Bruno,
great work and you're almost there. i would consider enclosing the top. maybe just some fire bricks stacked - one on each side and a couple across the top supported by them as a roof.this should keep the heat in more. {just an idea} You really don't want to shape the steel too much if it is not hot enough as you will face cracking and damage the steel structure.
Hope that helps or inspires a better idea to do it on the cheap for you.
Regards
Adam

Thanks. Now I only have to figure out where to get firebricks and firecement.
Apart from making forging easier, it should also make it easier not to hammer dents into the surface of my anvil.
My anvil is an old one, made by a blacksmith for taking along to horse shows etc.
He made it himself. It is nice enough for what I do, but it was made for hammering iron, not steel. So it does not have the surface hardness of a proper anvil.

Companies that sell refractory cement for kilns will most likely have the items you want. There are different grades of fire bricks, you just need the low temp version ( cost Less).

I have actually done this before and know that this can work. I was just using a fire pit but the old bbq is great!

1. I might be mistaken but it looks like the ashes you have in there are from firewood. Use charcoal since the entire piece of it burns at once and will be hotter.

2. More airflow might be needed. I was using a shop vacuum and had the hose hooked up to the side that blows the air out. I used the handy mans secret weapon (duct tape) to attach it to a piece of pipe so I would not melt the hose. Then I stuck the pipe into the fire pit.

Doing this I was able to get metal a nice bright red. I used this method to harden a throwing knife of mine and it is still straight.

Hope this works for you or at least gets you closer to your goal.

Bruno,

The big question is what are you using for fuel? If you are using wood it won't get hot enough and the ash will block the air flow. I would suggest using raw charcoal not I repeat not briquettes. Briquettes have clay binders and other additives not conducive to forging. In the US Walmart carries raw charcoal it in 5 and 20lb bags. Some sellers call it natural charcoal. Charcoal needs a fairly deep fire 6" at least.

The hair dryer should be enough for the air supply-maybe drill out the holes bigger. Make you fire smaller. Can't tell from the pictures but if there are holes in the entire bottom of the BBQ then that is the main problem. You are diffusing the air over too large of an area. A razor blank doesn't need a very big fire.

Cheap kitty litter (bentonite clay) mixed with wood ashes and some straw will make a decent refractory. May crack some but just repair with more of the mixture. You may have to soak it for a while to get it to soften to a moldable clay. Place it around the out side of your BBQ and form a rectangle about 4-5 inches wide by 8 inches long by 6 or so inches deep. This will seal off the holes you don't need. Drill out holes still showing.

Putting a top on it will help but most charcoal and coal forge are open. Fuel, airflow and fire containment are the big factors.

The holes were only in the middle 6 inches or so.
I used wood charcoal, but not enough I guess. Not 6" thick anyways. And it was cheap stuff with bigger and smaller lumps, and the bigger ones were probbaly part wood inside still.

Do I understand correctly that you advise to put the insulation mix on the outside?
And I guess that I need to fill the entire bowl with charcoal then, 6" deep?

EDIT: Is it correct that red hot is the correct point for forging?
And while forging the metal loses heat. At what point do I need to put it back in the fire? As soon as it is no longer red?

Originally Posted by Bruno

The holes were only in the middle 6 inches or so.



Do I understand correctly that you advise to put the insulation mix on the outside?
And I guess that I need to fill the entire bowl with charcoal then, 6" deep?

No.
Sorry, didn't explain very well. Meant the outside of the inside
Place the insulation mix on the inside of the bowl. The rectangle I described is a cavity centered over the air holes. You want to concentrate your fire over the air flow. So if you built a box say out of Styrofoam 5 " wide x 8" long By 6 " tall you would put it over the air holes and fill in your refractory/kitty litter around it. When the refractory dried you would pull out (probably have to break it up to get it out) your box and Voila there is your fire pit.

EDIT: Is it correct that red hot is the correct point for forging?
And while forging the metal loses heat. At what point do I need to put it back in the fire? As soon as it is no longer red?

With most steels you want to forge at a dark to maybe bright orange heat. When the steel cools to a dark red reheat.

Thanks. And then when I use it, I fill the entire cavity with charcoal?

Originally Posted by Bruno

Thanks. And then when I use it, I fill the entire cavity with charcoal?

Yep, maybe even mound it up a bit as well. Also, make sure that no air leaks between the hair dryer and the holes. The pile of charcoal will create some resistance to the air flow. The air will seek the path of least resistance so if there are any leaks they will let the air escape.

As you can see from the remains of the fire in the first picture, the hardwood charcoal is going to create a lot of ash and small pieces. You will have to clean them out periodically.