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TheAngryScrapsmith

Beginner - And a bit confused about what I've got...

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I have built a brake drum coal forge and have started trying to work a piece of steel from an old barbell into a spoon chisel for wood carving. I know it's probably too complicated a job for a beginner, but I'm a "dive right in" kind of guy. The problem I have is that the steel doesn't seem to stay very hot and workable for very long. When I pull the steel out of the coal it is red hot, but not a glowing bright white or yellow that I seem to see when people are working mild steel, and it cools pretty rapidly making my work that much harder. Is there anyway I could tell if I was heating it too little or why it won't stay workably hot for very long? 

Any feedback or help is greatly appreciated! I'm eager to get into this and make some cool stuff!

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Sound like you are not getting it hot enough to start with. What diameter bar? Any idea on what type of steel? Have you done a spark test on it? 

Photos or details of your forge setup might help and  what your using as a blower.  

Generally thicker steel needs more heat time. Red hot is not where you want to be forging it at and it will lose heat faster at that heat. If you have it in there a while and that's all your getting to then you may not have your forge working correctly or many other variables that we can't guess at. 

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Agreeing with Daswulf about thicker steel needing more heat. I'm working on a tool from a steel shaft about 1-1/4" diameter, and it takes a looooooong time to come up to forging temperature.

Keep in mind that forging at too low a temperature can create internal cracking. You don't want your tool to blow apart while you're heat treating it or using it for carving.

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Where you are located in the world might be a factor also. If you add your location to your profile, we won't have to ask every time you post something.

Like Das said, pics would help us come up with an idea as well

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I'm at Fort Hood, TX. I'm a Soldier, presently on a 24 hour shift. I'll upload the pics I have from working the forge Friday. I just joined this forum today. I have only been at this for a few days now, it took me a while to assemble all the scrap for my forge and build out my anvil pedestal, etc. It isn't easy when you're working 12-14hr shifts everyday for 2.5 months, haha.

The metal I'm working with is a piece of cut barbell. 

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Steel from a barbell is probably mild/medium carbon and probably won't harden enough to take an edge. Read the section on heat treatment.

Also, if you're interested in making woodcarving tools, you absolutely MUST read "The Complete Modern Blacksmith" by Alexander Weygers. Extensive sections on making tools from scrap, although some of his heat-treating information is a bit out of date.

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the outside of the metal can be red with the inside still not hot, you want the metal below the surface of the coals to get it hot but not right at the bottom.

bottom of the fire will be more oxidizing as there is unburnt oxygen there, you want the middle to top of the fire but with hot coals on top of it.

heat it up to bright red when you start, then put it on top of the fire for maybe a minute so the heat soaks in then put it back in the fire below the top coals until it is bright red or even orange, take it out and hit it, after you get it hot the first time just put it in once as the middle will still be hot

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One thing to beware of is the term "cherry red"  when that term started to be used as a reference to working temperatures Bing Cherries didn't exist and the cherries that did were more an orange to yellow colour.  Unfortunately nowadays the only cherries most people are familiar with are the dark red nearly black Bing cherries and so "cherry red" is probably 500 degF too low for proper working temps.

A hint to help your forge work better---install a "fence"---a piece of un painted or plated sheet metal that fits just inside the outer wall of your firepot and extends 4 to 6"above the top of the wall. leave a gap where the ends come together to alloy you to pile the fuel up higher and then stick the workpiece in horizontally through the hot spot.  Cutting a "mousehole" on the opposite side just above the wall will help get longer pieces hot in the middle for cutting or bending, (or punching or slitting or...) If you are using charcoal you may want to add some clay inside to make the firepot more bowl shaped so you use less fuel but with a deeper fire.

And if you're ever out at Fort Bliss give a shout; I've taken a forge there to the Old Fort Bliss replica for their celebration days...

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Welcome aboard and thank you for your service. We all start somewhere with forging. I know a bit about scrounging to build a forge. There's a lot of good reading on this site so in any free time you have where you can't hammer steel it's good to research. Personally I like brake rotors over drums for a cheap forge pot. Others here have other opinions. Aside from that tho it looks like your using a vent fan for a blower and what diameter piping is that going to the drum? Do you have a picture of how its hooked up at the drum? 

A couple guesses are that maybe your not getting the steel to the sweet spot in the fire, or could be not enough air, or? 

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Thanks for the advice gents. The fence is something I have toyed with the notion of doing. I have about 2.5 feet of 1/8" plate steel left and may use it for the fence, though I also considered welding it next to the pot for a coal shelf/table to store up extra fuel. I hadn't considered using the clay to bowl out the drum, though that seems obvious now that you say it. Is there any specific kind of clay that won't break apart if I jab it with a hot piece of steel? If I'm around Fort Bliss I'll be sure to give a shout out!

Daswulf, I've attached a pic of the forge top-down view. The grate seen in the pic is what I use to filter out clinkers. The vent fan is 50CFM going from a 4" tube to a 1 3/4" pipe. I ground it out as much as I could without messing up the drum. Coincidence I even have this pic, one of my Soldiers asked me for it a while back. Lucky me!

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1 hour ago, the iron dwarf said:

the outside of the metal can be red with the inside still not hot...

Although it's a different process, some of the videos of induction forging show this quite well.  The outside is so (nearly white) hot you'd swear the core has to be hot also but you can see on the end of the bar that the core is still dark.  It takes quite a bit of time for the heat to fully penetrate a bar.  

It was one of Dr. Hashasaki's favorite problems to torture us in Calculus---calculate the core temperature of some shape given time, thermal transfer, and outside heat.  He was proud of himself for proving the recipe for cooking a roast was wrong and the core would still be cold.  I remember about .001% of that stuff 35 years later.

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40 minutes ago, TheAngryScrapsmith said:

I have about 2.5 feet of 1/8" plate steel left and may use it for the fence, though I also considered welding it next to the pot for a coal shelf/table to store up extra fuel.

That coal shelf would also provide a base for a refractory brick fence that you could shape as required for the job in hand. I have a brake rotor forge and the braking surface of the rotor provides this facility.

 

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I burned a full bag of charcoal from start to finish and beat on my welds when it was fully engulfed. I wanted to make sure my welds wouldn't fail once I put coal in there and started work. (I had a previous incident where a leg weld broke off when I brutishly moved my forge around). I am using nut-sized bituminous for actual hot work though

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In the picture it also looked like your coal hadn't coked up yet. you want a good hot fire, especially if your working with steel that diameter or larger.

                                                                                       Littleblacksmith

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You may want to read Lessons in Blacksmithing Seeing Colors

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This is my drum forge. The 2 and 2-12 inch hole has one 3/8 inch bolt for a grate.

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the 3 inch hole has two 3/8 bolts. I can burn coal fines or coal dust with this set up. Nut coal would be no problem at all.

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You need a fire deep enough to have a fire ball about the size of a melon. The metal should go in about 1/2 to 2/3 up into the fire ball as shown in the drawing.

 

Let the metal soak up heat and get to the same temperature on the inside as the outside as mentioned earlier. Mild steel moves better at yellow and orange, but when it gets down to red it is time to go back to the fire and add some more heat. This temp colors can shift 2 or 3 or more colors depending if it is in the sun or in the shade.

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Charcoal dosn't really like bottom blast forges, you can make it work, but it will be a fuel hog, tho you can burn construction cutoffs in a bottom blast forge to make wood embers. One also must note that Kingsford or other brackets are not ideal ithere, stick to "lump" or real charcoal.

thanks for the compliment, JHCC, lol. IMHO side blast forges are simpler, less expensive and more versatile than bottom blast forges, tho portability can be an issue. 

This is a grafic from one of the other members.

 

 

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Tho this has a water cooler tuyere, a simple tuyere is fine, tho it is some what consumable (3/4" schedual 40 is affordable). 

Charcoal likes a fire ball about 6" across, and will heat your axle just fine. Vikings made swords, spears and axes with it. 

Thanks for your service, thanks to your family for loaning you to "us", it's been 30 years since I put on Uncle Sam's pickle suit. 

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I'm using Bituminous coal for the forge, I only used the charcoal to test my welds and fire pot for strength. 

5 hours ago, Glenn said:

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You need a fire deep enough to have a fire ball about the size of a melon. The metal should go in about 1/2 to 2/3 up into the fire ball as shown in the drawing.

 

I think my problem might lay in this diagram here. I don't think my forge is going to be big enough to get a melon sized ball of coke for working. The steel bars are 1- 1.5" thick and are (I'm assuming) very hard, high carbon steels. Besides the barbell (which may be low carbon) I have 3 hydraulic piston rods and 3 HMMWV axles. So, I guess I will build my fence up a bit tomorrow and try getting a bigger ball of coke. Should I be using smaller coal lumps due to the size of my fire pot? I saw mention of "rice" coal. I thought the smallest used for forging was pea...

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Ahh very high carbon steels tend toward brittleness I would not think that a weightlifting bar would be made such that it would break if dropped.  I would expect *tough* medium carbon steels for that purpose.

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Any heavy metal coating is bad. The old adige is "if it rusts" tho stainless is an exception, as is titanium. 

Side blast will be happy with coal as well, but as we have a bottom blast to deal with, let's see, what we can do, re shaping the bowl is a good idea, but the clay will vitrify and the clinker will stick to it like glue, sand and ash will help with that, think Adobe with ash added, again a 8" bowl is probably plenty wide , as we can only work about 6" by hand. If the bowl proves to deep consider a bullet grate (2" pipe cap with a 3/4" hole drilled in the center) a table is really convenient, especially for keeping hot coals from falling when you are moving stock in and out, so that 1/8" might be better used making a 24-30" table. That way you can better manage your fire, and coal needs to be herded like cats...

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Let us not mince words. Chrome and especially zinc are POISONOUS when heated. The fumes can injure your health and in some cases kill you. A friend of mine died burning the zinc off of galvanized metal 11 years ago. Read up, be cautious, and stay healthy.

SLAG.

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