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Jeff Dalbey

Any advice welcome

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This is my first attempt at building a forge and I've not forged a damn thing yet (though I did make a smelter from an old propane tank to melt down precious metal) ..so I'm building a three-torch forge from an old well pump tank I got for $25, the stand cost $20, pipes cost around $40 I suppose.  I've painted the inside with 2000° heat paint, then lining the outer layer with about 4" thick 2000°+ insulation followed by 1" ceramic insulation and then ITC-100 (or something cheaper if I can find where to buy).  I know it's huge, but I couldn't pass up the deal for the tank and it was already fitted with threaded connections that I reconfigured for my piping.  The second pic doesn't have the opening I put on the other end, and I'm replacing the hair dryer with an old leaf blower connected to a "dimmer" switch to control the forced air speed. 

 

Any thoughts, constructive criticism?  I've not tested the leaf blower, but the hair dryer wasn't enough power to get a good air /fuel mix on 2 torches so I know it won't do on three. 

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Edited by Jeff Dalbey

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Good start, but it sounds like a bit of overkill on the insulation and air supply. I made a heat treat forge for swords from a 100 lb propane tank, and my air supply is just a blower fan, which is usually not even ran at full delivery. A leaf blower, even throttle down, will probably be way more air than needed, and annoyingly loud on top of that.I will get a rating off my fan if possible and post it. Pipe size is possibly the issue.

heattreatforge.jpg

Edited by SteveShimanek
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That things a beast. Only input I have is you'll very likely need an opening in the back lest you want ALL of that heat in your face, hand, and everything within 6ft of that orifice becoming untouchable. Of course welding some angle iron above and below both opening's to allow setting in fire brick will let you control exhaust. You'll lose some heat but not enough to value a single opening. 

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Cripes, thats massive! what will you be forging ?!

 

Two bits of general advice, .....

 

Dont use it indoors for the first half dozen sessions, all the paint will gas off when it gets properly toasty.

 

If you decide to use it indoors, even in a ventilated workspace get a Carbon monoxide alarm, they are only about $20 for the ones that display in PPM. Forge that size out of tune will make you blue lips dead in the time it takes to say 'I feel a bit dizzy!' - CO is also a cumulative poison, so might take a few sessions to make you ill. I know of 3 bladesmiths which have had near misses with CO poisoning, one ended up in hospital from a small heat treat forge!

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3 hours ago, JohnK said:

That things a beast. Only input I have is you'll very likely need an opening in the back lest you want ALL of that heat in your face, hand, and everything within 6ft of that orifice becoming untouchable. Of course welding some angle iron above and below both opening's to allow setting in fire brick will let you control exhaust. You'll lose some heat but not enough to value a single opening. 

I do have a back opening but it was added after that first internal pic. I made it slightly larger than my fire brick to allow heat retention and allow some air flow as well.  Thank you for replying!  Very excited to get this going. 

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3 hours ago, SteveShimanek said:

Good start, but it sounds like a bit of overkill on the insulation and air supply. I made a heat treat forge for swords from a 100 lb propane tank, and my air supply is just a blower fan, which is usually not even ran at full delivery. A leaf blower, even throttle down, will probably be way more air than needed, and annoyingly loud on top of that.I will get a rating off my fan if possible and post it. Pipe size is possibly the issue.

I would definitely love some guidance in the piping area, currently using 3/4 black pipe.  How much was the blower? 

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That thing is big!  I'll second Steve's comment about the leafblower.  I've been using one on my forge for the last two years.  Waaaaay too much air, and incredibly annoying to listen too for hours at a time.  I had to put a gate valve on my piping and keep it barely cracked open in order to keep the airflow under control.  I recently replaced it with the exhaust blower fron an old water heater and I'm much happier.

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Personally I use a conair blow dryer in my oil forge and even the sound from it is ummm let's say not enjoyable. Let alone a leafblower. If it's propane then to some extent it should be self aspirated. So even a regular ole squirrel cage should do with slightly larger diameter pipe. Of course mine needs the air a dryer gives. Also if I may add, I did modify mine to run on DC. You'd be amazed how much power that heating element takes from the motor. Mine runs on 18v printer supply and I occasionally use it as a leaf blower to clean around my forge B)

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Personally, I'd be concerned about that insulation as well.  It says it's rated to be fire-resistant up to 2000 degrees.  What we usually use on forges is ceramic wool fiber (not mineral wool) rated to 2300 or 2600 degrees.  

That thing is indeed huge and will be quite the gas hog.  I use coal for welding and large objects, but my blade forge is little two-brick with a 3/4" venturi burner that will run at 2100 F for a week or more of four-hour sessions on a 20lb tank.

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Check out the Build a Gas Forge and the Ribbon Burner attachments on the Forge Supplies page at www.WayneCoeArtistBlacksmith.com.

Let me know if I can help you.

 

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10 hours ago, Alan Longmire said:

Personally, I'd be concerned about that insulation as well.  It says it's rated to be fire-resistant up to 2000 degrees.  What we usually use on forges is ceramic wool fiber (not mineral wool) rated to 2300 or 2600 degrees.  

That thing is indeed huge and will be quite the gas hog.  I use coal for welding and large objects, but my blade forge is little two-brick with a 3/4" venturi burner that will run at 2100 F for a week or more of four-hour sessions on a 20lb tank.

I did mention the 2000° insulation will be the outer shell and the ceramic insulation would be the inner (it's rated for 2400°).  Will the ITC-100 and the ceramic insulation be enough to protect the weaker insulation? 

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Ah, I missed the bit about ceramic wool,  sorry.  Yeah, that'll be fine.

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I foresee you putting that monster in a corner of your shop and building a much smaller single burner forge.  That thing might be what you need if you are heat treating really long blades but you can only work about 4"-5" inches of a blade at a time so for general forging that is major overkill.  When you build your next one try bringing the burners in at a tangent at the upper side of the forge to give you some swirling of the burning gas.  Burners pointing straight down will cause hot spots and burn the carbon out of the steel faster.

 

Doug

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Note: Cross posted with Doug.  I agree completely with his comments.

 

The other issue with the length of your forge is that, particularly as a beginner to forging, you will be heating far more of your stock than you can effectively hammer in one heating session.  A long forge like that one is really only useful if you have a power hammer or press and are working architectural scale (or are using it for relatively low temperatures for heat treatment of swords (though I think a vertical heat treatment tank, ala Don Fogg, is a better choice there).  The issue with heat treating too much steel for bladesmithing is more chance of decarb as well as wasted propane (not to mention a more complicated burner setup).  I visited Albert Paley's studio recently, and his gas forge is no larger than the one you plan on building.  IMHO an 8" forge length is pretty optimal for most bladesmithing (particularly if you have a dedicated heat treatment chamber).  The real problem with gas forges is that no one design works for all smithing operations.  That is where solid fuel forges shine.

 

If you keep the current configuration I would recommend the following (all my opinion, so take or leave as you will):

  1. Replace the vinyl propane hose with hard piped copper with flare fittings or at least propane rated hose.  Bubble test any joints up to the mixing tube.
  2. To run (3) 3/4" forced air/propane burners you will need a large propane source.  A standard 20 gal barbeque  tank will slurry up with that much draw.  You will also need an adjustable propane regulator (0-30 psi minimum).  Tank should be kept outside your building, if possible, with 1/4 turn shutoff valve at building entry.
  3. I recommend using a minimum 2" pipe size from the blower right up to the main mixer tube header (you can pipe your 3/4" individual burners for t-fittings off that header).  This will allow you to use a blower with a  reasonable airflow to static pressure ratio.  Blowers of this type will be quieter and more efficient.  I'm not going to do the calculations, but I expect that a blower that supplies around 160 CFM at 0.5" WG will be adequate.
  4. You will want some method of modulating the airflow from your blower.  If you are scrounging, the new high efficiency furnaces often have combustion inducers with ECM motors that can be controlled with a 0-10 VDC signal.  For a conventional blowers you will need a manual damper at the outlet or waste gate, to allow control of the airflow.  Note that dimmer switches will not work well for the typical cheap squirrel cage blower motors and likely not on your leaf blower either for extended use.
  5. Make sure your pipe reducer/burner flares are well covered by the inner insulation layer/refractory.  Otherwise they will burn up in use.
  6. It is extremely costly and difficult to coat the ceramic wool directly with ITC.  At bare minimum you need to seal the surface first with a solution of fumed or colloidal silica and water.  This will harden the refractory blanket and seal it.  Otherwise the fibers become friable after heating and will get into the shop and eventually your lungs.  Don't make my mistake and damage your lungs!  Personally I like to have an inner coating of at least 1/2" thickness of castable refractory (Kastolite 30, or similar).
  7. If you ever plan on forge welding with flux, you need to think again about the floor of your forge.  Hot flux will eat the blanket like water on cotton candy.
Edited by Dan Hertzson
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I forgot about #5.  I once turned a 12" black pipe nipple into a 6" nipple by not protecting it from the flame.

 

Doug

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Oh, whilst I am thinking about it, when you shut your forge off, the burner tubes act as a chimney, and basically end up the same temp as the inside of the forge! - I would reconsider the positioning of those ball valves on the burner tubes. I do not think they will last long there!

 

I pull my burner from the forge when I shut it down so it is not subjected to heat cycling. My burner enters at the forge floor level (its a venturi) - so I just slide it out when I shut the forge down. 

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5 hours ago, John N said:

burner tubes act as a chimney

 

In a forced air forge you can avoid this problem by running your air source for a few minutes after you shut off the gas.

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You can always put that big tank on a diet and cut it down to size.  I know its a temptation to use what's available, but propane forges made small can still make a lot of work. 

 

For really big forges, I see guys have little 1 or 2 burner forges.  When they need to heat something really long, they bolt another forge to another and so on.  That is for some serious hand rail work though.  Look at Wayne Coe's design for a clam shell/Super C forge.  I've seen home built forges like this that architectural people use as their main forge as it fits nearly everything.

 

On 10/13/2019 at 3:29 PM, John N said:

If you decide to use it indoors, even in a ventilated workspace get a Carbon monoxide alarm, they are only about $20 for the ones that display in PPM. Forge that size out of tune will make you blue lips dead in the time it takes to say 'I feel a bit dizzy!' - CO is also a cumulative poison, so might take a few sessions to make you ill. I know of 3 bladesmiths which have had near misses with CO poisoning, one ended up in hospital from a small heat treat forge!

 

If anyone can elaborate about cumulative CO poisoning, I think most of us understand that too much at once causes death, but I did also read an article that even low CO levels over time still produce brain damage. <--- That information I read in a blacksmith magazine and have not looked into any medical articles since.  I think there is something in OSHA that states acceptability CO levels per 8 Hours, but I'm not doctor.  When I asked a Dr. about CO poising over time, something came up about rate of exposure and how much at a time over how long of a time.

 

Edited by Daniel W

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OSHA regs specify you may be legally (not necessarily safely) exposed to 50 PPM of CO per hour, averaged over an eight-hour period.  That said, exposure to 70 PPM will cause noticeable symptoms in a few minutes, over 100 PPM can cause death if symptoms are ignored.  My detector goes off at 20 PPM, and has only done so when the coal stove has a backdraft.  

 

Here's what OSHA has to say about it:

 

"Carbon monoxide has over a 200-fold greater affinity for hemoglobin than has oxygen (5.18, 5.19). Thus, it can make hemoglobin incapable of carrying oxygen to the tissues. The presence of CO-hemoglobin (COHb) interferes with the dissociation of the remaining oxyhemoglobin, further depriving the tissues of oxygen (5.15, 5.16).

The signs and symptoms of CO poisoning include headache, nausea, weakness, dizziness, mental confusion, hallucinations, cyanosis, and depression of the S-T segment of an electrocardiogram. Although most injuries in survivors of CO poisoning occur to the central nervous system, it is likely that myocardial ischemia is the cause for many CO-induced deaths (5.18).

The uptake rate of CO by blood when air containing CO is breathed increases from 3 to 6 times between rest and heavy work. The uptake rate is also influenced by oxygen partial pressure and altitude (5.20).

Carbon monoxide can be removed through the lungs when CO-free air is breathed, with generally half of the CO being removed in 1 hour. Breathing of 100% oxygen removes CO quickly.

Acute poisoning from brief exposure to high concentrations rarely leads to permanent disability if recovery occurs. Chronic effects from repeated exposure to lower concentrations have been reported. These include visual and auditory disturbances and heart irregularities. Where poisoning has been long and severe, long-lasting mental and/or nerve damage has resulted (5.15).

The following table gives the levels of COHb in the blood which tend to form at equilibrium with various concentrations of CO in the air and the clinical effects observed (5.21):

Atmospheric
CO (ppm)
COHb in
Blood (%)
Symptoms
70 10 Shortness of breath upon vigorous exertion; possible tightness across the forehead.
120 20 Shortness of breath with moderate exertion; occasional headache with throbbing in the temples.
220 30 Decided headache; irritability; easy fatiguability; disturbed judgment; possible dizziness; dimness of vision.
350-520 40-50 Headache; confusion; collapse; fainting upon exertion.
800-1220 60-70 Unconsciousness; intermittent convulsions; respiratory failure; death if exposure is prolonged.
1950 80

Rapidly fatal."

 

 

 

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Plus it's not a good way to go.  It's heavier than air so fans don't disperse it, it can be explosive in the right concentrations, and if it's strong enough to knock you over, it can do that to anyone who tries to drag you to safety.  

 

When I was in graduate school I toyed with the notion of going into forensic anthropology (well before any of the CSI-type shows were around, I may add!), and as such got to work with Dr. Bill Bass, famous operator of what we called "The Facility," but which the rest of the world knows as "The Body Farm."  This is a facility where the effects of various environmental factors on human decomposition are studied.  Once each experiment has run its course, the remains must be gathered.  From this experience I can tell you that the purple you turn from CO poisoning is permanent (assuming you die from it), and renders you poisonous as well.  Prepare for a closed-casket service. 

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Great posts @Alan Longmire !

 

Basically CO is probably one of the most dangerous things in the forge.

 

I know a youngish lad, early 20's,  that built a 4 (!) burner forge he was asking me advice about during its construction, he was using it in a fairly small workshop. I bored him, and basically nagged him to get a CO alarm. He reluctantly picked one up. Got a message on facebook from him a few days later thanking me for the heads up. The alarm went totally off the chart when he first tested the forge :o 

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Incredibly important information guys. This stuff should be on the terms of service for any smithing site and not just a blow through to accept the terms of service either. From experience: around the age of 10 until 15 I use to smelt lead for casting and all around because it was fun. Didn't know the dangers. All I've ever heard was don't eat it. I developed vision problems that finally went away after 15+years. My eye sight was 20/15 before to 20/70or85 I think it was. Had to wear glasses in the army. A couple years ago I noticed things that were fuzzy like vanity plates I could read over 100ft away. My vision finally improved. However, as any doctor can tell you the brain didn't. I've had serious mood swings and definite anger issues turn up over the years. I can tell it caused permanent damage. Sweets are overbearing, I'm easily overwhelmed by well lit rooms or cloudless days. I can't focus well. I'm constantly nauseous. A myriad of issues from my dumb kid days. Even recently I experienced metal fume fever from a galvanized forge burner I built and once again ignorant of the possible danger. For a week I was extremely irritable, massive headache, couldn't stay awake, mood swings, and no appetite(even if I tried Id just puke). CO is just as bad if slightly short lived but just as damaging. Also heat exhaustion guys. Probably just as important. In my army days I'd see guys drop like flys in a gas chamber from dehydration and over heating. Hey I love to try and just finish those last few heat and hammering's but if your dizzy or just drained then just stop. Ain't no man ever been a real man if he's dead. 

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32 minutes ago, JohnK said:

Incredibly important information guys. This stuff should be on the terms of service for any smithing site and not just a blow through to accept the terms of service either. From experience: around the age of 10 until 15 I use to smelt lead for casting and all around because it was fun. Didn't know the dangers. All I've ever heard was don't eat it. I developed vision problems that finally went away after 15+years. My eye sight was 20/15 before to 20/70or85 I think it was. Had to wear glasses in the army. A couple years ago I noticed things that were fuzzy like vanity plates I could read over 100ft away. My vision finally improved. However, as any doctor can tell you the brain didn't. I've had serious mood swings and definite anger issues turn up over the years. I can tell it caused permanent damage. Sweets are overbearing, I'm easily overwhelmed by well lit rooms or cloudless days. I can't focus well. I'm constantly nauseous. A myriad of issues from my dumb kid days. Even recently I experienced metal fume fever from a galvanized forge burner I built and once again ignorant of the possible danger. For a week I was extremely irritable, massive headache, couldn't stay awake, mood swings, and no appetite(even if I tried Id just puke). CO is just as bad if slightly short lived but just as damaging. Also heat exhaustion guys. Probably just as important. In my army days I'd see guys drop like flys in a gas chamber from dehydration and over heating. Hey I love to try and just finish those last few heat and hammering's but if your dizzy or just drained then just stop. Ain't no man ever been a real man if he's dead. 

 

Before I knew better I once melted a couple of hundred kilos of lead on one session with an oxy propane rosebud, casting it into cylinders to be used to test the blow energy of a big hammer. Retrospectively i'm sure I was ill for weeks after from it, I wonder how much of it is still in my bone marrow ?!

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6 hours ago, Dan Hertzson said:

 

In a forced air forge you can avoid this problem by running your air source for a few minutes after you shut off the gas.

good advice! - I have not built a forced air forge, I am drawn by the simplicity of venturi burners. I got quite into learning about combustion when I first started, and built quite a few effective burners on the back of reading Mr Porters book on the subject. The hard inner shell of my forge holds some serious heat for a long time (hence pulling the burner after use)

 

My forge, I use for 99% of my work has the inside dimensions of about 10" dia, 10" high (it is a 'vertical' forge, with the burner entering at the bottom) - the front door is 4" x 4" , with a 2x2 pass through at the back. I built it over 10 years ago, and have pattern welded swords in it, and welded up some very big billets. Only built a bigger one recently because I had to do some small industrial test pieces, only used it a couple of times, it has a 1.5" 'Amal' venturi burner, and I guess it uses 3x the gas the small one does.

 

The daily user just has a single 1" venturi burner I built, uses a kilo (2.2lbs) of propane an hour on average, and if you wind it up can easily melt steel. Even with power hammers and presses I rarely long for a heat longer than 10" !

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4 hours ago, Alan Longmire said:

Plus it's not a good way to go.  It's heavier than air so fans don't disperse it, it can be explosive in the right concentrations, and if it's strong enough to knock you over, it can do that to anyone who tries to drag you to safety. 

 

I always hoped that putting up a few fans was going to help the situation.  My alarm went off once when it was directly above the forge. When I moved it to my anvil, never went off since. Since then I've tried to maximize the air flow in my little garage space by repairing the ridge vent, adding vents under the eves, set up a fan to act as an exhaust fan in an open window.  A secondary fan just to help move some air around, man door and both garage doors completely open.  Totally sucks as I do most of my work in the winter, but I also work alone and have that fear of dropping over dead and the stray cats getting to me.  

 

However, with all that, I've still been worried that I do expose myself to some CO.  Next step is to get a digital read out CO detector to monitor what levels are in the garage while I work.  Current CO detector is a cheapo $20 one. Also just before posting, I've read the appropriate/recommended height to place your detector is 5 feet from ground level. Also just having the detector is not enough, you must regularly test it!  I test mine as part of my pre-fire check list.  

 

I have that article somewhere and I should get to posting it up. 

 

 

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