Forges 101

[Buzzkill]

The bricks you have are not very good for a forge.  The light bricks which can be cut easily using a dull handsaw or hacksaw are much better for this application.  The bricks you have may be able to withstand the heat, but they will absorb and transfer heat at a significantly higher rate.  That means more time to heat the forge interior and more fuel used both for the initial heating of the forge and maintaining the desired heat.  

Over time you will burn far more fuel, which will cost a lot more than purchasing the lightweight insulating firebricks if you choose to use what you already have.

[Frosty]

Cam: not responding right away is nothing here, certainly no reason to apologize. Of course continued discussion may drift a . . . bit

The T burner is my design, the plans with directions are here. Well, DARN I thought they were, now I can't find them on the site. I'll have to send them as an attachment.

ARGHHH! I can't find them on my PC, they must've been lost in the crash and the page on Iforge seems broken as well as locked. 

Anybody out there have them saved? IIRC  "Illustrated T burner directions" 

Frosty The Lucky.

 

 

[Buzzkill]

Here you go:

T Burner Directions finished.pdf

 

[CamCarpenter]

1 minute ago, Buzzkill said:

Over time you will burn far more fuel, which will cost a lot more than purchasing the lightweight insulating firebricks if you choose to use what you already have.

Yes, I have heard this, and I read that one way around that was 2x 1" layers of Kaowool with a layer of castable refractory covering the Kaowool should decrease this effect. I've seen people use only propane tanks with 2" of Kaowool covered in a refractory cement and they say those forges work well. Is that a valid way to combat the issue? I have already spent a few hundred on materials haha. I'm hoping to get started sooner rather than later (and, as of the last time I checked, nowhere in my region stocks more than a couple of those fire bricks at a time that I can find, even if I did have the money)

I have the Kaowool and was going to buy a heavier duty refractory cement (I purchased some 2200°f Rutland from Amazon, but Frosty says that's too low) to cover it. I'm really trying to keep my costs down so I can buy steel next month instead of forge supplies.

Glad those instructions were found, thank you, Buzzkill! I've already downloaded them!

[Buzzkill]

The bricks you have are really only good for closing off the ends of the forge.

As you've seen we have an extensive forge section here.  Yes, using 2 layers of 1" thick 8 lb. density fiber blanket rated for 2300 degrees F or greater handles the insulating feature of a forge well.  However, those layers ideally will be rigidized and definitely should be sealed with something to prevent airborne fibers that can get into your lungs. 

A lot of us use Kastolite 30 to both seal the fiber blanket and to provide armor against mechanical damage in the forge as we move pieces in and out.   That material, or its equivalent, can handle the high heat and direct flame, it can take a fair amount of abuse, and it's somewhat insulating as well.

The Rutland 2200 degree stuff is really not suitable for a forge.  It is possible/likely that you will reach temperatures in excess of 2200 degrees F, and that material is made for joining pieces together, not to withstand direct flame impingement for extended periods of time.

Most of us are rather frugal people.  You can assume that if many of us are recommending the same materials then it is worth the expense.  If any of us had found a significantly less expensive way to construct a durable, effective, and efficient forge we would have already shared that information with the group.

Some of these materials seem pricey up front, but in the long run they pay for themselves.

[Another FrankenBurner]

Off the top of my head, I believe the insulated bricks are 8 ounces ish and the hard bricks are 4-8 lbs. 

The hard bricks are less expensive but don’t make for a good forge. They do work but you will spend more on fuel in short time then the cost of insulating bricks. 

I have both, I use the hard bricks as backers for torch work and other odd hot jobs like that.  I can take pictures of both of you like. The insulating bricks are porous with large bubbles. 

[Mikey98118]

On 5/22/2022 at 9:56 AM, Frosty said:

NARB came about for the same reason. The long established gun version was just crazy inefficient, no gas forge that has several FEET of dragon's breath is right. Sure they get steel HOT but look at all that propane burning OUTSIDE the forge! I have to pay for propane I want every joule I can get from it. It's that old ROE again.

Frosty The Lucky.

My own burner path wasn't very different from yours. My last job was in a metal artist big shop. I chose to work for him because I was already planning to slide back into ornament iron work, where I began; that was a bust. When it came to efficient tooling, Mr Artist was clueless; and that included his gas forge. The waste heat it put out was awful!

So, I started researching gas forges, and came across Ron Riel's Burner Pages. After building a gas forge with his burner heating it, I saw a trickle of blue flame emerging from the exhaust. Carbon monoxide exhaust flame? Ugh!

So, everything I learned about burners and gas forge design, was to stop waste heat, and Co pollution out of a future shop that never happened

[Goods]

Cam, if I understand right, you planned on using the hard bricks as the “body” of the forge, then line with KOA wool, Right? That use for the hard bricks is just fine, but sounds like more work than needed. If framed up right, it should be pretty stout. Just, make sure to use Mizzu(sp?), Kastolite30, or something similar over the KOA wool.

(Typically, we see new members trying to use the hard bricks as the insulation, so that is what everyone is just to…)

David

[CamCarpenter]

David,

Yes, I intended to use the bricks as the outer body of the forge, with Kaowool inside and a castable refractory (I keep hearing Kasto-lite 30 and that's what I'll look into getting) to cover the kaowool to keep fibres from getting into the air and consequently my lungs.

The issue is exactly the framing, I don't have a dead propane tank or anything to line with the kaowool, only the fire bricks and some angle iron. That's why I was thinking about using the bricks. They are what I have for fire-rated structural material. I know it's more work, but otherwise I have wood and I doubt that 2" of kaowool would keep that from catching fire haha

[Mikey98118]

1 hour ago, CamCarpenter said:

o buy a heavier duty refractory cement (I purchased some 2200°f Rutland

It wouldn't matter if it was 3000 F refractory cement. Forget all that and look for castable refractory. Refractory cement is used to hold refractory bricks together; none of it can stand up, when used as a flame face.

Plistex is cheap, heat reflective, and good to 3000F, which is why we keep advising its use.

[CamCarpenter]

That's the product I bought, they call it "Rutland Castable Refractory Cement" I thought all refractories would be cement products, so maybe that's where my misunderstanding came from. I will look into Plistex and Kasto-lite 30 before I buy, to make sure I get the right product for my forge.

Thanks, Mikey98118!

[Mikey98118]

I think they sell both products in small amount for iining forges, right here on IFI.

[Buzzkill]

44 minutes ago, CamCarpenter said:

The issue is exactly the framing, I don't have a dead propane tank or anything to line with the kaowool, only the fire bricks and some angle iron.

The outer shell can be almost anything.  I've used an empty refrigerant (freon) tank.  Those can often be picked up for free at an HVAC or automotive shop that deals with air conditioning. I used an empty disposable helium tank for inflating balloons.  Those tend to be about the same size as the refrigerant tanks.  I've used a section of thin sheet metal.  I've used part of a small grease drum (30 gallons I think) that I cut to the shape I wanted.  I never did this, but at one point I considered snapping together 2 or 3 sections of stove pipe for a shell. If you build a frame to hold the burner and/or doors in place the shell doesn't need to be structurally sturdy.  It's just there to help contain the fiber blanket and protect it from external damage. 

In extreme cases people have used chicken wire and rigidized fiber blanket to create a forge chamber.  That's not a recommendation - just an example. 

When you're starting out it's hard to know which things are ok to substitute and which things should not be compromised.  If you've done your research feel free to ask questions here and we'll let you know which ideas are viable and which ones should probably be abandoned.

[Frosty]

Thank you Buzz, I thought I'd uploaded an updated version but evidently not. There have been some recent changes.

#1, the 1/8" MPT brass fittings I specified in the directions aren't being made consistently now days so finding one with a through hole small enough to tap for the mig tip is getting difficult. One of the guys in our club either misunderstood or just winged it and used a 3/8" x 3/8" male brass fitting and uses a straight tap into the iron T.

The other main change is in construction. I now recommend leaving the iron T on the drill press and once it's tapped, install the brass fitting and chase and tap it for the mig tip in place. This keeps everything aligned as perfectly as reasonably possible.

If you decide to build a T burner let me know if you have questions.

Your fire brick isn't a total loss it's good for lining fireplaces, BBQs, fire pits, deck on a coal forge, etc. it just won't survive in a propane forge. Your proposed design on the other hand doesn't expose it to forge temperatures so it should serve as you drew it. 

However if we're talking about it as the forge shell it occurred to me that cement backer board would serve as well. It'll cut with a skill saw, a carbide blade will last a LOT longer but a monosteel blade will do for a while. You can score and snap it even. You've probably worked with it as a carpenter, yes?

A similar but simpler steel frame and you can build a cement board, hex forge without being limited by standard brick sizes and burdened by the weight. With 2" of kaowool and a castable flame face the backer board or your current stash of firebrick should never get very hot. 

Sorry, you bought refractory CEMENT it is not formulated for direct flame contact and will degrade quickly. It's "cement" intended to cement things together, fire bricks, etc. You'll need to check out the Iforge store refractory supplies for a small quantity of suitable castable refractory. Kastolite 30 is I believe on the cyber shelf. A 50lb. sack at the HVAC supply was around $80 when I bought one under our club's discount. 

I believe the store carries reasonable size packages of Plistex as well. 

The no weld forge produced at our club forge/burner build clinic is an excellent little forge and easy to build. Just the photo should be enough "plans" for someone who can build. IF it's suitably sized. There are 10 k-26 IFBs and a 1/2" T burner.

Emery cloth is sold in rolls. You can tear off a few inches and tape or maybe saw a slot in a piece of doweling wrap the emery cloth around the stick and use it in a hand drill to clean, shine or shape inside holes. A little creative use of tape or wire will form your "drum" sander into a cone and make short work of making a hole if K-26 IFB into a proper 1: 12 tapered burner nozzle. The stuff is easy to work you could carve it with a sharp piece of scrap metal or a pocket knife.

Which is best a gun (blown) or NA (naturally Aspirated) burner? Depends, which is better a Geo Metro or a 3/4 ton pickup? I don't have a dog in the fight on this question even though I came up with the T burner. Both have strong plusses and both have weaknesses so it depends on what you want and need.

A gun burner isn't nearly as effected by back pressure as a NA burner, the blower is forcing air down the mixing tube so if it isn't too blocked it's making a tuned flame. This is a big plus, the more you can close a furnace the longer the flame remains inside to transfer energy into the liner and the less area IR can radiate your energy to the outside world. 

Another upside is gun burners are easy to build, the tech data you have to bear in mind and required precision is minimal. They're easy to tune too.

Needing power is a downside but not horrible. AND you have to tune it every time you change heat output. It's not difficult but every time you turn the heat up or down you MUST adjust the fuel air ratio. 

If you go down the list of upside factors for gun burners you can slide them over to the downside of NA burners. They're trickier to build and a moderate degree of precision is required. Tuning them takes some effort and may be a challenge to trouble shoot. 

A real upside is once tuned they are tuned at any heat output, turn it up, turn it down the flame stays tuned. It's controlled with the Propane PSI at the regulator. The propane psi (primary pressure) is what powers a NA burner, that's where the name comes from Aspirate means to breath in or inhale Naturally Aspirated means it literally breaths without help. 

What makes a furnace HOT is how much properly balanced fuel air mix burns in it per second. NA or Gun, either type blows X amount of flammable mixture in the furnace per second where it burns and sheds thermal energy to the liner which radiates it back to do useful work for us. 

Okay, I've bounced back and forth between your post and my reply till my head is spinning, I have to call it for now.

When I was getting old enough to start school, my parents told me to get used to being called Jack. Being a pretty clueless 1st grader I introduced myself to the teacher as Jack Frost. She was so "delighted?" she told the class the story of Jack Frost at story time. NO WAY! I'm not the trickster, I'm one of the GOOD GUYS! I was pretty upset when I got home and my folks told me to go by Frosty instead. Frosty The Snowman is jolly, everybody loves him. I've gone by Frosty ever since though there are probably still people I went to school with that first year who think I'm Jack. 

The Lucky part of my signoff is because I was lucky on so many different counts to survive being hit by the tree. Support from the gang here went a long way towards keeping my Wife Deb sane through the ordeal and I've used "Frosty The Lucky." as my signoff here as a sign of thanks small though it may be.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

13 hours ago, CamCarpenter said:

Is there anywhere I can read about the Mikey burner?

Yes as a matter of fact he authored a book that is outstanding and is now available as a free down load in PDF form. I have a copy and Mikey is happy to share his knowledge with us.

Gas Burners for Forges, Furnaces and Kilns - M. Porter (2004) BBS.pdf

[ThomasPowers]

Last time I visited the scrapyard I started a count of "possible gas forge shells" gave up after I reached 3 dozen...

A light shell makes the forge easier to move.  A heavy shell can make it more stable in use.  I've built two propane forges at an ABANA affiliate gas forge building workshops; the first was a blown burner and using grain auger tubing---light; the second was using NA burners and used Oxy welding tank as the shell---heavy!  The light one is now on a shelf and I use the heavy one mounted on a gas grill cart, over 20 years now!  Just recently I replaced the burners with Frosty T burners and I've replaced the kaowool  liner multiple times.

[Mikey98118]

14 hours ago, Irondragon ForgeClay Works said:

Yes as a matter of fact he authored a book that is outstanding and is now available as a free down load in PDF form. I have a copy and Mikey is happy to share his knowledge with us.

Post book, I learned that the smaller a Mikey burner's gas tube is the shorter it can be and continue to contribute to complete primary flame combustion. First, Larry went from schedule #40 to schedule #80 1/8" pipe to simplify threading MIG tips into a burner's gas pipe, and found out that it made the gas tube so much more effective that short MIG tips would work properly in such a burner. I have continued in that vein and found that even smaller gas tubes can be even shorter.

Post book I learned that three air openings is the magic number no matter what size burner is being built.

These changes are important to keep in mind.

[CamCarpenter]

Frosty,

Thank you for the very in-depth response to my post! I appreciate the wealth of information and will try to keep questions minimal in posts for simplicity, haha.

I am very encouraged to hear that a gun burner is a good option. I lean toward it because it seems... safer? If I choose to go with a burner in the top of the forge, then having the blower keep running after the forge is off should prevent too much heat from going back up the tube. I also have a blower, so I want to use it. A dumb reason, I know, but if it's not a terrible idea, I kind of like it.

I have abandoned the hex forge for now. I want to make something simple and functional. I am looking to that photo you referenced a few posts ago for design notes. I am just trying to get a few details down before I commit any resources to the build. I've also been tremendously busy and have not had time for much more than reading some posts here and making one of my own these last few days, haha.

That's a well-seasoned name then! I'm sure glad I didn't keep my nickname from kindergarten. My mom asked me what I wanted to be called in school (meaning Cam or Cameron) and she tells me I answered "Sugar."  I'm glad yours has worked for you for a lifetime!

 

IronDragon ForgeClay Works, (that's a mouthful, haha (or a handful, I guess, typing)) thank you for the link to that book and thanks Mikey98118 for writing it! I have downloaded it and will look it over when I have some time. (which I do not, today)

ThomasPowers, do you think a heavier forge is better for everyone or does it just suit you? I know nothing about the practical side of blacksmithing, how important is the weight of your forge to its use? I had not considered that.

Mikey98118, thank you for the clarifying notes, I will refer back to those when I get to that section in the book. I appreciate being kept up to date!

 

Well, it looks like I will not be making a forge yet this week as I still have a bit more understanding to acquire before it makes sense to build! I will try to come up with a design based on what I've learned here and submit it later this week or early next week for feedback! I was reading through the post detailing optimal burner angle and I need to re-read that so I can figure out the best angle for my burner to come in to the forge... But that's for another post!

 

Cam

[ThomasPowers]

The heavier shell allows me to tack weld fixtures to it, it also resists the shell flexing during transport which is harder on rigid refractories.  My biggest plus is that I welded on some small sq tubing that a 3/8" sq stock L fits into making a third hand to hold longer pieces. In particular; by shear chance the stock "locks" in place. Rotate it slightly and it slips easily in and out, let it down and it won't move if bumped by student(s).

[CamCarpenter]

Well, I called over half a dozen local and regional HVAC suppliers this morning, none of them have any refrigerant tanks, not for free, not for sale. Not one had heard of any of the refractory products or even the existence of IFBs haha. I fear things are different here in Canada than the US. And the IFI store does "... not ship to Canada due to the high cost of shipping." (Quote Glenn) so I'll have to find somewhere local or online for my products.

I'm off to find a section on how to build a blower burner and read some of Mikey98118's book. I'm hoping to come up with a half-decent design by the end of the day today so I can start building it!

[Another FrankenBurner]

I started with a refrigerant cylinder because of Ron Reil’s mini forge page and I am an HVAC guy.  I think the forge would be awesome for a bladesmith but for general smithing, they end up a bit small in inner diameter and way too long for my liking. They could be cut shorter or walled off but you still end up with 3.5-4 inch inner diameter which yields a very narrow floor space. 
 

I do prefer the blanket, kast o lite, plistix way of building forges but now I make my own outer shells with sheet metal as I can make whatever I want.  I  like a lozenge shape because of the flat wider floor while still keeping internal volume lower.  I also like no longer/deeper than 8 inches.  With the refrigerant cylinder, I was always heating way more of the stock than I could work. 

[LeeJustice]

It is quite likely that an HVAC supplier is NOT going to let you have refrigerant tanks, full or empty, if you are not a licensed HVAC technician.  Try a scrapyard, yard/garage sale, ask people you know.

[Another FrankenBurner]

I don’t know about Canadian law so it may be different but you want to call around to hvac and appliance repair companies, not suppliers. The repair companies actually use the refrigerant and have the empties.  My company sells them for scrap otherwise.  Lots of them.

If you do get one, make sure it has been evacuated.  We evacuate them and drill a hole in the blow plug. 

[Frosty]

Brand names in Canada are often different than here and it can take a bit of research to find out. Heck product names change with location in The USA. Below is from their web site K is the brand available here and much of the US. The site lists Canada in their locations finder but doesn't show flags. A distributor search would be my next step but I'm doing this to show the products and information is there if you look in the right place. Conducting this kind of search is an acquired skill set and takes practice. Same for doing it on the telephone, my preferred technique. Anyway, the list below will give you more options. Were I looking I'd start with a web search for various product names but ONE per search. Search engines confuse too easily and getting 5 pages of hits for breakfast cereal ads isn't helpful.

Market leading brands JM®, K™ and TJM™ Insulating Firebricks (IFB) and SR-90 and SR-99 Firebricks

Frosty The Lucky.

 

[ThomasPowers]

How many "party" stores did you call about helium balloon tanks?

I've gotten so tired of folks not being able to find them themselves that I stock a few in my shop to give away: The pink ones are party balloon helium tanks, the white tanks are refrigerant IIRC---from a local mechanic that works on car air conditioner.  None cost more than scrap rate and most were free.