Forges 101

[Mikey98118]

Everything Frosty wrote was right on. On top of that, you must remember that ceramic fiber, being insulative, gets very hot and stays that way as long as the equipment is running.  The higher the sustained temperature the faster the fiber shrinks. It is the process of shrinking that breaks the fiber down. BUT colloidal silica rigidizer (when applied and fired to the fiber) acts like millions of little welds where the fibers cross oneanother, trapping the boken fibers in position far longer, instead of accummulating as toxic dust particles.

[Idk]

So we're on a more formal introduction here,

My name is John, I'm in my 50's and live in central west Florida.

I come from a building and fabrication back ground mainly but have a gift for mechanical ability.

 

My journey to building a forge.

Got interested about 10 months ago in building a forge but needed to do ALOT of research not only on the aspect of building the forge itself but understanding the characteristics of refractories (elements involved) in general.

People who have no clue really can't begin to understand the science (mind boggling) behind such not to mention what's involved with building a proficient burner to top it off.

I know I didn't.

One thing lead to another and I ended up building a furnace to get my feet wet and understand what and how such refractories acted, pros & cons.

The furnace has an inner core of COL 30+ w/ an outer lay of CFB.

I also ended up mopping on 2 coats of ITC100 on the inner walls.

Lord does that stuff stink for the first few firings.

I built probably 6 different types of burners trying to figure out what performed best, IMO, and was the easiest to adjust and modify should it need to be modified.

This finally decided I liked the Mickey burner design the best and proceeded with that route. Below is the a 3/4" burner I originally built for the furnace but ended up building a SS 1" burner to replace it.

At 5psi, 10psi & finally 15psi.

This is where I also learned NOT to have the flare nozzle inside the chamber as well. The pic below was taken approximately 1 minute after removing it from the furnace.

The furnace exceed my expectation and proceeded with this process to my forge which I finally got around to building.

Still has a few finishing touches to go along with the burners to be built but, all in due time.

With this furnace building aspect in mind I wanted the forge to have a somewhat easily replaceable inner core for the most part so I took some structural cardboard tubing and made a form which would result in an inner core of 1-1/2" thick.

I rammed it up w/ COL 30+.

One of the topics which has been discussed here is hot spots / cold spots and I wanted a design which would eliminate these issue, or at least for the most part.

Another topic is the "Vortex" action within a chamber.

So with this in mind and seeing what the furnace had to offer I proceeded to construct the mold and weld into position the side by side burner holders to create a Vortex within the forge chamber. Hence the angle of placement.

Back to the core.

I let it sit in the mold for a few days and then air dried it for a few more days.

It was then slow cured in the kiln at the recommend rate of 104* for the specified time periods.

It was then wrapped in 1" CFB and stuffed into the forge body.

Final fine turning of the holder ports within the COL inner shell was ground out to the properly position the holders as desired. Shrinkage of the COL caused the holders to deviate from my final desired position. I should have used larger PVC piping to accommodate for this when I made my mold. Live and learn.

The burner holders were then welded in place and then I proceeded to ram up the inner back section of the chamber w/ COL after placing and saturating the CFB behind it w/ rigidizer.

After welding 4 bolts to the inner side of the forge door and making a port form it was rammed up in the same manner.

Why 3 burner holders???

The side by side holders as already mentioned are for a super heated vortex.

The sole burner hold will act 2 fold.

1) As an exhaust vent for cool down purposes after shut down, want to keep as much escaping heat out of the burner tubes.

2) As a burner holder for direct flame placement on material should the need arise.

I used 2" ID pipe for the holders so they can accommodate whatever size burner is desired.

When a holder isn't in use it'll be plugged off with either a COL formed plug or a rigidized CFB plug. 

The stand is vertically adjustable up to 47" high while the horizontal material support arm extends out to 22".

Until about 10 months ago I never welded in my life.

Purchased a Invertig machine, full steam ahead and 10 full days later along with being my own worse critic I figured out how to not only properly weld steel but weld aluminum as well.

Side note, I'm completely Blind in 1 eye and need 3.0's to see out the other.

I'd also like to say a BIG thank you to Mike for his time, patience and shared knowledge in all of our private conversations we've had over the past 10 months.

Your a good man Mike. (Thumbs Up)

 

 

[Frosty]

And a formal howdy do back John. Boy can I see the fabricator in your furnace and forge builds! Reminds me of mine, different but just as over built. 

I'm not familiar with the term "COL".

This is the first time I've seen a burner port dedicated as a chimney, I'll be interested to see how it works.

The only criticism I have regards the split fire brick. If you want a easily replaced floor use a high alumina kiln shelf, it'll last longer and is pretty immune to forge welding fluxes. Hard fire brick isn't and it's a serious heat sink requiring more fuel to get hot and keep hot.

I have to say that's a beautiful bead for a new to welding guy. Well done.

Frosty The Lucky.

[Idk]

Thanks Frosty.

Hope your doing well these days.

In reference to the welding,  All about determination and the desire to succeed.

"COL" should have been "KOL"= Kast-O-Lite refractory. My bad.

I was just using stuff I already had around the shop or tucked away.

Mike advised as well about the brick.  Noted.

I'll be needing to add additional rails, etc. for the fuel supply lines.

Going with copper tubing, regulator, etc. unless there's a better way. I'm all ears.

I'm leaning strongly on making some SS Mickey burners for it since the one I built for the furnace performs so well plus I like the idea of being able to fully open up the air intake manifold to expel the heat after shut down.

Don't like the idea of all that heat rising up and upon the actual fuel jet (Mig tip) itself even if it has been turned off.

One thing I didn't mention was the chamber dimensions, 13" x 7.5".

Still have some fine tuning to do with it, one step at a time.

Here's a couple of port plugs I formed and casted out of the KOL. Broke one of the plugs during deforming. My fault.

I'm wondering if a good dose of colloidal silicate would weld that suck back together before firing it?

[Mikey98118]

 

I just finished answering your mail, only to find that you had already posted your excellent forge project to this page

I am pleased to see it here because it showcases so many important ideas.

First, you took the trouble to solve the problem of whether to use one burner or two by adding a third burner port and two plugs. The answer to your question about repairing the plug would be to use furnace cement on the refractory shell to make the repairs. I would avoid using rigidizer in a sealed part, as there will be a steam explosion otherwise. 

Your use of a heavy inner layer of refractory is standard with homemade casting furnaces, and it works very well in them. Here on IFI we "experts" tend to go for thinner layers of refractory (1/2" thick) or only a thin seal coating, followed by a heat reflective layer over ceramic fiber insulation; we do this out of concern for fuel efficiency. Wayne has championed a much thicker hot layer of semi-insulating high-alumina refractory (Kast-O-lite 30).

Which is best? My first casting furnaces featured 2" thick layers of Kast-O-lite 30 without any secondary insulation at all; they cast through 8 hour days on a five gallon cylinder of propane, but some of that time they were turned down will casting wise going on. Forges can run turndown hilel hammering is going on High/low switches are recommended on forges to facilitate these savings.

So, which is best? If your forge is going to be exposed to other hands then its builder's go Wanes way. If you can keep it away from childrens and monkeys...go for the added efficiency. 

There is no right or wrong choice; just a personal one

Then, there is the question of whether or not it is wise to add a hinged door to a forge; only if one wishes to get full use of it! You went to much trouble to make a fine forge; BRAVO!!!

I agree that you still have some featured like copper gas lines to add to that heating machine of yours; I call them add-ons for good reason. You can catch yourbreath after the central project is done before addressing them--just like the rest of us

[Frosty]

Once you've isolated the rubber hose away from hot zones the chimney effect isn't so important, the mig contact tips and copper pipe can take up to medium red heat without effect and even when another burner is running in the same chamber the burners don't get near red heat. 

Frosty The Lucky.

[Mikey98118]

 

 

 

I think he means to use copper tubing for his gas lines. It is one of the things I wish to discuss here. I have considered your preference for copper tubing with doubt because heat gain in small burners buried deep into forge insulation could present a problem than with small burners; in that case, the colder the incoming fuel the better.

On the other hand, copper tubing is far safer than rubber gas hose around a forge's heat, and the same changes in cold incoming gas that copper tube allows with small burners become very welcome in large burners running in winter or from small propane cylinders.

Finally, there are regular fuel fittings that can be silver brazed onto the copper tube, making an end run around the problems which sometimes accompany press-fit types.

[Idk]

Correct in your assumption of copper tubing for fuel line.

As you stated, even a slight ambient temperature change in the fuel changes the action within the flame/chamber.

I was contemplating on trying to find some thermal sleeving to slip over the lines to block or reduce any temperature changes due to the heat from the forge. 

Haven’t went a digging for that yet but have my doubts of anything on the market that would be beneficial for such an idea.

Only other way I see to tackle this is to place a piece of ceramic fiber board between the forge and fuel lines. 

Ideas or alternatives????

[Mikey98118]

Easily found rubber tubing presents no fire danger when used for insulation on the outside of copper gas lines 

[Frosty]

I don't understand the problem, does copper tubing absorb enough heat to actually effect fuel density? I admit I only use copper as a fire safety issue but I've felt the tubing at the fittings on the burner and the higher I turn the psi cooler it gets.

If it's a significant issue you could wrap it with fiberglass tape used in fiber glassing. Or muffler tape which is phenolic resin impregnated fiberglass and resistant to temps around 600f.  or better.

Or arrange the fuel lines so they're not in a hot zone. The forge I mounted my first ribbon burners in doesn't need the copper line, I use them because they're already connected to the manifold and hose.

Frosty The Lucky.

[Idk]

This being my first forge and not knowing how much heat will be emitted from the forge exterior walls I’m just wanting to air on the the precausionary side of things.

I have a tendency to over think things sometimes, but when in bout.... 

[Frosty]

It's only sensible to be cautious breaking into a new craft, can't fault you for that at all, it's also common to overthink it. It might be a good idea to hook up with the local blacksmith organization, make a meeting or meet someone using a propane forge so you can get a first hand feel for the things. You'll learn more every hour with an experienced smith than days trying to figure it out on your own. 

Frosty The Lucky.

[Idk]

Well stated Frosty.

I just read my own last post and this dang IPhone made me sound illiterate. 

Gotta love spell correct. 

[S-Bird]

Hey all,

I built this propane forge from found items, as is my preferred project method, and was gifted a venturi burner. Is it just too big? Getting lots of licking flame, good roar, but no direction. The air intake is wide open on the burner, got a regulator on the tank, and, no dice.  I pulled the burner further out to decrease exhaust and then it backdrafts out the air vent of the burner.

Design guidance/suggestions please and thank you.

[Andrew Golabek]

It looks to me like the burner is running way too rich, (even outside the forge) and the mounting tube is too long, preventing adequate airflow to the burner, increasing the problem when mounted in the forge

Also be sure to rigidize the ceramic blanket if not done already

[Irondragon Forge ClayWorks]

Welcome to IFI. I suggest reading this thread to get the best out of the forum.

https://www.iforgeiron.com/topic/53873-read-this-first/

Your burner looks like mine a GACO MR-750 kiln burner. The replaceable orifice was too large in mine so I purchased a new one and drilled it to reduce fuel input.  Everyone said the burner was too large, but our forge is running well with it. A link to our build using that burner.

20 pound propane tank forge in progress - Gas Forges - I Forge Iron

[S-Bird]

On it. Thanks much.

 

[Frosty]

Right now it's WAY too rich to tune, the choke plate is open already. I agree with IDFC it needs a smaller dia. jet. If you can buy one you're golden even if it needs a little chasing out with a drill or torch tip files.

You might want to think about what Andrew said about the mount, you want the nozzle of the burner just inside the shell, not several inches back from the shell. 

Frosty The Lucky.

[Idk]

Well Gents, waiting on SS supplies to build my burners for the forge and just couldn’t resist so I stuck the very first 3/4” Mickey burner I ever built in it tonight and here she is.

Had to pull the thermocouple probe out at  2100* because I didn’t want it to end up in a puddle.

Can only imagine the temps it’ll hit with (2) 3/4” burners in it.

 

[Mikey98118]

You will need to keep them turned down somewhat, or your work will end up as a puddle on the forge's floor

[Cory Cooper]

Frosty needs to make a youtube video showing how to make a forge start to finish, body, layer the insulative materials, rigidizers, coatings, mount burners, show burner ports, burner designs, ect. many of us are simply wanting a good recipe to start with for our first one and I have a hard time learning from forums ie words but am finding most of the best info here so struggling to ingest it all and figured video format would help. im wanting to make a forge to do forge welding of noble metals for jewelry but dont want to mess it up.

[Mikey98118]

Most of us here on IFI aren't real big fans of Youtube.

[Mikey98118]

The easy way to find regulators and gas hose

Input "QCC-1 braided hose" on Amazon.com to bring up two pages of the best deals on adjustable regulators and braided stainless steel propane hose at one shot, instead of spending days trying to locate a good deal on these products.

[Mikey98118]

 

                                                                                              Let the burner fit the forge

A soft flame, with a primary and secondary envelope, doesn't need to be precisely positioned in order to impact away from the center of the forge floor to avoid burning the heating stock. Loads of guys find that to be a valuable contribution to forge building because forge ports that don't need to be canted on an angle can be mounted with large nuts, in the Larry Zoelerfashion.

I have spent years promoting the hottest hardest possible flames because they save fuel and burn clean; the downside of this is the need to build the forge as exactly as the burner. Most people don't want to work that hard; especially on their first forge.

What I consider to be a mediocre burner (producing secondary flame) can make a comfortable fit with a more relaxed forge build. where do we draw the line? Look at the exhaust gases; it should be expected that some of them are blue in this forge. Blue exhaust flames indicate fuel that is still burning. You can bet that such an exhaust is producing carbon monoxide; a small amount can be handled by a powered exhaust system or by using the forge outdoors. A lot of Co will present a health hazard whatever you do; don't go there.

[Mikey98118]

Being able to view exhaust flames comes very late in the burner and forge build, but not too late. Improving burner performance is usually just a matter of making small incremental changes that were left out in the original build, until the flame is hot enough to suit your forge.