Need some highlights about forge 101 : Building an helium tank forge

[GuillaumeMarchand]

Hi all,

First of all, I'm writing from France, I'm not a native English writer, sorry for the errors, I'll do my best to be clear, don't hesitate to ask for explanations. 

 

I forge maybe 5 hours a month, mostly knives blades. My propane forge is made with an old propane tank (13kg, very common here). If I remember well, insulation is made with 75mm (around 3 inches ) of kaowool and JM28 bricks plus around 20mm (3/4") layer of hardbrick at the bottom. The burner is a 3/4" pipe with a 1mm mig nozzle.

This forge is in a distant workshop witch explains why I can't use it more.

Now I'd like to build a smaller portable forge to be able to forge at home and move it easily with my car if needed. I also noticed after a number of sessions of forging that this forge is maybe too large for most of my needs. Let's say 95% of the time. I think it leads to a waste of gas. 

I have an empty helium tank for inflating balloons (or whatever they put in these tanks). I have a small lathe so I can build a burner. A welder, a small milling machine etc... 

 

Here comes the question : 

I've seen in the Forge 101 topics some discussions about small forges built with these tanks. Most of the time, I understand the initial question but the huge amount of information in this topic, and the language some of you uses in the answers makes it difficult to me to find what I need. 

To be clearer : Can anybody lead me to a point of the discussion, or a specific topic, where I could find this answer : How do I dimension the burner for a such tank

I know it's always difficult to have a simple recipe for that.

Hope it's clear enough. Thanks you for your time

 

 

[Irondragon Forge ClayWorks]

Here is what I would do instead of trying to get the information from Forges 101, although this search will bring up some of the posts there. Use your favorite search engine and search like this...   helium tank forge site:iforgeiron.com     I tried that and it brought up a lot of threads and post's. Here is the first one to come up on Google.

Hope that helps.

I can't control the wind, all I can do is adjust my sails. ~ Semper Paratus

 

[Mikey98118]

That was good advice.

What you will need for a burner(s) is a single 1/2" size burner, or two 3/8" burners. Burner sizes go by pipe diameters, or a close equivalent of their inside diameters in tubing.

You will still use two 1" layers of ceramic fiber (Kaowool, etc.), but you need to add a 1/4" to 1/2" thick layer of 3000 F hard castable refractory as a flame face. Forget the brick floor. Use a high alumina kiln shelf from your local pottery supply store.

It would be pointless to try and discuss internal cubic area from your gas cylinder description. However, you will be okay following these instructions.

What size opening? Two openings or just one? In a knife makers forge, start out with a single opening. I like a 3" high by 4" wide opening on the forge size you are contemplating. Remember that, it is easier to add that second opening in the rear of the forge, if it is desired later on, then to enclose one to save fuel. It is also a lot easier to enlarge the front opening, then to shrink it later on, should you desire to.

[GuillaumeMarchand]

Thank you guys for the good advice and this helpful synthesis.

It sounds like a good project for the upcoming weekend.

[Mikey98118]

 

So, how did your "weekend" project turn out?

[GuillaumeMarchand]

You know what? Weekends are way too short. My belt grinder needed attention. All the wiring of the inverter to rebuild. 

I'm currently gathering the components. I have all the stainless sheets for the enclosure. I'll have the mortar for the internal coating of the fiber by the end of the week. 

Anyway, it might be more a "this summer project" than a "This weekend project" 

[Mikey98118]

Good!!! Most people are in such a hurry to build their first forge, that they have it half built before the realization sets in, that they didn't have a solid  plan. And now they wish they had done this, and they wish they hadn't done that...it's kind of sad.

You stated that you " have all the stainless sheets for the enclosure." I like that you chose stainless steel for your forge's enclosure (we usually just call that a "shell").

I hope that you are going to make that enclosure's shape worth the effort. As I recall, you were looking to build a min-forge (about two-gallon size). But, what shape? Box or tunnel forges are the simple choice, but oval shapes give you more usable area, which increases in importance as equipment. But, "D" shape forges share this same advantage with oval forges, and are a lot easier to build. Whacha think?

1 minute ago, Mikey98118 said:

which increases in importance as equipment.

Should read "...which increases in importance as equipment size shrinks."

[Mikey98118]

On 5/25/2023 at 4:55 AM, GuillaumeMarchand said:

How do I dimension the burner for a such tank

Given propane for your fuel, or LPG (mostly propane/butane mixtures), and given a burner that is a good enough design to make a neutral flame: Then a 3/4" pipe size burner will heat a properly constructed 350 cubic inch forge (five-gallon cylinder) up to welding temperature. For every reduction in pipe size, divide the cubic inches in half. For every increase in pipe size, multiply the cubic inches by two. A mini-forge is two-gallon equivalent, so one 1/2" burner, or two 1/4" burners will more than do the trick.      

    Nevertheless, I would advise you to use two 3/8" burners, and simply run them at lower fuel pressures. Naturally aspirated burners have long turn down ranges, so let them loaf along. So, why not choose 1/4" burners? Because 3/8 burners are a lot easier to construct; that's why!

[GuillaumeMarchand]

Hi Mickey,

My first idea was to build a tunnel forge, but I'm now thinking about building instead a D shaped forge (if I understand well, the straight line of the D is at the bottom) I will try to make a drawing of what I have in mind and show you. 

For the stainless steel, the point is that I've saved from the scrapyard some stainless steel parts which seemed perfect for a small forge, and it will now be a shame to mix it with iron. I'll have the most shiny forge of the next hammer inn ^^

For now, it's time to prepare the summer vacation (And you how a big deal it is here in France) so the next move might be in august now.

Thank you for your time and attention.

[Mikey98118]

Hi Guillaume,

Yes; the straight line of the "D" is at the forge's bottom. While my preference is for oval forges, I must confess that the "D" shape is way easier to construct, and "gives more bang for the buck." These forges also seem to be a natural fit with ribbon burners

  Tunnel forges are completely dated; they are the "well worn path," and as such they will continue for many years to come. But, eventually they will come to be laughed at; then, they will die out. Must pronouncements have exceptions, and mine is no different. Tunnel shaped forge/furnaces will stick around, and laugh back at the mockers

  Stainless steel is just a totally obvious choice; I notice ever more commercial builders are choosing it. I like that it is shiny, too. But where it stands out is twenty years down the road, when it still looks cool, and a mild steel forge is looking pretty beat up and burned out

2 hours ago, GuillaumeMarchand said:

For now, it's time to prepare the summer vacation (And you how a big deal it is here in France) so the next move might be in august now.

I know; the wife and her BFF keep getting on a plane and waiting for hours and hours to visit your country. Then. After a week they get on a plane, and wait for endless hours to come home; then wait for next year, to do it all over again! It's very strange; I think they need a hobby. They dragged me on a plane to do it once, and I discovered real french rolls...yum! People should Fly Air France whenever they can, is my advice. I don't like travel, but I totally liked Paris. Of course, it will ruin us for Yankee style (not so wonderful) Wonder bread...I better shut up, before I get the itch to travel again

 

[GuillaumeMarchand]

Yeah Ribbon burner. It seems to me to be the obvious way too. I'll add it to my drawings with rule of thumbs dimensions and I'm sure you'll give me good advices. 

About traveling to France, next year beginning of July (i've just attended this thing. I'm exhausted but it was fun) : https://fb.watch/lINFTJYtbq/ (hope this link will work for everybody)

It's a 3 hours road from Paris. And while you'll come with us to discuss ribbon burners, wootz or iron bloom, your wife would enjoy the beautiful countryside of Brittany or spend all your money in Paris. 

[Mikey98118]

I cannot give very much advice on ribbon burners: fortunately, there are others here who can, and will jump on the chance to.

Although they spend most short trips in Paris, Kathy and her BFF enjoy touring all of France, when they have time. Loved the photos.

[Frosty]

Show us some drawings and we'll make suggestions but we have to have some information to go on.

Frosty The Lucky.

[GuillaumeMarchand]

Here are some details about my initial design.

The design might seem curious for you but  top and bottom shell are already made (saved from scrap). The front and rear plates have to be made. Hopefully no welding needed. The internal insulation is made with kaowool and a JM26 soft-brick at the bottom. The soft-brick is protected by a 13mm (1/2in) thick high alumina hard-brick. The expected internal volume is around 2.6l (160 cubic inches). For more information, see the attached pdf file.

That being said, a D-shaped forge could be easily derivate from that, and after that, a ribbon burner. But you might already have some useful advice?

Thank you for your time. 

 

miniforge_overall.pdf

[GuillaumeMarchand]

And for the D-shaped forge, after a rapid sketch based on the previous design, the internal volume is of course much smaller : 1.6L / 100 cubic inches

It seems really small now. Not sure I'll continue with my round shells but rather build a new enclosure with correct dimensions

 

[Buzzkill]

I built a forge similar to  your last sketch with a ribbon burner.  The reality is that I sacrificed about a third of the floor space to install the ribbon burner in that orientation.  However, it did perform well and provided good even heat throughout the forge that way.

Since then I built a different forge with the ribbon burner mounted on the side.  It was more difficult to build and doesn't perform quite as well as the floor mounted burner in my opinion, but I prefer the extra floor space.

[Mikey98118]

And so it becomes time to consider modified "D" shapes, for ribbon burner forges. Nothing prevents us from making the top half of the forge wider

However, in your case, a ribbon burner probably is something of a waste of time. Small forges use small burners. The smaller the burner the closer it comes to a ribbon burner's efficiency. So, a ribbon burner in a 100 cubic inch "D" forge isn't going to work better than two 1/4" burners. But the ribbon burner will be a lot harder to build and mount correctly in this forge size.

Thanks for your input, Buzzkill; we need more of that kind of information from builders

[GuillaumeMarchand]

Ok so maybe, for such a small forge my first design would be ok?

Maybe I should think about having two holes for two burners and put the thermal probe in the rear wall?

 

[Mikey98118]

Unless you are using it for tempering, I foresee little use for a thermal probe. For every other task, judging temperature by forge color should suffice. Any heat treating and tempering that requires close temperature control is best done in an electric kiln. Any oven that only needs to accommodate 100 cubic inches can be run with minor electrical use, and built for little coin, except for the control circuit itself.

[GuillaumeMarchand]

The point is that I'm color blind, so I'm not really confident with my ability to judge temperature from colors.

I am sure that the probe will not be installed very often on the forge, but one day i'll need it. 

For example, during the hammer inn I talked before, under the sun, colors were useless. 

[Glenn]

Get a color chart of the color temperatures and compare to what you see on the chart.

[GuillaumeMarchand]

Well, that's not how color blindness works unfortunately. My eyes are not sensitive enough to the red color to see the difference between two different orange. They might look identical for me and obviously different for you. Even with a color chart.

 

[Mikey98118]

Agreed; you need an instrument, to cover this.

[Candidquality]

Are you looking at a type s(platinum/rhodium) probe?  Ran across a few on amazon for around $20 sealed, so no worries about the corrosive, just didn't get far enough to find a plug and play reader for it yet. 

Really don't want to watch voltages, compare to a chart and add in the additional drop for the joint change...

Thermocouple Type S can be used in oxidising or inert atmospheres continuously at temperatures up to 1600°C and for brief periods up to 1700°C. For high temperature work, insulators and sheaths made from high purity recrystallised alumina are used.

Some of the ones I found on the cheap only say up to 1300, so are not alumina sheathed. 

 

Mine was for curiosity sake, so haven't persued with much vigor yet.

 

Outside the forge, a standard infra-red handheld no touch model should get you close enough for anything but welding.  Just a quick check as you swing around to your anvil. Might even be able to mount one permanently pointed at your anvil with a laser pointer showing where to get a reading.  Not sure how long they last in continuous mode, but worth checking out.  

 

Btw if anyone is interested in checking their own color blindness online, it is called a Farnsworth test. 

It affects 1 in 12 men to some degree.  Women about 1 in 250 or so.  

And do understand you do not have a calibrated monitor, etc. So this is a reference only test. Best performed in a doctors office with a calibrated tile set, but I say they are about 90% so definitly points you in the right direction.   

Quick search for an online test is here:

https://www.colorblindnesstest.org/farnsworth-munsell-100-hue-test/

Gives you a visual showing where the issue lies, and a number, higher being worse, takes all of about 30 seconds on a mobile device.  I actually require this type of test for any inspection position who is going to be judging color as part of their job.  

They also have a half dozen other quick fun little tests if you are interested.  

 

There used to be a better version but it rins on shockwave which is no longer supported.  You might be able to find a better version on a free app.  

 

There are also glasses which can correct for some if these issues once known. Expensive like any medical device, but can be useful. 

 

 

[Mike BR]

A probe for the forge may not be the right answer.  Heat transfer is generally proportional to temperature difference, which means it takes a long time for your work to reach the same temperature as the inside of the forge.  My guess is that you want the forge to be at least a couple hundred degrees hotter than you want your work, if you're looking for reasonable heat times (and amounts of oxidation/scale).  Worse, if you can't tell how hot the stock is, you won't know whether you need to leave it in the forge for 5 minutes, 15 minutes, or 45 minutes.   

I'd look at an IR thermometer so you can directly check your stock temperature -- Amazon has ones that read up to 1500C for less than 100 USD.  There are also iPhone apps that are supposed to read heat color.  One of those might be worth a try, since you're only looking for an artificial eyeball, so to speak, and not necessarily a precise temperature measurement.